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Behavioral Ecology Exam #3
Terms in this set (180)
Competition among members of one sex for the opportunity to mate with members of the other sex
Theoretical approach to psychology that attempts to explain useful mental and psychological traits, such as memory and perception
Intersexual Selection? Who usually chooses? What helps choose?
Selection by members of one sex of which members of the other sex with whome to mate ("female choice", "mate choice,").
What type of selection best explains the evolution of certain traits? Can both types favor the same raits? Example of traits that come about through intra-sexual selection?
Intra-sexual selection explains better, as traits that develop through intersexual selection are tougher to distinguish. Yes. Example: Long tailed widowbird. - long tail is attractive to females but impractical.
Who do females often preferentially mate with? Why does intersexual selection get more attention than intrasexual selection?
Males with strange exaggerated traits. Essentially showy traits. Intersexual selection results in the evolution of strange traits, leading to the question, "What are females thinking?". It is more complicated. Females often show preference for show males with bright colors and enlarged ornamented traits, like peacock tails. They show preference for vocalizations. These traits may not be good for survival and may not be practical.
Parrot example? WHat does this lead to?
parrots females often mate with males with showy colors, enlarged ornamented traits, coloration, vocalization, other behavior. Like intrasexual selection, leads to evolution of sexual dimporphism.
Can traits favored by mate choice compromise a male's viability? Example?
Vocalizations in tungara frogs, they make calls to attract females, a whirr and a chuck to them. The females really like the chucks, the problem is they are preyed upon bats, who are really good at picking up the chucks. You can whirr all you want, wont get many females, chuck really gets the females going, but chuck gets the bats too.
What is the relationship between intersexual selection and speciation? Example?
- leads to trait divergence among isolated populations, which plays a role in reproductive isolation, ultimately speciation. Noles example with a changing dulap color which separates populations.
What is the direct benefit explanation of female preferences? Examples of direct benefits? How are choices made? Example?
Providing food, nest sites, protection from predators, offspring care - males provide some type of direct benefit to female, whether it be survival or reproduction. She chooses males based on the quality of that service. Female hangingflies prefer males who provide larger prey during mating - Females wont let males mate with them for very long if food item is small, the larger the food item the longer the mating. The duration of copulation correlates linearly with sperm transger, at about 20 minute mark that's maximum sperm transfer, no point in mating any longer, Therefore there is a standard prey size that you want that alows this 20 minute copulation.Lady beetle is best gift for copulation. Male catches fly and uses it as bait for female, advertising it by fanning its wings and releasing perfume from the abdomen.
What are the 2 problems with the direct benefit model?
1. Only works if the male provides a direct benefit, which is not the majority of cases, the males usually just mate and go away.
2. Direct benefits cannot explain the evolution of showy male characteristics. (maybe females choose showy males because they'll be eaten first by predators, but not sound logic, b/c females male children will also be subjected to this fate.)
Andean cock of the rock hypothesis example?
There is a hypothesis that mating carries risk, and males are more vulnerable. By a female choosing something showy, she is the less vulnerable one if a predator shows up while they are mating. But then her sons end up with the color and are more vulnerable, so this idea doesn't work.
Marginal Value Theorem?
Maximize energy intake; often tells us how long animals stay in a patch before giving up and going to another one. Maximizing a different currency like efficiency may result in staying in the patch longer, e.g., when bees try to maximize the amount that they carry to save the energy of moving back and forth
What are the theories for the evolution of mate choice when the female receives no benefits?
Good genes, runaway sexual selection, sensory exploitation.
What is the good genes theory? What is it driven by? What type of benefit is it?
Theory for evolution of mate choice when the female receives no direct benefits. The male is always donating genes for the offspring, and females want as good of genes as possible for the offspring. Therefore the genetic preferences lead them to select certain males, these genes are then passed on. Female choice. (indirect benefit)
How do females determine if genes are good for good gene theory (three categories, one has two supporting theories)? What does this preference potentially explain?
Leads to the question of how you tell that the genes are good. Females evolve a preference for male traits associated with high fitness (viability) in their offspring:
Physical characterstics - ex large body size, more dominant.
Physical displays - male call, frog call. Quality of the call. THe duration of the call, the longer the call, the more fit the male.
Elaborate ornamaentation - females sometimes pick traits that are negative to survival
handicap principile- energy to produce, to carry it around. Fittest are those who are able to carry it around and survive. Also parasite load theory, ornamentation is an indicator of helath (shows that trait may not be genetic, as healthy fish broduce bright colors, even though all are capable)..
It is a potential explanation for the energetic courtship displays. The energy or fitness required for the moves themselves can indicate the physical quality of a mate.
Female stickleback example?
Prefer males with red bellies. There is a direct negative correlation between parasite infection and how red they are. Increased redness means increased health and is an indicator of good genes. Red-bellies means that the males are well nourished and have good immune systems (from carotenoids). The offspring are resistant to parasites. This is an indirect benefit that supports the Good Genes hypothesis.
Lek exmaple? What does it support?
A bunch of males come together in the same spot and go through their displays. Frogs congregate in large numbers and start calling at ponds, and females come to the congregations and choose. The most dominant males end up in the middle. Females all choose the same males, and pick the ones with the best genes. Only a handful of the group does all the mating. Supports the Good Genes Theory.
Female moths example?
Iyengar and Eisner looked at offspring of mating with males that females choose. When they artificially picked the other male, the offspring do worse. Following the good gene theory, the female should choose the males that give their offspring better genes. With the male they chose, the offspring had higher body mass, fewer eggs lost, and increased mating success. The offspring of the preferred mates doing better is indicative of the good genes model.
What is runaway sexual selection? What does it explain? What drives it? What does it say about male value? What are the end results?
Theory for evolution of mate choice when the female receives no direct benefits - specifically, genetic-based female preference for extreme male trait. Driven by female choice for genetically based traits , pushes selection, making males evolve increasingly elaborate traits like bright colors that are impractical for survival. Is an indirect benefit model: females prefer males with extreme expressions of these traits (these traits only benefit the males when they are at their extreme). This indirectly benefits the female or her offspring. At the end, sons will be attractive and have more offspring. Proposed by RA fisher for rapid development of specific physical traits in male animals, eventually leads to male offspring are more likely to possess that physical trait, whereas female offspring are more likely to possess a preference for that trait in males. Over a longer time, the species may be characterized by extreme sexual dimorphism.
There must be a genetic-based male trait beneficial at its extremes. Then, evolution of genetic-based female preference for the extreme male trait occurs. The traits become correlated in offspring, and evolution of the male trait races forward due to correlated selection. Future generations will pass on the alleles for the trait (expressed in males) and the alleles for the trait preference (expressed in females). This can lead to fixation of the trait and preference through positive frequency-dependent selection. The male trait passes the optimal, and only stops when the detrimental value in terms of survival balances the increased mating success. End up with showy traits that initially correlated with fitness but no longer do. They are only maintained because of genetically based female preference in population.
What is the sexy son hypothesis?
Fisherian model. Part of runaway sexual selection. In the end, the indirect benefit to female is that sons are sexy. Sons will be attractive and have more offspring, so she'll have more grandchildren.
A gathering spot in which males congregate to show off their skills and colors
-Males in the center is most dominant, as being in the center makes you the least vulnerable to predators so you must be most fit, whereas subordinate males wait on edges
-Females tend to choose the same males over and over because they're the most fit
-If females tend to choose same dominant males over and over again why do all males congregate in the same area if they know most males do not get chosen to mate
Sensory exploitation? Frog example?
Female Choice Model
-Females may be more sensitive to certain sensory factors, they have an INTRINSIC preference for particular sensory stimuli. Males may evolve traits to exploit that preference. Males exploiting preexisting biases. Female's preference precedes the evolution of the preferred male trait. Male frog calls and female hearing sensitivity are exactly paired up
Swordtail exploitation example? Significance?
Sister species - males do not have sword (no reason for females to prefer swords)
artificially glued swords onto males, females loved swords
shows preexisting bias
--• Indicates that female preference arose in the past
Lizard exploitation example?
visual system keyed in on motion for detecting prey
o Males have displays that are jerky, motion based things like pushups
o Key into pre-existing sensitivities for prey and get noticed
o Exploiting biases that are already there
Finches exploitation example?
o finches - some have crests, others do not
added crests to non-crested birds
females prefer crests preexisting bias
Male ornaments exploitation example?
o male ornaments often co-opt sensory bias used in feeding/hunting
swordfish characin: "fishing lures" attract females
females diet co-varies with male morphology across populations (more ant-like vs. beetle-like)
females habituated on eating ants attracted more to "ant" lures
Sexual conflict leads to? What does that do? What can sexual selection lead to (in terms of fitness between sexes? 4 aspects of sexual conflict?
o Sexual selection/conflict can lead to antagonistic coevolution. Antagonistic coevolution- Selection favors trains in one sex that reduce the fitness of the other sex evolutionary arms race b/w the sexes
Evolutionary arms race between sexes
What are the mating decisions?
When and with who? - they may want to mate, but do you?
MATING DECISIONS Antagonistic coevolution at the level of gametes: Abalone? Drosophila example?
Example in terms of sexual conflict: mating decisions
• selection on sperm - increased speed at penetrating eggs
• selection on eggs - increases resistance, to prevent polyspermy which leads to aborted embryo
Proteins that make Drosophila sperm resistant to dislodging by other males are toxic to females
Antagonistic coeveolution at the level of individuals. Bedbug? Duck example? Chase away selection?
Example of sexual conflict: mating decisions
-Copulations leads to injury or death
-Ex. Traumatic insemination (bedbugs)
-Ex. Males drowning female ducks when mating
-Ex. "chase-away sexual selection" - select for female traits/preferences that confer resistance to males inducements to mate. Water Striders: males have evolved flattened abdomens that facilitate forced copulation, however, females have evolved spines to obstruct male's grip. May explain why female preference for a male trait is sometimes greatest in species where the trait hasn't yet evolved Example of sexual conflict: mating decisions.
Example of antagonistic coeovultion at the individual level, sexual confilct: mating decisions.
-This may result in increase female fitness (insubordinate male that cares for female)
-Sometimes decreases females fitness
-Ex. Inferior males get as close to dominant males with great call, so the females come to male with good call, but some of them will run into inferior males first and he will get to mate
antagonistic coevolution at the individual level (sexual conflict in mating decisions): mating decisions prey item - good/large = longer mating
• at some point males have transferred all sperm - if they can finish mating before she finishes eating they may steal prey item and give it to someone else
Example of antagoninstic coevolution. males are involuntary food items
• male praying mantid are very wary around hungry females - avoid being eaten at all costs
• try to jump from far away and mate without being eaten
NOT an example of angatgonistic cooevolution
males increase their own fitness by being eaten
• Australian red-back spiders - put themselves in front of female's mouth after mating - males that allow themselves to be cannibalized mate longer and produce more offspring
What explains our exceptionally good depth perception?
Theory - being in trees, depth perception. There is a theory that has gained a lot of support - being able to find snakes in our environment. Why is there an elevated fear of snakes? If you see a lion you can get away and feel safe. Snakes are scary because all of a sudden they are there. Mortality is significant from snakes
What explains why humans are really smart?
Brain size and intelligence are not coordinated. Driven by sexual selection, theres another theory that if you look at human intelligence that we're too smart. We're far smarter than anyone would need to be to survive in nature. Some theories tie that to mate choice, picking quality mates could have been a really big factor, contingent on brain development.
Significance of the hanging fly clip? Lars bird? Wagapan china bird? Bower bird? Golden bower bird? Little black and white birds?
hanging flies in north America, flies are there favorite food, she allows the male to mate, it takes 20 minutes, he wants to keep it and a wrestling match begins, he wins, another female is interested even with a second-hand meal. Bird - calls and dances, superb mimic, cleans area starts display, elaborate feathers, males have no parental duties - devote all time and energy to mating displays, females travel from one territory to another assessing males. China bird - elaborate colors, waddles on throat exposed when female approaches. Bower bird- When he puts the blue feather down, the bird doesn't like it at all. The male is responsible for building the showcase, females tour and assess them, a more dominant male appears and he steals the treasures, he's not only a thief, he vandalizes the hut the other bird made, he embellishes the walls with blue paste to impress the female. The golden bower bird - he has got another of the white flower, a female has a critical look. Different environments different bowers, different treasures, different actions. Little black and white birds: fly backwards and dance, 90% of daylight hours for 9 months, snap wings together, Other birds: he waves his butt in front of her, female will only respond if both males act together. Why should the help each other? The other in the apprentice who is learning the form
Sexual conclict-multiple matings?
o Once partners are paired - will the have other partners
o Males may guard females
o Males strongly negatively impacted females mating again
o For females, sometimes negatively impacted, sometimes not
sexual conflict -Parental care determination? The second sex? External fetilization? Internal fertilization? What is the cost of care?
• There are different theories of why males care or why females care of why both
• The second sex - do I care for the offspring or leave the other with them?
• External fertilization - females are the last one in possession of fertilized eggs, females make the second decision. Or fish, females will deposit eggs and males will fertilize them, this leads to male parenting
• The cost of care is loss of future offspring, the sex that has the higher reproductive potential ...
• Internal fertilization - more often males making second decision
sexual conflict-Infanticide? Lion example?
o Males killing young offspring, not in the best interest of the females, common in lions and in other species
o In lions, it account for 25% of lion cub death in the first year of life
o 10% of lion mortality overall
o Females hunt and the males eat first, males are LAZY, if they kill the offspring the females will immediately begin to cycle
o If territory is taken over, only about 30% will survive.
Why don't females prevent this: sexual dimorphism body size limits females ability to protect young
-If cubs are almost old enough to take care of themselves mothers will attempt to raise offspring in separate den away from the pride
Species' typical pattern of mate-finding, reproduction and parental care
-Generally both parents care for offspring
Polygyny? 4 basic types?
-1 male, multiple females: usually just female parental care
-Four Basic types: Female Defense, Resource Defense, Scramble Competition, Lek
-1 female, multiple males: usually just male parental care
-Male or female, different from multiple mates outside of monogamy because its not as aggressive and actually pretty rare in nature (multiple females and males)
Female defense polygyny? Red deer, elephant seals, spear nosed bat, siphonoecetine?
-Females in breeding condition aggregate, cluster for reasons like hunting, to defend feeding territories, they are not there to mat Males may then be able to monopolize a group of females. For example, male red deer or elephant seals. Males often fight with each other to control the females.
-Ex. Greater Spear-Nosed Bat: Natural Grouping
-Females cluster together in a roost, large male guards a roosting cluster of smaller females
-Ex. Siphonoecetine: Unnatural Grouping
-Male enforces it by building protective cases out of gravel and shells and collects females and glues them in their houses to their shell, this is a constant protection of females
-Benefits of being in a female group outweigh any benefit of monogamy
Resource defense polygyny? African Cichlid example?
-Females in breeding condition need access to some scarce resource. Males may be able to monopolize this resource. Females must allow the male to mate with them to have access to the resource. For example, wool carder bees. Males often fight with each other to control the resource.
-Ex. African Cichlid
-Extreme sexual dimorphism: males are 13x larger in body size than females
-Females need shells to lay their eggs in
-Males gather all the shells, so that when a female needs to mate, she has to go to where he keeps all the shells
Why don't females choose monogamy and pair up with a lonely male?
• Polygynous system there are a lot of lonely males, females have a choice for a polygamous pairing or a monogamous pairing.
• In general, female defense polygamy is possible because females cluster for their own reasons - hunting, to defend feeding territories, they are not there to mate, cooperative offspring care (see that in lions where females nurse offspring who are not their own)
• Benefits of being in a female group outweigh any benefits of monogamy
Polygyny threshold model?
Polygyny threshold model - predicts that female will accept role of 2nd mate (polygyny) when superior resources on males territory mean that female would do better there than as 1st mate on a poor territory
Function of difference in territory quality
polygny threshold model - Pied flycatcher example?
Pied flycatcher - refutes PTM in that PTM predicts higher female fitness in polygynous pairings vs. monogamous pairings, but this is not always the case.
Each female mated to a polygynous male has lower reproductive success than a monogamous female
Male's reproductive success is higher than that of a monogamous male
Try to deceive females into polygyny
Some males establish 2 territories don't provide help to female on second territory so the female has low reproductive success
Female is deceived into making a decision that's poor for her fitness think she's getting a monogamous male
If there is not a big difference between the 2 habitats, the females will go to the second one and have it all to themselves. But if there's a big difference in quality between the two the females will all pile into the better habitat to have a higher fitness
Decisions are determined based on the gap between the two curves
Runaway selection example - male birds with longer tails?
Males with longer tails have higher fitness.
Females develop preference for males with long tails spreads through population
Correlated in offspring with long tails
Females who prefer the genes for long tails will carry the gene for long tails in their offspring
Males with long tails are getting selected for twice the trait races forward
• Once for fitness
• Once because females like them better
Now males with long tails have no benefit for survival now fitness benefit is in the middle but females still like males with long tails so it continues to push the trait forward until it pushes it past optimal
Can lead to extinction
Offspring of most vs. least attractive males do not differ in viability or fecundity
But sons of attractive fathers have greatest mating success
Scramble competition polygyny? What is it? Examples? Explosive breeding assemblage? WIdely spaced females (key to this)?
o Mad scramble for position to fertilize eggs, usually associated with external fertilization.
Ex: frogs, horseshoe crabs
o Explosive breeding assemblage
Female available for short periods, spatially aggregated
As females come up the males rush up and fight to mate with that female
if o scramble competition Females widely space or hard to find
Males compete to locate females as fast as possible, mate as fast as possible and with as many females as possible
Key widely spaced females are unreceptive after mating
o Males display for females in predictable location (lek) and females come to the site to choose mates
o May defend small postage stamp territory
o Males provide no resources except gametes
o They do not help in raising young
o Females choose males on the basis of disappearance and displays
o Highly skewed mating success in normal in lekking system
A few males obtain the matings
o By mating with the best possible male, females obtain the best available genes for their offspring
Ex: Black Grouse and Sage Grouse lekking systems: <10% of males obtain 70-80% of the copulations
Lek paradox? why do males gather, what are the hypothesis for the evolution of lekking? Examples of both?
Hypotheses for evolution of lekking
"hot-spots" hypothesis males gather at sire where they are likely to encounter females
lek sites are important geographically sites where females are likely to be
o lekking bees, wasp and insects often use same locations for leks
o territories of flycatches, manakins and hummingbirds also often overlap
o gather along streams or ridgelines that act as highways for female movement
"hot-shots" hypothesis subordinate males cluster around more attractive males "hot-shots" on order to be seen by or to intercept females attracted to these males
o great snipe removing central dominant bird caused neighbors to leave territories
o removal of subordinates resulted in their territories being refilled
female preference hypothesis females prefer to choose from groups of males because comparisons are easier to make
• larger numbers of males as they start to congregate attracts females
• ex: ruffs female ruffs prefer groups of at least 5 males and visit such groups more often
• Mating system in which one male and one female form a pair bond and mate with only each other during a given breeding season
• Or prolonged, essentially exclusive bond maintained with a member of the opposite sex
• Or put another way neither sex is able to monopolize more than one member of the opposite sex
• There is some hanky-panky but most offspring are made from primary bond pair
o The bond is very noticeable a little extra pair copulation is just side activity
Why do monoggamous males exist?
• Evolutionary puzzle: monogamous males
o Low investment parents the parents donating the least why are they monogamous (male or female but generally male)
o Males generally provide little resources to young and have an abundance of sperm with which they could fertilize several females. Hence, males would be expected to benefit from seeking extra mates (see previous lecture):
Why don't they?
Monogamy is an armed compromise rather than a happy collaboration.
Monogamy - female/resource distribution explanation?
o Female/resource distribution ecology of the species may not permit males to have more than one partner
Females are too spread out and too hard to have more than one mate may lower fitness to try
Monogamy - mate guarding hypothesis?
Monogamy may be the best choice if female would mate again if male deserted her and if the 2nd male would fertilize eggs
Male spends time with mate to ensure fertilization
Mate guarding should pay of when females:
Are scarce and hard to find
Remain perceptive after mating
Ex: clown shrimp closely guard females for weeks surrounding the mating season
Male suicide as mate-guarding (ultimate sacrifice)
Honeybee drones mate only once and die after mating
The drone's genitalia break off during mating to form a mating plug
This doesn't stop the queen from mating with others but does prevent sperm from leaking out
Costs and benefits of male sacrifice
More likely to see male sacrifice idea if
• females are mating with many males
o if females mate with only one should never see this
• sex ratio is highly male-biased there are a lot of males in the population
Monogamy - mate assstance hypothesis?
males stays with partner because male assistance increases offspring survival
increase survival of young outweighs extra young gained by seeking extra mate
What level of care benefit is required? male care must be key or essential to offspring survival not just beneficial
The survival of offspring must outweigh the number of offspring that the male could have if he was not giving care and was not monogamous
Ex: hamsters males help deliver the offspring (like midwives)
Really important without them they don't make it
Monogamy- Female enforced monogamy?
Females act to limit males additional matings
Males would by better off being polygamous but females act to limit that
Key: females must care of males mate again
• Not love
• those mating must negatively impact female fitness
ex: burying beetles males bury a carcass and release pheromones to attract females females lay eggs inside carcass and offspring feed there
the carcass can support more than one female's worth of eggs but not enough to support 2
male fitness goes up if he has another mating can have more babies but negatively impacts the first female because some of her eggs may die
once the males attract the first female and lay eggs and the male tries to go up signal again but the female will knock him off
experiments: tether female to ground so she can't knock him off this works
• duration of pheromone emission:
o when females are untethered they have an emission duration of 0 minutes
o when females are tethered have males signaling for a long time
ex: razor bills
Males might benefit from additional partners but females may prevent them from doing so to monopolize their parental assistance
Razorbills nest in aggregations on cliffs
Females attack males that show an interest in a neighboring female
Is monogamy in mammals rare? Why? What results in lifelong monogmay? Example? What are the three types of monogamy?
• Monogamy in mammals very rare
o The mammalian traits of pregnancy and milk production by females makes parental investment and care of offspring female biased. This should select for polygyny.
Most mammals indeed are, but monogamy occurs in a few rare cases
3-5% of mammals are monogamous
• lifelong monogamy is even more rare ex: Prairie voles
o huge release of vasopressin following mating impacts care bonding
o have more vasopressin receptors
• sequential social monogamy monogamous for season or periods of season but if that mate dies switches
• social monogamy = pair bond
• genetic monogamy all the offspring only have one male and one female parent
What two hypothesis explain mate assistance with respect to mammal male parenting? Example? Where does monogamy in mammals come from?
o mate assistance hypothesis may apply to monogamous mammal species, as they often also demonstrate maale parental care
ex: primates, humans
few male mammals exhibit parental care, most of those are monogamous
infanticide reduction is the best benefitfor male parental investment and protection, male care increases offspring numbers
Monogamy in mammals may be connected with mate guarding
Social monogamy is correlates with situations in which females live apart in small territories ex: possums
It doesn't occur with large congregation of females
Polygynous males would have to leave a female while looking for other females.
When they do this they leave themselves open to cuckoldry lowers fitness
Monogamy in birds? Who are the offspring born two? Why is it more common with birds?
• Monogamy in birds Very common
o Genetic and social monogamy
Almost all offspring born of primary partners
o Why more common?
Chicks are needy incubation
Mate assistance hypothesis: male birds, unlike male mammals, can feed young as well as females
A key prediction is that male parental care should increase the number of surviving young. This can be readily tested.
o Birds can fly and are mobile females are highly mobile and able to move around a lot
Can mate with others so males want to guard mates
Spotless starling example?
: male parental care in birds increases the number of surviving young
Negative correlation between the amount of male testosterone and offspring survival
In the spotless starling, males whose testosterone levels were reduced by the anti-androgen cyproterone acetate (CA) provided more food for their broods and had the highest fledging rate per brood. Males given extra testosterone (T) provided less food and had the lowest fledging rate. Untreated controls were intermediate with respect to both feeding and fledging rates.
Shows male care is doing a lot making a difference
Starling bird monogamy example?
o Ex: starlings looked at males who incubated eggs vs. males who did not
Babies with biparental care stayed significantly warmer and more hatched
Bird monogamy tree swallow example?
In Tree Swallows polygynous males with multiple female partners father fewer surviving young (0.8 fledglings) than monogamous males (3.0 fledglings).
MAH: More offspring of polygynous males die because male can't help both females.
MGH: Females of polygynous males also mate with other males because male cannot guard two females effectively.
Monogamy best for both male and female Tree Swallows.
Facilitative monogamy? Obligate monogam?
• facilitative monogamy the male doesn't have another good option
o ex: females spread out males can't find another mate
o doesn't always lead to parental care - males provide little care to offspring
• obligate monogamy mate guarding
o good for offspring, parental care - male give care and are helpful bc offpsring cannot be raised by female alone.
What are EPCs? Difference between social and genetic monogamy?
extra pair copulation (the other part of monogamy)
• Social monogamy does not = genetic monogamy
o Most offspring result of primary partners but due to EPC there are some who are not even though they are socially monogamous
o Females - mating success is not limited by the number of mates, but the benefit from extra pair copulation is - increases variability, better partner, more males, more care, males are generally able to give care to the females they've mated with, protection
o One benefit for males is extra offspring
Why do females benefit from EPC (polyandry) #1?
o 1) Fertility insurance is once enough?
Generally, yes but EPC can increase average offspring number of female
Ex: prairie dogs monogamous females pregnant 92% of the time but females who mated with multiple males were pregnant 100% of the time
Not thought to be sufficient to explain EPC with a far inferior male
Why do females benefit from EPC (polyandry) #2? Sperm selection?
o 2) To enhance quality of offspring
Increase variation in variation
Can get a better mate? increase quality of offspring
If a female has the opportunity to mate with a male of higher genetic quality expect her to mate with him
Conflicts b/w good parent and high fitness highest fitness males aren't always the best parents
Ex: Bluethroat young of the bluethroat have a stronger immune response when they are the result of an EPC than when they are the result of a within-pair copulation
• Always mating with males of better quality
o Certain mates are more compatible with others - genetic compliment - EPC male is more likely to find perfect compliment
o Some pairings just don't work - some sort of biology there
o Females use certain things to pick males - seem to correlate with the mate that is more compatible with her genetically
Mate female with two males in following combos:
-Sibling-Sibling: female has lower proportion of eggs than mating with unrelated individual
-Non-Non: female has more offspring
-Sibling-Non: should be that the proportion falls somewhere in the middle (half are good from non, held are bad from sibling)
-Despite the fact that she is mating with sib and non, fitness still increases suggesting that the better sperm (from non) is beating the sib sperm and fertilizing more eggs
-Non-Sib: changed order to see if whoever mates with female last or first has better chance of fertilizing female, however same results were found and non-sperm competed and were more successful
Why do females benefit from EPC (polyandry) #3?
o 3) Material benefits
More males = more care and more resources
Threat of EPCs keeps males closer to home to prevent her wandering.
Better care/ protection
Ex: territorial males will allow neighbor's mate that they've mated with to come into territory
How is male quality judged for EPC benefit #2?
How the females judge the quality of males varies
o That look at the male's female
If their female is more open to EPC than the neighboring females think he is not beneficial to mate with
Polyandry? rare? 2 reasons why it happens? Example?
• Pretty rare b/c of high investment levels by females
• Happens for 2 reasons;
o Sex role reversal just as polygyny would be expected for males, when the sex role flips, this flips as well
Most common reason
o Equal opportunity sex lottery not a sex role reversal but females or something they need to reproduce (ex: nest sites) is in really short supply
Resources can't possibly be defended by one male males band together to defend her or the resource
Gives them a higher chance of paternity
Ex: Galapagos Hawk females are scarce
As many as 7 males will band together with one female to protect her and the nest site and give care and food
Generally produce 1 offspring per season but all have chance to be that parent and all raise that offspring
Does parental care always take place?
• Parental care doesn't always take place. In many species (ex: clams, barnacles, fish) eggs are shed into the water and abandoned
• Similarly, turtle young are on their own once they hatch
• Decisions about Parental Care are based on the costs/benefits
Why give care? What does the decision hinge upon? What is the effect in the greater investment?
• The decision to offer parental care depends on whether such care will increase the caregiver's lifetime reproductive success.
• Greater investment in individual young necessarily reduces the number of young that can be produced.
o Consequently, species choose between producing many, small, uncared for young or fewer, larger, cared for young.
o Whales and humans represent one end of the continuum and barnacles and clams the other.
benefits of parental care? Constraints surrounding parental care? How does it evolve?
• If parental care enhances survival and growth of young enough to compensate for the reduction in young produced then we would expect parental care to evolve
• Obviously, one potential constraint of parental care is the ability the parent has to affect the offspring's survival.
• Barnacles produce many thousands of eggs which are shed into the water and drift away. They develop into larvae and one day settle permanently on a fixed substrate.
o No parental care is not surprising for the barnacle
• Parental care in organisms that give it significantly enhances the prospects of offspring surviving to adulthood
• Ex: higher bodyweight in fledgling significantly increases a small bird's chances of surviving to adulthood
o Body weight is affects by parent they quality and amount of food delivered
Costs of parental care? Example?
• The price parents pay is not only in lost future offspring
o What else?
Time, energy, resources, risks to their own life (protecting young and more time spent foraging = more time they can encounter a predator)
• Extra investment (i.e. the parent's working harder to supply food) comes at a cost not just in additional offspring per season
o Time, energy, risk, lifespan, their own fitness?
Ex. Giving care often reduces the parent's prospects of surviving over the winter.
This effect has been documented in many studies in which brood sizes of parents were increased
• If you give parents more offspring less likely to be around next season
o Risk facto, not eating enough, etc.
Overall should not decrease fitness or they wouldn't do it
But it may reduce their living fitness but increases reproductive fitness
• Parental care detracts from future survival in willow tits
o Increase number of offspring survival chance of parents goes down
If giving parental care, how much parental care should you give? Example? What does this result in?
o The answer is not necessarily the same for parte and offspring
o The costs associated with increased investment in a given offspring cause parents to limit the investment they make so as to balance their prospects of survival and also to allow them to invest in future offspring
o The decision causes parent-offspring conflict
o Ex: weaning moms cut the offspring off and the offspring don't want to be (ex: mammals and birds)
What is the parent offspring conflict?
Parent-offspring conflict. Offspring are trying to acquire resources while the parent is trying to withhold them. The end of weaning occurs when the current offspring and parent are in agreement about the amount of care necessary. For full siblings, this is when the benefit to cost ratio drops below 1/2. Benefit is measured in benefit to current offspring, and cost is measured to reduction in future offspring. In instances where parents produce only half siblings, we should expect the conflict to last longer because the current offspring is less closely related to future offspring. Early on, the benefit to cost ratio is very high, and what the parent is investing in the offspring pays off. Over time, it will drop as the offspring is more able to protect itself and get its own food. Once the benefit to cost ratio drops below 1, resources would be better off given to another offspring. At this point, the parent is giving more to the current offspring than it would take to have another. From the parent's standpoint, it's time to move on, but the offspring still want more. For the offspring to move on, it only makes sense when the parent can care for 2 more offspring just as well
• However, a parent shares only 50% of its genes with the offspring and is equally related to all of its offspring, whereas the offspring is 100% related to itself, but only shares 50% of genes with full siblings (and less with half-siblings)
• As a result, at some point, a parent will probably prefer to reserve investment for future offspring rather than investing in the current one, while the current offspring will disagree.
How does parent offspring conflict relate to the weaning period? Example?
• This leads to a period of conflict called weaning during which the offspring tries to acquire resources and the parent attempts to withhold them : between 1 and .5
• The period of weaning conflict ends when both offspring and parent agree that future investment by the parent would be better directed at future offspring rather than to the current offspring.
• For full siblings, this is when the benefit to cost ratio drops below ½.
o As the offspring gets older and can protect itself and get its own food the benefit to the offspring drops
o The resources the parent is giving to that offspring is actually better served invested in another offspring
Current offspring requires more from me than it take for me to have another one
• In instances where parents produce only half siblings, we should expect weaning conflict to last longer because the current offspring is less closely related to future offspring.
o This has been confirmed in various field studies.
o brown cow-bird Begging loudness increases as relatedness within the nest decreases
What are two major influences on parental investment?
• The general the willingness of apparent to invest or take risk in an offspring should be influences by the:
o the parent's future prospects of reproducing
ex: if last mating season give more
older parents give more
o Relative value of the current offspring
How does age factor into parental investment?
• If reproductive value declines with maternal age, then older females should be willing to expend more on parental care
o as the mother gets older they throw more resources to offspring
o they get less healthy and their offspring are more valuable
How do birds with longer lives vs shorter lives deal with parental investement? Exposure to nest predators? Exsposure to adult predators?
o This is born out by studies of the behavior of long-lived versus short-lived birds.
In general, one would predict that long-lived birds should be less willing to risk their lives to protect their young, but that short-lived birds should be more willing to do so.
In general, North American birds are shorter lived than comparable South American species
o Ex: compared American Robin (live shorter) to Argentinian Rufous-bellied Thrush (live longer)
When researchers played tapes of Jays (which raid nests) near the birds' nests both species reduced feeding activity, but Robins reduced their activity more. Consistent with robins being less willing to risk the current brood
o Ex: When a stuffed Sharp-shinned Hawk (a predator of adults) was placed near the nest and calls played, again both species changed behavior, but this time the Rufous-bellied Thrushes (lives longer) reduced their nest visits more
The Robbins still come back and more willing to risk their lives because have shorter lives anyway
o Costs and benefits of parental care
These results suggest that the thrushes were less willing to risk their lives by feeding the current brood.
Selection on robins and thrushes thus appears to have fine-tuned behavior to take account of costs and benefits of risk-taking behavior.
Explanation for more maternal care than paternal care: Investment in young hypothesis?
-The parent that invests more in offspring, is more likely to give care
-NOT TRUE for explaining popularity of female parental care
-"Concorde Fallacy": The impact of the parental care and costs of parental care should be considered only in the moment the offspring are born; decision to give parental care should not be influenced by the parental investment before birth
-Parental care has no influence from prior investment before birth
PRE BIRTH PARENTAL INVESTMENT HAS NOT INFLUENCE ON PARENTAL CARE POST BIRTH!!!!
Explanation for more maternal care than paternal care: low reliability of paternity?
-The fact that males have to question whether the offspring in the nest are all theirs (parental uncertainty), would make us believe that they should not want to provide any parental care
-NOT TRUE for explaining popularity of female parental care
-If male care is required for the offspring to survive, males must give care regardless of whether they are 100% certain of their paternity, if they decide not to give care b/c they don't want to feed non related offspring then they risk accidentally not feeding their own
Explanation for more maternal care than paternal care: Association with young hypothesis?
-Both parents want to help, parental care will increase offspring survival, however females may be more associated with offspring in general and therefore have a better opportunity to help, males are not as proximal (close) or present so it's harder for them to provide parental care
-One of the most relevant hypothesis for explaining popularity of female parental care
Explanation for more maternal care than paternal care: order of gamete release hypothesis?
-Parenting sucks and nobody wants to stay and take care of offspring, but one sex is more closely associated with fertilized eggs, so they win up taking care because the less associated sex is already gone (usually female is left and male is gone)
-External vs. Internal fertilization:
-With external, male is usually last one associated with offspring and he is the one that provides the parental care
-One of the most relevant hypothesis for explaining popularity of female parental care
Internal vs external fertliziation in reference to male vs female parental care?
Internal fertilization male fertilizes and then leaves
Females give more care
External fertilization eggs laid down first and females leave and then the males fertilize them
The last one to be with the eggs are the males they give more care
What is the primary cost of giving care? To which sex is this most costly? When is giving care selected for? What factor makes it even more costly?
o Relative costs different b/w the sexes?
Costs= lost reproduction
o Primary cost of giving care loss of future offspring
o Which sex pays the higher cost the one with the highest reproductive potential
The males have higher reproductive potential
When males have opportunities to mate with multiple females, mates that give up that opportunity to engage in parental care will pay too high a price
Paternal care, wither with the female or alone, would be selected for only when the payoff is sufficient to outweigh the costs
Consistent patter is that male care is more likely when the costs are reduced for some reason
o Sex ration influences male parental care
A female biased sex ratio increases the costs of brood care for males because parental care detracts from mating
What is true of parental care in fish? How is care provided? Stickleback example?
o In fish, male parental care is quite common
Many males mouth brood eggs or care for eggs in nests
Costs of parental care seem to be lower for males than females
o Male sticklebacks can care for 10 clutches of eggs are once
o Males grow more slowly when caring for young, but because males are territorial and cannot range widely to look for food the additional cost of parental care is low.
o For a female stickleback parental care would severely limit her ability to forage and grow.
o Because body size is closely correlated with egg production loss of foraging opportunities would have a significant effect on future reproduction.
o In many fish, where male care is common, costs of parental care are higher for females than they are for males, paternal care may have evolved because males lose less from parental care than females do
FOR STICKELBACKS IMPORTANT REPRODUCTIVE POTENTIAL IS FEMALES ABILITY TO EAT GET BIG AND PRODUCE EGGS
Cost of directing parental care to non-offspring? How is this accounted for? Three examples?
Misdirecting parental care towards non-offspring is a costly mistake
-Many animals rear their young in colonies and need to develop ways to detect their own young
-Ex. Mexican Free-Tailed Bats: roost with thousands of other females and babies, moms use vocal and olfactory cues to identify their offspring in the nursery, though they sometimes male mistakes, the benefit of leaving a baby in a nursery (mainly for thermoregulation) outweigh the cost
-Ex. Cliff Swallows: they nest in large colonies so have developed highly variable calls among parents and offspring and the parents are highly skilled at distinguishing these calls. Barn Swallows nest solitarily so they don't need as sophisticated of a system
• Ex: Similarly, the young of colonial Bank Swallows produce distinctive vocalizations that their parents can easily recognize, but the non-colonial Rough-winged Swallow does not.
Adoption? When does it happen?
• Obviously it would appear beneficial to avoid adopting other individuals' offspring but such adoptions sometimes happen
• Ex: in colonially nesting gulls, chicks that have been poorly fed in their own nests sometimes leave their natal nest and join another brood, where they are often adopted
• Moving is often a good decision for the chick because it ends up being better cared for in a different nest
Why do parents tolerate adoption? Example?
• Adoptive parents on average lose fitness of their own as a result of the adoption so why do they tolerate the intruder?
o There is the possibility of an error its hard to tell which is yours (cost/benefit)
o If other chicks aren't wandering into your nest that often discriminating is probably not great because you might neglect one of your own
o Most likely explanation is that parents use an imperfect behavioral when deciding who to feed.
o Any chick that begs confidently is accepted and fed feeding whoever begs assumes it is your own
Why would this be a good strategy?
Risk of adoption is low and not significant and not worth kicking out your own offspring
o The reason that gulls do not discriminate more is probably that recognition errors would be too costly.
o Errors in which a gull fails to feed or worse attacks and kills its own chick because it thinks it is a stranger would be very costly.
o The cost of occasional adoptions appears to be low and risk of not feeding own high enough that selection has not favored higher levels of discrimination in gulls.
Example of no cost adoption? 3 major benefits:
-In some instances adoption appears to not come with a cost and may even be beneficial to the adopter
-Ex. Ducks: females will often accept extra eggs laid in their nests and accept stray ducklings into brood
-No Cost: Chicks forage for themselves so really no cost in taking on more
-Benefit: Predator Dilution Effect: additional young in the brood may reduce the odds a chick taken from the brood is actually the parents own offspring (similar to ostrich eggs)
-Kin Selection: potential benefit in adopting an egg from nearby that may be from an actual blood relative
Brood parasitism? Eamples?
obligate interspecific brood parasites. (female HAS to give offspring to another species to raise)
-These include: Old World Cuckoos, Old World Honeyguides and New World Cowbirds
-These birds lay their eggs in the nests of other birds and provide no parental care
-This behavior appears (through phylogenetic analysis) to have evolved independently three times and a large number of cuckoos are brood parasites, make up about 53 of 136 species of cuckoos.
How does brood parasitism evolve? Focus on explanations for the two different types and how they are linked? Cuckoos vs cowbirds?
o Intraspecific brood parasitism is common in birds and has been recorded in more than 200 species.
Only laying eggs in the nest of other birds of the same species
o Interspecific brood parasitism is believed to have originated as intraspecific brood parasitism.
o A plausible transition to interspecific brood parasitism would be for birds to begin laying eggs in the nests of closely related species.
o Today cuckoos concentrate on species that are not closely related to them, but as parasitism in cuckoos may be 60 million years old this may simply reflect the long period of evolution that has occurred since the origin of the behavior
o In cowbirds, which much more recently evolved brood parasitism (in past 3-4 million years) parasitizes only one other species and that belongs to its own genus.
Since then increasingly general brood parasitism appears to have evolved.
Effects of brood parasites on host? Examples of exploitation of a host - what do the parasites do when theyre in the nest? (5)
• Brood parasites have a significant effect on the reproductive success of the hosts.
o Ex: Baby cuckoos eject the eggs and young of the host so the host rears no young of its own
o The host species may not be as good at discerning the differences between the eggs and the young
o Exploit a parent's basic offspring care
Parents bring more food if they have more offspring
A cuckoo will mimic the sound of many young so that the parents think they have a lot and bring a lot of food
o Brood parasites exploit the host parents tendency to feed the largest young in a brood the most food and to reward the young that can reach highest for food.
o By laying in the nests of smaller birds, cuckoos give their young an advantage in the competition for food. So do cowbirds whose eggs hatch after a shorter incubation period which allows them to hatch before the host's young.
o The advantage of laying in the nests of smaller species has been shown in experiments in which nestlings of nonparasitic Great Tits and Blue Tits (smaller) were switched between nests.
o The smaller Blue Tits did badly in Great Tit nests, but Great Tits prospered in Blue Tit nests
Why tolerate a parsites eggs? (3 reasons, number 2 has 2 examples)
-Risk Of Making a Mistake:
-Some birds recognize parasitic eggs, however sometimes it's too card to tell and the parent doesn't want to risk throwing away one of its own eggs
-Unable to Remove Egg:
-Sometimes host parent is too small to remove egg
-These small hosts either accept the egg or abandon the nest which is an expensive option, especially if nest sites are scarce
-Ex. Prothonotary Warbler: more likely to abandon parasite if there are other nests near by
-Ex. Yellow Warbler: If it is near the end of the breeding season, they will just accept parasites because it's too late to start over
-Mafia Hypothesis: Parasite mother may monitor nest and harm host nest if egg is removed; seen in Cuckoos and Magpies (magpies have their nest parasitized) - threateninng magpie nest is effective as renesting is costly in the magpies seasonal enviornment.
What is the arms race between hosts and parasites? 2 examples?
o As selection operates on both hosts and parasites the differing selection pressures have resulted in an arms race between hosts and parasites.
o In the case of the European cuckoo and its hosts selection has led to extremely good mimicry of host eggs
o Individual cuckoos specialize on one host species and lay eggs that closely mimic only that species' eggs.
o Historical interactions between cuckoos and some hosts appear to have resulted in victory for the host.
Ex: European Blackbirds are rarely parasitized by cuckoos and even though under no current selection pressure, these birds reject parasitic eggs at a very high frequency
Apparently, blackbirds evolved rejection behavior on the past and cuckoos have moved on to other host species
Example of an ongoing arms race between hosts and parasites? How do the host and parasite respond to each other?
Horsfield's Bronze-cuckoo parasitizes the Superb Fairy Wren.
Fairy-wrens respond to cuckoo eggs laid before they have started laying by abandoning nest or building over the egg. They also abandon if cuckoo lays egg after incubation has begun
Bronze-cuckoos have responded by inserting eggs during fairy-wren laying period. Such eggs are generally accepted and incubated.
However, when young cuckoo pushes young wrens out of nest, fairy-wrens abandon the nest about 40% of the time and cuckoo starves.
In other cases cuckoo appears to fool parents into believing their sole chick is a fairy-wren.
An important factor in the chick's ability to fool the fairy-wren parents is its ability to mimic the begging call of young fairywrens.
The call is specific and very similar to the fairywren
Chicks of Horsfield's Bronze-cuckoo closely mimic calls of host fairy-wrens.
Shining Bronze Cuckoo which rarely parasitizes fairy wrens does not resemble fairy-wren chick and does not sound like it either.
Use of calls in parasite host arms race?
o Another example of the use of calls in the arms race between parasites and hosts is that of calls by European Cuckoo chicks in Reed Warbler nests.
The rate at which cuckoos call simulates that of a whole brood of Reed Warblers which encourages parents to feed at a much higher rate than they otherwise would.
Explain parental favoritism and siblicde? Example of parent facilitated siblicide?
-Parents may be equally related to offspring but that doesn't mean they treat them equally well
-Parents may actively discriminate against young or let siblings kill other siblings and sometimes even encourage the behavior
-Ex. African Black Eagles:
-The first hatched of two chicks attacks its younger sibling as soon as it hatches and pecks it to death, similar behavior in other birds
Why do parents allow offspring to engage in siblicide? two examples?
• Less work if not enough resources
• If the offspring is sick or runt
• Too many offspring to support
o But then would lead to fewer offspring and more care over the long term
o So, we don't see this a lot
o Species in the process of change or in a changing environment
• Ex: African Black Eagles the first hatched of two chicks attacks its younger sibling as soon as it hatches and pecks it to death.
• Ex: egrets, boobies, pelicans and other birds older siblings attack and drive younger offspring out of the nest where they stare to death
o The parents ignore this behavior they could easily scoop it back into the nest but they don't
What is hatching asynchrony? 2 examples?
-A method in which parents can encourage siblicide amongst offspring
-Laying eggs at different times results in them hatching in different amounts of time which establishes an age and size hierarchy within the brood - brids dont have to do this (ducks, even with large clutches, dont do this)
-Ex. Black Eagles lay first egg 3-7 days before second, giving first a large advantage
-Ex. Cattle Egrets, in addition to laying eggs at different times, they also inject the first born with androgens to make them more aggressive, advantage of later hatched chicks
Why do parents play favorites and facilitate siblicide (reason 1)? (3 examples). Specific name for the behavior? Reasons for doing this?
• Insurance against failure
o The most extreme form of brood reduction is obligate brood reduction younger offspring essentially always die - species with fewer offspring
The only way the younger one lives is if something happens to the first one
They only raise one the second one is only an insurance policy
Don't want any cost to the primary offspring
o When the first offspring arrives it kills its sibling (Black Eagle), the parents cover over the second egg (Harpy Eagles), the parents abandon the second egg (Hooded Grebes) or abandon the second born cub (Giant Pandas).
o Thus, the parents avoid prolonged investment in a back-up offspring. However, if the first offspring fails the second can step in and take its place.
o Examples of obligate brood reducers include: Black Eagles, Harpy Eagles, Giant Pandas, and Hooded Grebes.
o Why don't they rear the second baby?
o In many cases the parents would appear to be capable of rearing both but don't
Trade-offs b/w offspring number and quality as well as b/w offspring number and parental future reproductive success
For those species it is usually not possible to provide enough food to rear 2 high-quality young
Why do parents play favorites and facilitate siblicide (reason 2)? Parents policy? Two classes?
• Environmental uncertainty
o Many other species are facultative brood reducers which means that brood reduction does not always occur.
o These species practice a policy of parental optimism.
o They lay a clutch size that can be reared in a good year, but in a bad year will result in brood reduction.
Laying eggs to maximum reproductive potential
If not a good year they or their older offspring will kill the others
o In these species the brood contains two classes of offspring: core and marginal offspring.
Marginal offspring are handicapped by the parents and as in obligate brood reducers have insurance value, but mainly are produced so that parents can take advantage of a good year if one occurs to rear bonus offspring.
Born a little bit later so there is a clear hierarchy but not as big a difference as with obligate
Handicap that can be overcome
Example of facultative brood reducers?
o Ex: Thus, in cattle egret broods the effects of A and B chicks (the eldest chicks) aggression towards younger C and D chicks is moderated by food supply.
If food is plentiful, the younger chicks can tolerate the beating and may survive to fledge.
If food is scarce the younger chicks quickly starve or are driven out of the nest and die.
o The policy of hatching asynchrony thus creates a situation in which in good years conditions can be taken advantage of and extra babies reared, but in bad years the brood can be efficiently reduced to what foraging conditions will support.
o The amount of asynchrony in cattle egret broods appears to have been tailored by natural selection to maximize parents reproductive success and efficiency in rearing babies.
(artificially synchronised nests didnt do as well, more food needed less survivors, asynchrony exaggerated nests produced similar number to normal, but brood reduciton took place at younger ages, could limit ability of parents to rear large broods in good years)
Brood reduction as it pertains to humans? What is the pheonomeonon called? How do older women factor in?
• Twin births are rare, but twins conceptions are much more common and only one in ten to one on fifty twin conceptions produce twins. The other pregnancies result in only single births.
• The phenomenon is known as "vanishing twin syndrome"
• It may be that producing extra eggs is an insurance strategy against pregnancy failure due to defective embryos, Some of these early embryos have chromosomal defects and are quietly aborted by the mother.
• This idea is supported by the fact that older women are more likely to give birth to twins than younger women.
• Apparently this is because older women polyovulate more than younger women and older women are much more likely to produce chromosomally defective eggs.
• It is possible that other cases of disappearing twins may not be caused by an embryo failing because it is defective, but from a "decision" by the mother to reduce her brood, although a mechanism by which this might occur has not been identified
How do you evaluate the reproductive value of offspring? Example in birds? What does that trait correlate with? Two reasons for why parents select for it? Support for both reason?
• As we have seen not all offspring are created equal and even in the absence of parental manipulation of quality we would expect parents to assess offspring quality when deciding how to allocate scarce resources.
• It has been suggested that the gape (inside of mouth) color of baby birds may signal the quality of their immune system and thus offspring quality
• Red gape color is produced by carotenoid pigments in the blood and these are believed to enhance immune function
• Does correlate with fitness but also parents may notice that color more and feed them more and so this is selection on the offspring to get more resources from their parents
o Evidence of both
• In an experiment on barn swallows in which the chicks gapes were colored with food coloring, chicks whose gapes were reddened received more food although chicks whose gapes were yellowed did not receive less food. - both colors being more pronounced but one selected for more.
• Alternative explanations for the role of gape coloration have been put forward, however.
o An obvious alternative is that parents are not assessing offspring quality, but just feeding those chicks whose gapes are more conspicuous under the prevailing lighting conditions.
o Consistent with this idea Great Tit chicks whose mouths were painted yellow received more food than chicks whose mouths were painted red and were less conspicuous in a dark nest box.
o When a plexiglass lid was placed on the nest box however, both sets of chicks were equally well fed.
Coots example for disctiminating reproductive value in offspring?
Have prominent long orange tipped plumes on their backs and throats, and these may be a cue parents use in deciding which chicks to feed. Experimenters trimmed the plumes of half the members of a brood and saw whether or not it affected their care. Parents discriminated against offspring without orange plumes by ignoring or under-feeding them. The members who were ignored did not grow as fast. So the orange plume may be used as an indicator of offspring quality. Control broods in which all birds were trimmed survived as well as broods in which no chicks were trimmed. They appear to discriminate against trimmed chicks because they lacked orange plumes, not because they could not recognize them. The orange plumes may be a sign of offspring quality. Reduce brood size by pecking certain babies in their brood when they beg for food, and these quickly die
Altruism? examples? What is another way of referring to altruism? Three examples?
• An action that benefits another individual without advantage or even at a cost to the actor
o Darwinian puzzle how do you explain this behavior
o Ex: lions devote resources to other offspring that are not their own
o Ex: birds that stay with their parents and help raise siblings rather than rearing their own offspring
o Ex: warning calls in mammals - not really altruistic tho
Can a behavior really be altruistic? Define mutualsim? COmmensalism?
Behaviors that seem altruistic are usally more mutualistic. - individual selection can select for these behaviors
Commensalism - interaction b/w two species in which one benefits and the other is not effected.
Clownfish and anenomies thought to be commencialistic, the clownfish gets protection, anomeone gets nothing. Turns out there may be benefits for the anemone, which would be mutualistic.
Can an alarm call be altruistic? How do they develop?
• Individual selection - how can an alarm call be selfish? - in some cases it actually isnt, therefore individual selection selects for it.
o Chance of survival for alarm caller for bell's squirrels, the alarm caller less likely to be attacked. Turns out these alarm calls are not nearly as self giving as they appear. By giving that call, the ground squirrel may be telling the hawk, I see ya, go attack some other idiot. These things may not be as friendly as they look like.]
o However, in the case of a ground predator, this alarm call seems to be altruistic because being the alarm caller in this situation means you are more likely to die.
o Alarm calls generally have a negative impact on the caller, the squirrel example is an anomaly.
Reciprocal altruism? requirements? Who does this usually happen with?
not true altruism
o Benefits accrue long-term mutualism with a time lag
o In the moment it costs you but in the long run its coming back
o Requires stringent and specific conditions
Multiple interaction must be meeting the same individuals over and over again
Recognize each other and withhold benefits from cheaters
Benefit of receiving help when needed is greater than the cost of giving help when asked
o An alarm call can never evolve to reciprocal altruism because cant prevent it from getting to certain people
Benefit must be directed
o Tends to be with social animals and intelligent animals
Must remember and recognize each other
Must remember cheaters
Mammals (especially primates) are big on this
Ex: evolutionary psych humans remember those who have wronged them
Example of reciprocal altruism?
Vampire bats look for blood meal and if they miss out for 2-3 nights, they starve to death
Not all finding meals every night
If they come back and someone hasn't fed the one that has fed will regurgitate a little bit of blood so the other one doesn't starve
To give up a little doesn't harm them that much (not a big cost)
But if you are starving that is a huge benefit
Recognize each other and cheaters
Benefit that you can direct
Explanations for the evolutions of traits actually not beneficial to an individual?
• Natural selection
• Group selection - not true as individual is stronger.
• Kin selection
o There is a cost to individual fitness
Caveat: expands our ide of individual fitness instead of thinking about fitness
Kin selection as it pertains to altruism?
explanation for true altruism lies in kin selection.
o Kin selection - natural selection based on indirect fitness gains for an individual whose actions benefit its relatives.
o Inclusive fitness - the fitness of an allele measured by its effects on survival and reproduction of the organism bearing it and of the alleles borne by the organism's relatives.
= direct fitness + indirect fitness
• Direct - fitness gains from oneself and descendent kin - part of your direct line.
• Indirect - fitness gains from non-descendent kin siblings, nieces nephews cousins parents.
Are all relatives created equal?
animals May behave differently related on the level of relativity to the kin - pertains to kin selection
o Hamilton's Rule
rB - C > O expect that trait to be favored and genes should spread even if it costs the individual their direct fitness
r = relatedness (proportion of actor's genes that are shared, and identical-by-descent, with recipient) .5 = sibling
B = benefit to the individual receiving the act, 1 - saving life
C = cost to the actor
Example of a truly altruistic act directed at relatives?
• Truly altruistic acts directed at relatives
o ex: prairie dogs and alarm calling more relatedness of individuals around the more likely they are to alarm call
o more likely to give alarm calls at certain stages in life
• When living with birth coterie with parents sibs and other kin prarie dogs almost always alarm calls
o Once prarie dogs move out, not related to anyone in their new group, they haven't sired any offspring, they don't call.
o Once they have offspring they start to call.
Does trait evolving through kin selection always require relative recognition?
• For a trait to evolve through kin selection
o Don't have to always recognize kin - some species live in closely related groups, with a species like that, a behavior would be favored if altruisitic, because they are always around their relatives - this altruistic trait could be passed on without actually having to recognize anyone.
o When these species who live in closely related groups are dispered to non related groups, they still perform these acts, because these traits have evolved because of the presence of relatives even though they cant distinguish between kin and non-kin
Tiger salamander example?
o Can become a cannibalistic morph and eat other larvae in their pod. The trigger is relative body size relative to everyone else, another factor is how related they are
o Less likely to be cannibal morphs if they are in ponds with closely related individuals
Depends on how many different egg groups are in the pond
o Introduced cannibalistic morphs to food, discriminated between sibling or unrelated and first cousins and unrelated - they recognize first cousins and siblings in terms of relatedness, and pick them less
Tiger salamanders can distinguish kin, probably a pheromone or scent marking
If siblings around, less likely to turn, less likely to turn early, less likely to eat siblings
3 basic explanations for relative recognition?
o General rule - Hey whomever I'm raised with, I'[m related to. Those dudes in the nest with my are my relatives.
o Phenotype matching - species that meet relatives later that they've never met before and recognize them as relatives are not, based off of relatives they're raised with they develop a phenotype template and then apply that template later.
o Armpit effect - phenotype matching template, but you use yourself as a template. If you have never been raised around relatives.
Helpers at the nest?
o Forgoes your reproduction to help out in relative nest - when does that pay off?
How many are you losing? How many are you helping? Relative relatedness of different offspring
o May be young - not yet successful at reproduction * learning curve for raising offspring, gather resources)
They wouldn't be good at it this pint, help sibling until they have a handle on it - not profitable once she knows what she's doing.
Do nest helpers work at different levels? Cooperative helping? Example? WHat does it serve as evidence for?
European bee eaters a lot of cooperative helping
Males stay with original colony and help and females move on
High chick mortality and starvation without helpers
Sons can help double the surviving chicks in a nest
Evidence for kin selection - helpers increase parents offspring number by 2x, helpers are usually male (females move on), helpers direct help to related parents when they have a choice. There is a really strong effect. - IMPORTANT THAT THEY JUST DONT HELP OUT RANDOS< THEY HELP OUT RELATED PEEPS
Primary helpers? Secondary helpers? Delayers?
• Primary helper - infividual who will not breed in the first year, help parents and siblings, work hard, bring a lot of food, risk theyir life.
• Secondary helper - help unrelated pair raise offspring, marginally committed, not gonna work super hard or risk a lot.
• Delayers - sit out the the year, limited reproductive success
What are the reasons for the multiple roles/functions of nest helpers? (4 reasons)
most helpers aid relatives
experience gains/occasional young
Habitat Saturation as an ecological constraint
Lower fitness but no other options would like to go out and have their own nest but no nest sites etc.
Advantage to staying home longer/help out of instinct
Possible - evidence?
What are hymenoptera? Eusociality?
Hymenoptera (ants, bees, wasps)
o Eusociality: sterile castes rear offspring of reproducing individuals
Ex: Sterile workers help raise offspring extreme altruism
Queen bee has 2 sets of chromosomes and males only has 1
A sister gets one set of chromosomes from mother and one from father
Other sisters get one from mom and one from dad
50% chance share same set from mom but 100% chance that they have the same one from dad
level of relatedness in haploid/diploid systems for sisters is 75% higher than the relatedness b/w mothers and offspring
helping to produce more sisters would pass on more genes than having your own offspring
Higher r tips the balance in favor of raising siblings rather than offspring
o caveats for haplodiploid explanation of eusociality:
o Not all workers are full sisters (r isn't always 3/4)
multiple fathers, sometimes multiple queens
o Not all haplodiploid species are eusocial (and vice versa)
o So this suggests a role for factors other than haplodiploidy alone in the evolution of eusociality...
Naked mole rats example?
• Naked mole rates - same eusociality, not haplodiplopid, high levels of inbreeding. Alters levels of relatedness among siblings. It ends up looking kinda haplodiploid because of the high levels of inbreeding.
Define group selection? What is the interaction between group selection and individual selection? Example of an exception to this? How does it usually operate? Liimitations of group selection? Can group selection explain altrusitic traits?
• The differen'al rate of origination or extinction of populations on the basis of differences among them in one or more characteristics
o Canibal - eat all the young around me, great food source, high fitness. As cannibal jean starts to spread, cannibals start eating other offspring, reproductive output of pop is falling, ultimately more and more candibals, eventually you might go extinct
Theoretically can happen, only happens in that case
o Something VERY detrimental to group but positive for individuals can be overridden by group selection
• Much weaker than individual selection
• Generally operates in conjunction with individual selection
• Insufficient to explain altruistic traits
• Cannot lead to traits that are disadvantageous to the individual
What explains truly altruistic traits vs fake altruistic traits? LOOK AT THE SLIDE FOR THIS
• Many apparently altruistic traits may be explained by individual selection
• Truly altruistic traits must be explained through kin selection and inclusive fitness
Define communication?Mouse example of communication? Revised definition of communication?
• An action on the part of one animal that alters the behavior of another
• Relationship b/w signaler and receiver
o Mouse rustles the grass foraging and the hawk hears him and eats the mouse
o Is the mouse communicating with the hawk?
According to above definition yes
• Revised definition: Action on the part of one organisms that alters the probability pattern of behavior of another organism in a way that may or may not be adaptive to both
True communication? Manipulation/deceit? Exploitation/eavesdropping? Ignoring or spite?
• True communication both sender and receiver benefit
o True communication should evolve because its adaptive
• Manipulation or deceit sender benefits, receiver is unaffected or harmed
• Exploitation or eavesdropping sender is unaffected or harmed, receiver benefits
o Unintended receiver may have negative impacts that come back to signalers
• Ignoring or spite neither sender or receiver benefits, both may be harmed
o Don't see this a lot
Functions of Communication? (6)
-Recognition of species, individuals, neighbors, castes (social insects), kin or demes need to recognize mates, classes, groups or relatives
-Reproduction which involves courtship by males, female choice, or female receptivity (e.g, acceptance or rejection);
Courtship, stimulus-response chain, the behavior of one individual in turn releases a behavior of another individual
-Agonistic interactions and the establishment of social status; Competition and fighting, convey status or dominance relationships Without continual fighting
-Defense, Predator Avoidance, Alarm calls among group dwelling animals
-Food Communication, Information Transfer, Coordination among hunting animals
-Parental care parent offspring recognition and calls by offspring or actions to bring food
Chemical modality of communication? Advantagges? Diadvantages?
• Chemical - peeing
Can leave it there and then leave
Carry a long distance Good for large areas
Low energy investment
Good for night, obstacles, etc.
can be tracked as prey
Depend on wind for dissemination
Difficult to track and locate sender
Long fade time no complex signals
Delayed not fastest way
Visual modality of communication? Advtanges? Disadvantages?
Sender is easy to locate
Low energy (to send)
Complex, rich signals
Sender is easy to locate
High risk of predation
ACoustic modality of communication? Advantages? Disadvantages?
Not dependent on wind
Lind of sight not needed travels around obstructions, use at night
Water and air
High energy cost
Crickets lost 5% more body weight per day calling than not calling
Easy to locate sender (can be advantage if mating but disadvantage for predators)
Confusion not as direct/ immediately identifiable who is doing it in a large group
Ex: frogs in a group with bad calls will gather around frogs with good calls and pretend to call but not
Tactile modality of communication? Advantages? Disadvantages?
• Tactile (see in mammals)
Very short range low exploitation risk
Low energy cost
no illegititmate recievers
Must be close
o Used for mating, grooming, feeding
o Mammals (primates) do it a lot
• Specific vs. general
o Specific only have an effect members of the same species important for attraction and courtship
o General affects all animals, even predators
DIscreet vs. Graded
o discreet simple on/off signal
advantage of discreet signals is clarity, no chance of misinterpretation
o graded signals vary in strength
complex signal varies with intensity/motivation
facial expressions are graded tell us more than just happy/ sad how happy or how sad
chance for misinterpretation can read things wring
Why not always specific?
You may want to reach multipled individuals/species, territoriality want to tell other animals to **** off, working together, one species is a good lookout one is good at finding food.
Costs - complex signals take more energy or time, only see them evolve when there are big advantages to it
Result - complex signals evolve only when there are strong advantages to specificity.
Is there an upper limit to the amount of info conveyed?
• Used to think strong correlation b/w number of signals and amount of info conveyed not true there is an upper limit to how many displays animals will do
• If their displays aren't increasing how do they increase info?
• Number of displays are limited
• Information increased through enrichment devices
Enrichment devices? (5)
-Medley composite signal
2 paired signals have different meaning than either alone
ex: growling paired with the ears if they are forward or back
-Syntax sequence of displays is important
Ex: A B is different than B A
Used to be thought that only humans used this this is not true but it is limited to the most intelligent animals
Communication in general is not a sign of intelligence but certain aspects are like syntax
Dolphins, great apes understand syntax
-Metacommunication communication about the meaning of communication
To communicate something about how to interpret certain communication signals
Ex: puppies like to pounce and before they jump on you they lean back and stretch their paws out they are saying "I'm ready to play and everything I'm about to do is related to play"
-Regulate intensity/ duration using graded signals
-Contextual effect context matters
The same signal used for different receivers and in different situations means different things
Ex: lion's roar can be used to impress a mate, maintain spacing b/w prides, as a locating device, aggression
Redundancy? Advantages? How to do it?
saying the same things repeatedly
May do it depending on conditions if you don't think it'll get across well in the environment
Or if the receiver is distracted (ex: dog barking at sleeping human over and over)
Reduce the risk of misinterpretation
Reassessment of motivational state
Coordination and maintain sexual arousal
Increase memorability only for multiple signal types
o 2 ways:
repeatedly giving the same signal
paired presentation of 2 signals with the same meaning
multiple modalities increases memorability- only advantage of repetition of paired signals
Evoolution of signals? Where do they come from? How do they get incorporated into the system? 5 FUndamentals?
o Intention movement something that is always done before an action
Incomplete functional movements thwarted attacks
Ex: opening your mouth and baring teeth before biting since this always happens before a bite, this becomes a signal of aggression
o Displacement activities inadvertent actions at times of stress or motivational conflict
Urinatation, blushing, hair standing on end
Ex; when a puppy pees on the floor it is not that he was so scared that he couldn't help its that urination has become a display
o Completely formed but redirected acts
Ex: attacks on inanimate objects displaying toward another male, or maybe another female
o Contextually irrelevant displays
Ex: gulls in a territorial fight revert to preening
o Contextually correct and complete displays
Ex: Sleeking and ruffling feathers in aggressive displays
They are overheating and getting hot from being aggressive they ruffle and then they ruffle to show aggression even if not physically getting hot
What is ritualization? Where does it come from? Two examples?
o An evolutionary process by which behavior patterns become modified to serve as better signals
o Comes from an intention movement ex: cats put their paws up as a sign of aggressive
o As a result the movements get stereotypical and exaggerated
o Can lead to a change in function of behavior once they become part of communication system
o Ex: nest building become mating displays
To build a nest you have to pick up nest stuff but now the behaviors have been ritualized and the males display nest materials at one another (raising the sticks up in the air etc.)
What are some selective forces in shaping signals? (7) Things that contribute to divergence? COnfvergence?
o Identification and discrimination (=reduction of ambiguity)
General trend - signals diverge or converges
o Factors resulting in divergence
Species specific sexual displays
Female choice signals
Predator confusion - in order to confuse predators you want to be different
o Factors resulting in convergence
Similar ecological pressures
o Social complexity - as social complexity increases, number of singals increases
o Compromise and allocation
Bright color - good for signal, not for concealment
o Environmental constraints
o Sexual selection
o Predation pressure
o Intrasexual selection
functional system vs exploitative system? Example of exploitative?
o Functional system: signaler receiver
Positive fitness benefit for both
o Exploitive system: signaler illegitimate receiver (predator), illegitimate signaler (mimic) reciever
• Fire fly femme fatale miscommunictation - sister species predator flashes mating sign, then eats the male firefly
• When a raven finds a moose carcass calls and attracts others to the site instead of keeping it all to themselves
o Did experiments
o Thought ravens might be ineffective at tearing open carcass call to attract other species to rip it open and then eat it NOT TRUE thought it was for dilution effect NOT TRUE
o Sometimes they are not calling if advantageous to call why is it not at other times?
o Ravens are territorial so if a subordinate raven finds a carcass within someone else's territory will kick them out
Call to attract the crowd to overwhelm the defenses of the territorial resident overcome a superior competitor
If they are the one who holds the territory they are quiet
Pattern is that there are only 1 or 2 ravens (territory holders) at the site or like 15 nothing in the middle
Why do exploitative systems persist? 2 explanations.
o Novel environment - maladaptive behavior exists because the environment has changed in such a manner to make a previously adaptive behavior non-functional and there has not been time to "fix" the problem.
o Net benefit - the maladaptive response results from a sensory mechanism that may result in fitness declines in some situations for some indivifduals but this does not erase the fitness beenfits for twhich the response is evolved.
Remember - adaptations need not be perfect
Prediction responses essential to fitness are more likely to be exploited, because you cant stop responding to stuff like mating opportunities.
Does deception always occur on the outside (dealing with illegitimate signalers or recievers)? Example?
• Deceptions doesn't always occur on the outside can occur in the middle
o Sometimes being less than truthful gives bigger fitness gains than being honest
o Ex: balloon flies
Male presents female an empty silk balloon
How did this come about? over time evolved from nuptial gift to token
1) Predatory male doesn't feed a female
2) Predatory male feeds female
3) male entangles prey in silk feeds female
4) male wraps prey in balloons feeds female
5) complex balloon, small prey no feeding
6) complex balloon, minute prey no feeding
7) complex balloon, no prey
How big of a lie can you tell? Misinformation?
o Big lie = big reward, bigger risk
little lie, lower risk, more likely to be accepted.
o More likely to get away with a little lie early, as the receiver gets more experienced, less likely. With big lie, same thing, but falls off more quickly with experience.
o Benefits of a big lie early on greater than small lie, but over time you're better off with the little lies.
o When we start off not uncommon to see big lies, trails off to ssmaller manipulations over time.
Illegitimate reciever effect on the evolution of signals (calls in warblers)?
o Calls in warblers - higher frequency sounds don't travel as far as lower frequency sounds. Lower frequency sounds gets parents form farther away, but chance of attracting illegitimate recievers. Ground nest chicks call in a much higher frequency, more at risk to predators on the ground.
Great tit and hawk example?
calls b/w great tits and sparrow hawk that preys upon it
Mobbing call if they are flying around and see sparrow hawk kind of far away will do mobbing call and will attract a much of birds to the area and mob the predator
sparrow hawks can hear it but travels really far
Seat call if they see the hawk in the air and flying near them
lower frequency that the hawk doesn't hear as well to warn others nearby
o across song birds convergent evolution of seat calls to warn others that a predator is nearby
all sing birds who live near these sparrow hawks have same warning calls
Migration vs Dispersion?
o Key difference is the return. In dispersal, one-way movement away from previous home to another new area or home.
o Migration you come back.
Natal philpatry vs natal dispersal? Costs/benefits?
Staying in natal place, dispersing from natal place. Staying in place - cost - inbreeding and competition, benefits are inbreeding and local familiaryity. Leaving costs, energy use, increased predation, lack of familiarity. Benefits: reduced inbreeding, avoiding competition.
If costs are so high, why disperse? 3 explanations.
Inbreeding avoidance hypothesis
• One sex leaves, usually male
o Usually the sex least likely to benefit from kin selection
o Kin selection expireneced more by females raising offspring in a group.
Mate competition hypothesis
• Avoid competition with established adult males. Once the male lion reaches sexual maturity, not as big/strong experience, can't compete yet. Go nomad, get huge, come back, **** bitches.
Colonizaiton of new habitats
• Likelihood to find the new habitat - some risk. For some species it is likely, b/c they live in small populations.
• Reproductive success if found
o Red eft that wanders to find a new spot likely to be rewarded with new habitat.
define kin selection
natural selection in favor of behavior by individuals that may decrease their chance of survival but increases that of their kin (who share a proportion of their genes).
Usually think got it as long range, but some can also be short distances depending on the speices.
Should have periodic timing - not randomly wandering off, youre going somewhere as a destination, staying there for a bit, you come back. Implies periodic timing, could be annual, or lunar. Should occur repeatedly through time predictably.
Types and direction of migration?
Plane of movement
• Vertical migration - plankton in diff water temps
• Horizontal migration - what we usually think about
• Most are north south, albatross are east west.
Preparation for migration? Impact on migration?
• Highly energetic, preceded by increasing fat deposition, rapid eating, increase in stomach volume, increase in fat loads.
• For red eyed vireo, their fat deposition impacts their long distance stamina, migrate from south eastern coast of USA to Yucatan peninsula, If they've eaten well, they'll go straight across the water. If they haven't eaten well, they follow the coast.
Zugenruhe? What triggers it?
• In birds, when it gets close to migration time, they get really restless at night.
• Usually triggered by photoperiod, hormone levels impact this behavior.
One way migration?
population over time back and forth but individuals leave, lay eggs and die
Orientating vs navigatin?
Orientating - recognize and maintain compass direction
• Navigating is the active usek, having map and compass
• Tends to be instinctive, their ability to navigate is learned.
• W/ young orientating birds, they're heading north, even if you move them, they still head in the same direction.
• W/ older navigating birds, they adjust to you moving them and redetermine their positioning.
How do birds use stars?
put birds in planetarium, rotate stars, birds respond. When they're in zugenruhe, they want to orientate, you'll see the ink in a certain direcition. No zugenruhe, ink is dispersed in a random pattern.
Group formations? Best route? Examples of?
• Wing beats in a pelican when they fly, alone its high, when close in formation, they don't have to beat wings as often, easier to fly. Reduces energy costs.
• Best route - most European songbirds all cross the mediterrirarean at the nearrow point between southern spain and Africa, llonger journey, reduces overwater compenent, prevents risk of drowning.
EXAMPLE OF INDIVIDUALS ACTING TO REDUCE COST
Conditional migrants? Example? Three predictions?
1. Alternative strategies in evolutionary equilibrium. These could be genetic-based strategies that are fixed by selection at the given frequencies. This predicts equal fitness for both migrant types, and that the differences between them are genetic-based. The problem is that individuals can switch between both.
2. They could be making the best of a bad situation and the conditional part could be a behavioral assessment. It may be better to stay but perhaps only a select number can remain and all others must leave. This predicts the ability of birds to switch.
Behavioral assessment idea supported. They start leaving at a time when dominance contests increase in frequency. They switch to staying when they are older and more dominant. Sometimes migration isn't better. Individuals switch tactics.
• Any modification of behavior that results from experience rather than maturation that may be used for some indeterminate period of time.. Don't have to use it.
Non associative learning?
o Habituation - Decrease in response to repeated stimulus that has no positive or negative consequences (no reinforcement). Learning not to respond. This is important with young animals, who are typically hyper-sensitive. Can be disrupted by almost any change in the experimental conditions. If repeated presentation of one stimulus leads to habituation of a response, the same response can still be elicited by a different stimulus.
o Sensitization - Increased responsiveness to a stimulus. A period of high responsiveness following arousal by reward or punishing experience. Presentation of a particular significant stimulus (such as food or electric shock) lowers the threshold for the display of relevant behavioral response to the point where a second stimulus which would not normally illicit a response will now do so. Can be either adaptive or non-adaptive. Could be more adaptive if being frightened actually means a dangerous action is likely to follow. It is adaptive if stimuli and events are likely to be paired.
BEHAVIOR MODIFIED THROUGH AN ASSOCIATIONo Classical or pavlovian conditioning -
o Operant conditioning -
Are all associations possible?
Learning preparedness - what an animal is biologically programmed to learn - learning is only possible within the boundaries set by natural selection. Color is relevant to food quality in nature, size not so much. Weird colored bread no good, bigger than normal bread? No biggie. Color could be irrelevant to danger, but sound could be relevant to danger. Timeframe - easy to determine that food eaten yesterday made them sick, even though there is a time lag between consumption and sickness. The same cannot be said for being bonked on the head
insight learning is a type of learning or problem solving that happens all-of-a-sudden through understanding the relationships various parts of a problem rather than through trial and error.
Signs of higher intelligence in terms of learning? Examples?
o Learning is not a sign of higher intelligence
Some types are - not simply trial and error or associations
• Insight is a sign of higher intelligence. Ravens will come and pull up the fishing line, put it under their feet, eat the fish. Some could argue trial and error. Ravens are good problem solvers.
• Chimps in a cage with suspended banaa and boxes.
o Eventually stack boxes to get banana
Could be insight learning? Always an element of saying well it could be trial and error
6 signs of higher intelligence?
learning: Not just trial and error
•Language: Key lies in new contexts and association. Chimp flipping off trainer.
•Planning intentionality: Plan, act on later. Mom chimps rocks and nuts to kid
•Death: elephant bones, dolphin suicide, chimp pet cat said sad b/c dead. Dolphin saving people in ocean
Tools: higher intelligence?
signs of higher intelligence.
Language: higher intelligence? Example?
signs of higher intelligence.
o Aspects of grammar could be taught to songbirds.
o Syntax is a sign of higher intelligence
o Key lies in new contexts and associations
o Simpleton explanation - they get a reaction, they like it
o A chimp knew sign language, in a boat, they get to the shore, he signs to the chimp, go over and tie the boat up. Chimp says no. The chimp then flips him off. New context!! - dude im not tying the boat up. Sign of intelligence.
Self awareness: higher intelligence?
o Great apes are all self aware, dogs are not.
Know images in mirror are them, but red nailpolish on their forehead, they try to rub it off.
Planning and intentionality: higher intelligence?
signs of higher intelligence
o Chimps can plan. When a subordinate male lures a female away from a dominant male with a series of actions and behaviors, is that intentionality?
o Chimps have signed they were going to go do something, and then they went and did it.
Death: signs of higher intelligence?
o Elephants will act differently when they find elephant bones. Get in a circle, do a swaying thing, apes have also been known to mourn. People will argue, how can you understand whats going on in their heads?
Should chimps have rights? differences between chimps and humans?
o Non-humans, but definitely persons. Have self awareness, feelings, and high level cognitive powers. They don't talk about yesterday or tomorrow, cummincation is more instantenous. Share 98% of our DNA
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