65 terms

Evolution of Predator/Prey Relationships


Terms in this set (...)

The inherent capability of a species to adapt to circumstantial change in a manner that increases the survivability of that species.
Evolutionary Stabile Strategies (ESS)
There are a number of adaptive strategies that better enable a species to survive. Thus... they have evolved in many species
are successful solutions that tend to show up in lots of species.
Divergent evolution
___ evolution is adaptive
species diverges into two or more species, becoming increasingly different over time in response to different environments
-adaptive radiation of the finches in the galapagos island
Convergent evolution
The process by which unrelated species become more similar as they adapt to the same kind of environment
-have something that works like an ESS and have more and more of it
An ESS strategy to avoid predators
Protective coloration= Cryptsis= cryptic coloration
-thorny devil
-sea dragon
Dentition- the similarities of the teeth of many predators are examples of ___ evolution
the teeth of many herbivores also illustrate ___ evolution.
Divergent evolution
Pre-historic elephants has tusks that would serve as shovelers
other functions like turning on females or defense
now you have several types of elephants or animals with tusks ( woolly mammoth, woolly rhunocerous)
Henodus Cyclops
is an example of covergence evolution
it is now extinct.
has plates like a turtle. it was an eater of clams, oysters, and muscles. Had grinding teeth in the back of the mouth.
conversion and divergent evolution
Darwins Galapagos Finches
exhibit divergent evolution since they diverged to occupy ecological niches.
This Galapagos Finch phenomenon is an example of: Adaptive Radiation

The Galapagos finches, when compared to species on the mainland, exhibit divergent evolution.

Many other pacific islands have excellent examples of divergent and convergent evolution.

Probably linked to volcanic origin of the islands
(example- the Eye Eye in madagascar. there was no predators and had a woodpecker niche)
Because of lengthy competitive evolutionary processes between mainland species, the occupiers of various mainland ecological niches will be more efficient; each niche will be occupied by different species.

And... because of superb adaptations, those so adapted to a niche are difficult to dislodge from the niche they occupy

In the Galapagos Islands, there were no other species of birds, so the finches ___into the available unoccupied niches.

Again, Adaptive Radiation is also seen in Hawaii, New Zealand, and other S. Pacific islands
: Because of ___ an animal will evolve a mechanism to maximally exploit a resource
For example woodpeckers in Ecuador. There was no woodpeckers in the Galapagos but there was that niche, and now we have this finche that developed the ability to live in that niche.
The eye eye is a woodpecker finch in Madagascar.
Prey behavior
A wide variety of anti-predator behaviors have evolved. Very few are unique, i.e., many anti-predator behaviors are found in more than one species and are thusly considered ESSs.
Anti-Predator Behavior
A species typically has one well developed anti-predator behavior which is optimal in terms of C/B ratio.

Usually, there are several backups:

EX: A rabbit's first defense is to freeze, relying on camouflage. If camouflage does not seem to be working, then the rabbit will run erratically. Finally, when cornered, as a last resort, the rabbit will fight.
Several defenses
Species with a diverse genetic endowment that provides a hierarchy of ___ ___against predation are more likely to survive and therefore to reproduce.
Avoiding detection by predator/ Camouflage
the first strategy designed to avoid being eaten.
Often requires that the animal remaining motionless since many predators have excellent motion detectors.

use camouflage, body decorations,silhouettes.

These Zebras don't look like they are camouflaged at all and At night they don't look like they are in camouflage at all but the stripes break up the silhoute of the animal since most mammals are color blind (lions) so this works to break up the body image of the zebra. Evidence that these patterns confuse biting insects that suck blood-patterns decrease the biting animals.
second strategy to avoid being eaten

signals that warn of potential danger to predators.

These are clear signals - colors are typically BRIGHT, easily seen and recognized. Similarly, sounds that are easily heard (hissing; rattling).

Examples: Arrow frogs (display their bright toxic colors) Saw fly larvae, Blister beetles, Bombardier beetles (3rd chamber with toxins), moth caterpillars, Blue-ringed octopus
another word for warning
toxic animals
Blue ringed ocutopus-So fragile. Size of thumb. When it catches something that is dangerous (like a crab), it has a beak. The beak has a venom that will kill quickly.
When they are aroused it shows the blue rings. It is a warning- I am toxic.
Beak has different kinds of venoms that will kill very quickly.
Very good at camouflouge. And it warns you it is toxic.
Warnings is related to ____.
You see a lot of eyes, but they are fake eyes.
When an animals is going to attack it will usually go for the head, and the eyes are usually with the head.
So we see moth the bird sees it, so the moth spreads wings and shows eyes as the ones in owl. The owl predates the bird, so the bird stays away.
Hog nosed snakes- play dead: a lot of predators don't want to eat dead animalsm it wont work with vultures.
Bottom 2 pictures are snake caterpillars but they look like a snake. Fake eyes and fake teeth. Because it works
Mimicry (structure, color)
3rd strategy to avoid being eaten
____ of environmental objects for camouflage, dangerous animals
as in Batesian mimicry, distraction...

Usually the ____, ____etc. is what gets mimicked, but also, behavior may be mimicked... non-cobra snake spreading hood and rear up; non-rattle snakes shaking tail in dry leaves; fly mimicking dangerous insect when confronted by jumping spider.

Blister beetle is mimicking this bister beetle here
Robber fly does not sting but it is a mimicry of a bumble bee (yellow and black) people stay away from bc it will sting
Examples of mimicry
An octopus in New Guinea waters has
eight arms each of which mimics very
poisonous sea snakes (Sea Krait).

Hog nosed snake spreading a hood which mimics a cobra

Mimicking thorns, bird dung, leaves, and twigs (obviously camouflage).
Mullerian Mimicry
dangerous species mimic each other: It pays to advertize
if two species were confused with one another by a common predator, individuals in both would be more likely to survive.
Martensian Mimicry
very poisonous mimic less poisonous
predator will learn to recognize the warning
Distraction or misdirection
Related to mimicry - where an animal uses ___ or ___
to confuse predators - butterflies with fake heads; lizards' detached tails that continue to writhe after detachment.

Predators most often go for the head since if the head of the prey is incapacitated, the rest of body can't escape. So if the predator is deceived into attacking the hind end which is disguised as the head, the prey animal can escape...
Mimicking a dead animal
opossums, hog nosed snake, some fish

predators lose interest in prey that doesn't
" cichlid is a death feigner, it's not trying to avoidpredators, Tobler said in the March 2005 Journal of Fish Biology. It is
itself a predator, and feigning death is the way that it hunts."
Terminating pursuit

Antelope "Stoting" = leap straight up and land with stiff legs
The hypothesis is to tell the predator is "look at me, I am fit, look how high I can jump" don't bother me don't chase me catch another guy
Or maybe it is used to look for other predators, or social cohesion,
Or as a warning signal to tell other animals that there is a lion present.
Why stot? A
a. Advertise to the predator the fact that the animal is alerted, and, based on the vigor of the Stot, very fit.

b. Leaping helps the antelope to better spot other lurking, team-hunting predators.

c. Provides an "Alarm" signal which serves to alert offspring and relatives.

d. Social Cohesion: Stot serves to coordinate escape by the herd or even to attack as in mobbing.

e. Confusion: With so many animals running in so many directions, predators lose focus on any one animal...

If I throw one ball to you, you catch it; if five of us throw five balls at the same time, you miss all of them...
Detection and Vigilance
sensory capabilities in prey have evolved to provide optimal predator detection--- some animals optimize vision, others hearing, still others, smell.

Cross species defenses may augment

The prey species is going to have the ability to spot the approaching animal.
A war going on between the predator and the prey
You can stand still and a deer wont see you, they have great movement detectors.
Safe distance learning
C/B analyses for both predator and prey.
Lions are very fast, but quickly build up dangerously high heat levels when
attacking and pursuing; so lions try to get close by stalking.

Prey species are almost as fast, but have better endurance and have learned the distance that must be maintained in order to avoid capture...

But, other predators must also be simultaneously detected (lions cooperate in hunting... one in plain sight or up wind; others may lie in ambush).

Consider situations where a prey species continue to munch grass when a lion is in sight; they know the safe distance (or can spot a non-hungry lion).
they know the distance between the prey and predator to be maintain safe distance.
There is a safe distance, the lions can attack- how close can I get before an animal attacks.
The safe distance from a cheetah is much longer than the distance from a lion.
Use of Sentry
ducks, zebras, meercats, monkeys.

Meerkats; social animals, and easy to maintain. Have a fence post or a structure and you will see a meerkat standing on top looking for the approach of predators. (Smaller cats, reptiles or eagles)
Looking for predators( snakes, cats, eagles or rapture) serve as look out.
The rhesus moneky (on right) is serving as a sentry-the look out.
In the dvd clever monkeys-there is one monkey that is the sentry monkey and he doesn't report anything until one monkey gets eaten, the rest shame him.
??Does the animal that gives the warning put itself at risk???

The one who gives a warning cry is the one who mainly gets hurt. So it is an altruistic act.
Reciprocal altruism- "ill give the warning this time, but next time you can give the warning"
Kin altruism- I have brothers and sisters, aunts, uncles in this flock- if I give a warning cry they will benefit.
A characteristic of group is to give warning cries, those are then less eaten. (those groups that have someone giving warning cries are less eaten)
Interspecies cooperative vigilance
rhinos and tickbirds

The species that cooperates with one another
Might have 3 warning cries, one for each predator. Another species might have the same warning cries for other predators. So although they are different species, they all learn the warning cries of each species.

Cooperation between tick birds and rhinos. The folds of rhinos have ticks and the birds will get rid of ticks
Cooperation across species
Baboons and antelopes

Baboons and antelopes, Both understand the same warning cries.
For example when your dog barks you know him will enough to understand his warning.
Group defense
musk ox in protective circles, mobbing, stampedes.

There has to be a balancing act concerning group size, ability to forage, and likelihood of attracting predators (C/B ratios).

African cape buffalo, have immense horn. The only major predators are the lion. Lions are successful eating them through team lion approach. If you kill one you have food for the whole month.
Lions will also hunt giraffes and elephants.

Musk's oxen live in artic regions. They have long fur and long hair. And keeps them warm. If a predator, lie a pack of foxes, approaches them they form a circle with their horn pointing outward. And the little ones will get inside the circle.
largest concentration are sardines, and form a school that is miles long, will attract predators, sword fish and huge whales that will get below the school to eat the fish. Very often predated by fish and killer dolphins
Flocks of starlings: we had a problem in this campus with starlings, and were real slick and this thick, had electronic canons.

Owls waiting for bats to come out of cave.
Ganging up
Many goats surrodiing a nake, the all surrounded the snake and finally they ate it.

Took this lepord they killed and did taxidermy on it. Wired his head so it could turn around. Put tape recorders in it so it can give a loud roar and put it on a rail which was about 10 ft long. And when chimpanzees or baboons would approach the leopard roared, turned his head, and snaped his jaws. they used the same leopard twice: once with chimps and once with baboons. All chimpanzees are alarmed. A lot of the bigger males-(hair standing)- ready for war. They will start picking up branches, rocks, and beat the hell out of the leopard. Same thing with the baboons. The male soldier baboon came out for war.

Other examples of social insects are Bees and insects ganging up on you.

Another example: goats. Like a goat convention because they were all bleating. 6 goats surrounding a snake. Each goat would jump in to do a flamingo routine and finally they killed the goat.
Group defense woks.
In general, the more animals in a group, the better the detection and defense of the group.

BUT: The greater the size of the group, the greater the attraction for predators.
When predator pressures are high, the size of the group may decrease.

If Predators make two kills per day, then:

Herd size = 10, then % mortality = 20%

Herd size = 20, then % mortality = 10%

Herd size = 100, then % mortality = 2%

Herd size = 500, then % mortality = 0.4%
Dilution effects
- earlier we considered the fact that predators are attracted to groups of animals. We also mentioned group defense tactics.
__ ___refers to the decrease in probability of predator attack on any one prey as group size increases
the decrease of the threat to any group member as group size increases
Selfish Herd
groups whose members increase the probability of escape by using the herd as shield, distracter, or dilutor.
The penguins don't want to go in first or last bc the leopard seal can eat them. After the first one comes in, the leopaord seal attacks. So during this time all of the penguins at the same time get in the water.
The selfish heard- best strategy is to use the herd as a shield.
Example: a leopard seal under the ice waiting for a penguin to eat. The penguin know the leopard seals are there. They also know they don't want to be first or last. They want to be in the middle. The penguins then pretend to "jump" to get their buddies to jump.. And once one jumps they all jump. You don't want to be last. So the leopard seal only grabs one while the rest escape.
Fighting back
since predators are often more powerful than prey, fighting is often a backup plan of last resort, however, we do see animals whose primary mode of defense is to attack.
Mechanical devices - moose antlers, spiny sea urchins, porcupines, hedgehogs, certain fish, hooves, horns, teeth, etc.
Noxious chemicals
skunks, wasps, scorpions, caterpillar noxious spray and stinging spines (stone fish) and nematocyst stingers in the Box Jelly fish

Blister and Bombardier beetles, fire ants, toxic frogs, lion fish
Box jelly fish
Very fragile, but it is toxic. It is toxic bc it is fragile. If fish gets stuck in his tentacles it will be kill with his tarpoons.
If we get him, although he is flexible. He will sting.
Food prefers not to be eaten
When fruit is eaten together with non-digestible seeds, and later deposited, with a little fertilizer, away from parent plant, thereby propagating the fruit. Fruit must be ripe for this to work, so often fruit is "toxic" until ripe, and, changes in fruit color and/or odor often notify consumers as to
ripeness (and the maturity of the seeds within the fruit).
Problem with eaten behavior is that lots of food would prefer not to be eaten.
When the seeds are mature then the seeds changes its color and say. "I can be eaten now."
Its kind of like the plant saying "eat me now"
Most mammals are color blind. If you are a monkey and spot a persiman tree and has a lot of green you know not to eat them, but if it is orange you know when to eat them. Advantage of seeing color.
Generalist Feeders
will eat anything that doesn't eat them first.

AKA: Omnivores - exploit whatever food source is available.

BUT: Generalist (omnivores) are not adapted to a specific diet and can't compete with specialists for the specialists' food sources.

Sensory systems of omnivores are designed to detect a wide array of foods (contrast with specialists).

Teeth (dentition) - are not specialized. (contrast with specialists).

Digestive mechanisms are designed to digest variety of foods. (contrast with specialists).

Taste systems and taste aversion are well developed (contrast with specialitst)
Taste aversion
Generalist taste systems and ___ __ are well developed (contrast with specialist).

Omnivores (Generalists), being adventitious eaters, might ingest food that is toxic, and in many cases the toxicity of the substance does not become apparent (barfing, hurling, etc.) until sometime later.

Generalists can switch food sources as a function of seasonal variations in availability of food. This is a real advantage.

Generalists are usually found in temperate zones where there are seasons and therefore seasonal variations in types of foods can be exploited.
Omnivores are generalist. Live in temperate zones. Fruits and vegetables that are available in the spring.
Generalist almost always have some sort of a taste adversion. They are adventitious eaters. Find something and they get sick so they avoid that food/smell. They can switch food sources as a function of seasons. Found in temperate zones
Types of specialist
1. Fructivores
2. Herbivores
3. Carnivores
4. Insectivores
5. Other more specific.... Ex. Nectar
If specialist are competing with generalist for a specific food source, the specialist will win.
As a result of long-term competition, no two species occupy exactly the __ niche...
Think: African Browsers specialize in different vegetation
Specialist Feeders
well adapted to a specific diet in terms of locating, capture, consummation (using specialized dentition), and digestion of a specific food source.
Specialists have evolved sensory, dental, digestive, etc. mechanisms to best exploit their ecological niche.

BUT: Specialists are very dependent on the food supply so are usually found wherever their specialist food is available year round (tropics).

Alternatively, if food is not available year round, then they must hibernate, migrate, or store (hoard) food when supplies are adequate.
Diversity of Ingestive mechanisms
We see convergent evolution: Filter feeders include lots of animals - oysters, clams, etc.; whale sharks, baleen whales; sponge bob-square pants etc.
How do we get food in?
Clam-filter feeding. Sucks water through bottom and scraine outf food particles in the water at end. Clean up.
Baskin shark-open his mouth and gets lots of small animals, intake a lot of the water, have a drain,
Baleen whales- take in a a lot of quill- open their mouths and intake a lot of the water that has food particles and then squirt the water to drain the water out.
Sq is sponge/filter feeding
a food sources such as flowers' (nectar), in order to optimize pollination, evolved flower shapes and configurations 'designed' to optimize feeding by one specific species.
However, if pollinating insect becomes extinct, then the plant becomes extinct (and vice versa).
small particles
use of pseudopodia (amoebas), cilia, mucoid surfaces, flagella, nematocysts, tentacles, setous (threadlike).
pseudopodia (amoeba) e.g: sperm burst out of amoeba, uses the enzymes to escape the amoeba.
Glow worms- help insects get out so they follow the light and then eat the insect
Larger Particles
swallowing of particles or the substrate containing the food (earthworms).
Larger particles. A lot of particles, like earth worms. They eat the earth. Very good for garden. Nice natueal garden fertilizers.
Snail have latch that spread over and makes its bigger.
Scraping, boring - snail teeth, algae eaters
Seizing, constricting and swallowing-snakes
Anaonda biggest snakes in the world. It wasa able to eat caveman, was able to come out but the python killed it.
Altough heads are only so big the jaws can become UNHINGED to bite you
How does a snake know its prey is dead- answer if it isn't wurming, but in reality the skin can detect the heart beat. The snake can detect through the skin the hearbeat or the pulse. And when it stops it is time to eat it.
Mastication= chewing/shredding.
Another way of saying chewing or shedding
From ocatpus, located in the middle.
bird beaks
These different beaks are the results of adaptations designed to exploit different food sources

Kind of like aquatic birds where thry to get their prey.
The pink come from eating shrimp
Kiwi: Makes its livinf by looking at the forest floor for florenzini. the receptors in birds detect the electrochemical;
Flamingo is a filter feeder- sucks water through beak and strains out microorganism and shrimp. The pink feathers in flamingo comes from the shrimp
__ have evolved to fit a given type of food which therefore can be used to infer diets of extinct animals.
African Lion
Smilodon (Sabre-toothed)
tearing off chunks
big reptiles, lions
external digestion
Soft tissue of fluids
usually invertebrates but, think of vampires
Spiders inject toxin which paralyzes and subsequently digests the tissue inside exoskeleton

Mosquitoes, horse flies, ticks
respond to butyric acid smell {SS} of warm blooded mammals.
Butyric acid- you wouldn't like the smell. Serves as a sign stimulus to trigger a fix and response.
Some ticks can be
We have tick birds, in Africa, on animals like rhino (symbiotic relationship); not seen so much in North America. The range of the ticks is growing.
the butyric acid turns off ticks
Absorbtion through body walls
internal parasites such as tapeworms
Absorbtion through body walls-
This is a tape worm, scolex head with kind of like teeth.
Absorbs nutrients. Weight control medicine.
Tape worm eggs absorb 20% of calories taking in. when you lose enough weight you simply give them worm medicine and get rid of the worms.
This is actually done now.
parasitic in your eye brows (or worse... in inner ear)
Symbiotic micro-organisms such as bacteria or viruses
Food also ____ -Plants compete for sunlight - often grow high -C/B of trunk... Vines take shortcuts! Herbivores (Giraffe, Okapi, Gerenuks) specialize to exploit lofty leaves