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Terms in this set (36)
small scale: station keeping
all movements within a home range. an animal within its home range can move about to find resources, mark its territory, check to see where things are, put things in hiding
movements that go outside the home range. look for other habitats, mates, needs to be food from outside of that
scale: natal dispersal
movement away from cite of birth to cite of reproduction. often its not a return trip which makes it unique. usually its the males that leave the home range.
females are philopatric
stay where they are born and mate at that site
males stay females leave
pikas, kangaroos, chimps
largest scale movement pattern
persistent movements across different habitats in response to season. can migrate without coming back
migration comes with changes of seasons. why?
changes in resource availability or habitat quality, as the seasons change and habitats change, the animals have to move in order to keep them in a habitat that is good. when they move their physiology has to change. their responding to seasonal changes as well. has to be a trigger (zygeber: photoperiod, light changes) seasonal change is constant
causes of dispersal: proximate causes
parent offspring conflicts. if its the male leaving, there's a link to testosterone. testosterone leads to aggression, more hostility, parent offspring conflict is therefore enhanced. doesn't have to be linked to testosterone though, it could be crowded and pecking could be happening
causes of dispersal: ultimate causes
avoid inbreeding depression: reduction of reproductive fitness that comes from parents closely related to one another. offspring usually don't survive to reproduce.
why does inbreeding cause reduction of fitness
increase in homogenisity of DNA. without dominate alleles to mask deleterious recessives, they start to express themselves but when u inbreed u become homozyogus recessive.
linked to dispersal. predicts that one sex should disperse from a naval area. inbreeding will be avoided because parents one mate with offspring and closely related kin wont be able to mate
predicts that males should disperse since competition is mainly between males in most populations
if only reason to disperse is to avoid inbreeding, then dispersal should be far away as possible, but
leave natal area but don't go as far away as possible
matings occur between very very unrelated individuals. when completely unrelated, they also produce unfit offspring.
why does outbreeding depression produce unfit offspring
because genes that individuals possess are linked to environment, by breeding with someone from far away, introducing genes that are not beneficial to that environment, haven't been maintained through natural selection. called locally adaptive gene complexes.
when individuals with similar genotypes - typically relatives - breed with each other and produce offspring that have an impaired ability to survive and reproduce
there is an optimal degree of relatedness that produces the highest reproductive fitness. good to mate with individuals only slightly related to you, not highly related to you.
what maintains adapted gene complex and prevents inbreeding
mammals leave areas in which they were born but don't trabel far away but with individuals that are loosely related to them.
optimal inbreeding is linked to cooperative behavior
offspring are more adapted from individuals slightly related to us, look at this altruism directed to kin and see benefit there, get cooperative behavior increases as relationship is at optimal.
factors limiting dispersal: locomotive restrictions
any barrior that limits ability of animals to get from one point to another, limit how far they can disperse from one another
factors limiting dispersal: behavioral patterns
sometimes suitable environments are not selected by animals because of historical preferences of the species.historical preferences had been from evolution, changes in habitat use going on.
factors limiting dispersal: competition
trying to go somewhere and competing with others trying to go to the same place. limit where you disperse to
factors limiting dispersal: predation
going from point A to point B, subject yourself to potentially being preyed upon.
factors limiting dispersal: abiotic factors
all those things part of environment, nonliving parts of environment
temperature and moisture limit dispersal. could be light, pH, soil structure.
if its too hot to cross, then you can't go that way.
factors limiting dispersal: tradition
mountain sheep: males learn home range knowledge from dominant male. not on purpose but through example. gets passed on through generations
going from one habitat to another, learned where to go based on tradition
theories of habitat selection: optimal foraging
how long to stay based on benefit cost ratio.
by using this, we should be able to predict which patches would be selected by certain species once they start to move
predict when they should disperse, when they have trouble catching food that they need. time spent getting food
theories of habitat selection: ideal free distribution
as density increases, less desierable sites start to become occupied. animals spread out so they all have equal fitness. individual in poor habitat has larger home range than individual sharing richer habitat with a lot of others. can share richer habitat because they get what they want equally
predicts function of reproductive success
Ideal free distribution assumptions
-animals have complete and accurate knowledge of distribution of resources. know where resources are, don't have to guess.
-animals are passive towards one another and go to best possible site. know where all resources are distributed and can go from one site to another. if competition is employed we violate the model and no longer accurate.
as infraspecific competition increases, Despotic Distribution happens
some individuals monopolize resources and others don't have access to them.
homing process: path integration
dead reckoning: i recone home is over there because ive maintained in my head where i've gone away from home. instead of retracing their steps, they simply use the shortcut path (integrated path) if they're wrong, they're dead. don't need an external clue, can see that the more turns there are, the harder it is to reckon where home is. works well, but not good for long range homing. works for short scale movements
homing processes: piloting
use landmarks, distant visual cues in order to create a mental map of where you live. a mental map. landmarks closest to home are the most useful. error starts to increase as you get far away from home. use distant visual cues
homing processes: sun compass
the sun moves at a relatively constant rate throughout the day. if an individual orients itself off the sun and maintains a constant angle, they have a mechanism to get to another point
need a biological clock the sun moves 15 deg every hour. because we know this, it makes for clock shift experiments. shift animals 6 hours, they are off course by 90 degrees. showed repeatedly that many organisms are using sun compasses because they end up where they weren't supposed to because of the shift in time
important to stop migration as the day is ending, the sun sets due west. can orient off of this.
homing process: magnetic compass
they are obtaining directional info from geomagnetic cue. have to have some modification to cells in body to detect geomagnetic cue and orient from it. whale mice and mole rats.
homing process: cognitive maps
using the brain to create a representation of the geometric relationships among the home site, the surrounding terrain, sites of interest and terrain surrounding sites of interest.
males are better at creating cognitive maps than females
testosterone: hippocampus is involved, males generally have a larger hippocampus than females. so it may be that hippocampus responds to testosterone.
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