territories and migration Flashcards
state the ideal free distribution theory
there is no single ideal habitat
choice of habitat depends on current conditions and available choices
for warblers, if ideal habitat is densely populated, then a less densely-populated habitat may yield the same or better fitness benefits. this is referred to as _____________ selection.
density-dependent habitat
resource holding potential is the ability of an animal to competitively _______ and ______ territory and resources, maintaining their priority of access to them.
secure and defend
economic defensibility is the ________ for maintaining a __________.
cost-benefit tradeoff; territory
how do tiny pseudoscorpions transfer tree trunks?
by infesting bodies of harlequin beetles, riding on their bodies and flying btwn trees
an example of economic defensibility (cost-benefit tradeoff for maintaining territory):
chimpanzees form ______ that displace and kill rival community to expand territory, gain new resources, space nd new females. Are these conflicts/wars long lasting or short term?
boundary patrols
long lasting
territory winning redstarts are heavier. they get wet area habitats like black mangroves. they are better nourished and left earlier to return to breeding grounds, producing more fledglings.
what about subjugated birds?
the subjugated birds end up with:
1) lower quality, drier areas.
2) did not retain weight.
3) suffered shortening of telomeres a degradation of DNA ends associated with aging.
3 ways to track bird migration
- isotopic, genetic markers show location of origin
- metal banding techniques - ID tag animal for re-capture
- GPS tagging
what is migration connectivity?
movement between summer and winter sites, including all stopovers in between
3 reasons why subordinate to territory holders. (3 hypotheses)
- arbitrary contest resolution hypothesis
resident always wins territorial battles - resource holding ptential hypothesis
residents have an edge in physical combat - payoff asymmetry hypothesis
residents place higher value on territory than do rivals
what is the dear enemy effect
animals treating familiar rivals less aggressively, having already settling the resource holding potentioal difference (dominance) in past conflicts.
lowers costs of fighting, increases value of territory to tenured residents
what is dispersal
a permanent move from birthplace to somewhere else
there are high costs for dispersal, like encountering new risks and challenges, and knowing less about the habitat. so why do animals move from their birthplace to somewhere else?
- sex-based dispersal - to avoid inbreeding
*if dispersal not possible –> inbreeding depression - migration (seasonal movement away from and then returning to same locations)
what does it mean when an animal is philopatric?
stays around birthplace
which bird species has the longest migratory route?
what could be the 1st step to long-reange migration?
sooty shearwater ~ 60,000km/yr
short-range tropical migration
2 hypotheses to expain migration evolution are?
tropical origins hypothesis
- migrate from tropical to temperate breeding grounds for rich food resources to support reproduction
temperate origins hypothesis
- migrate from temperate during winter nonbreeding season, to tropics for milder climate
which resource does the v formation in migration save
energy
blackpoll warblers migrate from northern east coast of N america to S america wintering grounds. some fly over the ocean and some fly along the coast.
which route is faster?
over the ocean is half the distance of along the coast
also fewer predators, is quicker and timed with weather fronts and wind patterns to reduce energy needed.
some salmons migrate at night, and some engage in predator swamping (wait in predator free zones to group up befoore moving through dangerous waters). how does predation swamping protect the population?
dilution effect (as the number of prey increases, the risk of any individual being eaten decreases)
**This occurs because predators have a harder time focusing on and capturing a specific target in a larger group. The presence of more individuals can provide safety in numbers, making it less likely for any one individual to be selected by a predator.
besides for reproductive benefit and milder climate, what is one more reason animals migrate? which 2 animals migrate for this reason?
avoid predation risks.
salmon and warblers
what are the 2 main forces for migration?
bottom up - for food and resources
top down - predation risks
what is the main factor driving declines in monarch butterflies?
lost of forest cover, exposing them to open sky and low freeze protection
