lecture 25 Flashcards

behavior focus on genetic and physiological mechanisms (whatever triggered)

of behavior focus on its effect on reproductive success (why it did) (effects post-sting)

observable response of organisms to external or internal stimuli

behavior that benefits others at personal cost

Goal to pass on genes, for betterment of group, some individuals do not reproduce

evolution of altruism among non kin

benfit the individual's close relatives, or kin

to explain the existence of altruism

Natural selection produces beneficial outcomes for whole group/species

If group selfish, they would die out quickly due to overexploitation, but altruist fitness would increase

Group under attack via George Williams

Evolution works with individual selection not group, traits chosen for benefit of individual not group

-mutation

-immigration

-lack of an ability to predict future source availability

limited resources, mutated individuals use said mutation to advantage/offspring advantage (two eggs to three eggs given sufficient resources)

more eggs produced, could move away

group selection assumes that individuals can predict food availability within population

Pop. size controlled via competition (individuals want control as much resource as possible), results in infanticide (male bears killing cubs/lions killing cubs to take over pride)

Important to evolution of altruism, vested interest in protect related individuals (siblings, offspring)

rB>C

altruistic gene will be favored by natural selection

benefits received and given is greater than cost

total # of gene copies passed on to relatives + reproductive output

behavior that lowers fitness of individual, but enhances fitness of relative

organisms that have reproductive division of labor, overlapping generations, and cooperative care of young

[ex.] Bees have female workers, male drones, only queen reproduces, males die shortly after

[ex.] Naked mole rats also exhibit similar behavior to bees (however both parents are diploid)

sisters than own offspring

0.50 (from father) + 0.25 (from mother) = 0.75

More advantageous for females to stay and care for sisters

lifestyle NOT genetics

• Individuals are confined to burrows or nests and escape is difficult.
• A dominant individual (i.e., queen) can prevent other individuals from reproducing.
• Food is abundant enough to support high concentrations of individuals.
• These conditions are also met in colonies of naked mole rats, which are diploid mammals.
• Females do not reproduce and only the queen (shown resting on workers) has offspring

cost for altruism offset by likelihood of return benefit

[ex.] Female vampire bat will regurgitate some food to feed other females, high likelihood that behavior will be returned later

Games in nature, tit-for-tat strategy usually most stable (do what was done unto them)

players do unto others exactly as has been done unto them

if adopted by population, cannot be invaded by alternative (rare) strategy

Benefits usually outweigh costs

Benefits: Group defense (increased vigilance (many eyes hypothesis) and protection through numbers)

Frequency decrease as group size increases

Not as supported: duration decreases as size increases

• Take down predators of bigger size
• Can exploit discoveries of other individuals in group
• Orca Example: More than enough food for 3, stable enough with 5, not enough food for 6

• William Hamilton (1971)
• Individuals in group will choose position in center for greatest protection (like sardines), bunch together when under attack

To remain at food or seek out new source? - Analysis via optimality modeling (Animal should behave in way that maximizes behavior minus costs)

difference between energetic benefits of food consumption and the energetic costs of food gathering is maximized

• maximize benefits and minimize costs of food gathering -
• More net energy, greater reproductive success

[ex.] Northwestern crow example: only large whelks (fewest drops required to break open)

[ex.] Leafcutter ant example: larger ants only forage at night due to parasitic flies active during day, small ants forage during the day

Basically causes more snow in north

Heavier snowfall -> bigger wolf packs -> decrease in moose pop. -> more trees due to reduced moose pop.

fixed area where individual excludes other members of own species via marking or aggression

Provides exclusive access to resource

Larger territory = more resource, but more to defend (Usually big groups only defend mating/nesting areas instead of entire territory)

• Fighting strategy is frequency dependent.
• The ESS is often a mixture of different strategy types like Hawk, Dove, and Bourgeois.
• The ESS is dependent on the values of rewards.
• The frequency of Hawk behavior increases as the payoff increases. (frequency of duck increases as risk of injury increases)

1:1 sex ration is ESS as fitness of one gender reduced when overproduction of that gender

one male with many females (elk, elephant seals)

one female with many males, usually bigger than males (black widows)

both males and females mate with multiple females and males, respectively (bonobos, mollusks)

chance they are monogamous animals (golden eagles, swans, one species of mouse, etc.)

two hypotheses for monogamy

males stay with females to prevent other males from being fertilized by other males (some types of beetles and dunnocks)

males remain to help rear offspring (70% of bird species are monogamous)

females stop male partners from being polygamous (burying beetles)

• Older martins claim top levels of martin house
• Sing song to attract others
• Older martins then mate with females of less experienced males

territorial and monogamous are

polygynous [males bigger than females)

good nest sites in male territory (male lark buntings hold territories in shade -> females need shade for chicks to live)

common when females congregate in groups/herds (elephant seal harems)

leks, prairie chickens and mannikins

Honeybees, sandpipers (females defend territories, limited only by number of males to incubate eggs), hyenas (females usually bigger than males)

females choose males based on particular trait

males fight each other over mates