Lec 11- behavior and fitness Flashcards
ethology
study of behavior
behavioral ecology
study of behavior in ecological context
- focuses on vertebrate and invertebrate
- expanded to plants and microbes
what is behavior?
- difficult to define
- lack consensus on whether “motion” is prerequisite
- should it apply to plants and microbes
internally coordinated responses (actions or inactions) of whole living organisms (individual or groups) to internal and/or external stimuli
- any response
Hamilton’s 4 classes of social interaction
- based on fitness consequences
cooperation, altruism, selfishness, spite
cooperation
both donor and recipient benefit
- within species and often b/w related animals
- exchange resources and protection
altruism
recipient benefits, donor doesnt
selfishness
donor benefits and recipient doesn’t
spite
donor and recipient don’t benefit
fitness
of offspring contributed by individual relative
- no of offspring produced by other members of pop
donor
indivdual performing action
recipient
individual recognizing behavior
inclusive fitness
determined by survival and repro + the survival and repro of relatives
- behavioral interactions b/w 2 individuals may have +/- effects on either individuals inclusive fitness
- affects closest relatives and interpret social interactions like altruism
how does natural selection favor behavior?
increases inclusive fitness of individuals
- individuals selected for or against causing evolution within a population
- actions are on individuals but affects future generations
how does natural selection work on behavior?
only occur if behavior has a genetic base
honeybees and behavior
work is distributed based on age
- young stay in to care for young bees
- older go out to collect food
- work behavior tied to levels of specific protein kinase (PKG) produced by one gene
- more PKG = work out
- less PKG = work in
with age comes changes in work behavior
adaptive behavior
- acquired
- increases the fitness of organisms and will be selected for over multiple gen
- relevant to evolution
- range of options
expression (phenotype) depends on genes and environmental conditions
which 2 behaviors should be selected for by natural selection?
cooperation and selfishness
- increase donor fitness
which 2 behaviors should be selected against by natural selection?
altruism and spite
- decrease donor fitness
altruism
b/w relatives
- direct observations and molecular data
- red squirrel
- donor loses energy to care for recipient (distant relatives)
- recipient can pass on genes
why would donor commit to altruism?
- group selection
- manipulation
- reciprocal altruism
- kin selection
group selection
individuals neglect own needs in favor of group
- part of own population and genes are in relatives
manipulation
donor does not recognize it is being parasitized
- tricked so does not know they arent related
reciprocal altruism
recipient will pay back at one point in future
kin selection
individuals increase inclusive fitness by helping survival and repro of relatives (kin)
- able to spread genes for future generations
coefficient of relatedness (CR)
probability that an allele at given locus will be identical by descent among 2 individuals in population
- quantify relatedness
-
CR among kin
50% reduction in coefficient of relationship b/w each additional connection
- small = distant relatedness
- big = closer in relatedness
parent - self : 50% (direct)
grandparent - child: 25% (skip 1 gen)
altruism and kin selection
cost/benefit < CR
how does the cost get outweighed?
the more distant relationship, the smaller the CR, the larger the benefits
how does the benefits get outweighed?
the higher the CR, the more likely the donor will benefit from being altruistic
cowbird- selfishness
laying eggs in other nests
- obligate brood parasite
- parents dont waste energy to take care of eggs and others will care for genes to get passed on
phoebe and cowbird eggs
cowbird lay eggs in phoebe bc they look the same size and shape but diff colors
phoebe pov of cowbird eggs
raising eggs is altruistic behavior
- manipulation: donor has no means to recognize/prevent interactions
- doesnt know its being tricked
European badger
spite
- tuberculosis infected so leave area to infect others bc they have a fitness disadvantage
- spread to non-kin so they have fitness disadvantage
sociality
group of individuals living together and involves some degree of cooperation between individuals
- cooperative feeding (capture and eat together)
- defense of social group (diff roles w/in group)
- restricted repro opportunities (dominant M and F and no others can mate)
examples of social behavior
- mutual grooming (monkeys)
- group protection of young (young in and old out)
- highly complex societies (colonies)
cooperative breeders
live in groups (pack)
adults help with offspring
- defense
- prepare/maintain living area
- feed young
why does cooperative breeding work?
members most likely relatives
- inclusive fitness (increase fitness of close relatives)
tit for tat
- help the group then they will help you (reciprocal altruism)
eusociality
highly complex social behavior
eusocial animals
- individuals of more than one gen live together (multigenerational community)
- cooperative care of young
- division of individuals into sterile/non-reproductive and reproductive castes (excludes cooperative breeding animals except mole rat)
insects, crustaceans and mole rat
leaf cutter ants
eusocial
- one most socially complex organisms
- up to 7 casts
- workers have diff looks
naked mole rat
one of 2 eusocial mammals (Damarland mole-rat, south africa)
- 3 casts
comparing leafcutter and mole rat
queen - only reproductive person with M (interbreeding common as only have 1 Queen)
small - foraging and maintenance (convergent evolution)
large - defense
why has eusociality evolved?
kin selection- role as individuals in colonies have high degree of relatedness
ecological constraints- role in defense and maintenance of burrow sys
