Evolution Final

phenotypic plasticity

differential trait expression across differing environments

constant traits

phenotypes with fixed expression across environments

reaction norm

the distribution of phenotypes for one genotype over a range of environmental conditions

measuring reaction norms

phenotypic variation of the same trait across two or more environments; slope indicates degree of plasticity; intersecting slopes indicate gene–environment interaction

big four environmental factors in plasticity

diet, temperature/day length, parasites, social environment

new view of plasticity

plasticity is fundamental to how organisms cope with environmental variation

reversible plasticity

response that can be induced and later lost

irreversible plasticity

environment affects a trait early in development and cannot be reversed

adaptive plasticity

plasticity that increases fitness by broadening tolerance to environmental conditions

non-adaptive plasticity

plasticity that moves traits opposite the direction of adaptive evolution

changes to adaptive value

environmental cues alter trait value, such as seasonal coat color

genes leading or following ?

question of whether genes or phenotypes initiate adaptive

evolution traditional perspective

genes lead and phenotypes follow in adaptive evolution

alternative perspective

environmentally induced phenotypic variation creates conditions for

genetic adaptation canalization

evolution of mechanisms that constrain plasticity to produce

one phenotype genetic assimilation

environmentally induced trait becomes genetically

determined evolvability

capacity of a system for adaptive evolution

morphic speciation

speciation associated with changes in morph number

asexual reproduction

production of offspring from unfertilized gametes

sexual reproduction

joining of genetic material from two parents to produce offspring

costs of sex

search cost, genetic cost, pathogen cost, numerical cost

two-fold sex cost

asexual lineages multiply twice as fast as sexual lineages

anisogamy

production of two different kinds of gametes

isogamy

production of one kind of gamete

benefits of sex

clearance of deleterious mutations, combining beneficial mutations, generating novel genotypes

Fisher-Muller hypothesis

sex accelerates adaptive evolution by combining beneficial mutations

Muller’s ratchet

irreversible accumulation of deleterious mutations in asexual populations

Red Queen hypothesis

sex helps hosts keep pace with evolving parasites

sex role reversal

females are larger and more brightly colored than males

intrasexual selection

competition among individuals of the same sex

indirect benefits

benefits that improve offspring genetic quality

direct benefits

benefits that directly improve female survival or reproduction

indicator traits

ornaments that honestly signal male genetic quality

runaway selection

positive feedback between female preference and male traits

sexual dimorphism

differences between sexes in secondary sexual characteristics

alternative mating strategies

divergent male strategies maintained by negative frequency dependence

sperm competition

competition between sperm from different males to fertilize the same egg

sexual conflict

traits that benefit one sex but harm the other

apophallation

chewing off a mate’s penis

pyrosoma

colonial organism formed by cooperating individuals

behavioral ecology

study of ecological and evolutionary basis of behavior

game theory

mathematical study of optimal decisions in strategic interactions

payoff

fitness increase tied to a behavioral choice

cost

fitness decrease tied to a behavioral choice

cooperation

behavior not favored in single encounters with unrelated individuals

evolutionarily stable strategies

strategy that cannot be invaded by alternatives

reciprocal altruism

sequential exchange of altruistic acts

conflict

differing fitness interests between individuals

direct fitness

fitness through one’s own offspring

indirect fitness

fitness through relatives’ offspring

inclusive fitness

sum of direct and indirect fitness

gain in direct fitness must be higher than loss in indirect fitness

rule for beneficial behavior

infanticide

killing offspring

siblicide

older or larger siblings kill younger ones

benefits of cooperation

vigilance, dilution effect, defense, cooperative hunting, resource defense

dilution effect

individual predation risk decreases with group size

pack hunting

group hunting allows capture of larger prey

costs of cooperation

increased visibility, competition, reduced paternity certainty, disease

ways to evolve cooperation

kin cooperation and reciprocal altruism

kin selection

natural selection influenced by genetic relatives

kin cooperation

association with relatives increases fitness

kin competition

relatives compete for local resources

coefficient of relatedness

expected proportion of shared alleles identical by descent

Hamilton’s rule

altruism evolves when C < r × B

eusociality

reproductive division of labor in social groups

haplodiploidy

sex determined by chromosome number

coevolution

reciprocal genetic change in interacting species

mutualistic

interaction with positive effects

antagonistic

interaction with negative effects

antagonistic coevolution

negative on one positive on another ex. predator/prey

brood parasitism

one species exploits another to raise its offspring

evolutionary arms race

also called coevolutionary escalation, when species interact antagonistically in a way that results in them both developing adaptations and counter-adaptations against each other

character displacement

traits diverge more in sympatry (same geography) than allopatry

symbiosis

long-term interaction between species

mutualistic coevolution

both species benefit

obligate mutualism

partners require each other to survive

facultative mutualism

beneficial but not essential interaction

commensalism

one benefits other unaffected, or both are unaffected

rhizobia

nitrogen-fixing bacteria in legume root nodules

microbiome

microbial community associated with an organism

vertical transmission

transmission from mother to offspring

mimicry

advantageous resemblance between species

mullerian mimicry

multiple toxic species share warning signals

batesian mimicry

harmless species imitates toxic species

prime prediction of mimicry is after sympatry

mimicry evolves after species co-occur

Wallace’s three laws

models and mimics co-occur, mimicry is rare, mimics are less abundant

why snake mimicry persists ?

lethal predator mistakes and mullerian mimicry dynamics

caecilian

limbless burrowing amphibians with maternal skin-feeding

life history

investment in growth and reproduction affecting lifespan/other traits

a mutation that increases ______ should become fixed

longevity

fecundity

reproductive rate measured by gametes or offspring

most important life history traits

age of maturity, reproduction timing, fecundity, survival

cost of reproduction

reduced future fitness due to reproduction

semelparous

reproduces once in lifetime

iteroparous

reproduces multiple times

survivorship curve

graph of survival across ages

life table

framework converting life history traits into population growth predictions

population grows as density increases

density affects growth

r-selected species

high reproduction early in life

k-selected species

traits suited for high-density environments