Exam 2

fusion of gametes

mating and remating-males favor frequent mating and remating, females do not
duration of mating-males prefer longer mating to maximize the amount of sperm transferred, females prefer shorter bc it can be harmful due ot predation or antagonistic mating structures

where males and females have different desired traits for the same genes.

intermediate trait suboptimal for both sexes

only 4 options(ACGT)

Sex chromosomes-allow sex specific traits

avoid mate finding cost
two fold reproductive advantage(all alleles come from one parent as opposed to two)
Maintains “co-adapted” gene combinations(gene combos that create higher fitness always inherited together)

escape from deleterious mutations due to drift(mullers ratchet)
increases the efficiency of selection for beneficial mutations(Fisher-Muller effect)
increases the rate of response to sexually-reproducing antagonists(parasites) (“Red Queen Hypothesis”)

deleterious mutations eliminate high fitness genes over time via genetic drift
sex can escape by recombining high fitness genes and "reverting the ratchet"
eg. asexuals have no way of reducing deleterious mutations

ex.-Y chromosome is shrinking due to no recomb

increases the efficiency of selection for beneficial mutations
when multiple beneficial mutations arise in a population asexuals have no way of fixing them bc of interference, sexuals do

sex is favored because it enables continual counter-adaptation (via rare and/or novel genotypes) to escape ecological antagonists (parasites, predators, etc.)
increases the rate of response to sexually-reproducing antagonists

ex.-snail pops in new zealand show higher male freq(thus higher sex) where parasites are most common

sexual reproduction that involves the fusion of gametes of different sizes

a consistent difference in reproductive success for individuals that differ in access to mates or reproductive opportunities

on differences in attractiveness to the other sex
typically female choice of male quality

on direct competition for mates between members of one sex
often male-male competition

differences between males and females

males invest less in offspring than females
increased mating in females(beyond certain minimum) does not increase lifetime success, whereas in males it greatly increases lifetime success

resource aquisition(better nuptial gifts)
mate access(mate guarding, combat)

Larger marine iguanas maintain larger/ better territories and have more reproductive access to females

direct and indirect benefits
"handicap" indicates good genes

ex.-longer tails on birds show they are able to survive with larger chance of predation

direct-provide a direct fitness increase in the recipient(use of territory, nuptial gift, disease free mate)
indirect-fitness increases conferred on offspring(better genes)

good genes hypothesis-preferences are for traits that act as honest signal of father’s genetic quality(ie higher offspring fitness)
sexy son's hypothesis-preferences are for traits that will increase the mate-attracting or –acquiring ability of sons(ie higher offspring sexual desirability)

high variaition=strong selection
low variation=low selection

we expect lower variation in mating success in 'choosy' sex, higher in 'competing' sex

polygny-several females per male
polyandry-several males per female
monogamy-one mate per individual

polygny-low female mating variance, high male maiting variance
polyandry-high female mating variance, low male mating variance
monogamy-variation in mating is equal

the simplest explanation is prefered

Convergence- the independent evolution in different lineages of similar derived characters
Convergence is often due to parallel ‘solutions’ to the same That is, convergence is often
due to the same ecological challenge. often due to the action of natural selection

reversal-can incorrectly imply distant ecolutionary relationships

chameleons, phylogeography showed the dispersion theory to be true

descent with modification

the relative age of two species, which evolved more recently.

genes that control development of body structures

gremlin gene in ducks and chickens causes cell death. expression in chickens causes lack of webbing, vs non expression in ducks causes webbing

changes in timing of gene expression

neofunctionalization-new copy has different funciton
subfunctionalization-parts of new and old genes are functional and disfuncitonal
gene conservation-copy with same function is produced
nonfunctionlization-copy is disfunctional

vtg gene responsible for transport of nutrients to egg yolk los tin humans as placention and lactation became primary form of provisioning

duplication of hox genes associated with emergence of vertebrates from ancestral cordate lineage

fraction of total variation in trait that is due to additive genetic variation

measuring the similarity of parents and offspring(parent offspring regression)

twin studies-monozygotic vs dizygotic twins(heritability when MZ similarity>DZ similarity
common garden experiments-growing plants in greenhouse
cross fostering experiments-switching eggs

R=h^2S
R=response to selection(magnitude of change in offspring depends on:)
S=selection differential(magnitude of selection)
h^2=heritability

higher seleciton or heritability yields higher magnitude of change(R)

estimating heritability
predicting R and S
estimating number of loci contributing to a trait

• start with two different genotypes (parents) with different trait values
• cross these two parents to make a ‘hybrid’ (recombinant) population
• measure individuals for traits
• genotype individuals for molecular markers/alleles across the genome
• associate marker variation with trait variation, using statistics

beach mouse fur color

periodic mass extinctions
Massive ‘adaptive radiations’, often after mass extinction events
Increase in net diversity over the history of the earth

The process that produces a cluster of species, all evolved from a
recent common ancestor, that occupy a variety of ecological niches

experimental studies-direct evaluations of the function of variation
comparative studies-factors associated with differences in diversity among groups
studies of adaptive radiation-features of groups that have rapid rates of diversification

increased intensity of natural selection from biological antagonists and the environment
increased intensity of sexual conflict with reproductive partners
ecological opportunity’: changes in selective conditions

light/dark mice placed in light/dark substrate with owls
light/dark mice survived better in their respective substrates.

compare groups (of the same age) to identify factors associated with differences in diversity between them
ex. sister group studies

Phytophagy in insects, in 11/13 sister group comparisons a shift to phytophagy was associated with higher species diversity

By identifying unique features
of the adaptive radiation, we
can infer the conditions/forces
that contribute to increasing
diversity

‘Trophic specialization’ in African Cichlids and various new teeth types