E2 MC

According to Peer et al. (2011), waxwing rejection of cowbird eggs…

Is retained even when no longer under selection, which may indicate that the trait is not costly & may prevent cowbirds from rotating through hosts.

According to Dobson et al. (2012), Columbian ground squirrels…

Get indirect and direct fitness benefits from living near and being tolerant of close relatives.

According to Albo et al. (2011), male spiders present silk-wrapped non-food items to females…

If no food is available, because it gives the males equal mating success to males with food, though it may have fitness downsides relative to “real gifts.”

According to Dawidowicz et al. (2012), Daphnia evolve to mature quickly and die younger as an investment tradeoff…

When living near the water surface, because high visibility and predation mean that early reproduction may be all they get.

Which of the following would be most likely to maintain genetic diversity in a population?

Heterozygote advantage

Which of the following is the best explanation for why all three male phenotypes of marine isopods (P. sculpta) persist in populations?

All have equal fitness so long as the “sneakers” and “mimics” are rare and there are plenty of “alphas” for them to take advantage of.

A population of birds has a single gene that controls color. Blue phenotype is adaptive (blue birds attract mates easily), yellow relatively maladaptive. Which of the following accurately describes how sexual selection will affect blue allele frequency?

If blue and yellow are additive, then selection can increase it at low frequencies and eventually fix it.

A population of “flute-flowers” varies in shape: most flowers are long, but some are short. The flute-flowers are pollinated by moths that drink nectar from several species of flowers in the field. Which of the following is the most reasonable prediction about frequency-dependent selection (FDS) in this scenario IF ALL OF THE FLUTE-FLOWERS STOP PRODUCING NECTAR?

We’d expect a negative FDS favoring the short (more rare) type of flower.

In which way is artificial selection DIFFERENT from natural, sexual and kin selection?

It can be goal-oriented, for example breeding over generations to try to produce a more exaggerated phenotype than what currently exists.

The finches of Daphne Major are particularly useful as a model for measuring natural selection because…

They have a measurably changing environment and phenotype

Which of the following is NOT an explanation for how convergent complex traits may be made more likely to occur (not just increase once there) ?

Similar beneficial mutations are more likely to happen if similar selective pressures act on independent lineages.

If observed and expected genotype frequencies do not match, then according to Hardy-Weinberg principles this indicates…

That the population is currently evolving with respect to that gene.

Which of the following best explains why sexual selection often strongly selects for males that are competitive over reproduction more so than females?

High variance in repro success of males but not females

Which of the following is an example of intrasexual competition?

Males using genitalia to remove rival sperm

Which of the following is TRUE about sexual vs. asexual reproduction?

Sexual reproduction is LESS risky because it helps avoid “Muller’s Ratchet” by putting deleterious and beneficial traits into different individuals.

Which of the following is TRUE about Fisher’s Runaway and/or Sensory bias?

Both explain why female preference for a dishonest trait might arise.

Which of the following is TRUE about sexual dimorphism?

It suggests that a form of selection is acting more strongly on one sex than the other, which is less likely to occur outside of mating and reproductive contexts.

Which of the following would DECREASE the likelihood of antagonistic coevolution between the sexes?

Individuals are widely dispersed, and usually solitary

Which of the following would be most likely to FAVOR the evolution of monogamy?

Cryptic ovulation making mate-guarding beneficial

Which of the following is FALSE about red-winged blackbirds?

They are cooperative breeders where males in particular often help to rear their brothers’ offspring.

Eusociality likely evolved in Hymenoptera (bees, ants & wasps) because…

“r” is higher for full siblings then for offspring, so making “more sisters” can be better than making “more babies” of their own.

What two components are necessary for sexual dimorphism to evolve?

Genes on any chromosome that only create phenotype if paired with sex-specific hormones/genes AND either inter- or intra-sexual selection

Which of the following would you predict for a species with little parental care but production of large eggs?

Male-biased OSR, High male/ low female variance in reproductive success, high male / low female opportunity for selection.

What did researchers studying the tails of male swordtail fish discover?

Males with long tails swam faster and had larger hearts, thus they covered the cost of tail drag by investing in a (also energetically expensive) compensatory mechanism

Why might a dishonest signal come to be favored by intersexual selection?

If female preference evolved before the male trait (ie. due to other selective pressures

Which of the following would likely result in intersexual selection on traits?

Males sing and inflate balloons to attract females.

According to Hardy & Weinberg’s assumptions, which of the following is necessary for stability to be maintained at a given locus in a population?

Population must be large

Which of the following is TRUE about genetic drift?

It is more likely to fix common alleles than rare alleles

Can an allele that codes for a maladaptive trait increase in a population through selection?

Yes. Pleiotropic effects or linkage could allow selection to increase it.

Wings are examples of “complex adaptations” in which the full function (flight) requires coordination of many individual traits & structures. How, then, did flight likely evolve? (consider evidence from insects or birds)

Early structures were adaptive for reasons other than full flight

What is the best explanation for why so few mammals have wings?

Variations to existing traits that might make flight more possible often have costly tradeoffs since the structures likely have other functions and benefits

Our respiratory system shares space with our digestive system; both air and food pass through the pharynx. Which of the following is the most logical explanation of why this system evolved?

It is non-ideal (“sharing” can be lethal), but selection only acts on existing traits, and lungs provided enough benefits to offset the costs of sharing.

Which of the following would favor asexual over sexual reproduction?

Environment is relatively stable but harsh

Which of the following best explains “Müller’s Ratchet”?

It explains a significant cost of asexual reproduction, which is an inability to separate deleterious from adaptive traits over time.

Which of the following is TRUE about sexual dimorphism?

It evolves from both inter- and intra-sexual selection favoring the trait in one sex and may be coded for in genes on autosomal chromosomes.

Which of the following contributes to why males are more likely to compete for female mates than vice versa?

Various costs to maternal systems result in a male-biased operational sex ratio at any given moment

Which of the following scenarios would most likely result in intersexual selection?

A female lek visited by choosy males

Which of the following is true about why/how female choosiness for specific male mate traits might be favored by selection

Choice may be favored if the trait honestly conveys information about male quality, level of risk of mating with that male, or compatibility

Which of the following evidence would support sensory bias as a driving force in the evolution of female choice for a male trait?

Preference for the male trait is also demonstrated in an outgroup (ie. ingroups have trait and preference, outgroup has preference not trait)

Which of the following best describes the effects of Fisher’s Runaway?

Causes male traits to exceed optimum effect on survivability once female preference is fixed

Which of the following is the best match between benefit and mating system?

Monogamy: limits male risks that result from cryptic ovulation

Which of the following would likely stop or reverse “chase-away” selection driving antagonistic coevolution?

Increased adult dispersal & reduced adult interactions

Which of the following is TRUE about eusociality?

It is most likely to evolve when relatedness is high (as from inbreeding) and likelihood of independent survival is low.

For reciprocal altruism to evolve and be maintained by selection…

Helping must occur in both directions (group members are helped and help others)

According to game theorists, the tit-for-tat strategy (as employed by red-winged blackbird males) is more successful than defecting (“cheating”) in the Prisoner’s Dilemma game only when…

Individuals can “remember” and base their current strategy on the partner’s past strategy