Exam 17: Sexual Selection

Why did Milinski and Bakker test female choice between brighter and duller stickleback males in two different set-ups: one with unfiltered light and one with light from which red color was eliminated? The results from both trials are shown below.

What is the likely trade-off that bluegill sneaker males make according to the data on sperm longevity and density below? In one sentence,speculate on a possible constraint as a reason for this trade-off.

Part of the courting behavior of male jumping spiders consists of drumming the ground with their legs.Studies have shown that leg drumming decreases the longevity of the spiders.Why might male leg drumming have evolved in jumping spiders?

The figure below shows that male Rhodeus amarus fish have a greater variance in their total number of offspring than female Rhodeus amarus fish.Why is the mean number of offspring the same for both sexes?

You hypothesize that the size of prey items provided as nuptial gifts by male hanging flies is under sexual selection by the direct benefit model.Which of the following observations would support your hypothesis?

Name one direct benefit that females may receive from a particular mate choice.

What prediction of the runaway model that is never predicted for the good genes model may help to distinguish between the models in natural populations?

Must sexually selected traits be "honest indicators" under the runaway sexual selection model?

Which of the following factors should make females the choosier sex?

Experiments for testing the good genes model of sexual selection are notoriously difficult.One problem is separating environmental factors associated with a particular father (e.g.,brood care by father)from the effect of a father's genetics.Which of the following experimental designs resolves this problem?

The graph below shows the size of the male and female in a large number of matings of an insect species observed in nature.A separate study showed that large females produce more eggs than small females.Which of the following statements is a possible explanation for the observed pattern?

Consider a group of closely related species that vary in the average number of males a single female will mate with.Given the results of studies from the literature,which of the following patterns of sperm competition would you expect to see in each of the species?

The red deer population on the Isle of Rum off Scotland has been extensively studied over several decades.One of the findings was that the variance of breeding success in males was much higher than the variance of breeding success in females.Which of the following statements explains this difference in variance?

Name the four mating systems represented in the figure below.

Why is there a correlation between testis size and sperm competition in beetles?

Why are the data shown in the figure below consistent with,but not conclusive of,runaway sexual selection?

To study sperm competition in beetles,you sample a population that is effectively monogamous,as chances of meeting more than one mating partner in nature are extremely low.In the lab,you pair multiple individuals to create a polygamous mating system,but you also maintain a monogamous control line.Would you expect sperm competition in the polygamous line to increase,decrease,or remain the same relative to the monogamous control line (assuming there was heritable variance for this trait in the population)?

_________ first proposed sexual selection as an evolutionary mechanism.

In a bird species,males fight for exposed positions on treetops from which they can project their calls that exploit the inherent sensory bias of females.Which of the following classifications describes this suite of behaviors best?

In sticklebacks,females prefer to mate with males that have more red color.Why is the figure below consistent with runaway sexual selection as an evolutionary mechanism for the evolution of this preference?