Exam 16: The Evolution of Sex

Which of the following reproductive systems lends itself best to the study of the environmental factors that lead to the maintenance of sexual reproduction?

During bacterial conjugation, small circular chromosomes of DNA, called plasmids, are transferred from one bacterial cell to another. Why does this mechanism NOT fit the common definition of sexual reproduction?

The two figures represent an asexual and a sexual population. The letters indicate beneficial mutations. The shaded areas represent the frequency of particular combinations of mutations in the population over time. Why does it take longer for the beneficial allele combination of ABC to go to fixation in the asexual population than in the sexual population?

Several studies have looked at the different reproductive behaviors of male bluegill fish Lepomis macrochirus, identifying different morphs that exhibit different strategies when attempting to fertilize eggs. Which morph displays male-male competition through cuckoldry and sperm competition?

What are the two immediate benefits to sexual reproduction in unpredictable environments, according to Alexey Kondrashov?

For males, potential reproductive success is highest in a ________ mating system and lowest in a ________ mating system.

You catalog all obligate asexual species within a family of insects and notice that asexual species are rare and are all members of genera that consist predominantly of sexual species. None of the genera consist exclusively of asexual species, and many of the asexual species have gone extinct. Your phylogenetic analysis shows that asexual species tend to be short "twigs" on the tree. What could you conclude from these results?

What did Curt Lively (1987) discover when applying the Red Queen hypothesis to snail populations in New Zealand?

In an experiment, Jokela and colleagues reared 14 replicate populations of a snail species that is polymorphic for sexual/asexual reproduction under controlled, identical conditions in the lab. Each population started with 35% asexual and 65% sexual individuals. The figure below shows the percentage of asexual individuals after a year-long experimental run. Which of the following statements is NOT a possible explanation for these results?

Morphological or behavioral characteristics used to attract a mate can also have the consequence of drawing a predator's attention to the individual who possesses that trait, yet these so-called expensive traits persist in many species. This describes

The Amazon molly, Poecillia formosa, is a freshwater fish that is gynogenetic. In order to reproduce, individuals of this all-female species must mate with a male from a closely related species to initiate the development of their offspring. The male's genetic material does not, however, enter the Amazon molly's egg. What costs of sexual reproduction does the Amazon molly potentially experience?

Birds of paradise are a family of tropical birds known for their striking sexual dimorphism. The males are famous for their elaborate, colorful plumage that combines with a variety of behaviors to attract females in their species for mating. Females choose the males based on their morphological and behavioral displays, providing an example of

Explain how sexual reproduction overcomes the inherent disadvantage of generation time in the host of an asexually reproducing pathogen.

The figure shown illustrates the proportion of a particular asexual snail clone in a population and the degree to which it was infected with a particular parasite. Which prediction of the Red Queen hypothesis do these results appear to reflect?

In the crustacean genus Hyalella, females mate more often with males who have larger gnathopods. Males with larger gnathopods have been shown to be better protectors of females during amplexus. Which model of intersexual selection does this describe? A B

Develop a short hypothetical explanation (one sentence) for the observed distribution of obligate asexual reproduction under the environmental unpredictability model.

How could the number of gametes produced relate to a reproductive success differential in males?

Why do pathogens tend to evolve faster than their hosts?

According to the reasoning of John Maynard Smith, in a mixed population of asexually reproducing females and sexually reproducing males and females, the number of asexuals should grow at twice the rate of the sexually reproducing individuals because

What is the relationship between male quality and tail length in peacocks? Why do extravagant and metabolically costly traits like peacocks' tails persist in population?