Exam 16: The Evolution of Sex

Is it possible for a recombination event to turn Muller's ratchet "forward" in the population of chromosomes below? The dots on the chromosomes indicate deleterious mutations. Indicate the crossing-over event by placing an X on the figure.

Are there any costs when asexual organisms reproduce automictically as opposed to apomictically?

Counter the following argument: "Sexual reproduction is just an accident of evolution; once established it is irreversible. One does not need to postulate specific benefits to explain its maintenance."

Why is the twofold cost of sex only seen in anisogamous organisms?

What is the definition of "sexual reproduction"?

What evolutionary model for the maintenance of sexual reproduction do the following data appear to support?

Could HIV infection be considered a cost of sexual reproduction? Keep your answer to one sentence.

Why are transduction, conjugation, and transformation sometimes referred to as sexual processes, but are not considered to be sexual reproduction?

Why do some scientists consider automixis sexual reproduction?

What are coadapted gene complexes?

What do these data about the offspring of peacocks tell us about the good genes model of intersexual selection? B C

Does Muller's ratchet apply to both apomictic and automictic asexual populations?

What is the consequence of a deleterious mutation becoming fixed in a population?

Water fleas, Daphnia magna, can switch between asexual and sexual reproduction cycles. Which of the following observations support the hypothesis that sex is favored in unpredictable environments?

Do each of the following forms of reproduction represent asexual or sexual reproduction? A. Amphimixis B. Automixis C. Apomixis

Some mammals have demonstrated preferential attraction to individuals that carry immune system alleles that are complementary to their own. Which hypothesis does this observation support?

How does recombination in sexually reproducing organisms reverse the effect of Muller's ratchet?

Which step of the process of amphimixis produces new chromosomal variants?

What are two examples of asexual-like reproduction in the genomes of obligate sexually reproducing organisms?

Which of the following statements does NOT illustrate a potential cost of sexual reproduction?