FE2

Question 1

Sexual reproduction imposes a number of costs on organisms. List four distinctly different costs of sexual reproduction and briefly explain each.

Answer 1

• Cost of meiosis: because you’re mixing up the different genes, so you lose out half your genetic material
• Cost of males: they’re useless until used. It would be easier just to have females.
• Cost of recombination: successful ones could be broken up and harmful ones could be created
• Cost of mating: because time and energy invested.

Question 2

Given the costs of sexual reproduction, natural selection presumably favored this form of reproduction because it also provided fitness benefits to some organisms. List two distinctly different benefits of sexual reproduction and briefly explain each.

Answer 2

• Better able to adapt to the environment because recombinational load and mutations.
• Harmful mutations can’t accumulate because they won’t survive

Question 3

In light of the costs and benefits of sexual reproduction, explain why, all else being equal, we should expect parthenogenic (asexual—copies of yourself) reproduction to be more common in a hypothetical species having small body size and living in a cold, dry climate than in a hypothetical species having large body size and living in a warm, moist climate

Answer 3

• In warm climates, pathogens would likely to attack species and it would be hard to recover quickly and adapt.
• Small body size—you need less energy; and less surface area to lose heat. Less available resources as well.

Question 4

Some species are hermaphroditic, i.e., each individual is capable of playing either the male
role or the female role in reproduction. In some hermaphroditic species, mating sometimes
involves conflicts within a dyad over which role each individual will play. Provide an ultimate explanation for why such conflicts occur

Answer 4

• Ultimate (in terms of fitness and reproductive success)
• Parental investment—if they’re female they lose because they have to now invest time and energy into reproducing their offspring. The male can just inseminate and it’s done. He can leave.