Sexual selection

Question 1

What are the disadvantages of sexual selection

Answer 1

• courtship and mating takes time, energy and is dangerous
• finding and identifying a mate of the right species, age, sexual state is not always easy
• courtship is showy so attracts predators
• letting another individual close carries dangers of parasites and diseases as well as physical injury

Question 2

What are the advantages of more variation in offspring?

Answer 2

• sibling-competition is reduced - offspring survive in many different habitats and compete less as fewer in any one patch
• better protection against parasites

Question 3

What is muller’s ratchet

Answer 3

A process which, in the absence of recombination, results in an accumulation of irreversible deleterious mutations.

Question 4

What is the hill-robertson effect?

Answer 4

Getting multiple mutations into one individual is easier in sexuals

Question 5

Why do we need to consider individual benefits not population ones when explaining the evolution of sex?

Answer 5

• evolution depends on selection between individuals
• first mutant from asexual to sexual had to outcompete asexuals in its population
• benefits only obtained by population wouldnt spread a new allele for sex at expense of asexual allels
• not for the good of the population that traits evolve

Question 6

Why do parasites win the evolutionary race?

Answer 6

• evolve to penetrate defenses
• smaller and breed faster

Question 7

What evidences is there to show that sexual species survive longer?

Answer 7

• fossil record shows that asexual species occur less frequently and go extinct more often than sexual species
• widely assumed to be inability to adjust to new habitats