Sexual Selection

Question 1

Why is sexual reproduction less efficient?

Answer 1

1. Only half the individuals genes are present in each offspring- genetic dilution
2. Males don’t produce offspring directly

Question 2

What are the advantages of sexual reproduction at the individual level ?

Answer 2

More variation in offspring leads to:
1. Sibling-competition is reduced
2. Better protection against parasites

Question 3

What are the advantages of sexual reproduction at the population level ?

Answer 3

1. Muller’s ratchet
2. Hill-Robertson effect
3. Sexual species survive longer

Question 4

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

Answer 4

1. Because evolution depends on selection between individuals
2. The first mutant from asexual to sexual had to outcompete the asexuals in its population
3. Because benefits only obtained by the population wouldn’t spread a new allele for sex at the expense of asexual alleles
4. It’s not for the good of the population the traits that evolve

Question 5

What are the advantages of reduced competition with siblings ?

Answer 5

1. Offspring survive in many different habitats
2. Offspring compete less as fewer in any one patch

Question 6

What is Muller’s ratchet ?

Answer 6

The gradual accumulation of deleterious (harmful) mutations in asexual populations.
This is because in asexual reproduction, the parents are cloned to produce offspring with the same mutations, reducing their fitness to survive.
So it suggests that without sexual reproduction which can shuffle genetic material, asexual populations are at a genetic disadvantage as harmful mutations accumulate.

Question 7

What is the Hill-Robertson effect ?

Answer 7

Getting multiple mutations into one individual is easier in sexual reproduction.
It highlights the advantage of sexual reproduction as recombination helps to separate linked beneficial and harmful mutations, allowing natural selection to act more efficiently.