Evolutionary biology 18: Parasites and the evolution of sex

Question 1

Why would an organism evolve to be asexual?

Answer 1

Sexy is costly

• 2 fold cost (organisms reproducing with sex have half as many offspring on average)
• Sex can lead to genomic conflict

Question 2

Why would an organism evolve to be sexual?

Answer 2

Recombination accelerates rate of evolution -> populations adapt to environment quicker

Question 3

3 costs of sex?

Answer 3

The cost of males or ‘2-fold cost of sex’ -> in many species, males do not provide any resource to next generation

Cost-of-breaking favourable genetic combinations -> genotypes which survive until adulthood prove fitness, sex may disrupt genetic productive combinations

• genomic conflict via
• Can also create/destroy useful metabolish pathways etc

Costs associated with mating process -> finding a mate is resource and time costly, can increase risk of predation or parasite transmission
- mating may also harm female or affect future reproductive success

Question 4

Why do parasites select for sexual reproduction?

Answer 4

Parasites evolve quickly and provide rapidly changing environment where the quick recombination provided by sex is favoured