Question

1. Define genome dilution and cost of males with regard to sexual reproduction and explain why they are evolutionary costs. 3

Answer 1

Genome dilution, according to its original definition, refers to the fact that asexual mothers transmit all their genes to their offspring whereas sexual mothers transmit only half.

The sexual females must spend ∼50% of their resources making sons, which cannot themselves make offspring. The growth rate of the sexual population is thus predicted to be half that of the asexual population. This cost is called the “two‐fold cost of males.”

The cost is often attributed to the production of males (females waste half of their resources on producing males, who in turn invest minimally in offspring or to genome dilution (only half of the parental genome is transferred to offspring or, confusingly, to both. So both these are waste from the female side because they can't be further used for evolutionary purpose.