Question

How might same sex pairings increase fitness?

Why might some biologists consider sexual selection as more than “just” a type of natural selection?

Answer 1

Same-sex pairing is viewed as maladaptive, even though it is widespread among animals, as it is difficult to explain in an evolutionary context because it does not result in reproduction. The study comparing survival, fecundity and transition probabilities of female Laysan albatross showed how same sex pairing have adaptive alternative mating strategy, that resulted in lower fitness than different sex pairing. Females in same-sex pairs produced 80% fewer offsprings and had lower survival and skipped breeding more often than those in male–female pairs. The reduced reproductive output between the pair types would be enhanced over the lifetime of the species because females in same sex pairs appears to have lower survival, which would probably further reduce their lifetime fitness compared with females in different sex pairs.

Sexual selection (both intra- and inter-sexually) is considered to be a natural selection, as one of biological sex choose mates of the other sex to mate with (intersexual selection), and compete with members of the same sex for access to members of the opposite sex (intra sexual). These two forms of selection mean that some individuals have better reproductive success than others within a population, either because they are more attractive or prefer more attractive partners to produce offspring. Individuals who are better able to exclude competitors, have a greater chance to acquire mates and father offspring.