Saturday 24 June 2017

Gay flies 'suggest evolution bonus'

Research involving fruit flies points to the possible existence of inherited
Research involving fruit flies points to the possible existence of inherited "gay genes" on the male Y chromosome (Photo: University of Washington)

A study of gay fruit flies suggests that being homosexual might carry an evolutionary advantage.

The research points to the possible existence of inherited "gay genes" on the male Y chromosome.

They have been conserved in animals - including humans - because they are linked to fitness traits that help survival, scientists believe.

Without any benefit, genes that cause a species to avoid reproducing would have been weeded out by natural selection.

The study involved screening fruit flies (Drosophla melanogaster) for male-to-male courtship behaviour.

Analysis showed evidence of "complex" inherited genetic variation associated with same-sex sexual behaviour (SSB) seen in the flies.

A "strong paternal effect" with males rather than females passing on the trait indicated a Y chromosome link.

But the genetic influence on survival associated with fruit fly "gayness" appeared to affect females rather than males, causing them to be less fertile.

"Mothers from high-SSB (breeding) lines produced more offspring than those from low-SSB lines," the researchers reported in the journal Proceedings of the Royal Society B.

The scientists, led by Dr Nathan Bailey, from the University of St Andrews, added: "Like any other trait that potentially reduces fitness, the evolutionary maintenance of SSB requires a countervailing fitness benefit.

"Genetic models of SSB have illustrated that such a benefit need not accrue to the individual expressing SSB, but can occur as a result of a fitness advantage specific to the alleles (gene variants) influencing the expression of SSB."

They added that more genetic research across a "broader range of organisms" was required to shed more light on evolutionary theories about the origins of homosexuality.

Press Association

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