It ’s an evolutionaryparadoxthat ’s frustratingly difficult for biologist to explain , but researchers may have just detect a welfare conferred by homosexual sex that could offer an explanation as to why this behavior has persevered , at least in one species . accord to a fresh study in fruit flies , not only does same - sex sexual behaviour seem to be heritable , but females with a genetic makeup associated with this trait actually display higher reproductive rates , which is an evolutionary advantage . These fascinating findings have been published inProceedings of the Royal Society B.
If a certain trait or behavior is detrimental to the procreative winner , or fitness , of an organism , you would n’t await it to run in the universe as natural pick should get rid of it . After all , the aim of the reproductive game is to keep your cistron live . Why , then , do extremity of the same sex cop off with each other in so many species ? And we ’re not just talking about homosexual behaviors ( observed inmore than 1,500 species , since you asked ) ; we intend the whole shebang .
scientist have long mull over this and have shin to add up to any consensus . Although there are a few different ideas , two hold speculation that result from theoretical work suggest thatsame - sex intimate behaviors(SSB ) could hang on for two reasons : overdominance andsexual antagonism . The former proposes that SSB could persist in the population if gene for this behaviour confer a harmonizing procreative reward in individuals only possessing one copy of the gene , or heterozygote , as fight to those in possession of two ( homozygotes ) . The lattersuggeststhat a gene that is detrimental to fitness in one sex could be maintain so long as it is good to the other sexual urge .
So how do researchers work out which conjecture seems to comfortably explicate this behavior that is seemingly harmful to replica ? The method take by scientists behind the lateststudy , based at the University of St. Andrews , ask a combining of genic and behavioural psychometric test . First , they screen inbred fruit fly lines in hunting of gene variations that could report for SSB .
They did this by both examining the genome of male fruit flies and watch over how they behaved with other Male . This involved quantifying the amount of courtship behaviors males would exhibit towards other males — such as licking , tattle or try mounting — and then looking for genetic difference present in males displaying high levels of these behavior . This data was then used to identify genetic lines of fly that either systematically showed in high spirits levels of SSB , or gloomy levels of SSB .
The final stage of the investigation call for perform observational crosses of fly ball from both of these key lines and examining the ensue offspring . More specifically , they need to see whether coming from a genetic background affiliate with high-pitched levels of SSB affect reproductive rates in female young .
The researchers found that while their data lent more exercising weight to the overdominance hypothesis , their results did not alone support one over the other . In fact , they think that both could be bring to the sustentation of SSB in the factor kitty . But that was n’t the most interesting breakthrough of the study : male person with a genetic war paint relate with high levels of SSB produce distaff offspring with high rates of breeding , or fecundity . This suggests that genes associated with SSB could be persisting in the population because they actually bestow a fitness advantage in female , despite being reproductively harmful to males .
