Sexy males sire dowdy daughters and attractive females bear insipid sons – in fruit flies, at least.
This perverse pattern of inheritance may be one reason why not all individuals are highly attractive. It may even help explain why many of the showiest sexual displays are found in birds and butterflies, rather than other organisms.
The paradox arises because many of the traits that enhance a male’s reproductive success are detrimental to female success, and vice versa. For example, female flies that devote a lot of time to feeding may have more energy to put into egg-laying, whereas males may do better spending more of their time mating instead.
“Whenever you have two different gender roles, traits that make a really successful male aren’t going to be the ones that make a really successful female,” says Alison Pischedda, an evolutionary biologist now at the University of California at Santa Barbara, US.
She and Adam Chippindale, at Queen’s University in Kingston, Canada, decided to test how prevalent such genetic conflicts are. They screened a large population of fruit flies to select the three genotypes that were fittest and least fit for each sex. Then they crossed these selected flies in every possible combination and measured the fitness of their offspring.
Low quality offspring – In every case, they found, the fittest mothers produced fitter daughters but less fit sons, compared to less fit mothers. And the fittest fathers produced less fit daughters. The father’s genotype had no effect on the fitness of his sons, because most of the genes affecting mating success are on the X sex chromosome, which males inherit only from their mothers. The net result of these differences is that matings between the fittest males and the fittest females produced the lowest-quality offspring.
Read more at New Scientist
Post a Comment