Fêmeas de lagartos escolhem os genes certos para a descendência sexual certa

Lizard Moms Choose the Right Genes for the Right Gender Offspring

ScienceDaily (Mar. 10, 2010) — Two Dartmouth biologists have found that brown anole lizards make an interesting choice when deciding which males should father their offspring. The females of this species mate with several males, then produce more sons with sperm from large fathers, and more daughters with sperm from smaller fathers. The researchers believe that the lizards do this to ensure that the genes from large fathers are passed on to sons, who stand to benefit from inheriting the genes for large size.

The male of this species can be two to three times the mass of the female, but the females seem to be in control of the genetic destiny. (Credit: Photo by Joseph Mehling '69)

The study is published in the March 4 issue of Science Express, the advance online publication of the journal Science.

"This species has figured out a clever way to pass on genes with gender-specific effects on fitness," said Bob Cox, the lead author on the paper and a post-doctoral researcher at Dartmouth in Hanover, N.H. "Usually, when natural selection pulls genes in different directions for each gender, the species faces an evolutionary dilemma. But these lizards have solved this puzzle, they've figured out how to get the right genes into the right gender."

Cox's co-author is Ryan Calsbeek, an assistant professor of biological sciences at Dartmouth.

By manipulating opportunities for females to mate with males of different sizes, the researchers determined that females prefer larger males. But, when the choice of partners was limited to small males, females minimized the production of sons.

The researchers explain that the genes that make males more fit are often different from the genes that benefit females, which presents a conundrum because males and females share most of their DNA. The valuable traits for one gender are not always the same for the other. "In an evolutionary sense, what's good for the goose is not always good for the gander," said Cox.

...

Read more here/Leia mais aqui: Science Daily

+++++

Published Online March 4, 2010
Science DOI: 10.1126/science.1185550

Cryptic Sex-Ratio Bias Provides Indirect Genetic Benefits Despite Sexual ConflictRobert M. Cox* and Ryan Calsbeek

When selection favors sexual dimorphism, high-fitness parents often produce low-fitness progeny of the opposite sex. This sexual conflict is thought to overwhelm the genetic benefits of mate choice because preferred males incur a cost through the production of low-fitness daughters. We provide a counterpoint in a lizard that exhibits sexual conflict over body size. Using mate-choice experiments, we show that female brown anoles (Anolis sagrei) produce more sons than daughters via large sires, but more daughters than sons via small sires. Measures of progeny fitness in the wild suggest that maximal fitness payoffs can be achieved by shifting offspring production from daughters to sons as sire size increases. These results illustrate how the resolution of sexual conflict can restore the genetic benefits of mate choice.

Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA.

* To whom correspondence should be addressed. E-mail: robert.m.cox@dartmouth.edu

+++++

Professores, pesquisadores e alunos de universidades públicas e privadas com acesso ao site CAPES/Periódicos podem ler gratuitamente este artigo da Science e de mais 22.440 publicações científicas.