CarnalNation

A study by two Dartmouth biologists suggests that female lizards can control which genes they pass down to their offspring to select their sex in advance. They conclude that female lizards that mate with larger fathers are more likely to produce boys whereas mating with smaller sires increases the likelihood of giving birth to girls.

Robert Cox and Ryan Calsbeek studied the brown anoles in a laboratory setting and observed that females preferred larger male mates which could increase their chance of producing male babies. When only exposed to smaller male mates, the females produced fewer sons. Though the female mechanisms for controlling offspring gender are still unclear, the researchers suggest that it is possible that they use their immune systems to destroy Y-chromosomes while storing sperm in their “pockets” for up to four months.

They also tracked the survival of young brown anole lizards in the wild and found that males were more likely to survive if they had larger fathers while the survival chances of females were not influenced by their fathers’ size. Beneficial genes for males are therefore different that beneficial genes for females.

“In an evolutionary sense, what’s good for the goose is not always good for the gander.”

The full study is published online in Science Express.