Size Matters in the Battle Against Extinction for Amphibians

When it comes to avoiding extinction, size matters. Scientists have discovered that in the battle to diverse environments, animals that are sexually dimorphic, which means that the males and females differ in size, have a better chance at survival.

The conventional school of thought believes that different-sized sexes of the same species take up more resources. This means that they're less able to adapt and diversify than species where ecologically relevant traits like size are essentially the same between males and females. Yet this latest study shows that this doesn't seem to be the case.

In order to better understand what causes some species to survive and others to go extinct, the scientists examined research on global patterns of amphibian diversification over hundreds of millions of years. About 30 to 40 percent of the world's approximately 7,000 species of amphibians are currently in danger of extinction, which makes them a good group to study.

In the end, they found that sexually dimorphic species are actually a lower risk of extinction. This, in particular, shows why some species are doing well while others are in decline or disappearing.

"I think if our results bear on mass extinction at all, it suggests we maybe should start looking more closely at the traits of some of the species that are going extinct," said Stephen De Lisle, one of the researchers, in a news release. "Scientists might start thinking in a new way about how other traits, like sex differences in habitat use or diet, might play a role."

The findings reveal that sexual dimorphism is an important trait when it comes to influencing extinction. That said, the researchers plan future studies to see what other traits may be involved. This, in turn, may help with conservation efforts as some amphibian species continue to decline.

The findings are published in the journal Proceedings of the Royal Society B.

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