Graduate student Stephen De Lisle and Professor Locke Rowe of University of Toronto’s Department of Ecology & Evolutionary Biology wanted to better understand why 30 to 40 percent of the world’s approximately 7,000 species of amphibians were in danger of extinction. They wanted to understand why some species were able to survive while others were disappearing.
In a paper published today in Proceedings of the Royal Society B. the researchers presented their case for the supposition that when it comes to extinction, size does matter. De Lisle and Rowe, in their research, discovered that “sexually dimorphic” species, those in which the males and females are of different sizes, are at a lower risk of extinction, and are better able to adapt to diverse environmental conditions.
“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 researchers suggest that if sexually dimorphic species are able to independently develop differing traits in response to environmental diversity, then the adaptation helps them to survive extinction threats that others might not survive. De Lisle says classical ecological theory would not have predicted this about the amphibians, which include frogs, toads, salamanders, newts and caecilians, tropical amphibians that look like large worms or slick snakes.
Many scientists look at amphibians as “canaries in a coal mine,” with declines in this species an indicator that other plants or animals may be in danger of extinction. The researchers plan to do further studies to determine what other traits might be involved, hoping their findings will help conservationists in their efforts to control or slow the extinction of many of our amphibians.
