Most of the more than 6,000 species of frogs in the world lay their eggs in water. But many tropical frogs lay their eggs out of water. This behaviour protects the eggs from aquatic predators, such as fish and tadpoles, but also increases their risk of drying out. Justin Touchon, post-doctoral fellow at the Smithsonian Tropical Research Institute, discovered that climate change in Panama may be altering frogs’ course of evolution.
By analysing long-term rainfall data collected by the Panama Canal Authority, Touchon discovered that rainfall patterns are changing just as climate-change models predict. “Over the past four decades, rainfall has become more sporadic during the wet season,” said Touchon. “The number of rainy days decreased, and the number of gaps between storms increased.”
The eggs of the pantless tree frog, Dendropsophus ebraccatus, are extremely susceptible to drying. The embryos die within a day when there is no rain. Heavy rains trigger breeding, so as storms become sporadic, the chance of rain within a day of being laid decrease and so does egg survival. As weather patterns have changed, the advantage of laying eggs out of water has decreased, not only for pantless tree frogs but potentially for many species.
The above news item is reprinted from materials available at Smithsonian Science. Original text may be edited for content and length.
(Source: Smithsonian Science, 24.10.2012)