Salamander DNA reveals evidence of older land connection between Central and South America
by Smithsonian staff
The two continents are generally believed to have been joined together around three million years ago by the formation of a land bridge–what is now Panama–that sealed up the sea channel between them.
However, a new study of salamanders in South America by a research team lead by Kathryn Elmer of the University of Glasgow, has found evidence that challenges these assumptions and supports a controversial claim by Carlos Jaramillo, a paleontologist at the Smithsonian Tropical Research Institute in Panama, that most of the Isthmus of Panama was formed around 23 million years ago.
The fusion of both land masses led to a two-way migration of animals called the ‘Great American Biotic Interchange’, where animals that had previously evolved separately moved between the two continents, increasing the biodiversity in both regions.
The relative dearth of species of salamander in South America–around 30–compared to Central America, where there are more than 300 species, is usually attributed to the relatively short time the tiny amphibians have had to make their way south down the Isthmus of Panama–a thin strip of land only 30 miles wide at its narrowest point.
However, using DNA analysis, Elmer found that salamanders in South America had much greater genetic divergence from their Central American cousins than should be expected if salamanders migrated across a three- million-year-old land bridge…
(read more: Smithsonian Science)
(photos: T - Bolitoglossa sp. in the upper Amazon basin by Santiago Ron; B - B. peruviana by Kristiina Ovaska)
source: Carlos Jaramillo - Univ. of Glasgow