Endangered river turtles may owe genetic similarities to ancient civilizations (Via Herp Digest)

Maya Shell Game
Endangered river turtles may owe genetic similarities to ancient civilizations
Conservation Magazine 7/26/11

The ancient Maya empire that flourished in Central America more than a thousand years ago left behind plenty of eye-catching ruins and art. But it also appears to have left its mark on something a little less obvious: The DNA of an endangered river turtle. A new study suggests that ancient hunting, trading and raising of Central American river turtles has produced a "surprising" genetic jumble.

The critically endangered turtle, known to science as Dermatemys mawii, is entirely aquatic. It primarily lives in three isolated river basins in Mexico, Guatemala and Belize that are separated by high mountains. So when scientists launched a genetic study by collecting tissue samples from 238 wild turtles from 15 locations, they expected to find "a different genetic lineage in each drainage basin," says Gracia González-Porter of the Smithsonian Conservation Biology Institute.

Instead, the testing showed a "surprising lack" of genetic structure, González-Porter and her colleagues report in Conservation Genetics. "We found the mixing of lineages; it was all over the place," she says, suggesting the turtle populations had been in close contact for years.

How could that have happened? The answer, the researchers say, may rest with the Maya and even older Olmec culture, which appear to have traded the turtles for ritual and food use. Archeologists have found the remains of one turtle, for instance, in an ancient Teotihuacan burial site in Mexico, more than 186 miles outside of the turtle's current range. And there is an ancient sculpture of a river turtle that was found in the Basin of Mexico, more than 217 miles outside the current range.

"The turtle is tame and resilient," González-Porter explains, "which makes it easy to transport. Their shells give them lots of protection. People don't have refrigeration so they put the turtles in ponds in their back yards." And during the rainy season, floods could have allowed the captive turtles to escape and mix with the local turtles.

The ancient practice still persists today. In Guatemala, Central American river turtles are kept in medium-sized ponds where they can be easily captured when needed. Similarly, in the State of Tabasco, Mexico, captured turtles are kept in rustic ponds and raised until they are either consumed or sold.
Unfortunately, the taste for turtle meat is threatening the future of the turtle, the last surviving species of a once large family of giant river turtles. A kilogram of river turtle meat can now fetch $100, and the turtles are now largely restricted to remote areas that are inaccessible to humans. - David Malakoff July 24, 2011

Source: González-Porter, G. et al. 2011. Patterns of genetic diversity in the critically endangered Central American river turtle: human influence since the Mayan age? Conservation Genetics DOI: 10.1007/s10592-011-0225-x