Genetic Mapping may Save Diamondback Terrapins

Diamondback terrapins set themselves apart from other turtle species with their intricately grooved shells, however new research from the US Geological Survey suggest that the stuff beneath the turtles' groovy shells may be key to their survival.

Terrapins, which are the only North American turtle species that spend its entire life along coastlines and in marshes, are facing a number of threats due to habitat loss.

This new terrapin research, which is published in the journal Conservation Genetics, aims to help ecologists and biologists identify the genetic variance of terrapins across their range, which stretches along the Atlantic seaboard and into the Gulf of Mexico as far west as Texas.

"Before now, it was not clear how terrapin genetics varied across the range," said lead study author Kristen Hart, a USGS research ecologist. Understanding this variation across the landscape helps land managers develop conservation plans. For example, they may pinpoint areas where habitat protection can be supplemented with migration corridors."

Many states protect the terrapin, listing it as a species of concern. But coastal areas where terrapins are typically found are not always adequately protected, and more can be done to ensure that terrapins are able to survive and keep their gene pool diverse, the researchers said in a statement. 

"Diversity loss can be a silent threat to many species," said study co-author Maggie Hunter, a USGS research geneticist. "The threat to long-term survival of terrapins occurs if they become separated into isolated groups. Isolation can affect their overall survival several generations down the line."

Among the seven recognized terrapin subspecies, there are four genetically distinct populations, the researchers found.

By understanding genetic variations within a species, wildlife managers will be able to better ensure the health of terrapins, the researchers said.

"Healthy interbreeding doesn't mean that turtles from Maine have to interbreed with those from Texas," explained Hunter. "Once managers know where 'natural breaks' in populations occur, they can focus on keeping terrapin populations healthy by enabling reproduction within each of those distinct groups."

An additional benefit of the study is that when terrapins, which were considered a delicacy in the 1920s, still occasionally show up in food markets, a DNA test can be preformed to reveal the origin of the turtle. This will allow any rescued turtles to be returned to their natural habitat.