Biologists study evolution at turtle's pace
(Feb. 9, 1994)
The slow but persistent tortoise outran the hare in an old children’s fable. And in the Great Depression, it graced southern dinner tables as “Hoover chicken.” Now, the gopher tortoise is winning renewed respect from East Carolina University biologists.
The ECU scientists are studying genetic variations among populations of the gopher tortoise living in some of the deep south states.
The gopher tortoise (Gopherus polyphemus) is a land creature best recognized for its flat, elephant-like feet and its ability to produce impressive excavations. Some of its burrows are as much as 18 feet long, 10 feet deep and a foot or more in width. The tortoise can grow to the size of an army helmet and can live for 60 years or more.
“They are protected in South Carolina, Georgia, Florida, Louisiana, Alabama and Mississippi,” said Dr. Trip Lamb, an evolutionary biologist at ECU. Therefore, he said the research will help these states to manage and protect the gopher tortoise.
But, he said that his interest and the work of Matthew Osentowski, a graduate student, were directed, in part, to assess possible genetic differences between gopher tortoises on each side of Florida’s Apalachicola River.
The Apalachicola cuts through Florida’s panhandle region dividing the tortoise’s range. In sampling the mitochondrial DNA variations of tortoises, the biologists found that populations on the eastern side of the river and in Georgia are genetically distinct from those on the west side of the river from Florida to Louisiana.
Lamb said previous studies show that similar genetic changes east and west of the Apalachicola River also appear in many species of fish.
“The reason we are seeing these changes is because we are looking at a legacy of the past, from about two million years ago, when Florida and the gulf coast were affected by sea level rise and fall,” said Lamb. He said it is probable that water covered or fragmented the land masses and caused isolation among tortoise populations.
“What we are seeing today in their genetic structure is a historical reflection of that isolation,” he said.
While the genetic differences of tortoises fascinate the scientists, the state of Florida is more concerned about protecting the creatures. State laws require developers of subdivisions and shopping centers to relocate any of the creatures that may be harmed by human encroachment.
Lamb said it is important for relocated gopher tortoises to stay among populations that are genetically similar. For most cases, this means keeping the creatures on their respective side of the Apalachicola River.
The federal government names the gopher tortoise as a threatened species in Mississippi and Louisiana. The creatures are more abundant in Florida, Georgia and Alabama. In Georgia, the gopher tortoise is the state reptile. There are no records of the species in North Carolina.
As a source of food, the gopher tortoise is not a candidate because of its protected status. But, during the Great Depression, it found its way to the dinner tables at many homes. Some people nicknamed it the “Hoover chicken” because of President Herbert Hoover who was in office when the stock market crashed in 1929.
“There is not much edible meat on the tortoise,” said Lamb, as he held up a shell that was a little larger than an over-inflated football. “On this one, there was maybe a half pound.”