The gopher tortoise is considered a keystone species because many other species benefit from its burrows, which can go to a depth of 10 feet and a length of 40 feet. (Photo: Casey Phillips)

With its wide, spadelike claws and sturdy hind legs, the gopher tortoise seems built to move earth. Like shelled bulldozers, these reptilian excavators dig deep, winding tunnels beneath the scrublands and coastal dunes of the Southeast.

Their burrows provide crucial shelter for not just the tortoise but hundreds of other species, from eastern indigo snakes to gopher frogs to owls.

Despite the positive ripple effect they have on their ecosystems, gopher tortoise numbers have fallen by 80 percent in the past century. This includes those living on federal land and is primarily because of habitat loss and fragmentation caused by human activity.

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A continuing decline of a keystone species like the gopher tortoise would be a big problem for a lot of other animals.

“If they were to disappear and their burrows were to disappear, it would affect numerous species,” conservation biologist Dr. Josh Ennen of the Tennessee Aquarium Conservation Institute said. “The importance of the gopher tortoises is disproportionate to their abundance. By protecting this one turtle species, you’re actually protecting upward of 400 other species, which is very important.”

The genetically distinct population of gopher tortoises living west of the Tombigbee and Mobile rivers has been federally listed as threatened since 1987, while those living east of these rivers, despite facing a multitude of threats, lack federal protection. Maintaining their genetic diversity is crucial to ensuring the species’ long-term survival.

But until recently, scientists lacked a comprehensive examination of gopher tortoise genetics with which to ensure a healthy and robust gene pool for the species.

In a recently published study, Ennen and Tennessee Aquarium Conservation Institute geographic information systems analyst Sarah Sweat joined other southeastern researchers in producing a genetic survey of gopher tortoises across the species’ entire range. The group sampled more than 930 gopher tortoises from 47 sites in both the species’ listed and unlisted regions.

The study, appearing in the latest issue of the Journal of Fish and Wildlife Management, found the gopher tortoises actually comprise five distinct genetic groups, rather than two, as previously thought. Rivers such as the Mobile and Tombigbee are important barriers to genetic intermingling of these groups.

The findings pave the way to individually manage these subpopulations of gopher tortoises in order to preserve the species’ genetic diversity, an important step in formulating a long-term conservation plan.

“If you have separate populations that are different genetically, you want to maintain that evolutionary potential,” Ennen said. “It’s a great conservation value because when you protect this one species, you protect a whole ecosystem.”

Tennessee Aquarium guests can observe the way other animals use gopher tortoise burrows by visiting the Delta Country gallery inside the River Journey Building.

Learn more about gopher tortoises here.

Click here to read the full study.

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