Lexington, Virginia • August 10, 2009
They've been living on a small ridge in the Blue Ridge mountains probably for centuries, but only now are they being discovered.
What may prove to be a new species of salamander is being investigated in the George Washington National Forest by a Washington and Lee University professor and his students.
"I think it's very exciting from a local biodiversity perspective," said David Marsh, associate professor of biology at W&L.
"Some peaks in the Blue Ridge mountains are the equivalent of the Galapagos Islands for salamanders," said Marsh. "These mountains never had glaciers, so salamanders have been up there for a very long time. Groups of salamanders probably became isolated on some of the ridgetops and went off on their own evolutionary trajectories."
Marsh and two W&L students have spent the summer conducting ongoing research into a possible new species called the Sherando salamander. It lives on top of a tiny ridge 20 miles north of the University's Lexington campus. The range of the salamander appears to be only about six kilometers long and to extend three kilometers on each side.
"We want to find out if the Sherando is, in fact, a new species," said Marsh. "Where on the ridge does this new salamander begin and the other more common Red Back salamander, which lives further down the ridge, stop? How did the Sherando get on top of this one little ridge top by itself? How long has it been isolated?"
W&L junior Claire Bayer and senior Andrew Sackman are both biology majors who have spent the summer trying to answer these questions. They have been catching the salamanders, taking samples and then testing their DNA in the lab. Bayer is a Howard Hughes Medical Institute Fellow; Sackman is a R.E. Lee Research Scholar.
Although this summer's work has been primarily in the lab, the students started their research catching the salamanders in the field during a spring term class on field biology, since salamanders are most active in the spring and easier to find.
Easier is a relative term.
"We flipped over rocks, turned over lots of logs, and dug through leaf litter to try and find them," said Bayer. "Sometimes we would search for two or three hours and find only one or two salamanders."
The salamanders are small - their bodies are about four centimeters long with their tails adding another two or three centimeters. So they're hard to spot in the first place. But it's also difficult to distinguish between the Sherando and Red Back salamanders. Marsh described the Red Back as "a little brown thing with a red stripe. It's by far the most common amphibian in the eastern United States and the two species look very similar at first glance. This is one reason new species are still being discovered."
But the new species does have some differences. For example, the limbs of the Sherando salamander tend to be longer and the trunk is shorter because they have fewer ribs. Measuring those characteristics helped the students identify the new species.
Once they caught the salamanders, the students pinched off a little bit of tissue from the tail to take back to campus for analysis. "It's actually the least destructive technique to gather tissue samples," said Marsh, "because salamanders regrow their tails naturally."
Marsh explained that classifying the salamanders based on how they look is just preliminary, and that the main classification is done back in the lab.
Bayer said that although she prefers field work and seeing the creatures in their natural environment, the lab work is interesting. "We extract the DNA from our tissue samples and go through several steps to purify it and make sure there are no contaminants. Then we use a machine to sequence the DNA.
"We look at the string of letters we get from this sequencing. If all the Sherandos look one way and all the Red Backs look different, then we know we have two different species. But if the two species actually have some DNA in common. then that would prove they are interbreeding where their habitats overlap."
But it's not that clear cut. Bayer said it depends on your definition of species.
"Some scientists say that if they interbreed at all and have fertile offspring then they are not a new species. Other people say that even if they interbreed, as long as their DNA is different, then they are a different species," she said.
So what will happen if the Sherando is determined to be a new species?
Marsh said that the salamanders are found mostly on land managed by the U.S. Forest Service, and added that the Forest Service is paying for a good chunk of this work, "because they are responsible for managing all the rare species on Forest Service land. If this turns out to be a new species, it will be one of the most spatially restricted species in North America. It will affect how the Forest Service manages these lands and may affect timber harvesting policy, mining and other things that go on in the area."
Marsh said the research has progressed well this summer, and the W&L team hopes to provide the Forest Service with a definitive answer on the Sherando salamander by the fall.
R.E. Lee Research Scholars are part of the University's undergraduate research program and is in its fifth decade of operation. It was founded in 1960 by an 1899 graduate. Students must be nominated by their professors to be R.E. Lee Research Scholars. It involves either assisting a professor in research or carrying out a student-planned project under the supervision of a professor.
The Howard Hughes Medical Institute Grants include a research preparation course during a student's first Spring Term as a Fellow plus two intensive summer research periods with a chosen faculty mentor as well as academic year research opportunities with faculty mentor. Students are selected through an application process.