7/19/99

Contacts:
Brent Danielson, Animal Ecology, (515) 294-5248
Megan Kuhn, Agriculture Information, (515) 294-2957

ISU RESEARCHERS STUDY ENDANGERED SNAIL IN UNIQUE IOWA LANDSCAPE

AMES -- Iowa State University researchers have been studying a federally endangered species, unique to Iowa, looking for information about its genetic diversity with hopes of understanding how to better preserve different populations.

Brent Danielson, professor of animal ecology, and Tamara Ross, postdoctoral student in zoology, have been looking at the Iowa Pleistocene snail. It roamed freely in parts of Iowa and surrounding states more than 10,000 years ago, but now can only be found in very small, specific areas. The small, light brown land snail was believed to be extinct until rediscovered in 1972. It now can be found on less than 30 steep slopes in northeast Iowa and northwest Illinois.

These slopes are usually small areas of sharp cliffs near streams and rivers. Danielson describes the slopes as "unusual limestone structures with cracks allowing air to circulate." This creates natural air-conditioning, allowing a place for unusual plants and animals to live.

Temperatures on the slopes stay in a narrow range throughout the year, ranging from 15 to 50 degrees Fahrenheit. This is a major reason the snails live there, says Danielson, adding that the snails cannot survive in temperatures over 75 degrees.

Danielson and Ross looked at the genetic diversity of the snails within populations and also among different watersheds. "Because the snails are isolated in very small areas, there is more chance of inbreeding and reduced genetic exchange with other populations," says Danielson.

Danielson says snails require genetic researchers to know some special tricks. "Snails are a bit problematic because their body tissues are permeated with slimy mucus that makes DNA separation from the rest of the tissue rather difficult," says Danielson.

They found that within a watershed, genetics of snail populations were very similar. However, Danielson says the genetic makeup varied greatly when comparing populations from different watersheds. This information will help researchers prioritize populations for conservation.

"We would preserve the genetic variability better by preserving one population in each of five watersheds, rather than five populations in one watershed," says Danielson. This is important if the species is subjected to new threats in the future.

Even though the snails are on the endangered list, Danielson says they are abundant in their small habitat. Many of the slopes in Iowa are owned by the state, the U.S. Fish and Wildlife Service or private conservation organizations. Most are in some state of preservation within state parks.

However, the slopes are only partly protected, Danielson says. "People can still walk on them and they are extremely sensitive areas."

He says fencing off the slopes is not totally effective and there are bigger threats than human disturbance. Logging takes away the shade needed to help keep the area cool. Erosion clogs up cracks, causing poor ventilation. Once the cooling effect is lost, cold-adapted species, like the snail, cannot survive. Once that happens restoration of damaged slopes may not be possible, Danielson says.

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