If they do, this could show evolution at work since scientists know that where turtles nest - POTTER'S MARSH, Ill. (AP) - Fred Janzen kneels down on his knee pads and lies flat on the grass. He gently pushes at the earth, feeling for the nest of yellow, red and green striped baby turtles that lie inches beneath the surface.

"Bingo, right there," Janzen said of the silver-dollar sized hatchlings. "See the movement? This is great. I love these. Every nest is a little surprise."

Janzen's turtle camp is a patch of grass next to a lime-colored marsh brimming with perhaps 1,000 painted turtles on an island in the Mississippi River.

The turtles at south Potter's Marsh have been Janzen's passion and the focus of his research the last 15 years. An associate professor of zoology and genetics at Iowa State University, Janzen is trying to find out if the mothers transfer, through their DNA, a package of preferences that tells their offspring good places to nest when they reach adulthood. In a way, it's the nature vs. nurture argument.

Since the mother turtles don't raise their young, and probably wouldn't know them if they bumped into each other in the marsh, they're good test subjects, Janzen says.

By taking tissue samples from the mother and her babies, Janzen can see, from one generation to the next, if the young nest in locales similar to their mothers.

such as shady areas - influences the sex of the offspring and other traits, such as body size.

It's not clear what implications Janzen's work on turtles would have for humans since the two are very different. But he says it could help improve the general understanding of how behavior often associated with a mother's care - such as nursing a baby - could be transmitted genetically.

Every May, Janzen troops out with about 10 of his students to the marsh. During about six weeks of 18-hour work days, they watch the mother turtles lay their eggs and then tag the nests with numbered orange flags.

Janzen and his students return to the camp in September to unearth the nests. They take the hatchlings back to the labs at Iowa State to measure them and to create genetic fingerprints of each one.

There can be some surprises. In one nest, a student finds two hatchlings with white skin, pink eyes and fluorescent orange-colored shells on the underside of their bellies - better known as albinos.

The finding - the first of its kind at the camp - is extraordinary.

"I've seen hundreds, maybe thousands of nests and certainly thousands of hatchlings, and seen some pretty bizarre stuff," Janzen says, "but this about tops it."

The work can be trying.

"Every single year there's some weather anomaly that I really believe most people would just never subject themselves to in a tent."

This year, it was flash floods and storms. Last year, three windstorms flattened the camp and a tree branch slammed into a student's car. That doesn't include background annoyances - lots of mosquitoes, hot and humid weather, and camp food.

"It's getting old, so last year I gave in. I actually sleep on a cot now," the 40-year-old researcher says.

There are those who might think Janzen and his students are crazy to return to such camp life year after year.

"I'm sure we are," he says. "But there's got to be an element of crazy in any passion ... if you love this stuff, then you'll tolerate a lot."

ON THE NET

Janzen: http://www.public.iastate.edu/%7Efjanzen/

Potter's Marsh: http://www.umesc.usgs.gov/umr_refuge/umrsav/savpot.html