Washington: An ecologist from the Cornell University has brought back to life century-old eggs of zooplankton to better understand evolution.Nelson Hairston Jr., chair of Cornell``s Department of Ecology and Evolutionary Biology, achieved the seemingly impossible concept of resurrection.
This field is known loosely as "resurrection ecology," in which researchers study the eggs of such creatures as zooplankton - tiny, free-floating water animals - that get buried in lake sediments and can remain viable for decades or even centuries.
By hatching these eggs, Hairston and others can compare time-suspended hatchlings with their more contemporary counterparts to better understand how a species may have evolved in the meantime.
The researchers take sediment cores from lake floors to extract the eggs. The deeper the egg lies in the core, the older it is.
They then place the eggs in optimal hatching conditions, such as those found in spring in a temperate lake, and let nature take its course.
"We can resurrect them and discover what life was like in the past," said Hairston.
Hairston first became interested in the possibilities of studying dormant eggs in the late 1970s, when he was an assistant professor of zoology at the University of Rhode Island.
There, he noticed that the little red crustaceans - known as copepods - in the pristine lake behind his Rhode Island home, disappeared in the summer, only to return as larvae in the fall.
The observation prompted him to study why they disappear, research that revealed the copepods stay active under the ice in the winter, but they die out as their eggs lie dormant on the lake floor through the summer when the lake`s fish are most active.
When the fish become less active in the fall, larvae hatch from the eggs, and the copepods continue their life cycle.
This time suspension, where zooplankton pause their life cycles to avoid heavy predation or harsh seasonal and environmental conditions, also increases a species`` local gene pool, with up to a century`s worth of genetic material stored in a lake bed, according to Hairston.
When insects, nesting fish and boat anchors stir the mud, they can release old eggs that hatch and offer a wider variety of genetic material to the contemporary population.
First Published: Sunday, July 19, 2009, 17:06