Scientists have studied Daphnia for centuries because of its importance in aquatic food webs and for its transformational responses to environmental stress. Predators signal some of the animals to produce exaggerated spines, neck-teeth or helmets in self-defense. And like the virgin nymph of Greek mythology that shares its name, Daphnia thrives in the absence of males -- by clonal reproduction, until harsh environmental conditions favor the benefits of sex.
Arguably, more is known about the ecology and stress biology of the water flea than any other animal. The genome project was conceived with an expectation that many new gene functions would be uncovered when studied in light of the animal's natural environment -- not necessarily expecting to discover many more genes.
Yet, Daphnia's genome is no ordinary genome.
"Daphnia's high gene number is largely because its genes are multiplying, by creating copies at a higher rate than other species," said project leader and CGB genomics director John Colbourne. "We estimate a rate that is three times greater than those of other invertebrates and 30 percent greater than that of human."
"One theory is that Daphnia is so good at adapting to so many environments because it has this huge catalog of genes to call upon," says Thomas. The researchers note that more than one-third of Daphnia's genes are undocumented in any other organism they are completely new to science.
At UNH, where the relatively new field of environmental genomics is at the core of the HCGS mission, the Daphnia project resulted in productive collaborations around the university. "It was a significant part of starting many science careers," says Thomas, noting that many undergraduate, graduate and visiting students participated.
Jim Haney, professor of freshwater biology, helped with cultures
|Contact: Beth Potier|
University of New Hampshire