Scientists have discovered that the animal with the most genes--about 31,000--is the near-microscopic freshwater crustacean Daphnia pulex, or water flea.
By comparison, humans have about 23,000 genes. Daphnia is the first crustacean to have its genome sequenced.
The water flea's genome is described in a Science paper published this week by members of the Daphnia Genomics Consortium, an international network of scientists led by the Center for Genomics and Bioinformatics (CGB) at Indiana University (IU) Bloomington and the U.S. Department of Energy's Joint Genome Institute.
"Daphnia's high gene number is largely because its genes are multiplying, 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 humans."
"This analysis of the Daphnia genome significantly advances our understanding of how an organism's genome interacts with its environment both to influence genome structure and to confer ecological and evolutionary success," says Saran Twombly, program director in the National Science Foundation (NSF)'s Division of Environmental Biology, which funded the research.
"This gene-environment interplay has, to date, been studied in model organisms under artificial, laboratory conditions," says Twombly.
"Because the ecology of Daphnia pulex is well-known, and the organism occurs abundantly in the wild, this analysis provides unprecedented insights into the feedback between genes and environment in a real and ever-changing environment."
Daphnia's genome is no ordinary genome.
What reasons might Daphnia have so many genes compared to other animals?
A possibility, Colbourne said, is that "since the majority of duplicated and unknown genes are sensitive to environmental conditions, their accumu
|Contact: Cheryl Dybas|
National Science Foundation