Water Flea Genome Sequenced: Sentinel of Environmental Change
The water flea Daphnia pulex is a keystone species of freshwater ecosystems, a principal grazer of algae, a primary food source for fish, a sentinel of still water inland ecosystems, and a sentinel species used to assess the ecological impact of environmental change. The genome of this species has just been sequenced by DOE’s Joint Genome Institute (JGI). They find that the Daphnia genome is only 200 megabases in size, but contains at least 30,000 genes, which is thought to be about 25% more than in the human genome. More than a third of Daphnia’s genes have no detectable homologs in any other available proteome, and the largest gene families are specific to the Daphnia lineage. These Daphnia-specific genes, including many additional sequenced genes that have not been assigned any functions, are the most responsive genes to ecological challenges. These results will enable better understanding of real-world environmental changes through knowledge of how a genome responds to gene-environment interactions. The study is published in the February 4, 2011, issue of Science magazine.
Colbourne, J. K., et al. 2011. “The Ecoresponsive Genome of Daphnia pulex,” Science 331, 555–61.