There are over 26,000 species of Drosophila, all of which are segmented animals with paired, jointed appendages (legs), two pairs of wings, and a hard outer covering, or exoskeleton, but no internal skeleton as in humans. Drosophila simulans is a close relative of Drosophila melanogaster, which has been widely used as a model organism for research in genetics and developmental biology. The two species had a common ancestor 2-3 million years ago and are difficult to distinguish one from the other. Drosophila simulans was first described by the geneticist Alfred Sturtevant, when he discovered that flies in what was thought to be a Drosophila melanogaster colony at Columbia University were actually two distinct species.
Drosophila simulans has a short generation time, going from a newly-laid egg to a sexually mature adult in about a week. Females lay batches of small, white eggs on or near the surface of fermenting fruit or organic matter. Larvae emerge about 30 hours after the eggs are laid and feed near the surface of the fermenting material. The larvae feed for five to six days then crawl to drier areas of the food to pupate. The larva transforms into the pupa in the last larval skin, or puparium. The adult fruit fly emerges several days later. The newly emerged fruit flies are attracted to light and become sexually active in about two days. The adults mate more than once.
Drosophila simulans is one of several small flying insects that are sometimes called "fruit flies". Many of these fruit flies, including Drosophila simulans, are found throughout the world in association with humans. They are often found in kitchens on over-ripe fruit where they feed on the microorganisms that decompose the fruit and the sugar from the fruit itself, as well as lay their eggs.
One of the goals of this genome project was polymorphism discovery. To facilitate this, draft sequence was generated from multiple inbred strains. From the white strain 3-4x coverage was generated from plasmid and fosmid libraries. An additional 1x coverage from plasmids was generated for each of six other strains (C167.4, New Caledonia, Inbred 4, Inbred 6, MD199S, MD106TS) for a total coverage of 9-10x. The National Human Genome Research Institute (NHGRI), National Institutes of Health (NIH), provided the funding for sequencing the D. simulans genome.