Midge has smallest insect genome to date.

• Position: Antarctica

Scientists who sequenced the genome of the Antarctic midge suspect the genome's small size--the smallest in insects described to date--probably can be explained by the creature's adaptation to its extreme living environment.

The midge is a small, wingless fly that spends most of its two-year larval stage frozen in the Antarctic ice. Upon adulthood, the insects spend seven to 10 days mating and laying eggs, and then die. Its genome contains 99,000,000 base pairs of nucleotides, making it smaller than other tiny reported genomes for the body louse (105,000,000 base pairs) and the winged parasite Strepsiptera (108,000,000 base pairs), as well as the genomes of three other members of the midge family.

The midge genome lacks many of the segments of DNA and other repeat elements linked to the production of proteins, which are found in most animal genomes. The lack of such "baggage" in the genome could be an evolutionary answer to surviving the cold, dry conditions of Antarctica, says David Denliner, senior author of the research published in the journal Nature Communications.

"It has really taken the genome down to the bare bones and stripped it to a smaller size than was previously thought...