Researchers looked at how the Antarctic midge lives its extraordinary life cycle all on the smallest insect genome known to science.
The midge's larvae develop over two Antarctic winters, and lose over half their body mass each time, Washington State University reported. During this period the insect's body endures intense ultraviolet radiation, high winds, and salt. In adulthood the midge survives without wings and lives for only about a week, all on its exceptionally small genome.
"It's tiny," said Joanna Kelley, a Washington State University assistant professor who recently sequenced and analyzed the genome with colleagues around the U.S. "That was a huge surprise. I was very impressed."
The midge genome has 99 million base pairs (the "building blocks" of DNA), the human genome consists of 3.2 billion base pairs.
"We suspect that it's somehow an adaptation to the extreme environment," Kelley said. "And it opens up a lot of interesting hypotheses to hopefully test by sequencing additional Antarctic organisms or sub-Antarctic organisms, because there are other flies, or Diptera, on some of the sub-Antarctic islands. We're really interested to see whether or not they have similar genomes."
The research team found the midge has a great deal of genes geared towards the regulation and developmental processes. It has few odor receptors, most likely because it does not fly and only has to detect things at very short distances. Compared to other insects the midge has an "extremely economical" genome. It has few repeated genetic sequences and shorter DNA stretches than what is commonly seen.
"[The genome] opens up a lot of questions for me about genome evolution, and I'm looking at other related organisms to try and get at that question. What allows or inhibits a genome from being very large or small and what are the consequences of that?" Kelley asked.
"It's a pretty exciting fly," she said.
The findings were published in a recent edition of the journal Nature Communications.