In comparing the genome sequences of the 12 species, the team of scientists discovered, for example, that D. melanogaster shares only 77 percent of about 13,700 protein-coding genes with all of the other 11 species. The 23 percent of genes that differ are most likely the ones that have adapted themselves due to environmental pressures and sexual selection. For example, one specialist fruit fly, D. sechellia, eats only one type of fruit and is losing taste receptors five times faster than other fruit fly species that eat a wider range of foods.
Clark said there also is evidence of an evolutionary battle in immune systems of the flies as they repeatedly adapted their defenses against mutating bacteria. As bacteria find new ways to infiltrate a system, species evolve their own new defenses. Most of the genetic changes have been in each fruit fly species' ability to detect and recognize bacteria they confront, Clark said. Although species may respond differently to particular bacteria, overall their innate primary immune responses are similar and even share many features in common with human innate immunity.
One species, D. willistoni, surprised researchers because it had no genes that produce selenoproteins, which sequester selenium, an antioxidant found in many foods and a required mineral for nearly all higher organisms including humans. D. willistoni appears to be the first case of an animal that does not have genes to make selenoproteins, though the researchers cannot rule out the possibility that the species may have another way to encode selenium in its proteins.
Understanding gene regulation: Drosophila continue to offer signs -- and questions
In the cells of the tiny fruit fly (Drosophila), researchers in the 1930s found valuable resources known as polytene chromosomes -- giant bundles of chromo
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