The most comprehensive genetic study to date concerning the evolutionary relationships among the three animal species whose genes have been completely sequenced--the human, the fruit fly, and the nematode worm--has determined that the human species is more closely related to the fruit fly than to the nematode. "We compared 100 genes that are common among these three species--the largest data set ever used to address this question--and obtained a result that is unambiguous," says S. Blair Hedges, an evolutionary biologist at Penn State, whose research team includes other scientists from Penn State and Japan.
"Cost estimates for acquiring the human genome alone range between 300 million and 3 billion," Hedges comments. "After spending all that money and effort, we now should at least be able to know for sure how these animals are related." These three species, which were singled out for the extensive genome effort, each represent much larger groups of animals: vertebrates are represented by humans, arthropods are represented by the fruit fly, and nematodes are represented by one species of nematode.
The results of the study by Hedges and his colleagues overturn a popular recent hypothesis, based primarily on the study of a single gene, and have important implications for research in fields such as medicine and developmental biology. The study, published in the current edition of the web-based journal BMC Evolutionary Biology, also is expected to impact the content of biology textbooks.
"About five years ago, the journal Nature published an analysis of one gene common to these three species that inexplicably persuaded many scientists to abandon the classic hypothesis of their relationships, which was based on the long-standing method of comparing structural similarities," Hedges says. The new hypothesis, named "Ecdysozoa," argued that fruit flies and nematodes are more closely related to each other than to humans. The classic hypothesis, naPage: 1 2 3 4 Related biology news :1
Contact: Barbara K. Kennedy
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