Rodent's bizarre traits deepen mystery of genetics,...( WEST LAFAYETTE Ind. - A shadowy roden...)

WEST LAFAYETTE, Ind. - A shadowy rodent has potential to shed light on human genetics and the mysteries of evolution.

Purdue University research has shown that the vole, a mouselike rodent, is not only the fastest evolving mammal, but also harbors a number of puzzling genetic traits that challenge current scientific understanding.

"Nobody has posters of voles on their wall," said J. Andrew DeWoody, associate professor of genetics in the Department of Forestry and Natural Resources, whose study appears this month in the journal Genetica. "But when it comes down to it, voles deserve more attention."

Small rodents often confused for mice, except with shorter tails and beady eyes, voles live throughout the Northern Hemisphere and are often considered agricultural pests because they eat vegetation. Nevertheless, voles are an "evolutionary enigma" with many bizarre traits, DeWoody said. Understanding the basis for these traits could lead to better understanding of the same phenomena in human genetics and genetic disorders, and could have implications for gene therapy, he said.

The study focuses on 60 species within the vole genus Microtus, which has evolved in the last 500,000 to 2 million years. This means voles are evolving 60-100 times faster than the average vertebrate in terms of creating different species. Within the genus (the level of taxonomic classification above species), the number of chromosomes in voles ranges from 17-64. DeWoody said that this is an unusual finding, since species within a single genus often have the same chromosome number.

Among the vole's other bizarre genetic traits:

• In one species, the X chromosome, one of the two sex-determining chromosomes (the other being the Y), contains about 20 percent of the entire genome. Sex chromosomes normally contain much less genetic information.

• In another species, females possess large portions of the Y (male) chromosome
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