 June 19, 2009
"When we give something its own name we're saying this is a unit of biodiversity that deserves to be conserved," said Kris Hundertmark, of the UAF Institute of Arctic Biology. "If you name something that doesn't deserve a name, you are wasting resources that could be spent on worthwhile groups." Hundertmark will be presenting his research during the American Society of Mammalogists 89th Annual Meeting June 24-28 at UAF. The reference book Mammal Species of the World, which Hundertmark calls the "unofficial bible of what is a mammal species and what isn't," lists two species of moose. The two-species concept is based primarily on a difference in chromosome numbers and the physical structure, or morphology, of moose. Chromosomes are ranked and numbered by size, largest to smallest, and can be depicted in a standard format known as a karyogram. A typical chromosome is shaped like an X, though some are V-shaped. The karyogram for North American moose shows 70 pairs of chromosomes. A Eurasian moose karyogram shows 68 pairs. "We've always known that North American moose have one more pair of chromosomes than Eurasian moose," Hundertmark said. "But it is a minor rearrangement rather than a functional difference." The morphology argument is a nonstarter because similar physical differences exist among other animals considered one species and ... "moose are distributed throughout the Northern Hemisphere and would be expected to exhibit regional variation in morphology," said Hundertmark. One way of defining a species is whether two individuals can mate and produce viable offspring. If they can, they're the same species; if they can't, they're not. But transporting moose for breeding experiments is prohibitively expensive and, according to Hundertmark, it is not unreasonable to assume that the two types can interbreed until it is proven otherwise. To test the two-species hypothesis, Hundertmark examined the DNA from moose tissue samples collected by colleagues around the world. He arranged the samples into two groups based on the two-species hypothesis and into three groups based on continent of origin - Europe, Asia and North America -- and examined the distribution of genetic variation within and between groups. "It turns out that there
are actually three genetic groups of moose, not two, and the
genetic differences among those groups do not rise to the level
of separate species. It is just regional variation," Hundertmark
said.
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