The work is reported by Dr. Kermit Ritland and colleagues in this week's Current Biology.

The subject of their research is the elusive Kermode bear (ker-MODE-ee, also known as the Spirit or Ghost bear), a white black bear found only in the rugged rainforests of British Columbia's north coast islands.

The bears are not albinos, and while biologists had long suspected a hereditary basis for Kermodism, the biology behind the bears' white fur was unknown until Ritland and colleagues endeavored to obtain and analyze the bears' DNA.

Using ingenious fur snags to obtain DNA samples from 220 wild bears, the researchers found that the white coat arises from a single recessive mutation in a gene, mc1r, which encodes a melanocortin receptor, a protein that reads hormone levels and stimulates cells to produce pigment.

It was known that other mutations in melanocortin receptors also help provide the basis for coloring in domestically bred dogs such as yellow labs and golden retrievers, and the possible connection inspired Ritland to look there for the cause of Kermodism.

Ritland's team found that the mutation is unique to Kermode bears, as it does not occur in black bears of black, brown or cinnamon coloring.

At the same time that it answers a natural riddle, the work also raises questions about how genetics can inform conservation efforts.

Though protected from hunting, there are very few Kermode bears: in their range, which is almost exclusively comprised of three islands narrowly separated from the mainland, the Kermode exist as part of a mixed population of black bears, only 10% of which (100-200 individuals total) are the Kermode white phase.

According to Ritland, a key question is whether a single mutation, such as the Kermode allele, can be considered what's known as an "evolutionarily significant unit" ­- a measure of uniqueness that can allow legal protection of a population.

"It's an open question," says Ritland. "We're in unknown territory here."

Related website:

Current Biology

18-Sep-2001