PORTLAND, Ore. May 20, 2011. North American red foxes originated from two
separate genetic lineages that were isolated from each other by
glaciers some half a million years ago, according to a U.S. Forest
Service Pacific Northwest Research Station study.
Researchers extracted DNA from saliva left behind on the bait sock (tied around Tree) and determined that Sierra Nevada red foxes still lived in the area.
Photo credit: Kirby Calhoun,
in the April/May 2011 issue of Science Findings, a monthly publication
of the station—can assist
efforts aimed at conserving potentially imperiled montane populations
of the species.
When most people think of the red fox, they envision the ones that
thrive in low-elevation, human-dominated landscapes,” said
Keith Aubry, a research wildlife biologist at the station who led
the study. “But there are other extremely elusive and rarely
seen populations that live only in isolated alpine and subalpine
areas in the mountains of the Western United States.”
latter group—the montane red foxes—may be imperiled
by climate change and other contemporary pressures and were the
focus of Aubry’s doctoral work in the early 1980s. Contrary
to prevailing theory at the time, Aubry hypothesized that native
North American red foxes were descended from two distinct lineages,
not one, that were isolated from each other in both northern and
southern ice-free areas during the most recent Ice Age. Such an
evolutionary history would help explain the unique ecological adaptations
of the montane foxes, and why native red foxes in southern British
Columbia are so much bigger than the montane foxes that occupy
nearly adjacent areas in Washington’s Cascade Range.
If all of North America’s foxes originated from a single
lineage that had expanded its distribution in a wave across the
continent, you’d expect to see a more or less continuous
gradient in size,” Aubry said. “But there was an abrupt
discontinuity in size in that area, suggesting that the montane
red foxes had evolved in isolation from the northern populations,” Aubry
Only recently were Aubry and his colleagues
able to test this hypothesis through genetic analyses of 285 museum
and a close examination
of fossil, archeological, historical, and ecological records. They
found that North American red foxes did, indeed, stem from two
distinct lineages that diverged from each other while they were
isolated in both the southern and northern parts of the continent
during the last Ice Age. Moreover, Aubry suspects that montane
foxes’ smaller size and high-elevation habitat preference
is indicative of their being descendants of ancient foxes that
had inhabited the southern part of the continent.
of the evolutionary history and genetics of the North American
red fox, managers can distinguish native from nonnative
populations and can clarify genetic relationships among subspecies—knowledge
that, in turn, can be used to target conservation efforts to the
appropriate gene pool.
To read the April/May 2011 issue of Science
Findings online, visit http://www.treesearch.fs.fed.us/pubs/37702.
The Pacific Northwest Research Station is headquartered in
Portland, Oregon. It has 11 laboratories and centers in Alaska,