Sep. 12, 2011 Flitting among the cool slopes of the Appalachian
Mountains is a tiger swallowtail butterfly that evolved when two
other species of swallowtails hybridized long ago. It's a rarity
in the animal world, biologists have found. They discovered that
the Appalachian tiger swallowtail, Papilio appalachiensis,
evolved from mixing between the Eastern tiger swallowtail, P.
glaucus, and the Canadian tiger swallowtail, P. canadensis. The
Appalachian tiger swallowtail rarely reproduces with its
parental species and is a unique mixture of the two in both its
outward traits and inward genetic makeup. The research,
published September 12 in the journal PLoS Genetics, is funded
by the National Science Foundation (NSF) and the National
Institutes of Health. "Understanding species formation is
central to explaining the vast diversity of life on Earth," says
Sam Scheiner, program director in NSF's Division of
Environmental Biology. "But we are just beginning to understand
the process," says Scheiner. "These researc