Biology Reference
In-Depth Information
4.
Introduction Sources,
Cryptic Species, and Invasion Routes
“Identifying the geographical source of invasive species is a critical
component of invasion biology....Because historical human records are
often incomplete, inaccurate or simply nonexistent, molecular genetics
offers a powerful tool for identification of putative source populations.”
—T
SUTSUI ET AL
. (2001)
Clouded salamander (
Aneides ferreus
) is the name that was first given to a
salamander that occurs in forests along the Pacific coasts of northern Cal-
ifornia and Oregon, on Vancouver Island, and at one spot on the adjacent
mainland of British Columbia, Canada. Oddly, this salamander is absent
from the coast of Washington. All other known forest plant and animal
species that occur on Vancouver Island and also in coastal Oregon are also
found in coastal Washington State.The discontinuity of the clouded sala-
mander distribution raised the question, “What is the relationship of the
British Columbia population to the populations in Oregon and Califor-
nia, and how did the British Columbia population originate?”
Todd Jackman (1998) undertook a genetic analysis of animals from
populations at 25 localities throughout the range of this salamander. He
used allozyme analysis, mitochondrial DNA (mtDNA) analysis, and
examination of chromosome structure. His results revealed a surprising
relationship. British Columbia salamanders were nearly identical to those
of California and differed from those along the Oregon coast. This find-
ing suggested that the British Columbia population might have been
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