We are tracing the origins of invasive watersnakes, Nerodia spp., in California and Arizona
Tracing the molecular origins of and introduced population of Nerodia fasciata in Northern
California
Collaborators
 The Florida Water Snake is
native to the southeastern United States,
but an introduced population occurs in northern California. Invasive species are of
growing interest to conservation biologists because of their potential to cause
the extirpation of native species. The population in California occurs in close proximity to the
endemic Giant Garter Snake (Thamnophis
gigas)
listed as endangered under the U.S. Endangered Species Act. Eric
Stitt and ECORP Consulting are currently doing
field studies on the Florida Water Snake in California and have teamed
up with HOGL to incorporate a molecular component to their research.
We wanted to determine as closely as possible the source
population for the Folsom population of N. fasciata. Determining the source locale for these
snakes may provide insight into means by which they may be controlled in the
future, or may indicate physiological constraints to be exploited during future
eradication efforts. An invasive
population of this species has also been documented in Brownsville,
Texas population and it would be very
informative to know if source of the Folsom population is the same as that for
the Brownsville
population, such that it may be that the source population features especially "adaptive"individuals.
Tara Luckau of HOGL amplified the ND2 and cytochrome b regions of
mitochondria in the California
samples and compared them to sequences published in GenBank. Tara
examined over 2000 bp of sequence data for each individual and designed several
novel internal sequencing primers. The Folsom samples matched exactly that of "Haplotype" (accession # AY269791; Jansen & Karl, unpublished data),
associated with samples collected from Volusia, Pinellas, and Hillsboro Counties
in Florida,
and therefore represent individuals of Nerodia
fasciata pictiventris. Although our sample size for the genetic analysis
was small, the lack of any variability among samples suggests that the
introduced population came from a single maternal lineage.
Current Status:
The results were published in a US Fish and Wildlife Report,
which included Tara (while an undergraduate) as an author.
Stitt, E.W., P.S. Balfour, T. Luckau and T. Edwards. 2005.
The southern watersnake (Neroda fasciata) in Folsom, California:
History, population attributes, and relation to other introduced watersnakes in
North America. Final report to U.S. Fish and
Wildlife Service, Sacramento Fish and Wildlife Office, Sacramento, CA.
Cooperative agreement #11420-1933-CM02. 72 pp. plus appendices. usfws_nerodiareport.pdf
Photo Courtesy of Eric W. Stitt
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Conservation Genetics 
