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Journal
Publications
Worley K., Strobeck C.,
Arthur S., Carey J., Schwantje H.,Veitch A., and Coltman D.W. 2004.
Population genetic structure of North American thinhorn sheep
(Ovis dalli). Molecular Ecology. 13: 2545–2556.
(PDF = 314 KB)
Abstract:
The thinhorn sheep (Ovis
dalli ssp.) provides a rare example of a North American large mammal
that occupies most of its native range and maintains close to ancestral
population size. There are currently two recognized subspecies, Dall’s sheep
(O. d. dalli) and Stone’s sheep (O. d. stonei), the validity
of which remains uncertain. We investigated the spatial genetic structure of
thinhorn sheep populations representing both subspecies by genotyping
individuals (n = 919) from across the species range at 12 variable
microsatellite loci. We found high levels of genetic diversity within (HE
= 0.722) and significant genetic structure among the 24 sampled areas (FST
= 0.160). Genetic distance measures and Bayesian clustering analyses
revealed the presence of at least eight subpopulations that are delineated
by mountain range topology. A strong overall pattern of
isolation-by-distance is evident across the sampling range (r = 0.75, P <
0.001) suggesting limited dispersal and extensive philopatry. Partial Mantel
tests of this relationship showed mountain range distinctions represent
significant barriers to gene flow (P = 0.0001), supporting the Bayesian
analyses. Genetic structure was more strongly pronounced in southern Yukon
and Alaska than elsewhere. We also show evidence for genetic differences
between the two currently recognized thinhorn subspecies. |
