Population structure of California coyotes corresponds to habitat-specific breaks and illuminates species history
BENJAMIN N. SACKS,
*
SARAH K. BROWN
*
and HOLLY B. ERNEST
*†
*
Wildlife and Ecology Unit, Veterinary Genetics Laboratory, School of Veterinary Medicine, University of California, Davis, Davis, CA
95616-8744, USA,
†
Department of Population Health and Reproduction, School of Veterinary Medicine, University of California,
Davis, USA
Abstract
Little is known about the relationship between animal movements and the emergent structure
of populations, especially for species occupying large continuous distributions. Some such mammals disperse disproportionately into habitat similar to their natal habitat, a
behavioural bias that might be expected to lead to habitat-conforming genetic structure.
Coyote on the streets of Chicago
would exhibit such natal-biased dispersal, and
used 13 microsatellite loci to test, correspondingly, whether genetic structure conformed tomajor habitat breaks. First, we used a model-based approach to assign coyote genotypes to
distinct genetic clusters irrespective of geographical location.
Visualization on a geographical information system revealed a strong concordance between the lour data combined with previouslypublished data suggest a pattern of genetic isolation-by-distance throughout western North America, consistent with independent evidence that the western half of the coyote
range predates European settlement.
Received 23 September 2003; revision received 2 December 2003; accepted 2 December 2003
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Early characterizations of the coyote as a ‘prairie wolf’ and
anecdotal accounts of coyotes entering into small densely
forested areas after Europeans introduced roads and clear
cuts (Grinnell et al. 1937; Dobie 1949; Young 1951) have
apparently fostered a popular misconception that the
pre-European range of the coyote was restricted to the
central part of the continent (e.g. Moore & Parker 1992;
Parker 1995).
While the coyote range clearly has expanded
eastward recently, numerous accounts by European
explorers indicate that the southwestern most extent of the
current coyote range (coastal British Columbia to coastal
Mexico) predates European settlement (e.g. Dobie 1949;
Jackson 1951; Young 1951; Schmidt 1991) and fossils
suggest that it could date back to the early Pleistocene
(Nowak 1978, 1979).
The ages of the southern-most and northern-most extents of the coyote range are less certain(Dobie 1949; Young 1951), although evidence suggests these too may be pre-European (Jackson 1951; Nowak1978).
Overall, it seems the pre-European coyote range was
at least two-thirds its current area (Dobie 1949; Young
1951), suggesting a considerably less pronounced range
expansion than is commonly presumed.
Also, our findings are consistent with the pre-European
existence of coyotes in western North America. Combining
our data with those from a previous, continental-scale
microsatellite study of coyotes (Roy et al. 1994) provides
strong support for the isolation-by-distance pattern overall.
. Although different loci were used in the two
studies, in principle, different sets of loci should yield
similar estimates of Nm (number of migrants exchanged
per generation). The estimates of Nm by Roy et al. (1994)
were approximately of the magnitude predicted by extrapolation
from this study, suggesting that they are consistent
with isolation-by-distance despite the high levels of gene
flow indicated. If so, this supports the observation that the
time since establishment of the western portion of the
coyote range was well beyond that since European colonization.
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