Ecological divergence of prairie dogs

In many cases, genetic information about species identiy are in conflict with morphological or other data--and such conflict is often due to the biological reality that species do not diverge instantaneously.  For this reason, any attempt to classify species or subspecies should include as many types of data as possible.  Below are the combined results from ecological niche modeling of the two subspecies, overlaid by data from 18 nuclear microsatellites, which both support to the hypothesis of genetically and ecologically distinct subspecies.



Above:  Map of the geographic range of Gunnisons prairie dogs (black outline), with colored shading denoting the projected ecological niche of each subspecies.  Pies represent the microsatellite cluster composition of each population.



Nuclear and mitochondrial genetic signatures often differ.  We examined the correspondence between the two by plotting the frequency of the ‘montane’ microsatellite cluster against the frequency of the ‘montane’ mitochondrial haplotype (below right).  There is very close agreement in most populations, with the exceptions occurring in populations that fall along the geographical boundary between subspecies.





Ecological differentiation was also demonstrated in a Principal Component Analysis of temperature and precipitation for each of our 48 sampling sites.  Coupled with divergence in morphology, the evidence for distinct subspecies is multifaceted.


You can download a copy of the paper here.




Collaborators:

Andy Martin, University of Colorado

Amy Seglund, Colorado Parks and Wildlife

Rob Guralnick, University of Florida

Dave Wagner, Northern Arizona University

Joe Busch, Northern Arizona University



Amazing field assistants:  Erin Pikcilingis (my most invaluable asset), Max Mazzella, and Sarah Hale

 

Genetic and ecological differentiation in Gunnison’s prairie dogs

The U.S. Fish and Wildlife Service recently designated Gunnison’s prairie dogs (Cynomys gunnisoni) as a species of concern in the montane portion of its range, due to low population connectivity and high plague susceptibility in  this part of the range. Historically, two behaviorally (Renner 2003) and morphologically (Hollister 1916) distinct subspecies were recognized (C.g. gunnisoni and C.g. zuniensis), but early genetic studies questioned their distinctiveness (McCullough 1991).  We performed a comprehensive analysis of microsatellite and mitochondrial variation throughout the range of the species, coupled with assessment of the ecological conditions occupied by each subspecies and a morphological analysis of differentiation.