Body Size in Mexican Wolves
Richard Fredrickson
Department of Biology, Arizona State University, Tempe, AZ 85287-1501; Richard.Fredrickson@asu.edu
Philip Hedrick
Department of Biology, Arizona State University, Tempe, AZ 85287-1501; Philip.Hedrick@asu.edu
Abstract
The Mexican gray wolf
(Canis lupus baileyi) appears to be extinct in the wild and exists now onlyin captivity and in a single, small, reintroduced population. A recent study of captive animals
found no evidence for inbreeding depression in juvenile viability or litter size. We examined the
relationship between inbreeding and body weight in captive wolves. We found that captive wolves
with little or no known inbreeding had lower body size than wild caught wolves. In addition,
captive wolves with higher inbreeding had lower body size than captive wolves with little or no
inbreeding. The captive population was descended from three founders until two other lineages,
each descended from two founders, were recently added to the population. Consequently we
examined the potential statistical power associated with future comparisons of body weights
between inbred wolves and the offspring of cross-lineage matings. In this case it appears likely
that in the next few years there will be an adequate sample size to statistically evaluate differences
in body size between these groups.