Response to Hohenlohe et al.

Abstract

Hohenlohe et al. raise a number of concerns about our conclusions. We focus on those involving species status, divergence time, admixture, and D statistics because we regard them as the most consequential points. In general, Hohenlohe et al. largely recapitulate criticisms about sample composition, historic range, and the genuine species status of the eastern and red wolves made during the 25-year history of genetic research on the two forms. With the exception of Wilson et al. (1), which was a preliminary treatment, we know of no convincing genetic arguments for distinct species status of the red wolf. On the contrary, a large body of evidence, including genome-wide studies of large population samples, suggests that it is a hybrid between the coyote and a unique population of the gray wolf (2–8), and our complete sequence data reaffirm these past studies. The “eastern wolf" (or more generally the Great Lakes wolf population) has a controversial taxonomic status, and it has been argued to represent a distinct ecotype of the gray wolf admixed with coyotes (9) or a distinct species centered on Algonquin National Park and surrounded by a large admixture zone of coyotes, gray wolves, and eastern wolf hybrids. Gray wolves and coyotes are verified as interfertile by artificial insemination (10); however, these hybrids then reproduced without assistance in captivity, forming F2s (11). In addition to the empirical population genetic evidence (3, 4, 8, 9, 12–14), this purposeful and subsequent unintentional breeding experiment showed that hybrids of gray wolves and coyotes could readily be formed across two generations and do not follow Haldane’s rule expected for biological species or show any evidence of infertility, confirming that they are very recently diverged, as suggested by the sequence evidence (see below). These data provide suggestive evidence that red and eastern wolves, which are hypothesized to have diverged from the coyote lineage more recently than gray wolf and coyote, must likewise be genetically very similar, reproductively interfertile, and, at best, questionably distinct from coyotes or gray wolves.