Grey Wolves and the Endangered Species Act:
Concordance All the Way Down
On June 13, 2013, the U.S. Fish and Wildlife Service (FWS) proposed removing the grey wolf, Canis lupus, from the List of Endangered and Threatened Wildlife. Under this proposal, the species of grey wolves – which was at one time protected across the 48 contiguous U.S. states – would no longer be so protected. Only one subspecies of grey wolf would be granted protection: the Mexican wolf (Canis lupus baileyi). This would, in effect, protect only 75 of the wolves in the U.S., the size of the wild population of Mexican wolves at the time.
The proposed rule has been roundly criticized on a number of fronts, most notoriously for declaring that what had previously been considered the subspecies Canis lupus lycaon (Eastern wolf) should now be considered a species, Canis lycaon; this decision was based on a conclusion from Chambers et al. (2012), written by the FWS’s own employees and published in its own journal. But although decisions under the Endangered Species Act (ESA) are supposed to be based on “the best available scientific information,” this was in fact a conclusion that was (and is) still very much under dispute. Other aspects of the wide-ranging proposed rule have received less attention, such as its recommendation that the Pacific Northwest grey wolves not be listed because, the proposal claims, they are not a “Distinct Population Segment”, or DPS (under the ESA, species, subspecies, or DPSs can be listed). Aside from the intrinsic importance of the issue, the claim that Pacific Northwest grey wolves should not be listed played a central role in the claim that Canis lupus should not be listed at all. Whether the Pacific Northwest grey wolves should be listed as an endangered DPS or not will be the focus of my presentation; I will argue that they should be.
Chambers et al. (2012), again, the article that formed the basis for the proposed rule, relied on the genealogical concordance approach of Avise and Ball (1990) for species and the related genealogical concordance approach of Avise (2004) for subspecies, approaches that have at their core a requirement of reciprocal monophyly (or near reciprocal monophyly). Note that the genealogical concordance approach is not meant to be a species concept, as Chambers and colleagues recognize; rather, it describes operational criteria (i.e., species indicators or evidence for species).
However, as part of the independent expert external review of the FWS’s proposed rule, Robert Wayne argued that the genealogical concordance approach is not appropriate for wolf subspecies given their high mobility, ongoing gene flow, and relatively recent colonization of North America. Moreover, he suggests, the concordance approach was not used thoroughly or consistently; if it had been, “the diverse sources of evidence, integral to the concordance approach [would] support multiple taxonomic units in North American based on genetics, phenotype, and ecology,” for example, the pacific coastal wolf. Thus, there is concordance, even in the absence of reciprocal monophyly.
Here I propose to extend Wayne’s argument: the concept of DPS used by the FWS for wolves is neither species appropriate nor consistent with a concordance approach. A more appropriate approach (consistent with some past FWS rules and analyses) would allow for DPSs to be metapopulations, where metapopulations can be identified via concordance of a variety of factors (consistent with the metapopulation concept of Millstein 2010). Setting aside the question of what species concept or subspecies concept one should use, if one deploys a concordance approach toward evidence “all the way down,” from species to subspecies to DPSs, then there is reason to think that there is a listable entity in the Pacific Northwest, either an identifiable subspecies or a DPS or both. And it is likely that that entity would be considered endangered. If it is endangered, then the case for delisting Canis lupus as a whole is undercut.