Phylogenetic relationships within the extant Mustelidae (Carnivora): appraisal of the cladistic status of the Simpsonian subfamilies

Abstract

Cladistic analysis of extant mustelids based on a data matrix consisting of 30 characters derived from morphological study of the head skeleton in all 23 genera, and 16 characters gleaned from the literature, yielded 75 most parsimonious trees with a consistency index of 0.487 using PAUP 3.0s. The analysis strongly supports the monophyly of both the Mephitinae (skunks) and Lutrinae (otters). The Mustelinae (weasels, martens, wolverine, etc) is probably paraphyletic, but there is some support for a monophyletic group consisting of the mustelines and the honey badger Mellivora. The Melinae (badgers) is a polyphyletic group; the badger ecomorph probably evolved independently at least three times within the Mustelidae. On consensus trees, there is a lack of resolution concerning the relationships within the Mephitinae and Lutrinae and the positions of Galictis and Mustela. These results are broadly congruent with a cladistic interpretation of Simpson's intent in his influential 1945 classification. Thus, a paraphyletic Mustelinae is consistent with Simpson's conception of a horizontal grouping, whereas the Mephitinae and Lutrinae represent vertical divergent lineages. In contrast, the cladistic status of the Melinae is not consistent with Simpsonian classificatory principles. The status of the monotypic Mellivorinae cannot be evaluated without considering its putative fossil members; however, the clustering of Mellivora with the badger Taxidea is not consistent with Simpson's scheme. Some of the more inclusive clades in the most parsimonious trees are vulnerable to minor changes to the data matrix. The fossil record is consistent with the basic outlines of the cladistic pattern and explains various ostensible biogeographic anomalies. Bootstrap analysis identified marked variation in the support for the components of the cladistic pattern.

Evolutionary and biogeographic history of weasel-like carnivorans (Musteloidea)

“…Similarly, all martens have been grouped in a single genus (Martes); the weasels, polecats, and minks have, until recently, been united with the martens and wolverines in a subfamily referred to as Mustelinae; and the otters have been retained in their own subfamily Lutrinae (e.g., . Although the monophyly of all otters (both extant and extinct) remains to be established, our findings are congruent with earlier observations (e.g., Bryant et al, 1993;Fulton and Strobeck, 2006;Koepfli et al, 2008;Wolsan and Sato, 2010) that the living otters are monophyletic. Our results, however, also clearly indicate that the badgers, martens, weasels, polecats, and minks are each not monophyletic (Figs.…”

“…1-3). This observation agrees with the results of earlier phylogenetic investigations exploring sequence data from multiple DNA loci Fulton and Strobeck, 2006;Sato, 2006;Koepfli et al, 2008;Wolsan and Sato, 2010), but contradicts a hypothesis based on anatomical characters, which instead proposes Melogale as sister to all other mustelids and mephitids (Bryant et al, 1993).…”

“…The monophyly of the mustelines, ictonychines, and lutrines was also strongly supported, corroborating results obtained in other molecular studies (Dragoo and Honeycutt, 1997;Flynn et al, 2005;Fulton and Strobeck, 2006;Rozhnov et al, 2006;Koepfli 22 et al, 2008;Harding and Smith, 2009;Agnarsson et al, 2010;Eizirik et al, 2010;Wolsan and Sato, 2010), which conflict with competing (largely morphology-based) hypotheses (e.g., Bryant et al, 1993;Baryshnikov and Abramov, 1998;Bininda-Emonds et al, 1999). Previous molecular investigations have suggested that ictonychines are most closely related to either mustelines (Fulton and Strobeck, 2006;Rozhnov et al, 2006;Harding and Smith, 2009;Agnarsson et al, 2010) or lutrines (Dragoo and Honeycutt, 1997;Fulton and Strobeck, 2006;Eizirik et al, 2010;Wolsan and Sato, 2010), or are sister to a hypothesized clade composed of mustelines and lutrines (Dragoo and Honeycutt, 1997;Flynn et al, 2005;Koepfli et al, 2008).…”

“…Recent hypotheses based on anatomical data (Bryant et al, 1993) or on a combination of anatomical and mtDNA data or mtDNA data alone (Dragoo and Honeycutt, 1997;Marmi et al, 2004) have postulated a mellivorine affinity for Taxidea taxus (Taxidiinae) or have placed this species in a sister relationship to Meles alone or together with Arctonyx collaris (Melinae). Our results reject these hypotheses and instead strongly support Taxidiinae as sister to all other mustelids, corroborating in this respect the phylogenetic reconstruction inferred in Koepfli et al (2008).…”

“…Alternative hypotheses about the relationships of ictonychines (e.g., Bryant et al, 1993;Baryshnikov and Abramov, 1998;Bininda-Emonds et al, 1999;Agnarsson et al, 2010) are thus rejected.…”