| Evolutionary relationships of the order Carnivora have been extensively studied. However, phylogenetic studies based on different types of data, species samples, and methods of analysis provide contradictory results. Consequently, phylogenetic relationships of Carnivora are contentious. Within the caniform branch of Carnivora, phylogenetic relationships are unresolved among and within the families Procyonidae (raccoons), Ailuridae (red panda), Mustelidae (weasels and skunks), Ursidae (bears), Phocidae (true or earless seals), Otariidae (eared seals), and Odobenidae (walrus). Here, a method using primers binding at conserved regions of the mitochondrial genome is developed to rapidly collect homologous sequence data from carnivore species. The method is used to obtain the sequence of twelve mitochondrial genes (10 842 nucleotides) from 14 new species. Combined in a total of 38 carnivore species, these sequences form the largest molecular data set used to investigate the phylogeny of Carnivora. An analysis using maximum parsimony, maximum likelihood, and Bayesian approaches provides a unique and well supported solution to most contentious relationships within Caniformia. The clade Arctoidea is shown to consist of three major monophyletic clades: Pinnipedia, Ursidae, and Musteloidea. Within Pinnipedia, the families Otariidae and Odobenidae form a clade, sister to Phocidae. Within Musteloidea, there is a sister relationship between true mustelids (i.e. excluding the skunks) and procyonids, and between ailurids and mephitids (skunks). Despite a high level of confidence obtained at most nodes, uncertainty remains about the relative position of the three major arctoid clades. Likelihood-based tests of topologies and Bayesian posterior probabilities show that the mitochondrial data favour a sister relationship between the red panda and the skunks over six previously suggested alternative hypotheses. Agreement between different methods and high level of support are good indications that the analysis is converging toward the true mitochondrial tree. The mitochondrial phylogeny obtained in the present work emphasizes the need for a review of the morphological data, and for a comparison with similar studies of other markers, when these become available. A well-supported phylogeny of the order Carnivora will be most useful as a framework for research in several disciplines of carnivore and mammalian biology. |
