Whence the red panda?

The evolutionary history of the red panda (Ailurus fulgens) plays a pivotal role in the higher-level phylogeny of the "bear-like" arctoid carnivoran m ammals. Characters from morphology and molecules have provided inconsistent evidence for placement of the red panda. Whereas it certainly is an arctoi d, there has been major controversy about whether it should be placed with the bears (ursids), ursids plus pinnipeds (seals, sea lions, walrus), racco ons (procyonids), musteloids (raccoons plus weasels, skunks, otters, and ba dgers [mustelids]), or as a monotypic lineage of uncertain phylogenetic aff inities. Nucleotide sequence data from three mitochondrial genes and one nu clear intron were analyzed, with more complete taxonomic sampling of releva nt taxa (arctoids) than previously available in analyses of primary molecul ar data, to clarify the phylogenetic relationships of the red panda to othe r arctoid carnivorans. This study provides detailed phylogenetic analyses ( both parsimony and maximum-likelihood) of primary character data for arctoi d carnivorans, including bootstrap and decay indices for all arctoid nodes, and three statistical tests of alternative phylogenetic hypotheses for the placement of the red panda. Combined phylogenetic analyses reject the hypo theses that the red panda is most closely related to the bears (ursids) or to the raccoons (procyonids). Rather, evidence from nucleotide sequences st rongly support placement of the red panda within a broad Musteloidea (sensu late) clade, including three major lineages (the red panda, the skunks [me phitids], and a clearly monophyletic clade of procyonids plus mustelids [se nsu stricto, excluding skunks]). Within the Musteloidea, interrelationships of the three major lineages are unclear and probably are best considered a n unresolved trichotomy. These data provide compelling evidence for the rel ationships of the red panda and demonstrate that small taxonomic sample siz es can result in misleading or possibly erroneous (based on prior modeling, as well as conflict between the results of our analyses of less and more c omplete data sets) conclusions about phylogenetic relationships and taxonom y. (C) 2000 Academic Press.