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Conserved Primers for Rapid Sequencing of the Complete Mitochondrial Genome from Carnivores, Applied to Three Species of Bears

2002; Oxford University Press; Volume: 19; Issue: 3 Linguagem: Inglês

10.1093/oxfordjournals.molbev.a004090

1537-1719

Isabelle Delisle, Curtis Strobeck,

Genetic diversity and population structure

Phylogenetic relationships of the order Carnivora have been extensively studied. However, depending on the type of data, species sampling, and method of analysis used, carnivores have been placed in nearly every possible position throughout the eutherian phylogenetic tree (for a review, see Novacek 1992). The integrity of the order itself has, however, remained intact. Undisputedly monophyletic, the order Carnivora nonetheless constitutes a very adaptable and heterogeneous group (Wayne et al. 1989) whose evolution has been marked by several events of parallel or convergent evolution and rapid radiation. Consequently, phylogenetic relationships between and within many carnivore families are also still largely unresolved. For example, the families Procyonidae, Ailuridae, Mustelidae, Pinnidedia, and Ursidae are joined at a polytomy. Within Pinnipedia, the closer affinity of Otariidae to either Phocidae or Obodenidae has long been debated. Additionally, the monophyly of the family Mustelidae has been challenged, with true mustelids and mephitids thought to belong to different branches within the superfamily Musteloidea, also including Procyonidae and Ailuridae. The phylogeny of the family Ursidae is another typical example. Six species of bears, grouped under the subfamily Ursinae, are thought to have diverged at the beginning of the Pliocene through such a rapid radiation event (Thenius 1990) that the order of species divergence is difficult to determine. Hence, the speciation event that led to extant ursine bears (American black bear, Ursus americanus; brown bear, U. arctos; polar bear, U. maritimus; Asiatic black bear, U. thibetanus; sun bear, U. malayanus; and sloth bear, U. ursinus) is usually represented as a polytomy. Rapid radiations remain unresolved largely because available data contain very few informative changes essential to infer the correct phylogenetic tree. More resolving power can be reached by using longer DNA sequences to provide a sufficient number of informative characters. Moreover, it has been shown that the combination of multiple genes in a single large data set has the potential to raise a weak phylogenetic signal above the noise level (Bull et al. 1993). Combining these two advantages, complete mitochondrial (mtDNA) sequences (approximately 17 kbp and 13 protein-coding genes) offer great potential for recovering phylogenies.