Mitochondrial genomes reveal the pattern and timing of marten (Martes), wolverine (Gulo), and fisher (Pekania) diversification

Abstract

Despite recent advances in understanding the pattern and timescale of evolutionary diversification in the marten, wolverine, fisher, and tayra subfamily Guloninae (Mustelidae, Carnivora), several important issues still remain contentious. Among these are the phylogenetic position of Gulo relative to the subgenera of Martes (Martes and Charronia), the phylogenetic relationships within the subgenus Martes, and the timing of gulonine divergences. To elucidate these issues we explored nucleotide variation in 11 whole mitochondrial genomes (mitogenomes) from eight gulonine species and two outgroup meline species. Parsimony, maximum likelihood, and Bayesian phylogenetic analyses yielded fully resolved and identical patterns of relationships with high support for all divergences. The generic status of Pekania (P. pennanti), the monophyly of the genus Martes containing M. flavigula (subgenus Charronia) to the exclusion of the genus Gulo (G. gulo), and the M. foina (M. americana (M. melampus (M. zibellina, M. martes))) phylogeny of the subgenus Martes were strongly supported. Dating analyses (BEAST) using a set of five newly applied fossil calibrations provided divergence times considerably younger than previous multigene mitochondrial estimates, but similar to multigene nuclear and nuclear–mitochondrial estimates. The 95% confidence (highest posterior density) intervals of our divergence times fell within those inferred from nuclear and nuclear–mitochondrial sequence data, and were markedly narrower than in earlier studies (whether nuclear, mitochondrial, or combined). Notably, and contrary to long-held beliefs, our findings indicate that fossils older than the Tortonian–Messinian transition (late Late Miocene) do not represent Martes, excluding from this genus its putative members from the Early, Middle, and early Late Miocene. This study demonstrates the high informativeness of the mitogenome for phylogenetic inference and divergence time estimation within Guloninae, and suggests that mitogenomes can be highly informative also for other clades at similar levels of evolutionary divergence.