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Phylogenetic Relationships and Species Limits within Phyllotis (Rodentia: Sigmodontinae): Concordance between mtDNA Sequence and Morphology

Scott J. Steppan
DOI: http://dx.doi.org/10.2307/1382988 573-593 First published online: 20 May 1998


Phylogenetic relationships and species limits within the South American rodent genus Phyllotis were estimated using nucleotide sequence data from a 973 base-pair region of the mitochondrial gene, cytochrome b. Geographic variation and species limits were assessed by sequencing individuals from multiple populations and morphometric analyses of skulls and skins. Results supported the following clades: Phyllotis plus Auliscomys exclusive of Graomys, the darwini species group, and a northerly distributed species-pair of P. amicus and P. andium. The phylogeny, genetic divergence estimates, and morphology indicated that P. xanthopygus rupestris is polyphyletic and populations from the Pacific slope of the Andes currently assigned to that taxon are specifically distinct. These populations are placed in the newly elevated P. limatus and an emended diagnosis is provided. Biogeographic and phylogenetic patterns are most consistent with successive colonization of the Pacific slopes by P. xanthopygus, possibly through range expansion and contraction, over a short period of time relative to the age of the clade.

Key words
  • Phyllotis
  • phylogeny
  • cytochrome b
  • speciation
  • species limits
  • biogeography
  • Andes