MITOCHONDRIAL DNA PHYLOGEOGRAPHY OF PEROGNATHUS AMPLUS AND PEROGNATHUS LONGIMEMBRIS (RODENTIA: HETEROMYIDAE): A POSSIBLE MAMMALIAN RING SPECIES.

ABSTRACT

Substantiated cases of ring species in mammals are rare. I examined the variation in mitochondrial DNA (mtDNA) of Perognathus amplus and P. longimembris in and around Arizona to test the hypothesis proposed by Hoffmeister (1986) that these two taxa are members of a single ring species demonstrating circular overlap. Through digestion of purified mtDNA from 45 P. amplus and 35 P. longimembris with 16 type II restriction enzymes, I identified 38 distinct haplotypes that belong to eight different evolutionary lineages. I then amplified and directly sequenced a portion of the mitochondrial cytochrome-b region from individuals representative of the lineages identified by restriction fragments, and used these data for phylogeny reconstruction in both a parsimony and neighbor-joining setting. The resulting phylogeny was consistent with the ring hypothesis, but, based on the incompleteness of the ring of subspecies and the apparent timing of evolutionary events in this group, I conclude that P. amplus and P. longimembris are distinct lineages that have completed the speciation process.