Phylogenetic Implications of Mitochondrial-DNA Sequence Variation

in Deer Mice from California 

Lindsey D. Virdell

Scott E. Chirhart

Department of Biology

Centenary College of Louisiana

Mindy L. Walker

Dr. Ira F. Greenbaum

Dr. Rodney L. Honeycutt

Department of Biology

Department of Wildlife and Fisheries Sciences

Texas A&M University

        Previous research by Walker et al. (2004) was done to evaluate the specific validity and phylogeographic origin of P. sejugis. The authors concluded that P. sejugis is an insular isolate of P. maniculatus from Baja California because of a low level of sequence divergence between these populations. To identify the northern geographic extent of the P.manculatus (Baja)/P. sejugis haplogroup, we compared sequence variation in ND3/ND4L/ND4 mtDNA region of 38 individuals of P. maniculatus from central and northern California.  These populations were compared to reference sequences for P. keeni, P. maniculatus from Colorado and Washington, P. sejugis, and P. maniculatus from Baja and Southern California.  The level of sequence variation reveals a close association between P. maniculatus from Baja California and those from Southern California (sequence divergence of 0.80%) and Fresno (divergence of 0.85%). However, comparisons of the P. maniculatus from Baja with the individuals from the Johannesburg and Arcata populations resulted in high percent sequence divergences at 3.92 and 3.76, respectively. Conversely, when P. maniculatus from Colorado and Washington were compared to the Johannesburg and Arcata populations, low percent sequence divergences (0.80 and 1.75) were obtained; and when compared with individuals from S. California and Fresno, high divergence values of 4.17% and 3.99% resulted.  The northern geographic boundary for the Baja maniculatus/sejugis haplotype therefore seems to exist in the region between Arcata and Fresno.  These data thus support the assertion that P. maniculatus is polyphyletic.   Further, this study confirms the sister-group relationship between P. maniculatus (Baja, S. California, Fresno)/P. sejugis and P. keeni.

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