Evolutionary Relationships of Kangaroo Mice, Genus Microdipodops

Abstract

There is currently much controversy surrounding the issue as to whether kangaroo mice (Microdipodops) are more closely related to the kangaroo rats (genus Dipodomys; subfamily Dipodomyinae) or to the pocket mice (genus Perognathus; subfamily Perognathinae), or whether they represent a lineage distinct from both kangaroo rats and pocket mice. In an attempt to resolve this question, the two species of kangaroo mice were compared to seven other heteromyid taxa by means of cluster analyses based on a data matrix containing a broad spectrum of phenetic characters. The seven taxa selected for comparison with two species of Microdipodops include Perognathus intermedius, P. hispidus, P. flavus, P. longimembris, Dipodomys merriami, D. ordii, and D. panamintinus. Results of the analyses indicate clearly that Microdipodops is phenetically most similar to the silky pocket mice (subgenus Perognathus) as represented by P.flavus and P.longimembris. It is hypothesized that Microdipodops was derived from perognathine stock and evolved largely in situ in the Great Basin of North America during the Blancan age. That Microdipodops may represent the end-point of a third lineage distinct from those giving rise to either Perognathus or Dipodomys is considered, but appears presently unanswerable in the absence of a fossil record of Microdipodops.