Convergent evolution among desert rodents: a global perspective

The biogeographic histories of New and (3ld World deserts are discussed from the viewpoints of small mammal adaptation to aridity and the development of small mammal communities in deserts. Morphoecological characteristics of rodents are compared between deserts using multivariate statistical techniques. In one analysis, Sonoran and Iranian (Kavir) rodents are shown to be more similar to one another than are the more closely phylogenetically related rodents of the Sonoran and Monte deserts of the New World. It is proposed that the rodents in the two northern deserts have had a longer time to adapt to arid conditions than have those of the Monte, thus convergent evolution is more pronounced between them. Nevertheless certain suites of traits (that is, locomotion and trophic characteristics) are associated in reversed ways among some species in the more ecologically similar deserts; parts of the "niche" of these species have been switched.