Diversity of Desert-Dwelling Mammals: A Comparison of Australia and North America

Abstract

There are more species of desert-dwelling mammals in North America (109) than in Australia (73), but this difference does not appear to be due to the comparative age, size, or physiography of the desert regions. An analysis of the trophic structures of the two faunas shows that the greater mammalian diversity in North American deserts is due mainly to the abundance of granivorous species. Granivorous birds and ants are more diverse in Australian deserts, and it seems likely that these groups have secured the granivorous trophic role at the expense of mammalian granivores. In contrast, insectivorous mammals are richer in species in Australian deserts; in North America the insectivorous trophic role is at least partially filled by omnivorous rodents. The differences in the two mammalian faunas suggest that convergence between them is limited.