Numbers of Mammal Species in North and Central American Forest Communities

Latitudinal trends in the species diversity of North and Central American Mammalian communities are documented by examining seven habitats ranging from the tundra of central Alaska to the moist tropical forest of central Panama. The communities are compared with respect to the numbers and kinds of species in each habitat and their size, spatial, and trophic relationships. Fifteen to 16 species occur in the two Alaskan habitats examined, 31—35 species in three forests in the eastern United States, and 70 species in two Panamanian forests, Observed latitudinal changes in species diversity, ecological diversity, and community structure are primarily a result of a southward increase in the number of bat species. The greater variety and year—round availaility of food resources such as fleshy fruits and insects, rather than increased spatial heterogeneity, appear to account for the greater diversity of mammals in the tropical habitats. The structure of Old and New World tropical mammalian communities appears to be very similar. One major difference is that among the bats there are relatively more fruit—and/or pollen—eating species and fewer insect—eating species in the Panamanian community than in Malaya.