Taxonomic, functional, and phenetic components of latitudinal gradients in biodiversity: Perspectives on the community ecology of New World bats

The explanation of the mechanistic basis to latitudinal gradients in diversity has challenged ecologists for more than a quarter of a century. Although the ubiquity of the latitudinal gradient in species richness is well documented at coarse scales of resolution, it is unclear to what extent this pattern is recapitulated at not only the level of local communities but also for any other aspect of biodiversity. Because biodiversity represents the totality of variation in living things, it is likely that no one measure such as species richness, or any one perspective, such as that of taxonomic diversity, can provide a complete characterization. Investigations that explore a number of distinct aspects of biodiversity (i.e., taxonomic, functional, or phenetic diversity) will provide for more refined measures and potentially allow for deeper understanding into its distribution across space and time. I examined the way in which attributes of New World bat biodiversity varied with each other and with latitude. Species abundance distributions for 32 intensively sampled local sites between 42.25°N and 24.12°S latitude provided data from which I determined three suites of diversity measures, each of which provided a distinctive yet related characterization of biodiversity [taxonomic diversity (14 indices), functional diversity (4 indices), morphological diversity (6 indices)]. All components demonstrated similar relationships with each other as well as with latitude. Components of diversity were related by virtue of changes in magnitude and not changes in evenness and their highest diversities were found toward the equator and lowest diversities were found toward the poled. Nonetheless, gradients in functional and phenetic diversity not be accounted for solely by variation in taxonomic diversity. Moreover, quantitative differences regarding latitudinal gradients exist among components. These results exemplify that variation in biodiversity is complex throughout the New World. Moreover, its multifaceted nature admonished the difficulty of its estimation using single indices such as species richness. Future conservation efforts should embrace the complexity of biodiversity and strive to protect it in its numerous and varied forms.