PARENT SESSION
Oral Session # 62: Biodiversity I.
Presiding: P Baker
Thursday, August 7. 8:00 AM to 11:30 AM, SITCC Meeting Room 100.
Latitudinal gradients in the phylogenetic diversity of New World bat communities.
Stevens, Richard *,1, 1 National Center for Ecologial Analysis and Synthesis, Santa Barbara, CA
ABSTRACT- Although described for many taxa, latitudinal gradients in biodiversity have typically focused on the number and relative abundances of species. Nonetheless, other measures of biodiversity, especially measures of functional, morphological, and phylogenetic diversity may exhibit complementary yet more informative geographic gradients. I investigated latitudinal gradients in the phylogenetic diversity of 32 New World bat communities. I used a supertree of all extant bat species generated by Jones et al. (2002) to characterize the phylogenetic relationships among taxa. I then quantified four aspects of the phylogenetic diversity of communities: 1) average pair-wise nodal distance among species, 2) average nearest-neighbor nodal distance, 3) variance of pair-wise nodal distances among species, and 4) variance of nearest-neighbor nodal distances. Significant latitudinal gradients exist regarding phylogenetic diversity. Nonetheless, these gradients could result from the underlying latitudinal gradient in species richness. I performed a suite of randomization analyses to characterize latitudinal gradients in phylogenetic diversity that would be expected given the observed gradient in species richness. A number of phylogenetic-diversity gradients were different from simulated expectations. In general, phylogenetic diversity was lower and decreased with increasing latitude at a faster rate in the observed communities than in simulated ones. To the extent that phylogeny reflects the evolutionary and ecological attributes of organisms, measures of phylogenetic diversity should characterize emergent properties of communities that reflect meaningful variation among species. Although taxonomic and phylogenetic diversity gradients are complementary, it is likely that mechanisms other than those that affect taxonomic diversity affect the phylogenetic composition of species within communities.
Key words: Phylogenetic diversity, Bat communities, Latitudinal gradient, Biodiversity