Phylogenetic diversity-area relationships reveal macroecological patterns
Species-area curves have a long history in ecology, however their phylogenetic analogs, phylogenetic diversity –area curves, have received much less attention. Previous work has developed theoretical expectations for these relationships, but empirical patterns have rarely been investigated. Species-area curves and phylogenetic diversity-area curves are likely to provide different pictures of how diversity scales with area, and by examining both we are likely to arrive at a more complete understanding. Both of these diversity-area relationships can be calculated either spatially (preserving spatial arrangement when increasing the area sampled) or non-spatially (increasing area by random draws from a set of sites). The differences between these spatial and non-spatial curves provide a metric of how diversity of distributed across the landscape, while the differences between species-area curves and phylogenetic diversity-area curves provides a metric of the relative distribution of species vs phylogenetic diversity.
For New World plants and birds (taxa that are likely to represent strong differences in dispersal ability) we calculate both spatial and non-spatial species-area curves, phylogenetic diversity-area curves, and expected phylogenetic diversity-area curves.
Our results show that phylogenetic diversity increases more rapidly than species diversity, suggesting that phylogenetic diversity is more resilient to habitat destruction than species richness. We also show that comparisons between both spatial and non-spatial phylogenetic diversity-area curves and observed and expected phylogenetic diversity-area curves suggest that phylogenetic diversity is relatively spatially clustered. This spatial clustering of phylogenetic diversity may be driven by limited dispersal or strong environmental filtering.