Synthetic macroecological models of species diversity

A major unsolved problem in macroecology and biogeography is the origin and maintenance of species richness gradients. Biogeographers are currently divided into three major camps: those who favor historical or phylogenetic mechanisms, those who favor explanations based principally on geographic patterns of contemporary environmental variables, and those who advocate the incorporation of null model approaches. In the existing catalog of simple null models, species¿ geographic ranges are randomized within a bounded domain, producing a middomain effect (MDE)¿a peak of species richness towards the center of the geographical domain. This working group will seek to develop a novel synthesis of historical, contemporary environmental, and MDE hypotheses, by modeling species¿ geographic ranges in an environmentally heterogeneous geographical domain, with spatially explicit colonization, range expansion, speciation, and extinction.