The Geography of Speciation in Neotropical Salamanders

摘要

Geography plays a paramount role in many aspects of speciation, including the amount of morphological and niche variation expected between sister species. Current species distributions, when coupled with phylogenies, offer valuable information on likely modes of geographic speciation. I briefly review past studies of the geography of speciation in neotropical plethodontid salamanders and analyze the spatial distributions and climatic overlap between sister species of this group. Using 66 pairs of sister species distributed from Mexico to Ecuador, I find that vicariant allopatric speciation probably played a dominant role in divergence of the bolitoglossines, but that peripatric and parapatric speciation were likely also important in generating the high diversity of the group. I find no evidence for latitudinal variation in speciation mechanisms within the tropics. Future studies incorporating physiology, spatial modeling, and population genetic estimates of demographic parameters will be critical in determining the importance of these nonvicariant speciation modes in the bolitoglossines, with implications for tropical biodiversity in general.