Meeting Abstract
How did Pleistocene glacial cycling affect the diversity of rainforest life? Over the past several decades, biologists have tested the hypothesis that forest contraction and fragmentation drove speciation in rainforest animals, concluding that in most cases species-level divergences predate the Pleistocene. Consequently, focus has turned to the role of Pleistocene refugia in preserving lineages, effectively acting as “museums” of biodiversity. We tested this model in a lineage of tiny dispersal-limited arachnids distributed throughout in the rainforests of the Australian Wet Tropics. We generated a model of habitat suitability for the dispersal-limited mite harvestman genus Austropurcellia (Arachnida, Opiliones, Cyphophthalmi, Pettalidae) and projected it onto paleoclimate data layers dating back to the Last Glacial Maximum (LGM). We compared the power of present-day and past distribution of suitable climatic conditions to the predict present-day distribution of diversity across subregions of the Wet Tropics. We found that the distribution of suitable climatic conditions during the LGM is the best predictor of both number of species and phylogenetic diversity in our study system, outperforming current distribution of suitable climatic conditions. This finding is consistent with a model in which historical refugia have played a significant role in shaping present-day biogeographic patterns.
