Origin and Diversification of Pseudoscorpions on Granite Outcrops in Southwestern Australia

Date of Completion

January 2011


Biology, Evolution and Development|Biology, Systematic




The origin of new species is a central issue in evolutionary biology. My dissertation research focuses on the of Synsphyronus Chamberlin (Garypidae: Pseudoscorpiones), a genus of pseudoscorpions with an Australasian distribution. One facet of my dissertation research assessed the diversity of pseudoscorpions restricted to granite outcrops in southwestern Australia. My first two field seasons focused on the fauna restricted to the granite outcrops in southwestern Australia. Islands are natural laboratories in which to study diversification and the outcrops function as a terrestrial archipelago. Only one described species, known only from its type locality, had been recorded from this granite outcrop system when my research was initiated. My collaborator at the Western Australian Museum, found two new species on a nearby outcrop. I tested the hypothesis that each outcrop had a unique lineage; my research has shown this not to be the case but the diversity is high relative to the spatial scale. I have sampled over 100 outcrops, collecting six morphotypes. After developing a molecular toolkit for pseudoscorpions, utilized molecular data to infer the origins of, and estimate the phylogenetic relationships among, the lineages I collected. Molecular data suggest the outcrops harbor more than six independent lineages. Preliminary data suggested the outcrop lineages were not monophyletic and thus I sought to increase my geographic sampling. My third field season, I traveled cross-country in order to sample more broadly, collecting new species and new populations of described species. Species level phylogenies generated using four nuclear genes suggest there are three major clades in Synsphyronus, all of which colonized the outcrop habitats. In addition, my data suggest dispersal has led to in situ speciation across the outcrop islands. A three-gene combined dataset was assembled and the estimated phylogeny was used to examine biogeographic patterns of the group. The ancestral states of habitat type and biome were reconstructed. Lastly, I used scanning electron microscopy to survey ultrastructures on the chelicera; the focus was on the grooming organs. A papillary region was observed on the serrula exterior lamellae of Synsphyronus. ^