Testing A Vicariance Model To Explain Haplotype Distribution In The Psammophilic Scorpion Paruroctonus Utahensis

A model of vicariance speciation has been proposed to explain the proliferation of psammophilic (sand loving) species in several endemic genera of scorpions. The current distribution of Paruroctonus utahensis (Williams, 1968) populations on isolated sand dunes seems to fit this model; therefore, this species was examined to test the model for psammophilic population distribution and haplotype variation. A portion of the mitochondrial rDNA gene was sequenced from 44 individuals representing 7 populations of P. utahensis. Three individuals of Paruroctonus gracilior (Hoffmann, 1931) and 1 individual of Paruroctonus boquillas Sissom and Henson, 1998, were used for outgroup comparison. A maximum parsimony heuristic search indicated that the basal populations were in the south and derived populations occurred in the northeastern portion of the range. A nested clade analysis found a statistically significant correlation between haplotypes and their geographical distribution at several clade levels. The biological cause of this association was best explained by allopatric fragmentation. Our data supported the vicariance model of isolation by fragmentation of a larger habitat to explain the variation seen among populations of P. utahensis