Phylogeography of the A rizona hairy scorpion ( H adrurus arizonensis ) supports a model of biotic assembly in the M ojave D esert and adds a new P leistocene refugium

Abstract

Aim As data accumulate, a multi‐taxon biogeographical synthesis of the M ojave D esert is beginning to emerge. The initial synthesis, which we call the ‘ M ojave A ssembly M odel’, was predominantly based on comparisons of phylogeographical patterns from vertebrate taxa. We tested the predictions of this model by examining the phylogeographical history of H adrurus arizonensis , a large scorpion from the M ojave and S onoran deserts. Location Mojave and S onoran deserts, U nited S tates and M exico. Methods We sequenced mitochondrial cytochrome c oxidase subunit I ( COI ) data from 256 samples collected throughout the range of H. arizonensis . We analysed sequence data using a network analysis, spatial analysis of molecular variance (SAMOVA), and a M antel test. We then used a molecular clock to place the genetic patterns in a temporal framework. We tested for signals of expansion using neutrality tests, mismatch distributions and B ayesian skyline plots. We used Maxent to develop current and late‐glacial species distribution models from occurrence records and bioclimatic variables. Results Phylogenetic and structure analyses split the maternal genealogy basally into a southern clade along the coast of S onora and a northern clade that includes six lineages distributed in the M ojave D esert and northern S onoran D esert. Molecular dating suggested that the main clades diverged between the late P liocene and early P leistocene, whereas subsequent divergences between lineages occurred in the middle and late P leistocene. Species distribution models predicted that the distribution of suitable climate was reduced and fragmented during the L ast G lacial M aximum. Main conclusions Genetic analyses and species distribution modelling suggest that the genetic diversity within H. arizonensis was predominantly structured by P leistocene climate cycles. These results are generally consistent with the predictions of P leistocene refugia for arid‐adapted taxa described in the M ojave A ssembly M odel, but suggest that a northern area of the L ower C olorado R iver V alley may have acted as an additional refugium during P leistocene glacial cycles.

Bibliographic Information