Phylogeography and microendemism in Uroctonus in California

Robert Bryson Jr and co-workers have recently published a phylogeographical study looking at microendemism in Uroctonus Thorell, 1876 (Chactidae) in California (USA). Understanding historical processes that generates diversity in an area is important, and the current study suggest tectonic plate rafting, mountain uplift, river drainage formation, and climate-induced habitat fragmentation have all likely played a role in the diversification of Uroctonus in the study area.

Abstract:
The California Floristic Province (CFP) in western North America is a globally significant biodiversity hotspot. Elucidating patterns of endemism and the historical drivers of this diversity has been an important challenge of comparative phylogeography for over two decades. We generated phylogenomic data using ddRADseq to examine genetic structure in Uroctonus forest scorpions, an ecologically restricted and dispersal-limited organism widely distributed across the CFP north to the Columbia River. We coupled our genetic data with species distribution models (SDMs) to determine climatically suitable areas for Uroctonus both now and during the Last Glacial Maximum (LGM). Based on our analyses, Uroctonus is composed of two major genetic groups that likely diverged over two million years ago. Each of these groups itself contains numerous genetic groups that reveal a pattern of vicariance and microendemism across the CFP. Migration rates among these populations are low. SDMs suggest forest scorpion habitat has remained relatively stable over the last 21,000 years, consistent with the genetic data. Our results suggest tectonic plate rafting, mountain uplift, river drainage formation, and climate-induced habitat fragmentation have all likely played a role in the diversification of Uroctonus. The intricate pattern of genetic fragmentation revealed across a temporal continuum highlights the potential of low-dispersing species to shed light on small-scale patterns of biodiversity and the underlying processes that have generated this diversity in biodiversity hotspots.

Reference:
Bryson Jr RW, Savary WE, Zellmer AJ, Bury B, McCormack JE. Genomic data reveal ancient microendemism in forest scorpions across the California Floristic Province. Mol Ecol. 2016;Accepted manuscript online: 30 May 2016. [Subscription required for full text]