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Authors: Bryson, R.W., Jr., Savary, W.E., and Prendini, L.
AimThe aim of this study was to assess the impact of pre‐Quaternary tectonics and orogeny relative to that of Pleistocene climate change on diversification within thePseudouroctonus minimuscomplex, a group of vaejovid scorpions with stenotopic habitat requirements.LocationSouth‐western North America (United States and Mexico).MethodsMultilocus sequence data (1899 base pairs from two mitochondrial and two nuclear genes) were generated from 65 samples of scorpions in theminimuscomplex. Phylogeographical structure within theminimuscomplex was explored using model‐based phylogenetic methods and a general mixed Yule coalescent model to identify independent geographical clusters. A time‐calibrated multilocus species tree was reconstructed using a multispecies coalescent approach. Ancestral areas were estimated at divergence events across the tree using a probabilistic Bayesian approach.ResultsExtensive geographical structure was evident within two well‐supported clades. These clades probably diverged over 25 million years ago (Ma), based on estimated mean divergence dates, followed by 14 divergences in the Miocene (25–5 Ma) and 4 divergences in the Pliocene and Pleistocene (< 5 Ma). The ancestral origin of theminimuscomplex was reconstructed to be across California and the Mexican Highlands. The Chihuahuan Desert was colonized twice from the Mexican Highlands, and one dispersal event occurred from the Mexican Highlands back to California.Main conclusionsSpatial and temporal patterns of evolution in theminimuscomplex support predictions that stenotopy promoted pre‐Quaternary diversification. Miocene and Pliocene geomorphology, perhaps in concert with climate change, induced allopatric divergence across the heterogeneous landscape of south‐western North America. Stenotopic scorpions such as theminimuscomplex provide a model for exploring correlations between Earth history and biological diversification.