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Community phylogeographic patterns reveal how a barrier filters and structures taxa in North American warm deserts


Provost, Kaiya; Myers, Edward A.; Smith, Brian (2021), Community phylogeographic patterns reveal how a barrier filters and structures taxa in North American warm deserts, Dryad, Dataset,


Aim: The study of biogeographic barriers has been instrumental in understanding the evolution and distribution of taxa. With the increasing availability of empirical datasets, emergent patterns can be inferred from communities by synthesizing how barriers filter and structure populations across species. We assemble phylogeographic data across a barrier and perform spatially-explicit simulations to quantify spatiotemporal patterns of divergence, the influence of species traits on these patterns, and the statistical power needed to differentiate alternative diversification modes. Location: North America Methods: We incorporate published datasets to examine taxa around the Cochise Filter Barrier, separating the Sonoran and Chihuahuan Deserts of North America, to synthesize phylogeographic structuring across the community with respect to organismal functional traits. We then use simulation and machine learning to assess the power of phylogeographic model selection. Results: Taxa distributed across the Cochise Filter Barrier show heterogeneous responses to the barrier in levels of gene flow, phylogeographic structure, divergence timing, barrier width, and divergence mechanism. These responses correlate with locomotor and thermoregulatory traits. Many taxa show a Pleistocene population genetic break, often with introgression after divergence. Allopatric isolation and isolation-by-environment are the primary mechanisms structuring genetic divergence within taxa. Simulations reveal that in spatially-explicit isolation-with-migration models across the barrier, age of divergence, presence of gene flow, and presence of isolation-by-distance can confound the interpretation of evolutionary history and model selection by producing easily-confusable results. We re-analyze five empirical genetic datasets to illustrate the utility of these simulations despite these constraints. Main Conclusions: By synthesizing phylogeographic data for the Cochise Filter Barrier we show that barriers interact with species traits to differentiate taxa in communities over millions of years. Identifying diversification modes across the barrier for these taxa remains challenging because commonly invoked demographic models may not be identifiable across a range of likely parameter space.