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

Aim The study of biogeographic barriers is 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, quantifying spatiotemporal patterns of divergence, the influence of traits on these patterns, and the statistical power needed to differentiate diversification modes. Taxon Vertebrates, Invertebrates, Plants Location North America Methods We incorporate published datasets, from papers that match relevant keywords, to examine taxa around the Cochise Filter Barrier, separating the Sonoran and Chihuahuan Deserts of North America, to synthesize phylogeographic structuring across the communities 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.

Automated summary

The study of biogeographic barriers is crucial for understanding the evolution and distribution of taxa. By synthesizing phylogeographic data across a barrier and conducting simulations, this research demonstrates how barriers interact with species traits to differentiate taxa over millions of years. However, identifying diversification modes for these taxa across the barrier remains challenging due to the limitations of commonly used demographic models.