Exploring the drivers of population structure across desert snakes can help to link micro and macroevolution

To understand the underlying mechanisms generating population genetic divergence and structure is a critical step towards understanding how biodiversity evolves at both micro- and macroevolutionary scales. At the population-level, geographic isolation as well as adaptation to local environmental conditions can generate different patterns of spatial genetic variation among populations. Specific organismal traits as well as the characteristics of the environment might influence the process under which populations become spatially structured. In a From the Cover article in this issue of Molecular Ecology, Myers et al. (2019) present an integrative approach to investigate if the Cochise filter barrier (CFB), lying between the Sonoran and Chihuahuan Deserts, and the surrounding river networks were relevant in driving the population structure of 13 snake species. While local environmental conditions seem to predominantly contribute to lineage divergence, traditionally studied vicariant barriers seem to have played a minor role in shaping population structure across the studied species. This study brings insights into how population-level processes could contribute to the formation of incipient species, which ultimately might affect the speciation rates measured at macroevolutionary scales. Hence, Myers et al. (2019) not only represents an integrative study aiming to understand the drivers of population genetic divergence, but also a potentially important contribution to our ongoing challenge in linking micro- and macroevolution.