Phylogeography and Genetic Diversity in North American Deserts

North American deserts represent some of the most dynamic landscapes for the study of phylogeography and genetic diversity, combining complex geological histories with recent climatic oscillations. This arid region encompasses multiple ecoregions, from the Mojave and Sonoran to the Chihuahuan and Baja California deserts, each punctuated by mountain ranges, river corridors and historical refugia. Phylogeographic investigations reveal how Pleistocene glacial–interglacial cycles drove population contractions into refugial areas, followed by expansion and secondary contact, shaping modern patterns of genetic variation. Vicariant events such as the inundation of land bridges, uplift of mountain ranges and the formation of the Sea of Cortez have further structured lineages in both plants and animals. Across taxa, studies highlight contrasting responses: some species exhibit deep lineage divergence concordant with ancient barriers, whereas others retain genetic connectivity via gene flow across apparent obstacles. The balance between selection, drift and dispersal underpins local adaptation to xeric conditions, while habitat fragmentation has generated high levels of endemism and fine‐scale population structure. Understanding these processes informs conservation priorities in a region facing accelerating anthropogenic change, guiding efforts to preserve evolutionary potential and ecosystem resilience.

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Phylogeography and Genetic Diversity in North American Deserts publication trend

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Technical terms

Phylogeography: The study of the historical processes that shape the geographic distributions of genetic lineages within and among species.

Genetic structure: The non-random distribution of genetic variation across populations, often resulting from barriers to gene flow or historical demographic events.

Refugium (pl. refugia): A location where populations persist during adverse climatic conditions, serving as sources for post-glacial recolonisation.

Haplotype: A group of alleles or sequence variants at adjacent loci on a chromosome that are inherited together.

Ecological niche modelling: A computational method that predicts a species’ potential geographic distribution by correlating occurrence data with environmental variables.

References

1. Molecular genetic analysis of two native desert palm genera, Washingtonia and Brahea, from the Baja California Peninsula and Guadalupe Island. Ecology and Evolution (2017).
2. Genome-Scale Data Reveal Deep Lineage Divergence and a Complex Demographic History in the Texas Horned Lizard (Phrynosoma cornutum) throughout the Southwestern and Central United States. Genome Biology and Evolution (2021).
3. Phylogeography and population genetics of pine butterflies: Sky islands increase genetic divergence. Ecology and Evolution (2019).