Life in the "dead heart" of Australia: The geohistory of the Australian deserts and its impact on genetic diversity of arid zone lizards. (24th February 2021) - Pepper, Mitzy
Abstract: Aim: The Australian deserts are home to a remarkable diversity of taxa that might appear to have evolved in the absence of topographic and physical barriers to dispersal. In fact this is a biogeographical illusion, as the dunefields of the modern arid zone obscure the fossil landscapes of the wet desert that existed for much of the Cenozoic. As the geohistory of Australia's arid zone is not widely understood by biologists, we review its geological development and contemporary landscapes in an accessible way, and describe eight biogeographical hypotheses centred on how geomorphology, evolutionary history and contemporary ecological factors interact to shape diversification patterns in the desert lowlands. Location: Australia. Taxon: Lizards. Methods: We review the arid zone landscapes before and after the development of the vast dunefields. As lizards represent a significant component of genetic studies that sample widely across the arid biome, we focus on this taxonomic group to establish emerging patterns. Results: Recent geological work suggests that the dunefields never formed extensive mobile landscapes such as in the Sahara, but rather were a mosaic of vegetated and stable dune surfaces with scattered bare, mobile patches. Large fluvial systems in the eastern arid zone during the Pleistocene also are at odds with the general perception of an arid landscape during this time. Incorporating this geohistorical insight, understanding where landscape heterogeneity is greatest within the arid zone, and where relative homogeneity might facilitate connectivity and gene flow, are at the heart of our biogeographic hypotheses. Main conclusions: Patterns are emerging that reflect the underlying influence of geomorphological processes on the genetic structure of Australian desert taxa. Quantifying finer‐scale edaphic complexity across the arid zone, widespread genetic sampling from disparate taxonomic groups, and a more detailed understanding of species ecology and life history will greatly improve our understanding of the ecological and historical drivers of diversity gradients in the Australian deserts.