Convergent evolution of increased urine concentrating ability in desert mammals

Abstract

One of the most celebrated textbook examples of physiological adaptations to desert environments is the unique ability that desert mammals have to produce hyperosmotic urine. Commonly perceived as an adaptation mainly observed in small rodents, the extent to which urine concentrating ability has independently evolved in distinct lineages, including medium-sized and large desert mammals, has not previously been assessed using modern phylogenetic approaches. Here, we explicitly test the general hypothesis that desert-dwelling mammals have evolved increased ability to concentrate urine compared to non-desert species, controlling for body mass and other covariates. Phylogenetic generalized least-squares models show that the mean aridity index of a species range largely predicts its urine concentrating ability, even when accounting for body mass differences and phylogenetic correlations. In contrast, we find much weaker correlations between mass-adjusted basal metabolic rate and environmental variables.

Evolution of a fatty acyl-CoA elongase underlies desert adaptation inDrosophila

“…To survive rapid water loss in deserts, species from different taxa evolved high levels of desiccation resistance via similar physiological changes such as reducing water evaporation from the body, lowering metabolism, and minimizing water excretion (Gibbs, 2002;Merkt and Taylor, 1994;Williams and Tieleman, 2005). While there are some research on these independently evolved physiological traits (Gibbs and Matzkin, 2001;Rocha et al, 2021a;Xu et al, 2020), the underlying molecular and evolutionary mechanisms remain largely unknown. Recent association studies using genomic and transcriptomic studies have identified some candidate genes that may contribute to physiological adaptation in desert organisms (Gonzalez-Tokman et al, 2020;Rocha et al, 2021b;Wang et al, 2021), but the function of these genes are not characterized.…”