Genomic insights into the convergent evolution of desert adaptation in camels and antelopes

High temperature and water scarcity present formidable challenges to large desert-dwelling mammals. In addition to camels, antelopes of Hippotraginae and Alcelaphinae exhibit remarkable desert adaptation abilities. Among these species, the critically endangered addax (Addax nasomaculatus) stands out as the most well-adapted antelope to desert life. However, the evolutionary mechanisms and potential shared genetic adaptations of these species in desert environment remain largely unexplored. Herein, we present a high-quality genome assembly of the addax and investigate the molecular evolution of desert adaptation in camels and desert antelopes. We identified 136 genes with convergent amino acid sites involved in crucial biological processes, including water reabsorption, fat metabolism, and stress response. Notably, a convergent R146S amino acid mutation of PTGER2 (Prostaglandin EP2 receptor) significantly reduces its biological activity, potentially facilitating the adaptation of large mammals to desert environments. Additionally, we identified genetic innovations unique to desert antelopes and discovered important conserved noncoding elements, some of which exhibited significant regulatory changes in in vitro cellular function assays. We speculate the potential impacts of introgression and genetic load on the adaptation of desert antelopes. Our findings provide insights into the stepwise evolutionary processes driving desert tolerance and highlight the roles of convergent evolution in response to environmental challenges in large mammals.