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Side-blotched lizards (Uta stansburiana) play a biological rock-paper-scissors game in which three differently colored male morphs utilize alternative mating strategies. We identified the genetic basis of this polymorphism, which was previously posited to arise from three alleles at one locus. Orange usurper and blue mate-guarder morphs are associated with two divergent haplotypes in the regulatory region of the sepiapterin reductase gene, but yellow sneaker morphs appear to arise through phenotypic plasticity from the same genetic background as blue morphs. Our simulations show that rock-paper-scissors dynamics can better maintain a polymorphism with a genetic system of two alleles plus plasticity than with a three-allele system. This form of balancing selection that combines genetic determination with phenotypic plasticity expands the possibilities for how stable polymorphisms arise in nature. 

Global warming poses a threat to lizard populations by raising ambient temperatures above historical norms and reducing thermoregulation opportunities. Whereas the reptile fauna of desert systems is relatively well studied, the lizard fauna of saline environments has not received much attention and—to our knowledge—thermal ecology and the effects of global warming on lizards from saline environments have not been yet addressed. This pioneer study investigates the thermal ecology, locomotor performance and potential effects of climate warming on Liolaemus ditadai, a lizard endemic to one of the largest salt flats on Earth. We sampled L. ditadai using traps and active searches along its known distribution, as well as in other areas within Salinas Grandes and Salinas de Ambargasta, where the species had not been previously recorded. Using ensemble models (GAM, MARS, RandomForest), we modeled climatically suitable habitats for L. ditadai in the present and under a pessimistic future scenario (SSP585, 2070). L. ditadai emerges as an efficient thermoregulator, tolerating temperatures near its upper thermal limits. Our ecophysiological model suggests that available activity hours predict its distribution, and the projected temperature increase due to global climate change should minimally impact its persistence or may even have a positive effect on suitable thermal habitat. However, this theoretical increase in habitat could be linked to the distribution of halophilous scrub in the future. Our surveys reveal widespread distribution along the borders of Salinas Grandes and Salinas de Ambargasta, suggesting a potential presence along the entire border of both salt plains wherever halophytic vegetation exists. Optimistic model results, extended distribution, and no evidence of flood-related adverse effects offer insights into assessing the conservation status of L. ditadai, making it and the Salinas Grandes system suitable models for studying lizard ecophysiology in largely unknown saline environments.