RESILIENCE TO DROUGHTS IN MAMMALS: A CONCEPTUAL FRAMEWORK FOR ESTIMATING VULNERABILITY OF A SINGLE SPECIES.

ABSTRACT The frequency and severity of droughts in certain areas is increasing as a consequence of climate change. The associated environmental challenges, including high temperatures, low food, and water availability, have affected, and will affect, many populations. Our aims are to review the behavioral, physiological, and morphological adaptations of mammals to arid environments, and to aid research- ers and nature conservationists about which traits they should study to assess whether or not their study species will be able to cope with droughts. We provide a suite of traits that should be considered when making predictions about species resilience to drought. We define and differentiate between general adaptations, specialized adaptations, and exaptations, and argue that specialized adaptations are of little interest in establishing how nondesert specialists will cope with droughts. Attention should be placed on general adaptations of semidesert species and assess whether these exist as exaptations in nondesert species. We conclude that phenotypic flexibility is the most important general adaptation that may promote species resilience. Thus, to assess whether a species will be able to cope with increasing aridity, it is important to establish the degree offlexibility of traits identified in semidesert species that confer afitness advantage under drying conditions.