Physiological and biochemical changes associated with acute experimental 1 dehydration in the desert adapted mouse , Peromyscus eremicus

34 Characterizing traits critical for adaptation to a given environment is an 35 important first step in understanding how phenotypes evolve. How animals adapt 36 to the extreme heat and aridity commonplace to deserts represents is an 37 exceptionally interesting example of these processes, and has been the focus 38 of study for decades. In contrast to those studies, where experiments are 39 conducted on either wild animals or captive animals held in non-desert 40 conditions, the study described here leverages a unique environmental chamber 41 that replicates desert conditions for captive Peromyscus eremicus (cactus 42 mouse). Here we establish baseline values for daily water intake and for serum 43 electrolytes, as well as the response of these variables to experimental 44 dehydration. In brief, P. eremicus’ daily water intake is very low. It’s serum 45 electrolytes are distinct from many previously studied animals, and its 46 response to acute dehydration is profound, though not suggestive of renal 47 impairment, which is atypical of mammals. 48 49 50 Introduction 51 Understanding the evolution of adaptive traits has long been one of the primary 52 goals in evolutionary biology. The study of the relationships between fitness 53 and phenotype, often powered by modern genomic techniques (59), has provided 54 researchers with insight into the mechanistic processes that underlie adaptive 55 phenotypes (15, 28). Systems in which the power of genomics can be combined 56 with an understanding of natural history and physiology are well suited for 57 the study of adaptation (9, 44) especially when researchers have the ability 58 to assay the link between genotype and phenotype in wild animals and then 59 conduct complementary experiments using representative animals in carefully 60 controlled laboratory environments. The study described here, characterizing 61 the physiology and serum biochemistry of Peromyscus eremicus is the first step 62 in a larger study aimed at understanding the genomics architecture of adaptation 63 to desert environments. 64 65 . CC-BY 4.0 International license peer-reviewed) is the author/funder. It is made available under a The copyright holder for this preprint (which was not . http://dx.doi.org/10.1101/047704 doi: bioRxiv preprint first posted online Apr. 8, 2016;