Subterranean Fishes of the World

4781

2020

Journal of Experimental Zoology. Part B Molecular and Develepmental Evolution

530-539

334

Studying how different genotypes respond to environmental variation is essential to understand the genetic basis of adaptation. The Mexican tetra, Astyanax mexicanus,has cave and surface‐dwelling morphotyp es that have adapted to entirely different environments in the wild, and are now successfully maintained in lab conditions. While this has enabled the identification of genetic adaptations underlying a variety of phy- siological processes, few studies have directly compared morphotypes between lab‐ reared and natural populations. Such comparative approaches could help dissect the varying effects of environment and morphotype, and determine the extent to which phenomena observed in the lab are generalizable to conditions in the field. To this end, we take a transcriptomic approach to compare the Pachón cavefish and their surface fish counterparts in their natural habitats and the lab environment. We identify key changes in expression of genes implicated in metabolism and physiology between groups of fish, suggesting that morphotype (surface or cave) and environment (natural or lab) both alter geneexpression.Wefindgeneexpressiondifferencesbetweencaveandsurfacefishin their natural habitats are much larger than differences in expression between morpho- types in the lab environment. However, lab‐raised cave and surface fish still exhibit numerous gene expression changes, supporting genetically encoded changes in livers of this species. From this, we conclude that a controlled laboratory environment may serve as an ideal setting to study the genetic underpinnings of metabolic and physiological differences between the cavefish and surface fish. KEYWORDS Astyanax mexicanus, cavefish, comparative transcriptomics, lab strains, liver, wild population

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