Physiological stress and the maintenance of adapti

Authors: Zachary W Culumber Christian E BautistaHernández Scott Monks

Publish Date: 2013/06/27

Volume: 28, Issue: 1, Pages: 117-129

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Abstract

The importance of genetic variation in evolution is well established Yet the mechanisms by which genetic variation—particularly variation in traits under selection—is maintained in natural populations has long been an evolutionary puzzle Understanding individual variables driving selection and their functional mechanisms is increasingly important in the context of global change and its potential consequences for biodiversity Here we examined intrapopulation performance among allelic variants of a pleiotropic locus in response to thermal stress in the variable platyfish Xiphophorus variatus The wildtype tailspot allele exhibited significantly lower heat tolerance than all three pattern alleles found in the population conforming to predictions based on previously observed correlations between temperature and pattern frequencies in the wild Furthermore differences between tailspot pattern frequencies in adults and juveniles were broadly consistent with this trend Thus it appears that physiological stress and reduced performance of the wildtype allele at higher relative temperatures is a mechanism balancing its frequency in natural populations Temperature variation and not dissolved oxygen alone as previously reported is likely a important abiotic variable contributing to the maintenance of adaptive polymorphism Furthermore our findings underscore the potential implications of rising temperatures and physiological stress for levels of genetic variation in natural populationsWe would like to thank the Mexican Government for collecting permits We thank Gil Rosenthal Texas AM University College Station TX who allowed us to use the facilities at the CICHAZ field station http//wwwcichazorg/ This work was supported by a Consejo Nacional de Ciencia y Tecnología CONACyT Grant in basic science Clave 0127310 to SM which supported ZWC as a postdoctoral researcher CEBH was supported by a CONACyT scholarship Clave 254023

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