Stressful environments induce novel phenotypic variation: hierarchical reaction norms for sperm performance of a pervasive invader

Ecology and Evolution

Craig F. Purchase¹ 

[1] Fish Evolutionary Ecology Research Group, Departments of Biology & Ocean Sciences, Memorial University, St. John's, Newfoundland and Labrador, Canada

关键词: Brown trout;    CASA;    cryptic variation;    fertilization;    genotype × environment interaction;    invasive species;    pH;    phenotypic plasticity;    Salmo trutta;    sperm quality;   

DOI  :  10.1002/ece3.364

来源: Wiley

【 摘 要 】

Abstract

Genetic variation for phenotypic plasticity is ubiquitous and important. However, the scale of such variation including the relative variability present in reaction norms among different hierarchies of biological organization (e.g., individuals, populations, and closely related species) is unknown. Complicating interpretation is a trade-off in environmental scale. As plasticity can only be inferred over the range of environments tested, experiments focusing on fine tuned responses to normal or benign conditions may miss cryptic phenotypic variation expressed under novel or stressful environments. Here, we sought to discern the presence and shape of plasticity in the performance of brown trout sperm as a function of optimal to extremely stressful river pH, and demarcate if the reaction norm varies among genotypes. Our overarching goal was to determine if deteriorating environmental quality increases expressed variation among individuals. A more applied aim was to ascertain whether maintaining sperm performance over a wide pH range could help explain how brown trout are able to invade diverse river systems when transplanted outside of their native range. Individuals differed in their reaction norms of phenotypic expression of an important trait in response to environmental change. Cryptic variation was revealed under stressful conditions, evidenced through increasing among-individual variability. Importantly, data on population averages masked this variability in plasticity. In addition, canalized reaction norms in sperm swimming velocities of many individuals over a very large range in water chemistry may help explain why brown trout are able to colonize a wide variety of habitats.

【 授权许可】

CC BY-NC   
© 2012 The Authors. Ecology and Evolution published by Blackwell Publishing Ltd.

Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.