Cold tolerance, the ability to cope with low temperature stress, is a critical adaptation in thermally variable environments. An individual's cold tolerance comprises several traits including minimum temperatures for growth and activity, ability to survive severe cold, and ability to resume normal function after cold subsides. Across species, these traits are correlated, suggesting they were shaped by shared evolutionary processes or possibly share physiological mechanisms. However, the extent to which cold tolerance traits and their associated mechanisms covary within populations has not been assessed. We measured five cold tolerance traits—critical thermal minimum, chill coma recovery, short- and long-term cold tolerance, and cold-induced changes in locomotor behavior—along with cold-induced expression of two genes with possible roles in cold tolerance (heat shock protein 70 and frost)—across 12 lines of Drosophila melanogaster derived from a single population. We observed significant genetic variation in all traits, but few were correlated across genotypes, and these correlations were sex-specific. Further, cold-induced gene expression varied by genotype, but there was no evidence supporting our hypothesis that cold-hardy lines would have either higher baseline expression or induction of stress genes. These results suggest cold tolerance traits possess unique mechanisms and have the capacity to evolve independently.
|Number of pages||14|
|State||Published - Jul 1 2020|
Bibliographical noteFunding Information:
This work was completed due to financial support from the USDA National Institute of Food and Agriculture (grant ID: 2015‐67012‐2279, 2018‐67012‐2800, and Hatch Project 1010996), and National Science Foundation (OIA‐1826689). We would like to thank Gregory Ragland and Joseph Styga for providing analytical support. Further, we would like to thank Eleanor McCabe for her assistance with fly rearing and husbandry. We are also grateful to anonymous reviewers for their invaluable suggestions on earlier versions of this manuscript.
© 2020 The Authors. Evolution © 2020 The Society for the Study of Evolution.
- Cold tolerance
- Drosophila melanogaster
- genetic variation
- heat-shock proteins
- trait correlation
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Agricultural and Biological Sciences (all)