Artificial selection on chill-coma recovery time in Drosophila melanogaster: Direct and correlated responses to selection

J Therm Biol. 2016 Jul;59:77-85. doi: 10.1016/j.jtherbio.2016.04.004. Epub 2016 Apr 22.

Abstract

Artificial selection can be used to create populations with extreme phenotypic responses to environmental stressors. When artificial selection is applied to a single component of a stress response, this selection may result in correlated responses in other stress responses, a phenomenon called cross-tolerance, which is ultimately controlled by the genetic correlations among traits. We selected for extreme responses to cold tolerance by selecting for chill-coma recovery time from a single temperate population of Drosophila melanogaster. Chill-coma recovery time is a common metric of low, but non-lethal, cold temperature tolerance. Replicated divergent artificial selection was applied to a genetically variable base population for 31 generations, resulting in two cold resistant, two cold susceptible, and two unselected control lines. To quantify the relationship between selection on chill-coma recovery and other metrics of thermal performance, we also measured survivorship after acute cold exposure, survivorship after chronic cold exposure, survivorship after cold exposure following a pre-treatment period (rapid cold hardening), starvation tolerance, and heat tolerance. We find that chill-coma recovery time is heritable within this population and that there is an asymmetric response to increased and decreased chill-coma recovery time. Surprisingly, we found no cross-tolerances between selection on chill-coma recovery time and the other environmental stress response traits. These results suggest that although artificial selection has dramatically altered chill-coma recovery time, the correlated response to selection on other stress response phenotypes has been negligible. The lack of a correlated response suggests that chill-coma recovery time in these selection lines is likely genetically independent from measures of cold survivorship tested here.

Keywords: Artificial selection; Chill-coma recovery; Cross-tolerance; Drosophila melanogaster.

MeSH terms

  • Acclimatization
  • Animal Nutritional Physiological Phenomena
  • Animals
  • Breeding
  • Cold Temperature
  • Cold-Shock Response*
  • Drosophila melanogaster / genetics
  • Drosophila melanogaster / physiology*
  • Female
  • Male
  • Phenotype
  • Selection, Genetic
  • Stress, Physiological