Temperature preference and temperature tolerance are wired differently in Drosophila

Abstract

Thermal preference, heat tolerance and heat survivability are key determinants for the adaptation and survival of an organism in a warming world. These temperature parameters are crucial for ectotherms, as these organisms cannot maintain their internal body temperatures. This study investigates thermal choice and performance under stressful temperatures in an outbred population of Drosophila melanogaster collected from the Western Himalayan orchards. A significant within-population variation was observed in all the traits. When isofemale lines were exposed to a thermal gradient (15–35 °C), most lines preferred the colder and the medium temperature zones more than the hotter zone. A static heat knockdown assay at 39 °C revealed widespread differences across lines. At the same temperature, a heat survival assay emphasized the differences in resilience and showed high phenotypic variability within the population. Notably, a highly significant positive correlation emerged between heat tolerance and heat survivability, indicating that lines more resistant to heat knockdown also had higher heat survivability. Interestingly, no relationships were observed between temperature stress traits and thermal preference. Within-population variations in the phenotypes of these thermal traits indicate wider colonization of this species across continents. © 2025 The Association for the Study of Animal Behaviour.