Mating success at high temperature in highland- and lowland-derived populations as well as in heat knock-down selected Drosophila buzzatii

Abstract

Thermal-stress selection can affect multiple fitness components including mating success. Reproductive success is one of the most inclusive measures of overall fitness, and mating success is a major component of reproduction. However, almost no attention has been spent to test how mating success can be affected by thermal-stress selection. In this study, we examine the mating success in the cactophilic Drosophila buzzatii Patterson & Wheeler (Diptera: Drosophilidae) derived from two natural populations that nearly represent the ends of an altitudinal cline for heat knock-down resistance. Furthermore, we extended the analysis using laboratory lines artificially selected for high and low heat knock-down resistance. Mating success at high temperature was found to be higher in the lowland than the highland population after a heat pre-treatment. Moreover, individuals selected for heat knock-down resistance showed higher mating success at high temperature than did individuals selected for low knock-down resistance. These results indicate that adaptation to thermal stress can confer an advantage on fitness-related traits including mating success and highlight the benefits of earlier heat exposure as an adaptive plastic response affecting mating success under stress of higher temperature.