Effects of exposure to short‐term heat stress on fitness components in Drosophila melanogaster

Abstract

Effects of thermal stress on survival and reproductive success in ten recently collected isofemale lines of Drosophila melanogaster were compared for flies treated as follows: always held at 25" C, placed in an incubator set at 37" C for 120 min, or exposed to 40" C in an incubator for 90 min, with or without previous exposure to 37' C. Short-term exposure to the higher temperature greatly reduced adult survival, the mating frequency of males and females, and female fecundity, which was measured as offspring produced over ten days. Male fertility, measured as the progeny produced by a female mated once, differed little among treatments. Previous exposure to a high, but non-lethal, temperature before exposure to the higher one, improved survival of males and females, and improved offspring production of females. Genetic variation was present among lines for offspring production, but genetic variation for survival was not significant, and genotype by environment interactions for fitness components of females were small. These results indicated low genetic variation in thermal resistance in the studied population, such that a threshold for temperature stress probably exists, above which local extinction is more likely than the evolution of resistance.

Life history consequences of temperature transients inDrosophila melanogaster

“…Weather fronts may not only alter an organism's performance during the front itself, but also induce carry-over effects that persist even after weather returns to normal. Surprisingly little is known about the impact of such thermal transients on the physiology and life history of ectotherms, except in regards to short-term exposure to extreme temperatures (Bubliy and Loeschcke, 2001;David et al, 2003;Gibert et al, 2001;Hercus et al, 2003;Krebs and Loeschcke, 1994a;Krebs and Loeschcke, 1994b;Lee et al, 1987;Maynard Smith, 1958;Rohmer et al, 2004;Sisodia and Singh, 2006;Zani et al, 2005a;Zani et al, 2005b).…”

“…If flies are damaged by the thermal transient (Krebs and Loeschcke, 1994a), their fecundity may not return to normal levels for some time, if ever. Because the transient temperatures we selected were intentionally nonextreme (David et al, 1983), this outcome is unlikely in our experiments, but would be likely following more extreme treatments.…”

Heat-shock tolerance and inbreeding in Drosophila buzzatii

“…The conditioning treatment was exposure to 36.5°C (within vials) for 75 mm, which was performed 24 h before flies were exposed to a potentially lethal heat stress at 40.7°C (within vials) for varying periods of time. Both conditioning and exposure to the heat stress were performed in inverted food vials with stoppers moistened and inserted fully to obtain nearly saturated humidity (treatment details described in Krebs & Loeschcke, 1994b). After treatment, flies were returned immediately to 25°C.…”

Variation on Male Mating Success to Short-Term High Thermal Stress among Three Geographical Strains of Drosophila melanogaster

“…However, some of the previous studies tested the temperature effect on life history traits immediately after the stress and the others test its effect after a relaxation period (Krebs & Loeschcke, 1994b;1999;Patton & Krebs, 2001;Fasolo & Krebs, 2004;Krebs & Thompson, 2005;Nishinokubi et al, 2006;Sisodia & Singh, 2006). My data show that relaxation period had a negative effect of male mating success.…”

“…According to the results of the previous studies, very small quantity of induced heat shock proteins may affect life history traits such as development, stress resistance, life span and fecundity (Silbermann & Tatar 2000;Patton & Krebs, 2001;Sorensen et al, 2003;Sisodia & Singh, 2006;). The presence of genetic variation without pre-treatment, is best explained by variation for non-stress quantities of those proteins that are mass produced in the presence of a stress, or by differences in the activation temperatures for the rapid transcription of these proteins (Krebs & Loeschcke, 1994b). Beside, Bourg et al (2001) studied the hsp70 protein expression exposed to 45-minutes long heat shock at 37°C.…”