The ability to tolerate temperature stress is an important component of adult fitness. In holometabolous insects like Drosophila melanogaster, adult stress resistance can be affected by growth conditions experienced during the larval stages. Although evolution under crowded larval conditions is known to lead to the correlated evolution of many adult traits, its consequences on adult heat stress tolerance have not been investigated. Therefore, in the present study, we assessed the adult heat stress tolerance in populations of D. melanogaster adapted to a stressful larval crowding environment. We used replicate populations of D. melanogaster, selected for adaptation to larval crowding stress (MCUs), for more than 230 generations, and their respective controls (MBs). Larvae from selected and control populations were grown under crowded and uncrowded conditions, and their adult heat shock resistance at two different temperatures was measured. Further, we compared Hsp70 expression in crowded and uncrowded larvae of both populations and also measured the Hsp70 expression after a mild heat treatment in adults of selected and control populations. Our results showed that adaptation to larval crowding leads to the evolution of Hsp70 gene expression in larval stages and improves adult heat stress tolerance ability in males, but not in females.

中文翻译：

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适应幼虫拥挤的黑腹果蝇种群中性别特异性热应激耐受性和幼虫 Hsp70 表达的进化。

耐受温度压力的能力是成人健康的重要组成部分。在像黑腹果蝇这样的全代谢昆虫中，成虫抗逆性会受到幼虫阶段生长条件的影响。尽管已知在拥挤的幼虫条件下进化会导致许多成虫性状的相关进化，但尚未研究其对成虫热应激耐受性的影响。因此，在本研究中，我们评估了适应压力幼虫拥挤环境的黑腹果蝇种群的成体热应激耐受性。我们使用了黑腹果蝇的重复种群，选择用于适应幼虫拥挤压力 (MCU)，超过 230 代，以及它们各自的对照 (MB)。来自选定种群和对照种群的幼虫在拥挤和不拥挤的条件下生长，并测量了它们在两种不同温度下的成虫抗热震性。此外，我们比较了两个种群拥挤和未拥挤幼虫中 Hsp70 的表达，还测量了选定种群和对照种群的成虫在温和热处理后 Hsp70 的表达。我们的结果表明，对幼虫拥挤的适应导致幼虫阶段 Hsp70 基因表达的进化，并提高了雄性成虫的热应激耐受能力，但在雌性中则不然。我们比较了两个种群拥挤和未拥挤幼虫中 Hsp70 的表达，并在选定和对照种群的成虫中进行了温和热处理后测量了 Hsp70 表达。我们的结果表明，对幼虫拥挤的适应导致幼虫阶段 Hsp70 基因表达的进化，并提高了雄性成虫的热应激耐受能力，但在雌性中则不然。我们比较了两个种群拥挤和未拥挤幼虫中 Hsp70 的表达，并在选定和对照种群的成虫中进行了温和热处理后测量了 Hsp70 表达。我们的结果表明，对幼虫拥挤的适应导致幼虫阶段 Hsp70 基因表达的进化，并提高了雄性成虫的热应激耐受能力，但在雌性中则不然。