School of Biological Sciences and Centre for Environmental Stress & Adaptation Research, Monash University, Clayton, Melbourne, Australia.
J Evol Biol. 2010 Nov;23(11):2484-93. doi: 10.1111/j.1420-9101.2010.02110.x. Epub 2010 Sep 28.
We examined latitudinal variation in adult and larval heat tolerance in Drosophila melanogaster from eastern Australia. Adults were assessed using static and ramping assays. Basal and hardened static heat knockdown time showed significant linear clines; heat tolerance increased towards the tropics, particularly for hardened flies, suggesting that tropical populations have a greater hardening response. A similar pattern was evident for ramping heat knockdown time at 0.06°C min(-1) increase. There was no cline for ramping heat knockdown temperature (CT(max) ) at 0.1°C min(-1) increase. Acute (static) heat knockdown temperature increased towards temperate latitudes, probably reflecting a greater capacity of temperate flies to withstand sudden temperature increases during summer in temperate Australia. Larval viability showed a quadratic association with latitude under heat stress. Thus, patterns of heat resistance depend on assay methods. Genetic correlations in thermotolerance across life stages and evolutionary potential for critical thermal limits should be the focus of future studies.
我们研究了来自澳大利亚东部的黑腹果蝇成虫和幼虫耐热性的纬度变化。使用静态和斜坡测定法评估成虫。基础和强化的静态热击倒时间显示出显著的线性梯度变化；耐热性向热带地区增加，特别是对于强化的苍蝇，表明热带种群具有更大的强化反应。在以 0.06°C min(-1)增加的斜坡热击倒时间上，也出现了类似的模式。在以 0.1°C min(-1)增加的斜坡热击倒温度（CT(max)）上，没有梯度变化。急性（静态）热击倒温度向温带纬度增加，可能反映了温带苍蝇在澳大利亚温带夏季承受突然温度升高的能力更强。在热应激下，幼虫存活率与纬度呈二次关联。因此，耐热性的模式取决于测定方法。未来的研究应关注不同生命阶段的耐热性遗传相关性和关键热极限的进化潜力。
