Krebs Robert A, Thompson Kimberly A
Department of Biological, Geological and Environmental Sciences, Cleveland State University, 2121 Euclid Ave., Cleveland, OH 44115, USA.
Genetica. 2006 Sep-Nov;128(1-3):217-25. doi: 10.1007/s10709-005-5704-x.
To demonstrate how insects may adapt to ecologically relevant levels of heat stress, we performed artificial selection on the ability of Drosophila melanogaster to fly after an exposure to a high but non-lethal thermal stress. Both tolerance and intolerance to heat stress arose very quickly, as only a few generations of selection were necessary to cause significant separation between high and low lines for heat tolerance. Estimates of heritability based on the lines artificially selected for increased flight ability ranged from 0.024 to 0.052, while estimates of heritability based on the lines selected for the inability to fly after heat stress varied between 0.035 and 0.091. Reciprocal F1 crosses among these lines revealed strong additive effects of one or more autosomes and a weaker X-chromosome effect. This variation apparently affected flight specifically; neither survival to a more extreme stress nor knockdown by high temperature changed between lines selected for high and low heat tolerance as measured by flight ability. As the well-studied heat-shock response is associated with heat tolerance as measured by survival and knockdown, the aspects of the stress physiology that actually affect flight ability remains unknown.
为了证明昆虫如何适应与生态相关的热应激水平，我们对黑腹果蝇在暴露于高温但非致死性热应激后飞行的能力进行了人工选择。耐热性和不耐热性很快就出现了，因为仅经过几代选择，耐热性高的品系和低的品系之间就出现了显著差异。基于人工选择以提高飞行能力的品系的遗传力估计值在0.024至0.052之间，而基于热应激后无法飞行的品系的遗传力估计值在0.035至0.091之间。这些品系之间的正反交F1杂交显示一个或多个常染色体有很强的加性效应，而X染色体效应较弱。这种变异显然只影响飞行；在通过飞行能力选择的耐热性高和低的品系之间，在更极端应激下的存活率或高温击倒率均未改变。由于经过充分研究的热休克反应与通过存活率和击倒率衡量的耐热性相关，实际影响飞行能力的应激生理学方面仍然未知。
