Azevedo Ricardo B R, James Avis C, McCabe Jennie, Partridge L
Department of Biology, Galton Laboratory, University College London, Wolfson House, 4 Stephenson Way, London, NW1 2HE, United Kingdom.
Evolution. 1998 Oct;52(5):1353-1362. doi: 10.1111/j.1558-5646.1998.tb02017.x.
In dipterans, the wing-beat frequency, and, hence, the lift generated, increases linearly with ambient temperature. If flight performance is an important target of natural selection, higher wing:thorax size ratio and wing-aspect ratio should be favored at low temperatures because they increase the lift for a given body weight. We investigated this hypothesis by examining wing: thorax size ratio and wing-aspect ratio in Drosophila melanogaster collected from wild populations along a latitudinal gradient and in their descendants reared under standard laboratory conditions. In a subset of lines, we also studied the phenotypic plasticity of these traits in response to temperature. To examine whether the latitudinal trends in wing:thorax size ratio and wing-aspect ratio could have resulted from a correlated response to latitudinal selection on wing area, we investigated the correlated responses of these characters in lines artificially selected for wing area. In both the geographic and the artificially selected lines, wing:thorax size ratio and wing-aspect ratio decreased in response to increasing temperature during development. Phenotypic plasticity for either trait did not vary among latitudinal lines or selective regimes. Wing:thorax size ratio and wing-aspect ratio increased significantly with latitude in field-collected flies. The cline in wing:thorax size ratio had a genetic component, but the cline in wing-aspect ratio did not. Artificial selection for increased wing area led to a statistically insignificant correlated increase in wing:thorax size ratio and a decrease in wing-aspect ratio. Our observations are consistent with the hypotheses that high wing-thorax size ratio and wing aspect ratio are per se selectively advantageous at low temperatures.
在双翅目昆虫中，翅膀的拍击频率，进而产生的升力，会随着环境温度的升高而呈线性增加。如果飞行性能是自然选择的一个重要目标，那么在低温环境下，较高的翅胸比和翼展比应该更受青睐，因为对于给定体重，它们能增加升力。我们通过研究沿纬度梯度采集的野生果蝇种群及其在标准实验室条件下饲养的后代的翅胸比和翼展比，来验证这一假设。在一部分品系中，我们还研究了这些性状对温度响应的表型可塑性。为了检验翅胸比和翼展比的纬度趋势是否可能是对翅面积的纬度选择的相关反应导致的，我们研究了在人工选择翅面积的品系中这些性状的相关反应。在地理品系和人工选择的品系中，发育期间随着温度升高，翅胸比和翼展比均下降。这两个性状的表型可塑性在不同纬度品系或选择方案中并无差异。在野外采集的果蝇中，翅胸比和翼展比随纬度显著增加。翅胸比的梯度变化有遗传成分，但翼展比的梯度变化没有。人工选择增加翅面积导致翅胸比有统计学上不显著的相关增加，而翼展比下降。我们的观察结果与以下假设一致：高翅胸比和翼展比本身在低温下具有选择优势。
