Khazaeli Aziz A, Van Voorhies Wayne, Curtsinger James W
Department of Ecology, Evolution and Behavior, University of Minnesota, 1987 Upper Buford Circle, St Paul, MN 55108, USA.
Exp Gerontol. 2005 May;40(5):377-85. doi: 10.1016/j.exger.2005.02.004. Epub 2005 Mar 19.
Among mammals, body size and life span tend to vary inversely within species, but the pattern is less clear in invertebrates. Here, we report on survival and weight of male flies from 29 laboratory strains of Drosophila melanogaster. Natural variation in body mass was enhanced by rearing larvae under normal and limited food conditions. Strain, weight, and larval treatment have significant effects on survival, but higher order interactions are also significant, indicating strain specificity. For pooled data the overall relationship between mass and life span is slight, positive, and statistically significant, but mass explains < or =1% of the variation in survival. This result is opposite to the common prediction of an inverse relationship between longevity and body size. Effects of artificially reduced body size vary substantially in both sign and magnitude from strain to strain, though long-lived strains generally retain their enhanced survival characteristics. Within-line regressions of life span on mass also vary dramatically from strain to strain; in Canton-S, the most extreme case, mass explains >40% of the variation in survival. For long-lived 'O' lines reared under normal larval conditions, smaller flies live 16% longer than larger flies; the latter are significantly underrepresented in the most advanced age class. We conclude that the body size-life span relationship is highly strain-specific; that inconsistencies in the literature probably reflect real biological variation; and that variation in body size can be a significant source of experimental noise in survival studies.
在哺乳动物中，同一物种内体型和寿命往往呈负相关，但在无脊椎动物中这种模式不太明显。在此，我们报告了来自29个黑腹果蝇实验室品系的雄蝇的存活率和体重情况。通过在正常和有限食物条件下饲养幼虫，增强了体重的自然变异。品系、体重和幼虫处理对存活率有显著影响，但高阶相互作用也很显著，表明存在品系特异性。对于汇总数据，体重与寿命之间的总体关系微弱、呈正相关且具有统计学意义，但体重仅解释了存活率变异的≤1%。这一结果与寿命和体型呈负相关的普遍预测相反。人工减小体型的影响在不同品系之间，在正负号和幅度上都有很大差异，不过长寿品系通常保持其增强的存活特征。品系内寿命对体重的回归在不同品系之间也有很大差异；在最极端的情况即Canton - S品系中，体重解释了存活率变异的>40%。对于在正常幼虫条件下饲养的长寿“O”品系，体型较小的果蝇比体型较大的果蝇寿命长16%；在最高龄组中，体型较大的果蝇明显占比过低。我们得出结论，体型与寿命的关系具有高度的品系特异性；文献中的不一致可能反映了真实的生物学变异；并且体型变异可能是存活研究中实验噪声的一个重要来源。
