Leroi Armand M, Chippindale Adam K, Rose Michael R
Department of Ecology and Evolutionary Biology, University of California, Irvine, California, 92717.
Evolution. 1994 Aug;48(4):1244-1257. doi: 10.1111/j.1558-5646.1994.tb05309.x.
Trade-offs among life-history traits are often thought to constrain the evolution of populations. Here we report the disappearance of a trade-off between early fecundity on the one hand, and late-life fecundity, starvation resistance, and longevity on the other, over 10 yr of laboratory selection for late-life reproduction. Whereas the selected populations showed an initial depression in early-life fecundity, they later converged upon the controls and then surpassed them. The evolutionary loss of the trade-off among life-history traits is considered attributable to the following factors: (1) the existence of differences in the culture regimes of the short- and long-generation populations other than the demographic differences deliberately imposed; (2) adaptation of one or both of these sets of populations to the unique aspects of their culture regimes; (3) the existence of an among-environment trade-off in the expression of early fecundity in the two culture regimes, as reflected in assays that mimic those regimes. The trade-off between early and late-life reproductive success, as manifest among divergently selected populations, is apparent or not depending on the assay environment. This demonstration that strong genotype-by-environment interactions can obscure a fundamental trade-off points to the importance of controlling all aspects of the culture regime of experimental populations and the difficulty of doing so even in the laboratory.
生活史特征之间的权衡通常被认为会限制种群的进化。在此，我们报告了在为后期繁殖进行的10年实验室选择过程中，一方面早期繁殖力与另一方面后期繁殖力、抗饥饿能力和寿命之间权衡关系的消失。虽然选定的种群在早期繁殖力上最初出现了下降，但它们随后与对照组趋同，然后超过了对照组。生活史特征之间权衡关系的进化丧失被认为可归因于以下因素：（1）除了故意施加的人口统计学差异外，短世代和长世代种群的培养条件存在差异；（2）这两组种群中的一组或两组适应了其培养条件的独特方面；（3）在模拟这些条件的试验中所反映的，两种培养条件下早期繁殖力表达存在环境间的权衡。在不同选择的种群中明显存在的早期和后期繁殖成功之间的权衡，根据试验环境的不同而明显或不明显。这种强基因型与环境相互作用会掩盖基本权衡的证明，指出了控制实验种群培养条件所有方面的重要性，以及即使在实验室中这样做的难度。
