Department of Biology, University of California, Riverside California 92521, USA.
Evolution. 2011 Apr;65(4):1021-36. doi: 10.1111/j.1558-5646.2010.01188.x. Epub 2010 Nov 30.
Life-history theory predicts that increased predation on juvenile age/size-classes favors delayed maturation and decreased reproductive investment. Although this theory has received correlative support, experimental tests in nature are rare. In 1976 and 1981, guppies (Poecilia reticulata) were transplanted into localities that previously only contained a killifish, Rivulus hartii. This situation presents an opportunity to experimentally test this life-history prediction because guppies prey upon young Rivulus. We evaluated the response to selection in Rivulus by measuring phenotypic and genotypic divergence between introduction and upstream "control" localities that lack guppies. Contrary to expectations, Rivulus from the introduction sites evolved earlier maturation and increased reproductive investment within 25 years. Such evolutionary changes parallel previous investigations on natural communities of Rivulus, but do not comply with predictions of age/size-specific theory. Guppies also caused reduced densities and increased growth rates of Rivulus, which are hypothesized indirect effects of predation. Additional life-history theories show that changes in density and growth can interact with predator-induced mortality to alter the predicted trajectory of evolution. We discuss how these latter frameworks improve the fit between theory and evolution in Rivulus.
生活史理论预测，对幼年年龄/体型类别的捕食增加有利于延迟成熟和减少生殖投资。尽管这一理论得到了相关支持，但在自然界中进行的实验测试却很少。1976 年和 1981 年，将孔雀鱼（Poecilia reticulata）移植到以前只含有食蚊鱼（Rivulus hartii）的当地。这种情况为实验测试这种生活史预测提供了机会，因为孔雀鱼捕食幼鱼食蚊鱼。我们通过测量引入和上游“对照”地点（缺乏孔雀鱼）之间的表型和基因型差异，评估了食蚊鱼对选择的反应。与预期相反，引入地点的食蚊鱼在 25 年内进化出更早的成熟和增加的生殖投资。这种进化变化与以前对食蚊鱼自然群落的研究一致，但不符合年龄/体型特异性理论的预测。孔雀鱼还导致食蚊鱼的密度降低和生长速度增加，这被假设是捕食的间接影响。其他生活史理论表明，密度和生长的变化可以与捕食者诱导的死亡率相互作用，改变进化的预期轨迹。我们讨论了这些后者框架如何提高食蚊鱼理论与进化之间的契合度。
