NATURAL SELECTION FOR ENVIRONMENTALLY INDUCED PHENOTYPES IN TADPOLES
NATURAL SELECTION FOR ENVIRONMENTALLY INDUCED PHENOTYPES IN TADPOLES
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环境诱导蝌蚪表型的自然选择
DOI：
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发表时间：
1997
期刊：
影响因子：
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通讯作者：
E. Werner
中科院分区：
文献类型：
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作者：
J. Van Buskirk;S. A. McCollum;E. Werner
模型表明，在最佳表型因时间或空间而异的情况下，表型可塑性得以维持，因此选择在不同的环境中以不同的方向起作用。一些实证工作支持这一预测的一般前提，因为在特定环境中测试时，由特定环境诱导的表型有时比其他表型表现得更好。我们已经扩展了这些结果，通过估计在没有捕食者和幼虫Anax蜻蜓的环境中的Pseudacris triseriata蝌蚪的选择目标。蝌蚪表现出显着的行为和形态的可塑性时，饲养在存在和不存在非致命的蜻蜓在牛坦克32天。我们测量选择的情况下，自由的捕食者回归生长和生存的坦克对活动和几个措施的尾巴和身体的形状。我们测量的选择在捕食者的存在下，暴露组的10只蝌蚪Anax过夜捕食试验和回归的平均表型的幸存者对蝌蚪死亡的数量。两种环境中的选择对尾巴和体形的作用方向相反，尽管受影响的适应性成分不同。在Anax的存在下，具有浅而窄的身体，深的尾鳍和宽的尾肌的蝌蚪存活最好。在没有自由捕食者的情况下，尾肌窄的蝌蚪生长速度明显快于尾鳍浅、身体深的蝌蚪。活动是无关的生存或生长在任何环境中。尾部形状的发育可塑性与选择密切相关，因为长期暴露于Anax后，尾鳍深度增加，尾部肌肉宽度趋于增加。与此相反，没有可塑性的身体形状，尽管强烈的选择减少身体的深度。因此，当面对一个捕食者时，三列拟步行者蝌蚪几乎完全按照阿那克斯的选择方向调整它们的尾巴形状（而不是身体形状）。这些结果表明，一些形态性状，如尾深和尾肌宽度，在间歇性选择下进化的蜻蜓。其他经历蜻蜓选择的特征，如身体形态，似乎是发展刚性的，也许是因为历史上强烈的自然选择或其他限制。
Models suggest that phenotypic plasticity is maintained in situations where the optimal phenotype differs through time or space, so that selection acts in different directions in different environments. Some empirical work supports the general premise of this prediction because phenotypes induced by a particular environment sometimes perform better than other phenotypes when tested in that environment. We have extended these results by estimating the targets of selection in Pseudacris triseriata tadpoles in environments without predators and with larval Anax dragonflies. Tadpoles displayed significant behavioral and morphological plasticity when reared in the presence and absence of nonlethal dragonflies for 32 days in cattle tanks. We measured selection in the absence of free predators by regressing growth and survival in the tanks against activity and several measures of tail and body shape. We measured selection in the presence of predators by exposing groups of 10 tadpoles to Anax in overnight predation trials and regressing the average phenotype of survivors against the number of tadpoles killed. Selection in the two environments acted in opposite directions on both tail and body shape, although the affected fitness components were different. In the presence of Anax, tadpoles with shallow and narrow body, deep tail fin, and wide tail muscle survived best. In the absence of free predators, tadpoles with narrow tail muscle grew significantly faster, and those with shallow tail fin and deep body grew somewhat faster. Activity was unrelated to survival or growth in either environment. Developmental plasticity in tail shape closely paralleled selection, because tail fin depth increased after long‐term exposure to Anax and tail muscle width tended to increase. In contrast, there was no plasticity in body shape in spite of strong selection for decreasing body depth. Thus, when confronted with a dragonfly predator, P. triseriata tadpoles adjusted their tail shape (but not body shape) almost exactly in the direction of selection imposed by Anax. These results suggest that phenotypic plasticity in some morphological traits, such as tail depth and tail muscle width, has evolved under intermittent selection by dragonflies. Other traits that undergo selection by dragonflies, such as body morphology, appear developmentally rigid, perhaps because of historically strong opposing selection in nature or other constraints.