GENETIC VARIATION FOR PHENOTYPIC PLASTICITY IN THE LARVAL LIFE HISTORY OF SPADEFOOT TOADS (SCAPHIOPUS COUCHII)
GENETIC VARIATION FOR PHENOTYPIC PLASTICITY IN THE LARVAL LIFE HISTORY OF SPADEFOOT TOADS (SCAPHIOPUS COUCHII)
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铲足蟾 (SCAPHIOPUS COUCHII) 幼虫生活史中表型可塑性的遗传变异
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发表时间：
1994
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影响因子：
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通讯作者：
R. Newman
中科院分区：
文献类型：
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作者：
R. Newman
生活史性状的表型可塑性很常见。表型和环境之间的关系，或反应规范，与生活史可塑性相关，可以通过自然选择进化，如果在一个群体中存在遗传变异的反应规范，如果所涉及的性状影响健身。与其他性状一样，对特定性状的可塑性或对特定环境因素的反应的选择可能会受到影响适应性的其他性状的权衡的限制。在本文中，我实验性地评估了变态时年龄和大小的反应规范对两个环境因素（食物水平和温度）的广义遗传变异。在所有处理中，全同胞家族之间在一个或两个性状上的差异都很明显。然而，家庭之间的变化，他们对每个治疗（基因型-环境相互作用）的反应，导致治疗之间的变化，估计遗传力和遗传相关性。变态年龄同样敏感的温度在所有的家庭，但在变态的大小是更敏感的温度在某些家庭比其他家庭。在变态的大小是同样敏感的食物水平在所有的家庭，但在变态的年龄是敏感的食物在一些家庭，但在其他家庭。在高温或低食物下，变态时年龄和大小之间的遗传相关性是正的，在早期变态以获得更高的幼虫存活率和后期变态以获得更大的大小之间产生潜在的权衡。这种权衡延伸到不同的处理：在变态时具有最大平均尺寸的家庭在变态时具有最长的平均尺寸和最大的可塑性。其他家庭实现较短的平均幼虫期表现出更大的可塑性在变态的大小，但在变态的平均大小最小。这种权衡可能反映了对所有环境做出最佳反应的能力的潜在功能限制，导致反应规范的持续遗传变异。
Phenotypic plasticity in life‐history traits is common. The relationship between phenotype and environment, or reaction norm, associated with life‐history plasticity can evolve by natural selection if there is genetic variation within a population for the reaction norm and if the traits involved affect fitness. As with other traits, selection on plasticity in a particular trait or in response to a particular environmental factor may be constrained by trade‐offs with other traits that affect fitness. In this paper, I experimentally evaluated broad‐sense genetic variation in the reaction norms of age and size at metamorphosis in response to two environmental factors, food level and temperature. Differences among full‐sib families in one or both traits were evident in all treatments. However, variation among families in their responses to each treatment (genotype‐environment interaction) resulted in variation among treatments in estimated heritabilities and genetic correlations. Age at metamorphosis was equally sensitive to temperature in all families, but size at metamorphosis was more sensitive to temperature in some families than in others. Size at metamorphosis was equally sensitive to food level in all families, but age at metamorphosis was sensitive to food in some families but not in others. At high temperature or low food, the genetic correlation between age and size at metamorphosis was positive, generating a potential trade‐off between metamorphosing early to attain higher larval survival and metamorphosing later to achieve larger size. This trade‐off extends across treatments: families with the largest average size at metamorphosis achieved larger size with the longest average and greatest plasticity in age at metamorphosis. Other families achieved shorter average larval periods by exhibiting greater plasticity in size at metamorphosis but had the smallest average size at metamorphosis. This trade‐off may reflect an underlying functional constraint on the ability to respond optimally to all environments, resulting in persistent genetic variation in reaction norms.