The heritability of inducible defenses in tadpoles.

The evolution of plastic traits requires phenotypic trade-offs and heritable traits, yet the latter requirement has received little attention, especially for predatorinduced traits. Using a half-sib design, I examined the narrow-sense heritability of predator-induced behaviour, morphology, and life history in larval wood frogs (Rana sylvatica). Many of the traits had significant additive genetic variation in predator (caged Anax longipes) and no-predator environments. Whereas most traits had moderate to high heritability across environments, tail depth exhibited high heritability with predators but low heritability without predators. In addition, several traits had significant heritability for plasticity, suggesting a potential for selection to act on plasticity per se. Genetic correlations confirmed known phenotypic relationships across environments and identified novel relationships within each environment. This appears to be the first investigation of narrow-sense heritabilities for predator-induced traits and confirms that inducible traits previously shown to be under selection also have a genetic basis and should be capable of exhibiting evolutionary responses.表型可塑性性状（plastic traits）的演化需要存在表型权衡（phenotypic trade-offs）与可遗传性状，然而后者这一前提却未得到足够的研究关注，针对捕食者诱导型性状（predator-induced traits）的相关探究尤甚。本研究采用半同胞设计（half-sib design），探究了林蛙（Rana sylvatica）幼体的捕食者诱导型行为、形态以及生活史性状的狭义遗传力（narrow-sense heritability）。诸多性状在捕食者（笼养长跗蜓Anax longipes）环境与无捕食者环境中均存在显著的加性遗传变异（additive genetic variation）。尽管多数性状在两类环境中的遗传力均处于中等至较高水平，但尾深性状在有捕食者环境中表现出较高遗传力，而在无捕食者环境中遗传力较低。此外，部分性状的表型可塑性存在显著遗传力，这表明选择可直接作用于可塑性本身。遗传相关（genetic correlations）分析验证了已被报道的跨环境表型关联，并揭示了各环境内部此前未被发现的全新关联。本研究或为首次针对捕食者诱导型性状开展的狭义遗传力探究，同时证实了此前被证明处于选择压力下的诱导型性状确实存在遗传基础，且能够产生演化响应。