Collaborative proposal: Evaluating phenotypic plasticity's role in adaptive evolution

许多生物可以通过显著改变其形态、行为或生理来应对环境的变化，这种能力的广泛存在引发了激烈的争论。一方面，许多生物学家坚持认为，改变外观、行为或生理的灵活性与进化无关，因为进化需要遗传变化。另一方面，越来越多的研究人员认为，这种灵活性通过启动遗传变化在进化中发挥着关键作用。这项研究将通过调查外观，行为和/或生理学的变化是否先于（并使）主要的，新的，遗传编码特征的进化起源来帮助解决这一争议。这项研究将专门评估预先存在的，饮食诱导的灵活性是否有助于铲足蛙进化出一种新的，复杂的体型。因此，这项研究不仅将为进化过程提供重要的见解，还将为生物学的一个持久的谜团提供新的线索：复杂的特征是如何起源的。这项研究还将通过培训在校儿童和大学生以及在博物馆组织公开讲座来促进教育推广。这项研究将检验适应性进化的可塑性第一假设。为此，拟议的研究将集中在铲足蟾蜍。像大多数青蛙一样，Scaphiopus属的蝌蚪只能发展成典型的“杂食性”形态。相比之下，Spea属的蝌蚪表现出惊人的可塑性：根据它们的饮食，它们要么发展成杂食动物，要么发展成一种新的“食肉动物”形态。有趣的是，这种独特的食肉动物形态的某些成分可以在Scaphiopus中被饮食诱导。此外，一些Spea种群已经失去了杂食-食肉可塑性，成为单态。事实上，在某些种群中，选择有利于食肉动物形态的接近固定。因此，作为一个群体，铲足类似乎代表了新的食肉动物形态进化的不同阶段：从可能的初始诱导（Scaphiopus），到作为新的发育“开关”的一部分（在许多Spea种群中），再到最终的固定（在一些Spea种群中）。计划中的研究将评估这种新的食肉动物表型是否是通过可塑性优先进化产生的，方法是对比不同物种/种群的发育、遗传变异和表现，这些物种/种群在这种独特形式的起源中处于不同的进化阶段。在此过程中，研究将评估可塑性第一假设的关键预测。这项研究将有助于阐明可塑性在进化创新中的作用，并为其他人提供一个路线图，以测试可塑性第一的假设。这个奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

Many organisms can respond to changes in their environment by dramatically altering their morphology, behavior, or physiology, and the widespread occurrence of this ability has provoked a spirited debate. On the one hand, many biologists maintain that the flexibility to change appearance, behavior or physiology are of no relevance to evolution, because evolution requires genetic change. On the other hand, a growing number of researchers have suggested that such flexibility plays a critical role in evolution by jump-starting genetic change. This research will help resolve this controversy by investigating whether changes in appearance, behavior and/or physiology precede (and enable) the evolutionary origins of major, new, genetically-encoded features. The research will specifically evaluate whether pre-existing, diet-induced flexibility has contributed to the evolution of a novel, complex body form in spadefoot frogs. Thus, not only will this research provide important insights into the evolutionary process, it will also shed new light onto one of biology's enduring mysteries: how complex features originate. The research will also promote educational outreach by training school children and undergraduate students and by organizing public talks at museums.This research will test the Plasticity-First hypothesis of adaptive evolution. To do so, the proposed research will focus on spadefoot toads. Like most frogs, tadpoles in the genus Scaphiopus develop only into a typical 'omnivore' morph. By contrast, tadpoles in the genus Spea exhibit striking plasticity: depending on their diet, they develop into either omnivores or a novel 'carnivore' morph. Interestingly, certain components of this distinctive carnivore morph can be diet-induced in Scaphiopus. Moreover, some Spea populations have secondarily lost the omnivore-carnivore plasticity and become monomorphic. Indeed, in some populations, selection has favored the near fixation of the carnivore morph. Thus, as a group, spadefoots appear to represent different stages in the evolution of the novel carnivore morph: from its possible initial induction (in Scaphiopus), to its refinement as part of a novel developmental 'switch' (in many Spea populations), to its ultimate fixation (in some Spea populations). The planned research will evaluate whether this novel carnivore phenotype arose through plasticity-first evolution by contrasting development, genetic variation, and performance in different species/populations that serve as different evolutionary stages in the origins of this distinctive form. In doing so, the research will evaluate the critical predictions of the plasticity-first hypothesis. This research will thereby help to clarify plasticity's role in evolutionary innovation and provide a roadmap for others to test the plasticity-first hypothesis.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.