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

许多生物可以通过显著改变它们的形态、行为或生理来响应环境的变化，这种能力的广泛出现引发了一场激烈的辩论。一方面，许多生物学家坚持认为，改变外表、行为或生理的灵活性与进化无关，因为进化需要基因变化。另一方面，越来越多的研究人员表示，这种灵活性通过启动基因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/或生理的变化是否先于(并使能)主要的、新的、遗传编码的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铁蹄青蛙进化出一种新的、复杂的身体形态。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谜团提供新的曙光：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本科生以及在博物馆组织公开演讲来促进教育推广。这项研究将检验适应性进化的可塑性优先假说。为了做到这一点，拟议中的研究将集中在铲足蟾蜍上。像大多数青蛙一样，Scaphiopus属的蝌蚪只发育成一种典型的杂食动物。相比之下，斯帕属的蝌蚪表现出惊人的可塑性：根据它们的饮食，它们要么发育成杂食性动物，要么发育成一种新颖的食肉动物。有趣的是，这种独特的食肉动物形态的某些成分可以在Scaphiopus中由饮食诱导。此外，一些Spa种群已经继而失去了杂食-食肉动物的可塑性，变成了单形性。事实上，在一些种群中，选择倾向于对肉食性变种的近乎固定。因此，作为一个群体，铲足似乎代表了新的食肉动物形态进化的不同阶段：从可能的最初诱导(在Scaphiopus中)，到它作为新的发育‘开关’的一部分的精炼(在许多Spa种群中)，到它的最终固定(在一些Spea种群中)。计划中的研究将通过对比作为这种独特形式起源的不同进化阶段的不同物种/种群的发育、遗传变异和表现，来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。在这样做的过程中，研究将评估可塑性优先假说的关键预测。因此，这项研究将有助于澄清可塑性在进化创新中的作用，并为其他人测试可塑性优先假设提供路线图。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.