The role of phenotypic plasticity in rapid adaptation

可塑性被定义为生物体改变表型表达以应对环境变化的能力。可塑性变化可以由非生物和社会条件引起，改变结构、生理、代谢和行为（例如[2][3][4][5]）。先前的研究强调了可塑性在快速适应中的作用，表明它可能是理解生物如何应对快速变化的世界（如全球变暖、森林砍伐、污染）的关键。[6][7])。此外，塑性反应本身的强度已被证明是进化和多样化的。这些发现激发了人们对更新的现代进化综合的兴趣，解释了发育可塑性（例如[9][10][11]）。然而，也有人提出，可塑性可能会保护种群免受选择，减缓适应（例如b[12]）。此外，当存在对社会环境的可塑性时，复杂性会增加，而且这种形式的可塑性如何影响进化轨迹尚不清楚。为了更新进化模型和预测生物如何应对快速的环境变化，必须确定促进快速表型变化的潜在遗传和环境因素；确定社会和非生物可塑性如何相互作用以形成进化结果；并最终解决关于表型可塑性是否是一种进化适应的争论。结合实地和实验室研究，并采用稳健的实验设计，该项目旨在利用快速进化的夏威夷蟋蟀来完成这些任务，明确确定可塑性在快速适应中的作用。在夏威夷蟋蟀种群（Teleogryllus oceanicus）中，有一定比例的雄性蟋蟀失去了唱歌的能力，原因是前翅上的发声结构被基因突变抹去了。这种改变有利于生存，因为它保护个体免受以声音为导向的寄生蝇（Ormia ochracea）的捕食。与此相反，这种变异消除了雄性吸引雌性的主要策略——唱歌。尽管如此，自从2003年首次出现在考艾岛以来，这种沉默的变种已经迅速蔓延到夏威夷群岛。沉默变种的繁殖成功表明，它们的繁殖是由对社会环境的可塑性所促成的：雄性改变性信号策略，雌性调整标准来决定雄性的质量。事实上，先前的研究发现，“沉默”种群对社会环境的可塑性明显高于正常种群[6]，并且有人假设，对社会环境的可塑性可能与“沉默”突变[6]共同进化。夏威夷蟋蟀种群为研究可塑性在快速适应中的作用提供了最佳机会。该项目将包括三个主要阶段：1)进行实地研究，调查非生物和社会条件，确定它们在自然界中如何协同变化，并测试促进或阻碍沉默形态入侵成功的因素；2)通过探索不同水平的营养可得性如何影响对社会环境的可塑性反应，实验验证对非生物环境和社会环境的可塑性如何相互作用来塑造适应性；3)通过操纵社会环境来匹配或不匹配先前的社会经验，从而测量适应性，从而检验可塑性作为一种进化适应对社会环境的作用。

Plasticity is defined as an organism's ability to alter phenotype expression in response to environmental change [1]. Plastic changes can result both from abiotic and social conditions, altering structure, physiology, metabolism and behaviour (e.g.[2] [3] [4] [5]). Previous research has highlighted the role of plasticity in rapid adaptation, suggesting it may be the key to understanding how organisms cope with the challenge of a rapidly changing world (e.g. global warming, deforestation, pollution)(e.g. [6][7]). Furthermore, the strength of plastic responses themselves have been shown to evolve and diversify [8]. These findings have sparked interest for an updated modern synthesis of evolution, accounting for developmental plasticity (e.g. [9] [10] [11]). However, it has also been suggested that plasticity may shield populations from selection, slowing down adaptation (e.g. [12]). Furthermore, when plasticity to the social environment is present, complexity increases, and it is still unclear how this form of plasticity affects evolutionary trajectories. In order to update evolutionary models and predict how organisms cope with rapid environmental change, it is imperative to define the underlying genetic and environmental factors which promote rapid phenotypic change; determine how social and abiotic plasticity interact to shape evolutionary outcomes; and definitively settle the debate over whether or not phenotypic plasticity is an evolved adaptation. Combining field and laboratory studies, and using robust experimental designs, this project aims to use the rapidly evolving Hawaiian cricket to achieve these tasks, definitively determining the role of plasticity in rapid adaptation.In Hawaiian cricket populations (Teleogryllus oceanicus) a percentage of males have lost ability to sing due to mutations which erase sound producing structures on the forewings [13]. This alteration is beneficial for survival as it protects individuals from predation from an acoustically-oriented parasitoid fly (Ormia ochracea). In contrast, the mutation removes the male's main strategy for attracting females, singing. Despite this, since first appearing in the island of Kauai in 2003, the silent morph has spread rapidly across Hawaiian Islands [13]. The reproductive success of silent morphs is indicative that their proliferation is enabled by plasticity to the social environment: males alter sexual signalling strategies and females adjust the criteria to determine male quality. In fact, previous research has found that plasticity to the social environment is significantly higher in "silent" populations than in normal-wing populations [6], and it has been hypothesised that plasticity to the social environment may be co-evolving with the "silent" mutation [6]. Hawaiian cricket populations then present an optimal opportunity to study the role of plasticity in rapid adaptation. This project will be comprised of three main stages: 1) conduct field studies to survey abiotic and social conditions, determine how they covary in nature and test what factors promote or hinder the invasion success of silent morphs; 2) experimentally test how plasticity to the abiotic and social environments interact to shape adaptation by exploring how different levels of nutritional availability affect plastic responses to the social environment; and 3) test the role of plasticity to the social environment as an evolved adaptation by manipulating social environments to either match or mismatch previous social experience, subsequently measuring fitness.