The role of phenotypic plasticity and resource polymorphism on the evolution of fish populations

在达尔文的《物种起源》中首次提出了物种多样化和物种形成的机制，过去几年发表的评论强调，这个问题仍然是进化生态学中最具挑战性和最令人兴奋的问题之一。研究表明，可塑性通过单一基因型在不同环境条件下产生不同表型的能力，促进了新表型的起源。表型可塑性被认为是资源多态性表达的一种机制，即当同一种群的个体表现出与不同生态位利用相关的形态、行为和生理性状的差异时。资源多态性可能反过来导致遗传分化，并最终导致适应性辐射。然而，在自然系统中检验这些最新的理论发展仍然是进化生态学中最具挑战性的任务之一。我的研究计划的长期目标是研究表型可塑性和资源多态性如何促进适应性辐射。我使用来自加拿大盾湖的鳟鱼Salvelinus fontinalis作为模型物种。布鲁克鳟鱼表现出微妙的资源多态性，我们的研究结果表明，这些湖泊代表了该物种进化分化的早期阶段。这使得它们对理解生态物种形成的早期阶段所涉及的过程特别感兴趣。该研究是在该系统15年工作的基础上提出的，将使我们能够1)提高我们对温度在变温动物资源多态性进化中的作用的理解，2)测试两种离散生态型表型环境之间的功能关系，以及3)确定鱼类适应性状传播的机制。除了对自然种群进行研究外，拟议的研究项目在概念上是原创的，将共同有助于更好地了解动物适应辐射的机制。此外，该研究还将培养2名硕士和2名博士候选人，以及10名研究助理。这些学生将获得扎实的概念和实践技能，这些技能受到公共组织、私营企业和学术机构等雇主的高度追捧。

Understanding the mechanisms underlying species diversification and speciation was first addressed in Darwin's The Origin of Species, and reviews published over the past few years have highlighted that this question is still one the most challenging and exciting issues in evolutionary ecology. It has been shown that plasticity promotes the origin of novel phenotypes through the capacity of single genotypes to produce different phenotypes in response to varying environmental conditions. Phenotypic plasticity has been proposed as a mechanism for the expression of resource polymorphism, i.e., when individuals of the same population exhibit differences in morphology, behaviour, and physiological traits associated with differential niche use. Resource polymorphisms could in turn lead to genetic differentiation and ultimately to adaptive radiation. However, testing these recent theoretical developments in natural systems is still one of the most challenging tasks in evolutionary ecology. The long-term objective of my research program is to study how phenotypic plasticity and resource polymorphism promote adaptive radiation. I use the brook trout, Salvelinus fontinalis, from Canadian Shield lakes as the model species. Brook trout exhibits a subtle resource polymorphism, and our results suggest that these lakes represent the early stages of evolutionary divergence of this species. This makes them of particular interest for understanding the processes involved in the early steps of ecological speciation. The proposed research is built on 15 years of work in this system and will allow us to 1) improve our understanding on the role of temperature in the evolution of resource polymorphism in ectotherms, 2) test the functional relationship between phenotypeenvironment in two discrete ecotypes, and 3) identify the mechanisms underlying the transmission of adaptive traits in fishes. In addition to being done on natural populations, the proposed research projects are conceptually original and will collectively contribute to a better understanding of the mechanisms of adaptive radiation in animals. Furthermore, the proposed research will allow to train two M.Sc. and two Ph.D. candidates as well as 10 research assistants. These students will acquire solid conceptual and practical skills, which are highly sought by employers like public organizations, private industries, and academic institutions.