The predictability and limits of evolution in response to increased temperature: insights from a natural 'experiment'

预测对环境变化的进化反应的能力对未来的保护工作至关重要。可以说，人为气候变化导致的气温上升是自然生态系统最广泛和最戏剧性的变化，其影响预计将随着时间的推移而变得更加严重。气温的升高可能会改变物种分布，或推动当地种群的发展和进化变化。因此，了解目前现存的种群如何能够或已经随着气候变暖而发生变化将是极其重要的。在这里，我们建议调查种群如何在生长、生理和解剖方面改变，以响应长期暴露在温度升高的环境中。我们还将确定除了表观遗传变化(即环境诱导的基因组结构变化，影响其功能但不改变DNA序列)之外可能发生了哪些遗传变化，并将这些与表型变化联系起来。为了解决这个问题，我们将使用冰岛的一系列独特的研究地点，在那里，三刺鱼种群生活在地热加热的池塘和邻近的非加热(即凉爽)池塘中。这对相邻的种群(出现在几个地方)在这种不同的温度下生活了数千代，初步调查显示，它们之间存在进化分歧的证据。这个范围广泛的项目将使用比较和实验方法来量化当动物经历温度上升时表型、基因组和表观基因组是如何相互作用的。实验室实验将利用这些来源种群的鱼来研究1)环境(凉爽)和‘温暖’种群在基因组和表观基因组水平上的差异，2)在相互温度条件下饲养的刺鱼的表型性状(包括代谢率、形态和运动能力)和表观基因组状态的遗传，3)温暖条件下可能限制进化的发育变化，以及4)不同温度下表型性状变化的遗传和表观遗传学基础。这个项目将是整体的，因为它有能力允许可塑性和可遗传的表观遗传效应与遗传变异一起进行评估。它将揭示当种群暴露在变暖的气温下时，是否存在一致的(因此也是可预测的)进化和表观遗传变化，并将探索可塑性在塑造适应反应中的作用。因此，它将提供关于人口在多大程度上能够适应全球变暖的新信息。

The ability to predict evolutionary responses to environmental change is of central importance for future conservation efforts. Increases in temperature from anthropogenic climate change are arguably the most widespread and dramatic alteration of natural ecosystems, with its impact predicted to become more acute with time. These increases in temperature are likely to shift species distributions, or drive developmental and evolutionary changes in local populations. Therefore, knowing how currently extant populations can or have changed in response to warmer conditions would be extremely important. Here we propose to investigate how populations change with respect to their growth, physiology, and anatomy in response to long term exposure to increased temperature. We will also determine what genetic changes may have happened in addition to epigenetic changes (i.e. environmentally-induced structural alterations of the genome that affect its function but don't change the DNA sequence), and relate these to phenotypic variation. To address this we will use a series of unique study sites in Iceland where populations of threespine stickleback live both in geothermally heated ponds and in unheated (i.e. cool) ponds in close proximity. These pairs of adjacent populations (which occur in several places) have lived at these contrasting temperatures for thousands of generations and preliminary investigation shows evidence of evolutionary divergence between them. This broad-ranging project will use both comparative and experimental approaches to quantify how the phenotype, genome, and epigenome interact when the animal experiences rising temperatures. Lab experiments will use fish from these source populations to investigate 1) population level differences between ambient (cool) and 'warmed' populations at the genomic and epigenomic level, 2) the inheritance of phenotypic traits (including metabolic rate, morphology and locomotor performance) and epigenomic states in sticklebacks reared under reciprocal temperature regimes, 3) alterations of development under warm conditions that could limit evolution, and 4) the genetic and epigenetic basis for variation in phenotypic traits under different temperatures. This project will be holistic through its ability to allow plasticity and heritable epigenetic effects to be assessed together with genetic variation. It will reveal whether there are consistent (and hence predictable) evolutionary and epigenetic changes when populations are exposed to warmer temperatures, and will explore the role of plasticity in shaping adaptive responses. As a result, it will provide novel information on the extent to which populations can adapt to a warming world.