Breaking boundaries: quantifying the influence of demography and seascape in driving adaptive variation in the ubiquitous protist Oxyrrhis marina.

打破界限：量化人口统计和海景对驱动无处不在的原生生物 Oxyrris 码头适应性变化的影响。

• 批准号: NE/F005237/1
• 负责人: Phillip Watts
• 金额: $ 52.02万
• 依托单位: University of Liverpool
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2008
• 资助国家: 英国
• 起止时间: 2008 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FF005237%2F1
• 关键词: Breaking; boundaries; quantifying; influence; demography

Biodiversity at all hierarchical levels, from communities to species and populations to genes, is critical for ecosystem health. It is essential, therefore, to provide a robust framework to understand mechanisms that promote or constrain adaptive divergence and potential response to new environments. A first step is to assess these processes within species. We will do this by employing an interdisciplinary approach that provides a unique examination of the interplay between landscape and key demographic parameters that drive adaptive divergence. Two key processes determine adaptive divergence: gene flow (gene movement by dispersing individuals) and effective population size (ie only those individuals that contribute genes to the next generation). High gene flow is a cohesive evolutionary force that limits genetic differentiation, thus restricting opportunity for ecological specialisation and ultimately speciation. Conversely, many species are locally adapted as a result of low gene flow, sometimes due to large geographic distances, but often because populations are distributed throughout heterogeneous landscapes with specific barriers, not distance per se, limiting movement. Genetic divergence is promoted also by small effective population size, but this process may be non-adaptive as under such circumstances random processes rather than natural selection shapes genome structure. Our study is designed specifically to resolve two broad questions: 1) how much adaptive divergence occurs between populations? 2) how do the demographic parameters, gene flow and effective population size, promote or constrain divergence? It is easy to visualise that in patchy terrestrial and freshwater systems demographic parameters (dispersal, effective population size), are intimately linked with the landscape matrix. However, this is less obvious for marine pelagic environments, which are traditionally viewed as 'open systems' with few barriers to gene flow. This view is now challenged, particularly by emerging research into the marine landscape (seascape) that recognises oceanographic features limit dispersal of metazoans. In contrast, small planktonic organisms, such as protists (single-celled eukaryotes), are speculated to be ubiquitously dispersed as they can be readily transported by wind and water currents. The corollary is that adaptive divergence of protist populations will be limited, in contrast to that described for metazoans; this presents an apparent paradox given the large taxonomic and functional diversity exhibited by protists, implying that either gene flow is limited or strong environmental pressures (eg temperature, salinity) drive adaptation. This issue requires addressing as protists are ecologically important and understanding the extent of ecological specialisation is critical to predict response to environment change. Specifically, we address this issue by applying experimental and molecular techniques to a protist model to resolve four questions: 1) where are protist population boundaries? 2) what are the values of gene flow and effective population sizes? 3) how do populations respond to key environmental variables in the marine system: temperature & salinity? and 4) are metazoans and protists similarly influenced by seascape? It is essential to simultaneously address these questions to truly understand the interplay between gene flow, effective population size and seascape. Our answers promise to offer fundamental insights into dispersal and adaptation of plankton, potentially guiding management of marine resources as plankton can have beneficial (eg influencing food web carbon flux) and harmful (eg toxic blooms) influences on ecosystem health. These data also have a major bearing on wider issues, by determining 1) the extent to which adaptive divergence occurs despite, or in the absence of, high gene flow and 2) whether there are fundamental differences between protist and metazoan evolutionary processes.

从群落到物种，从种群到基因，所有层次的生物多样性对生态系统健康至关重要。因此，必须提供一个健全的框架来理解促进或限制适应性分化和对新环境的潜在反应的机制。第一步是评估物种内部的这些过程。为此，我们将采用跨学科的方法，对推动适应性差异的景观和关键人口参数之间的相互作用进行独特的研究。两个关键过程决定了适应性分化：基因流动（通过分散个体进行的基因运动）和有效种群规模（即只有那些向下一代贡献基因的个体）。高基因流是一种凝聚的进化力量，它限制了遗传分化，从而限制了生态特化和最终物种形成的机会。相反，许多物种由于基因流量低而适应于局部，有时是由于地理距离较远，但通常是因为种群分布在具有特定障碍的异质景观中，而不是距离本身限制了迁移。较小的有效群体规模也促进了遗传分化，但这一过程可能是非适应性的，因为在这种情况下，随机过程而不是自然选择形成了基因组结构。我们的研究是专门为解决两个广泛的问题而设计的：1)种群之间发生了多少适应性差异？2)人口统计参数、基因流动和有效人口规模是如何促进或抑制分化的？很容易想象，在斑驳的陆地和淡水系统中，人口统计参数（分散、有效人口规模）与景观矩阵密切相关。然而，这在海洋中上层环境中就不那么明显了，因为海洋中上层环境传统上被视为“开放系统”，基因流动几乎没有障碍。这种观点现在受到了挑战，特别是对海洋景观（海景）的新兴研究，这些研究认识到海洋特征限制了后生动物的扩散。相比之下，小型浮游生物，如原生生物（单细胞真核生物），据推测是无处不在的分散，因为它们可以很容易地通过风和水流运输。由此推论，与后生动物不同，原生动物种群的适应性分化将受到限制；考虑到原生生物在分类和功能上表现出的巨大多样性，这就提出了一个明显的悖论，这意味着要么是基因流动有限，要么是强大的环境压力（如温度、盐度）驱动了适应。这个问题需要解决，因为原生生物在生态学上是重要的，了解生态专业化的程度对于预测对环境变化的反应至关重要。具体来说，我们通过将实验和分子技术应用于原生生物模型来解决这一问题，以解决四个问题：1)原生生物种群边界在哪里？2)基因流动和有效种群规模的价值是什么？3)种群如何响应海洋系统中的关键环境变量：温度和盐度？4)后生动物和原生动物是否同样受到海景的影响？同时解决这些问题，才能真正理解基因流动、有效种群规模和海景之间的相互作用。我们的答案有望为浮游生物的扩散和适应提供基本的见解，潜在地指导海洋资源的管理，因为浮游生物可以对生态系统健康产生有益（例如影响食物网碳通量）和有害（例如有毒水华）的影响。这些数据还对更广泛的问题产生重大影响，通过确定1)在高基因流的情况下或在没有高基因流的情况下，适应性分化发生的程度，以及2)原生动物和后生动物的进化过程是否存在根本差异。

项目成果

A TALE OF TWO SEAS: THE ATLANTIC-MEDITERRANEAN TRANSITION IMPOSES A STRONG GENETIC BREAK IN THE PROTIST OXYRRHIS MARINA

两片海洋的故事：大西洋-地中海的转变给原生生物奥克里斯码头带来了强烈的遗传断裂

• 作者: Christopher Lowe (Author)

Who is Oxyrrhis marina? Morphological and phylogenetic studies on an unusual dinoflagellate

• DOI: 10.1093/plankt/fbq110
• 发表时间: 2011-04-01
• 期刊: JOURNAL OF PLANKTON RESEARCH
• 影响因子: 2.1
• 作者: Lowe, Chris D.;Keeling, Patrick J.;Montagnes, David J. S.
• 通讯作者: Montagnes, David J. S.

Genetic and functional diversity in the ubiquitous protist Oxyrrhis marina: a step towards quantifying adaptive variation

普遍存在的原生生物Oxyrris marina的遗传和功能多样性：迈向量化适应性变异的一步

• 作者: Christopher Lowe (Author)

Collection, isolation and culturing strategies for Oxyrrhis marina

• DOI: 10.1093/plankt/fbq161
• 发表时间: 2011-04-01
• 期刊: JOURNAL OF PLANKTON RESEARCH
• 影响因子: 2.1
• 作者: Lowe, Chris D.;Martin, Laura E.;Montagnes, David J. S.
• 通讯作者: Montagnes, David J. S.

Global phylogeny of Oxyrrhis marina

尖鞭藻的全球系统发育

• 作者: Laura Martin (Author)