Collaborative Research: A mechanistic understanding of biogeographic patterns and life histories in benthic organisms in advective coastal environments

在海洋中建立和维持物种边界的生物和物理机制是有争议的。促成因素是浮游幼虫被实际转移到其出生范围之外的物种的后代，以及成虫在被移植到直接超出其自然分布的地区时茁壮成长。然而，还不清楚为什么底栖生物幼虫的远距离传播应该在进化的时间尺度上持续下去。有更多的幼虫从出生的栖息地扩散，而不是看起来是有利的。此外，已知较长的幼虫持续时间会增加物种持续繁殖的产量，使种群不太可能保留有利的等位基因，并降低种群的遗传多样性。Co-PI研究表明，维持物种的范围边界受类似于沿海海洋等位基因频率/遗传倾斜率的函数控制。与生物多样性理论的其他最新进展一样，这项工作表明，维持等位基因在物种内分布的条件与维持物种本身分布的条件之间存在趋同。这种理论的融合为在平流环境中发展物种间和物种内的竞争提供了实质性的机会。它可能会统一遗传和种群水平的理论，并创建平流环境中生命的整体观点。从初步工作中可以清楚地看出，合成将严重依赖于扩散模式和成功繁殖输出之间的权衡。这一理论的发展既要突破其分析极限，又要利用现有的大量数据库来定量地限制繁殖和扩散之间的权衡。例如，尽管幼虫数量与质量之间的权衡(即许多“能量廉价”的幼虫和少数“高度供应”的个体)长期以来一直是定性模型的主题，但它们并没有针对不同底栖海洋类群的生活史特征进行定量定义。结合分析发展和观察到的生活史权衡，将提供1)一系列扩散策略的进化稳定状态，2)将物种边界定义为物理(例如，海流中的温度和沿岸变化)和生物(如幼虫死亡率)参数的函数的机制，以及3)局部保留幼虫的扩散行为的定量起源，并导致物种间和物种内适合性之间的关系。这些发现将根据当地循环、环境条件及其梯度来预测物种边界位置和各种扩散策略的存在/不存在。作为广泛的文献和数据库搜索的一部分，预测将与收集的物种范围数据进行验证。更广泛的影响：这项研究将允许更好地机械性地理解由于地球气候变化而发生的物种范围。例如，这项研究将检验这样的假设，即气候变暖有利于幼虫浮游持续时间更长的物种。因此，随着气候变暖，目前由直接开发物种主导的高纬度地区将转变为浮游分散者和直接开发者的混合体。这项研究将使管理者能够了解对栖息地的破坏如何通过改变浮游幼虫的近岸来源和运输来改变物种范围。物种范围的量化理论也将帮助管理者了解是什么设定了最近引入的外来物种的最终限制，从而允许改进管理策略。这项建议包括以下教育内容。两名研究生将接受定量系统地理学和生物地理学领域的尖端技术培训。此外，每年两名本科生将协助该项目的所有方面，并将在全国会议上介绍他们的工作。学生将被指导向国家科学基金会撰写REU建议书。本科生将在路易斯·斯托克斯少数群体参与联盟的帮助下招募，UGA是该联盟的旗舰成员。本科生也将从UNH的研究和发现计划中招募，来自本科生研究机会有限的大学。

The biological and physical mechanisms that establish and maintain species boundaries in the ocean are controversial. Contributing factors are offspring of species with planktonic larvae being physically transported outside their natal range, and adults thriving when transplanted into regions immediately beyond their natural distributions. It is unclear, however, why long-distance dispersal of a benthic organism's larva should persist on evolutionary timescales. There is more larval dispersal from natal habitat than would seem propitious. Furthermore, long larval duration is known to increase reproductive output for species persistence, makes population retention of favorable alleles less likely, and reduces the genetic diversity of the population.The Co-PIs have shown that maintenance of range boundaries for a species are governed by a function analogous to that derived for allelic frequency/genetic clines in the coastal ocean. As with other recent advances in biodiversity theory, this work suggests a convergence between conditions that maintain the distribution of alleles within species and those that maintain the distribution of species themselves. This confluence of theory provides substantial opportunity for development of inter- and intra-species competition in an advective environment. It potentially would unify genetic and population-level theory, and create a holistic view of life in advective environs. It is clear from preliminary work that a synthesis would depend critically on tradeoffs between dispersal mode and successful reproductive output. The theory would be developed both by pushing its analytical envelope, and by drawing upon extensive, existing databases to quantitatively constrain reproductive and dispersal tradeoffs. For example, although tradeoffs between larval quantity versus quality (i.e., many "energetically cheap" larvae versus few "highly provisioned" individuals) have long been the subject of qualitative models, they have not been quantitatively defined for life history characteristics of different benthic marine taxa. Combining analytical developments and observed life-history tradeoffs would provide 1) evolutionarily stable states for a range of dispersal strategies, 2) mechanisms that define species boundaries as a function of physical (e.g., temperature and alongshore variation in currents) and biological (like larval mortality) parameters and 3) quantitative origins of dispersal behaviors that would locally retain larvae, and result in relationships between inter- and intra-species fitness. Such findings would predict species boundary locations and the presence/absence of various dispersal strategies as a function of local circulation, environmental conditions and their gradients. Predictions would be tested against data on species ranges gathered as part of an extensive literature and database search. Broader impacts: This research would allow a better mechanistic understanding species' ranges that occur due to changes in the Earth's climate. For example, this study will test the hypothesis that warming favors species with longer larval planktonic duration. Therefore, high-latitude areas now dominated by species with direct development would shift to a mixture of planktonic dispersers and direct developers as the climate warms. The research would allow managers to understand how disruption to habitat can alter species ranges by changing alongshore sources and transport of planktonic larvae. A quantitative theory of species range will also help managers understand what sets the ultimate limits of recently introduced exotic species, allowing improvement of management strategies. This proposal includes the following education components. Two graduate students will be trained in cutting-edge techniques in the fields of quantitative phylogeography and biogeography. In addition, two undergraduate students each year will assist with all aspects of the project and will present their work at a national meeting. The students will be mentored to write REU proposals to NSF. Undergraduates will be recruited with the help of the Louis Stokes Alliance for Minority Participation, of which UGA is a flagship member. Undergraduates will also be recruited from the Research and Discovery Program at UNH, from colleges with limited opportunities for undergraduate research.