Patterns and mechanisms relating seagrass genotypic diversity and ecosystem response to biotic and abiotic stress

物种多样性与生态系统功能之间的关系一直是研究和争论的焦点。相比之下，物种内部基因型多样性对个体相互作用、种群过程和生态功能影响的评估数据却很少。许多海洋底栖生物和浮游生物群落由单一物种主导：海带森林中的巨囊藻，温带海草床中的带状藻，以及少营养开放海洋系统中的原绿球藻。这些物种的遗传多样性可能与其他系统中的物种多样性起着类似的作用，但很少有数据将基因型的功能分化与其对群落和生态系统水平过程的影响联系起来。初步研究表明，大叶藻（Zostera marina）的克隆多样性增强了对放牧鹅干扰的抗性，但这种影响的机制以及在一系列干扰类型和强度下这种影响的重要性尚不清楚。Zostera是世界上许多温带浅水群落中唯一的大型植物，在初级生产、养分循环、沉积物稳定和为相关动物物种提供栖息地方面发挥着关键的生态系统作用。该系统为评估基因型多样性不仅对个体和种群过程，而且对群落和生态系统过程（如初级生产力和相关动物的丰度和多样性）的影响提供了机会。pi将进行一系列的实验室，中生态和野外实验，以调查Z. marina遗传变异的功能（生态）后果，以及这种变异如何促进遗传多样性与生态系统过程之间的关系。具体来说，他们将：(1)量化光合速率、养分吸收和短期生长等关键生理参数的无性系变异；(2)研究受干扰和不受干扰条件下无性系与无性系间的相互作用及其对大叶藻整体产量的影响；(3)研究大叶藻基因型多样性与干扰对大叶藻茎密度、幼苗招募和幼苗生长的影响。(4)在自然种群存在和不存在干扰的情况下，量化基因型多样性随时间的变化，以及这些变化对生态系统其他部分的影响。鉴于海洋系统中大叶藻和其他关键基础物种的广泛减少，了解个体变异对种群和群落过程的影响至关重要。事实上，人类活动正在造成海草遗传多样性的下降，在测量生态系统过程的规模上，这项研究将为联邦政府授权的恢复工作提供急需的信息。最后，该项目将培养未来的科学家，包括博士后，研究生和本科生研究人员，包括来自代表性不足群体的成员。

Considerable research and debate has focused on the relationship between species diversity and ecosystem function. In contrast, few data are available to assess the impact of within species genotypic diversity on individual interactions, population processes, and ecological functions. Many marine benthic and planktonic communities are dominated by a single species: Macrocystis in kelp forests, Zostera in temperate seagrass beds, and Prochlorococcus in oligotrophic open ocean systems. Genetic diversity within these species may play an analogous role to species diversity in other systems, but few data are available that link functional differentiation of genotypes with their effect on community and ecosystem-level processes. The PIs' preliminary work suggests that clonal diversity in the eelgrass (Zostera marina), enhances resistance disturbance by grazing geese but the mechanisms underlying this effect and the importance of the effect under a range of disturbance types and intensities are unknown. Zostera plays a key role as the only macrophyte species in many temperate shallowwater communities worldwide, where it provides a critical ecosystem role, in terms of primary production, nutrient cycling, sediment stabilization, and provision of habitat for associated animal species. This system provides an opportunity to assess the effects of genotypic diversity on not only individual and population processes but also on community and ecosystem processes such as primary productivity and the abundance and diversity of associated animals. The PIs will conduct a series of laboratory, mesocosm, and field experiments to investigate the functional (ecological) consequences of genetic variation in Z. marina and how this variation contributes to the relationship between genetic diversity and ecosystem processes. Specifically, they will: (1) Quantify clonal variation in key physiological parameters such as photosynthetic rate, nutrient uptake and short term growth, (2) Investigate inter-shoot interactions between clonemates and non-clonemates and their impacts on overall eelgrass production under disturbed and undisturbed conditions, (3) Examine the inter-relationship between eelgrass genotypic diversity and disturbance on shoot density, seedling recruitment, and the associated community of seagrass epibionts in a factorial field experiment, and (4) Quantify changes in genotypic diversity over time in the presence and absence of disturbance in natural populations and the consequences of these changes for the rest of the ecosystem. Given the widespread decline of eelgrass and other key foundation species in marine systems, it is critical to understand the consequences of individual variation for population and community processes. Indeed, human activities are causing declines in genetic diversity in seagrasses at the scale at which ecosystem processes are measured and this research will provide much-needed information for federally mandated restoration efforts. Finally, this project will develop future scientists including a postdoctoral, and also graduate student and undergraduate researchers, including members from underrepresented groups.