Collaborative Research: The effect of inbreeding on metapopulation dynamics of the giant kelp, Macrocystis pyrifera

了解种群在空间和时间上波动的原因是生态学家非常感兴趣的，关于这一主题的知识在保护和环境管理中有着广泛的应用。认识到许多物种生活在高度碎片化的景观中，导致了元种群理论的发展，这一理论广泛适用于陆地和海洋系统。从最简单的形式来看，“元种群”的概念代表了这样一种观点：适合当地种群的栖息地斑块要么被占据，要么没有被占据，而斑块之间的连通性起到了“拯救”已灭绝的当地种群的作用。最近几项关于近亲繁殖的研究挑战了传统观念，即生态因素是当地种群减少和最终灭绝的主要原因。然而，迄今为止，关于近亲繁殖抑制在多大程度上驱动了一个元种群的本地种群动态的调查很少。巨藻（Macrocystis pyrifera）是检验超种群理论的理想系统，因为它出现在离散的斑块上，在几年的时间尺度上经历频繁的局部灭绝和重新定居。研究人员将测试五个相关的假设，旨在确定南加州湾巨型海带的超种群是否至少部分受到反复和不同步的近亲繁殖衰退的调节。本研究的动机是先前研究者在斑块大小和隔离程度、孢子扩散和遗传连通性模式以及近交抑制对海带繁殖的不利影响方面的研究结果。本项目将：(1)评估南加州湾巨藻种群近亲繁殖的程度和模式；(2)确定繁殖减少导致的近亲繁殖抑制对南加州湾巨藻超种群斑块动态模式的影响程度。最近的研究进展将极大地促进研究：(1)用于表征巨藻种群遗传学的高多态性微卫星标记，(2)用于估计巨藻本地种群之间连通性的高分辨率海洋学模型，以及(3)利用Landsat卫星图像估计南加州湾所有离散巨藻斑块有效种群大小的新方法。更广泛的影响：巨大的海带森林是全球温带海洋浅海礁的显著特征，是地球上最具生产力的生态系统之一。巨藻本身为各种各样的消费者提供食物和栖息地，其中许多消费者在商业和娱乐上都很重要。因此，由于巨藻林提供的生态系统服务具有很高的价值，巨藻林成为保护主义者、资源管理者和决策者特别关注的栖息地。主要研究人员有与政府机构合作制定旨在保护这些系统的管理计划的历史，这项研究的结果将有助于这些正在进行的努力。拟议的研究还将有助于在3个不同机构的本科生、研究生和博士后层面进行跨学科研究的学生培训和指导。主要研究人员将与加州大学圣迭戈分校和加州大学圣迭戈分校现有的外展项目合作，将他们的研究成果提供给k-12和高等教育机构、教育工作者、社区团体和公众。

Understanding the causes for populations to fluctuate in space and time is of great interest to ecologists and knowledge on this topic has widespread application for conservation and environmental management. The recognition that many species live in highly fragmented landscapes led to the development of metapopulation theory, which is widely applicable to both terrestrial and marine systems. In its simplest form the concept of a metapopulation represents the idea that habitat patches suitable for local populations are either occupied or not and that connectivity among patches acts to "rescue" extinct local populations. Several recent studies on inbreeding have challenged the traditional belief that ecological factors are the primary causes of local population reduction and eventual extinction. However, to date there have been few investigations of the extent to which inbreeding depression drives local population dynamics in a metapopulation. The giant kelp, Macrocystis pyrifera, is an ideal system for testing metapopulation theory because it occurs in discrete patches that undergo frequent local extinctions and recolonizations on time scales of a few years. The investigators will test five related hypotheses aimed at determining whether the metapopulation of the giant kelp in the Southern California Bight is regulated at least in part by repeated and asynchronous episodes of inbreeding depression. This research is motivated by previous findings of the investigators on patterns of local population extinction and recolonization with respect to patch size and degree of isolation, patterns of spore dispersal and genetic connectivity, and the adverse consequences of inbreeding depression to kelp reproduction. This project will: (1) Assess the extent and pattern of inbreeding in populations of giant kelp in the Southern California Bight, and (2) Determine the extent that inbreeding depression via decreased reproduction contributes to the pattern of metapopulation patch dynamics of giant kelp in the Southern California Bight. The research will be greatly facilitated by recent developments of: (1) highly polymorphic microsatellite markers for characterizing the population genetics of giant kelp, (2) a high resolution oceanographic model for estimating connectivity among local populations of giant kelp, and (3) a novel method for estimating effective population size for all discrete patches of giant kelp in the Southern California Bight using Landsat satellite imagery. Broader Impacts: Giant kelp forests are prominent features on shallow reefs in temperate seas worldwide and are among the most productive ecosystems on Earth. Giant kelp itself provides food and habitat for a diverse assemblage of consumers many of which are commercially and recreationally important. Consequently, giant kelp forests are targeted by conservationists, resources managers and policy makers as habitats of special concern due to the high value ascribed to the ecosystems services that they provide. The principal investigators have a history of working with government agencies in developing management plans aimed at protecting these systems and findings from this research will contribute to these ongoing efforts. The proposed research will also contribute to student training and mentoring in interdisciplinary research at the undergraduate, graduate, and post doc levels spread across 3 different institutions. The principal investigators will partner with existing outreach programs at UCSC and UCSB to deliver the results of their research to k-12 and post-secondary institutions, educators, community groups and the general public.