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问题，有关这一主题的知识在保护和环境管理方面具有广泛的应用。由于认识到许多物种生活在高度破碎的景观中，集合种群理论的发展导致了广泛适用于陆地和海洋系统的集合种群理论的发展。在最简单的形式下，集合种群的概念代表了这样一种想法，即适合当地种群的栖息地斑块要么被占据，要么没有被占据，斑块之间的连通性起到了拯救已经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，即生态因素是当地人口减少和最终灭绝的主要原因。然而，到目前为止，关于近亲繁殖衰退在多大程度上推动集合种群中的局部种群动态的研究还很少。巨藻是测试集合种群理论的理想系统，因为它发生在离散的斑块中，在几年的时间尺度上经历了频繁的局部灭绝和重新克隆。研究人员将测试五个相关假设，旨在确定南加州海湾巨型海带的集合种群是否至少在一定程度上受到近亲繁殖衰退反复和不同步的影响。这项研究的动机是研究人员以前的发现，即关于斑块大小和隔离程度的当地种群灭绝和重新定居的模式，孢子扩散和遗传连通性的模式，以及近亲繁殖衰退对海带繁殖的不利影响。该项目将：(1)评估南加州海湾巨型海带种群近亲繁殖的程度和模式，以及(2)确定由于繁殖减少而导致的近亲繁殖衰退对南加州海湾巨型海带集合种群斑块动态的影响程度。以下方面的最新进展将极大地促进这一研究：(1)用于描述巨藻种群遗传学的高度多态的微卫星标记，(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)利用陆地卫星图像估计南加州海湾所有离散的巨藻斑块有效种群规模的新方法。更广泛的影响：巨藻森林是世界各地温带海域浅礁上的突出特征，也是地球上生产力最高的生态系统之一。巨型海带本身为不同的消费者群体提供了食物和栖息地，其中许多消费者具有重要的商业和娱乐价值。因此，巨大的海带森林被自然资源保护者、资源管理者和政策制定者列为特别关注的栖息地，因为它们提供的生态系统服务具有很高的价值。主要调查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，这项研究的发现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、研究生和博士后水平上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伯克利分校和加州大学伯克利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、社区团体和普通公众。

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.