Holocene Phylochronology and Ecology of the Northern Fur Seal

历史和古生态数据为物种的行为、生态和生物地理提供了重要的背景信息，特别是那些在20世纪前因采伐而大量灭绝的物种。这些数据可以作为判断近期生态变化重要性的基准，并指导影响物种保护的管理决策。本研究的目的是利用遗传和同位素工具来探索环境和人为因素是如何相互作用的，以产生在过去5000年中太平洋东北海岸的顶级海洋消费者——北方海狗（Callorhinus ursinus）的生态变化。这些变化的最完整记录是在沿海考古遗址中发现的，在那里可以研究过去陆地和海洋生态系统的动物，以调查古生态变化。此外，认识到主要的生态变化对于考古学家试图破译整个全新世东北太平洋边缘的人口和资源利用变化将是重要的。同位素和考古数据表明，在过去的5000年里，北方海狗已经改变了它的繁殖和迁徙行为。对北方毛海豹骨骼的直接测年表明，当地繁殖种群的崩溃并不是在太平洋边缘同步发生的。这些数据表明，加利福尼亚中部和北部沿海种群在约800年前经历了一个史前瓶颈。这项研究将使用来自一系列地理位置不同的古代遗传数据和来自全新世的几个时间单位直接测试这些结果。结果将使用最近开发的揭示历史人口连通性和有效人口规模的系列聚结模型进行分析。因此，我们将能够探测到南方种群的局部灭绝是如何或是否会对整个北美物种范围的其他地方产生重大影响。这项研究将展示如何从考古数据中了解濒危物种的生态。这对孑遗种群中的物种很重要，它们目前的生态可能受到最近的开发或环境变化的影响。所研究的物种目前在东北太平洋正经历着严重的数量下降，但这种下降的原因还远不清楚。这项工作将为该物种的遗传多样性和种群/种群结构在深层和历史时间上提供基线数据，并表明它们在过去是否经历过与人为和/或环境扰动相关的类似下降。调查人员将与保护生物学家和有蹼的生态学家合作，为指导管理决策的人提供数据。DNA序列将在Genbank上公开。科学对教学和教育的影响是广泛的。该项目将有助于斯坦福大学博士后、研究生和本科生的跨学科教育。古代DNA和化石的广泛吸引力继续激发普通社区的教育，并通过公共实验室日和示范激发儿童（7-10岁）的科学思维。

Historical and paleoecological data provide crucial contextual information on the behavior, ecology, and biogeography of species, particularly those that were decimated by pre-20th century harvesting. These data serve as a baseline against which to judge the significance of recent ecological shifts and to guide management decisions affecting species conservation. The objective in this research is to use genetic and isotopic tools to explore how environmental and anthropogenic factors interacted to generate ecological shifts of a top marine consumer, the northern fur seal (Callorhinus ursinus) on the northeastern Pacific coast over the past 5000 years. The most complete record of these changes is found in coastal archaeological sites, where the faunas of past terrestrial and marine ecosystems can be studied to investigate paleoecologic shifts. Furthermore, the recognition of major ecological shifts will be important for archaeologists attempting to decipher changes in human demography and resource utilization along the northeast Pacific margin throughout the Holocene. Isotopic and archaeological data show that the northern fur seal has changed its breeding and migratory behavior over the past 5000 years. Direct dating of northern fur seal bones show that the collapse of local breeding colonies was not synchronous across the Pacific margin. These data suggest that the central and northern California coastal populations experienced a prehistoric bottleneck at ~800bp. This research will directly test these results using ancient genetic data from a series of geographically distinct locations and from several time units through the Holocene. The results will be analyzed using recently developed serial coalescent models that reveal historic population connectivity and effective population size. Thus, we will be able to detect how, or if, local extinction of the southern population resulted in major effects elsewhere across the North American species range. This study will show how insights into the ecology of threatened species may be gleaned from archaeological data. This is important for species in relict populations, whose current ecology may be shaped by recent exploitation or environmental change. The species of study is presently undergoing severe population declines in the northeast Pacific Ocean, but the cause(s) for this decline are far from clear. This work will provide baseline data on the genetic diversity and population/stock structure of this species over deep and historic time, and indicate whether or not they experienced similar declines in the past in relation to anthropogenic and/or environmental perturbations. The investigators will work with conservation biologists and pinniped ecologists to make the data available to those directing management decisions. DNA sequences will be made publicly available on Genbank. The scientific impact on teaching and education is extensive. This project will contribute to the interdisciplinary education of postdoctoral scholars, graduate and undergraduate students at Stanford University. The broad appeal of ancient DNA and fossils continues to motivate the education of the general community and stimulate scientific thought in children (age 7-10) with public lab days and demonstrations.