Doctoral Dissertation Improvement Grant: Ecological niche evolution of Homo and Paranthropus at East Turkana, northern Kenya

对物种进化史的全面理解包括确定驱动其适应的生态因素。所有物种都占据着一个特定的生态位，其广度由非生物(例如气候和扩散障碍)和生物(例如竞争)影响的相互作用决定。一个物种的生态位很少随着时间的推移而保持不变，不可避免的变化可能会导致各种结果，包括进一步的适应、物种形成和灭绝。虽然在历史上很难重建化石分类群的生态位，但最近发展起来的古生态技术意味着，现在有可能检验关于生态在两个重要的早期原始人系不同的进化史中可能发挥的作用的假说。确定我们的早期人类祖先如何与他们的环境相互作用是理解人类进化史的基础。化石记录表明，我们的人属起源于大约240万年前(Ma)的东非，并与一种密切相关的物种boisei共享环境。然而，记录也表明，到了大约1.3 Ma，类人猿血统灭绝了，人族已经扩大了它在非洲以外的地理范围。尽管这些谱系在时间上共存，但我们缺乏一个逻辑框架来测试与这一时期的生态相关的假说。这篇由博士生David Patterson(在乔治·华盛顿大学勒内·博贝博士的指导下)的论文项目将通过使用新的方法来生成这两个谱系的生态位的第一个高分辨率重建，从而有助于解决我们知识中的这些差距。该项目将哺乳动物群落生态学的定量方法与稳定同位素地球化学相结合，在空间受限的古代生态系统中调查人和类人的生态位。这项拟议的研究将使用直接从这些古人类化石所在地收集的古生态数据，以及从肯尼亚北部Koobi Fora组约2.0至1.4 Ma之间的考古遗址收集的数据。通过集中于同一区域内的特定化石组合，这项研究将为这两个谱系的生态位提供新的见解。这项研究的影响将通过联合PI参与国家自然历史博物馆(NMNH)的陆地生态系统进化(ETE)计划和Koobi Fora野外学校(KFFS)而得到放大。作为ETE的一部分，合作-PI将通过在受赞助的研讨会上的讲座和通过NMNH Q？Rius科学中心向教育工作者传播项目成果。此外，Co-PI将为古生物系的博客空间创建一系列基于现场和实验室的条目。该合作小组还将参加“科学家在”计划，该计划将使公众有机会向研究人员询问他们的研究，以及其他与人类起源相关的话题。最后，联合和平协会的实地工作将与KFFS一起完成。肯尼亚国家博物馆和GWU之间的合作为来自肯尼亚、埃塞俄比亚、南非和美国等几个国家的学生提供了在古人类学方面的实践经验。

A comprehensive understanding of a species' evolutionary history includes determining the ecological factors that drove its adaptations. All species occupy a particular ecological niche whose breadth is determined by the interplay of abiotic (e.g., climate and dispersal barriers) and biotic (e.g., competition) influences. The niche of a species is rarely static through time and the inevitable changes can result in a variety of outcomes, including further adaptation, speciation and extinction. Although it has historically been difficult to reconstruct the ecological niches of fossil taxa, recently developed paleoecological techniques, mean that it is now possible to test hypotheses about the role of ecology might have played in the separate evolutionary histories of two important early hominin lineages.Determining how our early human ancestors interacted with their environments is fundamental for understanding human evolutionary history. The fossil record suggests that our genus, Homo, originated in eastern Africa around 2.4 million years ago (Ma), and shared the environment with a closely related species called Paranthropus boisei. However, the record also suggests that by approximately 1.3 Ma, the Paranthropus lineage went extinct and Homo had expanded its geographical range outside of Africa. Although these lineages coexisted in time, we lack a logical framework for testing hypotheses related to their ecology during this period. This dissertation project by doctoral student David Patterson (under the supervision of Dr. René Bobe, The George Washington University) will contribute to addressing these gaps in our knowledge by using novel methods to generate the first high-resolution reconstruction of the ecological niches of these two lineages. This project combines quantitative methods from mammalian community ecology with stable isotope geochemistry to investigate the ecological niches of Homo and Paranthropus within a spatially constrained ancient ecosystem. The proposed study will use paleoecological data collected directly from localities where these hominin fossils occur, and from archaeological sites dated to between approximately 2.0 and 1.4 Ma in the Koobi Fora Formation of northern Kenya. By concentrating on specific fossil assemblages within the same region, this study will provide new insights into the ecological niches of these two lineages. The impact of this research will be amplified via the Co-PI's involvement with the Evolution of Terrestrial Ecosystems (ETE) program at the National Museum of Natural History (NMNH) and with the Koobi Fora Field School (KFFS). As part of ETE, the Co-PI will disseminate project results to educators through lectures at sponsored workshops and via the NMNH Q?rius Science Center. Additionally, the Co-PI will create a series of field- and laboratory-based entries for the Paleobiology Department's blogspace. The Co-PI will also participate in "The Scientist is in" program, which will give the public the opportunity to ask researchers about their research, as well as about other topics associated with human origins. Lastly, the Co-PI's fieldwork will be completed in conjunction with the KFFS. This collaborative effort between the National Museums of Kenya and GWU provides students from several countries, including Kenya, Ethiopia, South Africa, and the United States with hands-on field experience in paleoanthropology.