ELT Collaborative research: Evolutionary and ecological responses of small mammal communities to habitat and climate change over the last 5 million years

ELT 合作研究：过去 500 万年小型哺乳动物群落对栖息地和气候变化的进化和生态反应

• 批准号: 1338243
• 负责人: Pratigya Polissar
• 金额: $ 11.02万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-08-15 至 2017-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1338243&HistoricalAwards=false
• 关键词: ELT; Collaborative; research; Evolutionary; ecological

Technical description: The goal of this project is to test three models of faunal change in response to biotic and abiotic forcings during the transition to the modern grassland ecosystem in the Great Plains over the last 4.5 My: the Red Queen, the Court Jester, and the Equilibrium Theory of Island Biogeography. In doing so, we will answer four specific research questions: 1) Do long-term changes in local habitat or climate control taxonomic diversity dynamics? 2) Does climate change associated with the onset of Northern Hemisphere glaciation at 2.5 Ma impact diversity dynamics or the ecological structure of communities? 3) How do catastrophic events (major ashfalls) impact diversity dynamics and ecological structure of communities? 4) How are immigrant species accommodated in the ecological structure of the contemporary community? We will analyze diversity dynamics with an existing database of species occurrences in the Meade Basin, SW Kansas in relation to reconstructions of local paleoecology, paleoenvironment, and paleoclimate. We will characterize ecological structure of communities with body sizes estimated from tooth dimensions and trophic categories reconstructed from carbon isotope compositions of tooth enamel using laser ablation isotope ratio mass spectrometry and a novel combination of morphometric analyses based on high resolution microCT scans. Interpretation of paleodiet proxies will be constrained by isotopic and morphometric analyses of modern species with known diets and habitats from existing museum collections and live trapping in grasslands around Meade, KS. Paleoenvironmental and paleoclimatic reconstructions will be based on a comprehensive suite of proxies measured on paleosol carbonates and bulk sediment samples collected in stratigraphic association with known fossil sites and major ashfalls: carbon isotope ratios of bulk organic matter, carbon and hydrogen isotope ratios of leaf wax n-alkanes, lignin phenol ratios, plant phytolith assemblages, carbonate clumped isotope paleothermometry, and paleosol elemental geochemistry and mineralogy. Paleoclimate proxies and isotopic data will be compared to output of regional scale, isotope-enabled paleoclimate simulations under various forcings. Finally, we will construct ecological niche models for modern mammal species and genera in the region and use paleoclimate model output to test how climate change may have forced range shifts and taxonomic turnover in the Meade record.Non-technical description: Understanding the origin of modern communities is a fundamental goal of ecology, but reconstructing the history of communities that include species with stratigraphic durations on the scale of hundreds of thousands to millions of years necessarily requires data from the fossil record. Similarly, inferences about the paleoecology of past communities are most robust when informed by data from both living and fossil populations of extant species. Despite the logical connections between ecology and paleoecology, relatively few studies have bridged the gaps in the characteristic observational timescales and methodologies of these disciplines to achieve a comprehensive view of the long-term evolution of specific modern communities. The need to bridge these disciplinary gaps is increasingly pressing in the face of anthropogenic climate change and uncertainty about the magnitude and direction of responses by local communities. This project will examine the ecological, environmental, and climatic context of the origin of the modern small mammal community in the grasslands of the central USA over the last five million years. We will test the effects of both biological and non-biological factors on long-term taxonomic turnover and ecological change in a stratigraphic sequence of local communities using a combination of ecomorphology, biogeochemistry, paleoclimate modeling, and biogeography. This project will link evolution, ecology, and paleoecology with biogeochemistry to trace the emergence of a modern ecosystem over geological time.

技术描述：该项目的目标是测试过去 4.5 年大平原向现代草原生态系统过渡过程中响应生物和非生物强迫的动物区系变化的三种模型：红皇后、宫廷小丑和岛屿生物地理学的平衡理论。在此过程中，我们将回答四个具体的研究问题：1）当地栖息地或气候的长期变化是否会控制分类多样性动态？ 2) 与北半球 2.5 Ma 冰川期爆发相关的气候变化是否会影响多样性动态或群落的生态结构？ 3）灾难性事件（重大火山灰）如何影响群落的多样性动态和生态结构？ 4) 移民物种如何适应当代社区的生态结构？我们将利用堪萨斯州西南部米德盆地现有的物种发生数据库分析多样性动态，并重建当地古生态、古环境和古气候。 我们将使用激光烧蚀同位素比质谱法和基于高分辨率显微 CT 扫描的形态测量分析的新颖组合来表征群落的生态结构，其体型大小根据牙齿尺寸估计，营养类别根据牙釉质碳同位素成分重建。对古饮食指标的解释将受到对现代物种的同位素和形态分析的限制，这些现代物种的饮食和栖息地来自现有博物馆藏品以及堪萨斯州米德周围草原上的活体诱捕。古环境和古气候重建将基于对古土壤碳酸盐和在与已知化石地点和主要灰烬的地层关联中收集的大量沉积物样品测量的一套全面的代理：大量有机物的碳同位素比，叶蜡的碳和氢同位素比-烷烃、木质素酚比率、植物植硅体组合、碳酸盐簇同位素古测温法和古土壤元素地球化学和矿物学。古气候代理和同位素数据将与区域规模、同位素在各种强迫下的古气候模拟的输出进行比较。最后，我们将为该地区的现代哺乳动物物种和属构建生态位模型，并使用古气候模型输出来测试气候变化如何迫使米德记录中的范围变化和分类更替。非技术描述：了解现代哺乳动物的起源群落是生态学的一个基本目标，但是重建群落的历史，包括地层持续时间达数十万至数百万年的物种，必然需要来自化石记录的数据。同样，根据现存物种的现存种群和化石种群的数据，对过去群落的古生态学的推论最为有力。尽管生态学和古生态学之间存在逻辑联系，但很少有研究能够弥合这些学科的特征观测时间尺度和方法论之间的差距，以全面了解特定现代社区的长期演化。 面对人为气候变化以及当地社区应对措施的幅度和方向的不确定性，弥合这些学科差距的需求变得越来越紧迫。该项目将研究过去五百万年来美国中部草原现代小型哺乳动物群落起源的生态、环境和气候背景。我们将结合生态形态学、生物地球化学、古气候模型和生物地理学，测试生物和非生物因素对当地群落地层序列的长期分类更替和生态变化的影响。该项目将进化、生态学、古生态学与生物地球化学联系起来，追踪现代生态系统在地质时期的出现。