Evolution of Marine Mammal Foraging Behavior Based on Ca and C Isotope Ratios in Bioapatite

基于生物磷灰石中 Ca 和 C 同位素比率的海洋哺乳动物觅食行为的演变

• 批准号: 0519052
• 负责人: David Fox
• 金额: --
• 依托单位: University of Minnesota-Twin Cities
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-10-01 至 2008-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0519052&HistoricalAwards=false
• 关键词: Evolution; Marine; Mammal; Foraging; Behavior

Though the trophic structure of marine ecosystems is known to haveincreased in complexity over time, methods of quantifying this change are lacking. The proposedresearch will expand upon promising preliminary work using Ca isotope ratios as paleoecologicalindicators and develop this isotopic system as a proxy for the trophic level of extinct marine mammals.By combining Ca isotope analyses with C isotope ratios, which vary with foraging habitat in marineecosystems, this project will provide a new means to examine the structure of ancient marine vertebrateecosystems. Since the trophic structure of foodwebs has a significant influence on the pathways by whichnutrients and energy move within and between ecosystems, analysis of the Ca isotope composition ofbiogenic hard parts may aid in elucidating how nutrient cycling and energy flow have fluctuated overtime. Furthermore, by expanding current knowledge of how ancient ecosystems functioned and how theydiffered from today s ecosystems, a44Ca measurements can help improve interpretations of how climaticand environmental perturbations have impacted or were impacted by the Earth s biosphere. Ultimately,this project will provide new insight into the evolution of whales, whose from a terrestrial ancestorrepresents one of the most remarkable transitions in the history of life on Earth.Although the ultimate objective of this research is to understand the role of temporal changes inforaging behavior in the evolution of Cetacea (the clade that includes living whales, porpoises, anddolphins), the influence on Ca isotope ratios of factors other than trophic level must be examined first inmodern species before Ca isotope ratios can be applied to extinct species. Samples of marine mammals infour, distantly related groups (sirenians, mustellids, cetaceans, and pinnipeds) will be analyzed as a meansof addressing the impact of phylogenetic history on a44Ca values; the degree of similarity of a44Ca valuesfor species at the same trophic level will verify whether a44Ca values reflect trophic level differencesregardless of evolutionary history. The C isotope composition of each sample will be analyzed as a proxyfor foraging habitat preference; a stronger correlation between a44Ca with trophic level rather than a13Cvalues will indicate that trophic level has a stronger influence on a44Ca values than the foraging habits ofa species. Variation in a44Ca within a single individual will be explored by analyzing the Ca isotopecomposition of multiple skeletal elements from a single individual from each of the four modern groupsof marine mammals sampled. Once the factors influencing a44Ca values in modern marine mammalshave been constrained, the Ca and C isotope composition of Eocene and Oligocene cetacean and sirenianbioapatite will be analyzed to assess the potential of this proxy for paleoecological studies. Thediversification of cetacean feeding strategies in the Oligocene should coincide with a large change ina44Ca and a13C values of cetacean bioapatite, providing a clear signal of whether original a44Ca values canbe preserved and interpreted from the fossil record. Fossil bones of sirenians will also be analyzed as acontrol for potential changes in seawater a44Ca values, since the trophic level of this group has remainedconstant over time and any changes in the a44Ca values of this group will reflect changes in seawatera44Ca values.Broader impacts. The broader impacts of this project are threefold. First, the grant will furtherthe training and development of a recent Ph.D. who will be supported as a postdoc. Under thesupervision of the PIs, this researcher will have primary responsibility for refining the methodologies,acquiring and analyzing the samples, and interpreting and disseminating the results. Second, the researchwill provide a new and potentially powerful paleoecological tool to the broader community that can beapplied to other ancient marine ecosystems and, after further development, may also have applications interrestrial ecosystems. Finally, the results will complement our increasingly detailed knowledge of whaleevolution. Once the proposed research is completed, the ecological and morphological changesassociated with the evolution of whales will be one of the best documented cases of macroevolutionarychange in the vertebrate fossil record. Given the historical place of whale origins in anti-evolutionpolemics, this research will surely have lasting impact in undergraduate and K-12 class rooms.

虽然海洋生态系统的营养结构随着时间的推移而变得越来越复杂，但缺乏量化这种变化的方法。本研究将在Ca同位素比值作为古生态学指标的基础上，进一步发展Ca同位素比值作为已灭绝海洋哺乳动物营养水平的代用指标，并将Ca同位素分析与C同位素比值结合起来，为研究古海洋脊椎动物生态系统的结构提供新的手段。由于食物网的营养结构对营养物质和能量在生态系统内和生态系统之间移动的途径有着重要的影响，因此分析生物硬部的钙同位素组成可能有助于阐明营养物质循环和能量流动如何随时间波动。此外，通过扩大对古代生态系统如何运作以及它们与今天生态系统如何不同的现有知识，44 Ca测量可以帮助改善对气候和环境扰动如何影响地球生物圈的解释。最终，该项目将为鲸鱼的进化提供新的见解，鲸鱼从陆地祖先进化代表了地球生命史上最显着的转变之一。尽管这项研究的最终目标是了解鲸类进化中觅食行为的时间变化的作用。（包括活鲸、鼠海豚和海豚的进化支），在Ca同位素比值可以应用于现代物种之前，必须首先检查营养级以外的因素对Ca同位素比值的影响。灭绝的物种将分析四个远亲类群（海牛、鼬、鲸类和鳍足类）的海洋哺乳动物样本，作为解决系统发育历史对α 44 Ca值影响的一种手段;在同一营养级的物种的α 44 Ca值的相似程度将验证α 44 Ca值是否反映营养级差异，而不管进化历史如何。每个样品的C同位素组成将被分析作为觅食生境偏好的代理; a 44 Ca与营养级之间的相关性比a 13 C值更强，这表明营养级对a 44 Ca值的影响比物种的觅食习性更强。通过分析现代海洋哺乳动物四个类群中每一个个体的多种骨骼元素的Ca同位素组成，探讨单个个体中α 44 Ca的变化。在限制了现代海洋哺乳动物a ~（44）Ca值的影响因素后，我们将分析始新世和渐新世鲸类和海牛类生物磷灰石的Ca和C同位素组成，以评估这一代用指标在古生态学研究中的潜力。鲸目动物在渐新世摄食策略的多样化应该与鲸目动物生物磷灰石的a44 Ca和a13 C值的巨大变化相一致，这为原始a44 Ca值是否可以保存和从化石记录中解释提供了明确的信号。海妖的化石骨骼也将作为海水中α 44 Ca值潜在变化的对照进行分析，因为这一群体的营养水平随着时间的推移而保持不变，这一群体的α 44 Ca值的任何变化都将反映海水中α 44 Ca值的变化。该项目的广泛影响有三个方面。首先，这笔赠款将进一步培训和发展最近的博士学位。他将获得博士后的资助在PI的愿景下，该研究员将主要负责改进方法，获取和分析样本，以及解释和传播结果。第二，这项研究将为更广泛的社区提供一个新的和潜在的强大的古生态学工具，可以应用于其他古老的海洋生态系统，并在进一步发展后，也可能应用于陆地生态系统。最后，这些结果将补充我们对鲸鱼进化越来越详细的知识。一旦拟议中的研究完成，与鲸鱼进化相关的生态和形态变化将成为脊椎动物化石记录中宏观进化变化的最佳记录案例之一。鉴于鲸鱼起源在反进化论论战中的历史地位，这项研究肯定会对本科生和K-12教室产生持久的影响。