Doctoral Dissertation Improvement: The Competitive Environment of the Origination and Early Diversification of Euprimates in North America

由博士生Laura Stroik（亚利桑那州立大学）在加里·施瓦茨博士的监督下进行的这项研究的目标是确定饮食竞争相互作用的模型，该模型是北美始新世真灵长类动物（最早的“真正”灵长类动物）起源和早期多样化的特征。五千五百万年前。研究了三种竞争相互作用的模型：（1）不存在饮食竞争，（2）存在强饮食竞争，导致非优灵长类物种的竞争性排斥，（3）存在弱饮食竞争，导致优灵长类和非优灵长类物种共存。竞争是由生态位重叠定义的，每种假设都可以通过其独特的预测模式来区分物种之间的饮食生态位重叠。化石类群的饮食生态位重建使用臼齿的形态学措施，发现区分饮食制度内的比较样本现存的哺乳动物。在一个单一的网站，大角盆地在怀俄明州的一系列化石样本之间的分离程度重建的生态位的早期优灵长类动物和他们的竞争对手进行了统计评估。竞争环境的检查之前，优灵长类动物的起源，然后在其辐射在北美的初始阶段。观察到的模式的饮食生态位重叠随着时间的推移，连同物种丰度和气候变量，进行比较，每个竞争模型的预期模式。建立饮食竞争的环境中，euprimates的出现，使一个直接的测试的常设假说euprimate起源，证明饮食是否，事实上，早期euprimate进化的主要驱动力。此外，在真正的灵长类动物起源的时候，也出现了与今天类似的气候变暖过程;因此，该项目的结果直接适用于研究全球气候变化对现代动物的影响，特别是那些濒临灭绝的动物。这项研究促进了本科生的培训，这项研究的结果（包括方法技术，定量数据和计算机算法）可以通过在线数据库访问其他研究人员和教育工作者。

The goal of this research by doctoral student Laura Stroik (Arizona State University), working under the supervision of Dr. Gary Schwartz, is to determine the model of dietary competitive interaction that characterized the origination and early diversification of Eocene euprimates (earliest "true" primates) in North America, ca. 55 million years ago. Three models of competitive interaction are examined: (1) absence of dietary competition, (2) presence of strong dietary competition, resulting in the competitive exclusion of non-euprimate species, and (3) presence of weak dietary competition, resulting in the coexistence of euprimate and non-euprimate species. Competition is defined by niche overlap, and each hypothesis is distinguishable by its unique predicted pattern of dietary niche overlap among species through time. Dietary niches of fossil taxa are reconstructed using morphological measures of molar teeth that are found to discriminate dietary regimes within a comparative sample of extant mammals. The degree of separation between reconstructed niches of early euprimates and their competitors is evaluated statistically across a series of fossil samples at a single site, the Bighorn Basin in Wyoming. Competitive environments are examined just prior to the origin of euprimates and then during the initial phase of their radiation within North America. Observed patterns of dietary niche overlap over time, together with species abundance and climatic variables, are compared to the expected patterns of each competition model. Establishing the dietary competitive environment in which euprimates arose enables a direct test of the standing hypotheses of euprimate origins by demonstrating whether diet was, in fact, a primary driver of early euprimate evolution. In addition, climatic warming processes comparable to those seen today were also present during the time when true primates originated; thus, the results of this project are directly applicable to studies of the effects of global climate change on modern animals, particularly those at risk of extinction. This research promotes the training of undergraduate students, and the results of this study (including methodological techniques, quantitative data, and computer algorithms) are accessible to other researchers and educators through an online database.