Early evolution of trophic disparity in Pachycormidae (Actinopterygii)

Pachycormidae是硬骨鱼的一个谱系，以巨大的悬浮饲养者的进化而闻名，但也包括小型到中型的鱼类和鱿鱼食用物种。最早记录于欧洲侏罗纪早期，厚皮龙的特征是身体形状，大小和饮食的多样性，分析恢复了两个关键的进化辐射：一个由巨型悬浮饲养者组成的群体，以及一个大型食肉（“牙齿”）血统。该项目旨在研究Pachycormidae进化史早期的物种生成和生态（饮食）多样性。拟议的项目将寻求回答以下问题：是Pachycormidae物种水平多样性的早期爆发伴随着饮食多样性？这个问题将从两个互补的角度来处理。(1)生态学视角（对最早的厚壳类动物饮食差异的详细研究）;（2）进化视角（在明确的进化背景下，牙齿和颌骨形状在很长时间内的多样性）。这两种观点的结合将解决物种多样性和饮食之间的关系，在地质上的短期和长期的时间尺度，以提供一个完善的画面上的规模，其结果适用。Pachycorbae在德国的早侏罗世Posidonienkenefer组的化石记录中首次出现时已经相当多样化。然而，在这些早期形式的饮食分歧是不太好的特点，在最基本的水平，牙齿和颌骨形态和饮食生态之间的关系还没有得到有力的证明。第一个项目目标将是通过比较形状与保存的胃肠道内容物来检验形态与饮食有关的假设。其次，该项目将通过分析形状的多样性来解决牙齿和颌骨形状在地质学上的短时间间隔内如何变化。这将在标本水平执行，以尽量减少种属内与种属间形状和饮食差异的潜在混淆影响。该项目将继续研究解剖学和饮食之间关系的进化意义。要做到这一点，将涉及到一个强大的物种水平的系统发育假说Pachycormidae的生成。这一更详细的系统发育假说将提供一个框架，以分析进化速率和进化分歧的牙齿和颌骨形状随着时间的推移在厚角科。我们的目标是测试是否率的形态演变是最高的早期历史组，并评估是否生态形态分歧遵循类似的爆炸性轨迹或逐渐增加，随着时间的推移。

Pachycormidae is a lineage of bony fishes best known for the evolution of gigantic suspension feeders, but also comprising small- to mid-sized fish- and squid-eating species. First recorded from the Early Jurassic of Europe, pachycormids are characterized by diversity in body shape, size, and diet, with analyses recovering two key evolutionary radiations: a group comprising the giant suspension-feeders, and a macrocarnivorous (‘toothed’) lineage. The proposed project aims to examine the generation of species and ecological (dietary) diversity early in the evolutionary history of Pachycormidae. The proposed project will seek to answer the following question: Is the early burst of species-level diversity in Pachycormidae associated with concomitant dietary diversity? The question will be addressed from two complementary angles. (1) An ecological perspective (a detailed study of dietary divergence in the earliest pachycormids); and (2) an evolutionary perspective (diversity in tooth- and jaw shape over deep time in an explicitly evolutionary context). The combination of these two perspectives will address the relationship between diversity in species and diet over both geologically short and long timescales to give a refined picture of the scale on which the results apply. Pachycormids are already rather diverse by their first appear in the fossil record, in the Early Jurassic Posidonienschiefer Formation of Germany. However, dietary divergence in these early forms is less well-characterized, and at the most basic level, the relationship between tooth- and jaw morphology and dietary ecology has not been robustly demonstrated. The first project objective will be to test the assumption that morphology relates to diet by comparing shape with preserved gastrointestinal contents. Secondly, the project will address how variation in tooth and jaw shape changes over a geologically short interval by analyzing diversity in shape. This will be executed at the specimen level, to minimize potentially confounding influences of shape and dietary variation within species vs. between species. The project will go on to examine the evolutionary implications of the relationship between anatomy and diet. To do so will involve the generation of a robust species-level phylogenetic hypothesis for Pachycormidae. This more detailed phylogenetic hypothesis will provide a framework with which to analyze evolutionary rates and evolutionary divergence in tooth and jaw shape over time in Pachycormidae. The objective is to test whether rates of morphological evolution are highest early in the history of the group, and to assess whether ecomorphological divergence follows a similarly explosive trajectory or increases gradually over time.