Collaborative Research: Examining Origination, Extinction, and Recovery in Terebratulide Brachiopods: The Integration of Phylogeny, Morphometrics, and Biogeography

大规模灭绝，或物种死亡率急剧增加的事件，一再扰乱地球上现存的生命多样性。虽然对这种扰动对分类多样性的总体影响有一个很好的想法，但对于这些扰动的其他几个维度，比如灭绝和存活的分类群之间的谱系关系和大小和形状的变化范围，以及分类群在空间(古生物地理学)和时间(地层学)上的分布，都有相对较差的想法。PIS建议详细研究海洋无脊椎动物的一个分支(共享同一共同祖先的有机体)，腕足目Terebratulida，在大约2亿年的时间里，该分支经历并从四个不同的大灭绝时期反弹：埃米西亚末期、弗拉斯期末、维西期末和二叠纪末。PIS研究将重建Terebratulide进化史的三个组成部分，并解释它们与大灭绝事件中的灭绝或生存的关系。早期Terebratulide属(下泥盆世至三叠纪)之间的系统发育关系将主要用基于简约的系统发育推断方法重建。将使用几何坐标和基于轮廓的方法来计算和评估这些大规模灭绝事件前后的Terebratulide的定量形态特征。随着时间的推移，伴随着这些形态、系统发育和分类学变化的全球古生物地理模式将在汇编了主要文献中的分布数据后进行研究。综合PI三部分研究的结果，有可能检验一个耐人寻味但相对未经检验的假设，即大规模灭绝是宏观进化的动因--灭绝生存的选择能否在物种或支系层面上运作，而不是简单地在个体或种群上运作？

Mass extinctions, or episodes of dramatically increased species mortality, have repeatedly perturbed the standing diversity of life on Earth. Although there is a good idea of the general effect such perturbations have had on taxonomic diversity, there are relatively poor ideas of several other dimensions of these perturbations, such as the genealogical relationships and the range of variation in size and shape among taxa going extinct and those surviving, as well as taxon distribution in space (paleobiogeographic) and time (stratigraphic). PIs propose to investigate in detail one clade (organisms sharing a single common ancestor) of marine invertebrates, the brachiopod order Terebratulida, over a period of roughly 200 million years during which the clade experiences and rebounds from four distinct mass extinction episodes: end-Emsian, end-Frasnian, end-Visean, and end-Permian. PIs research will reconstruct three components of terebratulide evolutionary history, and interpret them in relation to extinction or survival at mass-extinction events. Phylogenetic relationships among early terebratulide genera (Lower Devonian through Triassic periods) will be reconstructed using primarily parsimony-based methods of phylogenetic inference. Quantitative morphometric characteristics of terebratulides before and after these mass-extinction events will be calculated and evaluated using geometric-coordinate and outline-based methods. Global paleobiogeographic patterns that accompany these changes in morphology, phylogeny, and taxonomy through time will be studied after compiling distributional data from the primary literature. Integrating the results of PIs three-part study has the potential to test the intriguing but relatively untested hypothesis that mass extinctions act as agents of macroevolution - can selection for extinction survival operate at the level of species or clades, rather than simply on individuals or populations?