COLLABORATIVE RESEARCH: Graptolite Macroevolution: Phylogenetic Analysis and Testing Hypotheses of Directional Change

“合作研究。笔石宏观演化：系统发育分析与方向变化假说检验”。查尔斯·米切尔和丹尼尔·戈德曼。进化论中最具争议的问题之一是进步的概念。一些科学家主张对主要群体的进化进步有一定的期望，而另一些人则认为，我们应该期待以非进步为主导的进化史。量化进化模式的努力产生了相互矛盾的结果。因此，自然选择是否导致长期进步趋势的问题仍然存在争议和令人沮丧。这项研究的中心目标是确定在一组被称为笔石的化石中是否存在显著的渐进进化趋势。笔石是一组灭绝的海洋生物，它们在大约5.05亿到3.1亿年前繁盛。笔石化石记录提供了一个绝佳的机会来对定向进化进行严格的测试，原因有二。首先，笔石的进化模式长期以来一直被用作渐进进化的教科书范例。其次，笔石的化石记录非常好，它们的时间和生物地理分布已被深入研究。这里提出的工作预计将大大有助于增加对笔石演化机制及其下降途径的理解。人们还预计，这将导致古生物学家用来研究进化模式和过程的方法的改进。人们认为，这两种结果都可能对更广泛的问题产生积极影响，即测试化石记录，以寻找进化过程的证据，以及进化过程可能发生的方式。

"Collaborative Research. Graptolite Macroevolution: Phylogenetic Analysisand Testing Hypotheses of Directional Change".Charles E. Mitchell and Daniel Goldman. One of the most contentious issues in evolutionary theory is the notion of progress. Some scientists have argued for a qualified expectation of progress in the evolution of major groups while others have argued that we should expect evolutionary histories that are dominantly non-progressive. Efforts to quantify evolutionary patterns have produced conflicting results. Thus, the question of whether natural selection leads to long-term progressive trends remains controversial and frustrating. The central goal of the proposed research is to determine if there were significant progressive evolutionary trends within a group of fossils called graptolites. Graptolites are a group of extinct marine organisms that flourished from approximately 505 to 310 million years ago. The graptolite fossil record offers an outstanding opportunity to make a rigorous test of directional evolution for two reasons. First, graptolite evolutionary patterns have long been used as textbook examples of progressive evolution. Secondly, the fossil record of graptolites is exceptionally good, and their temporal and biogeographic distributions have been intensively studied. The work proposed here is expected to contribute substantially to an increased understanding of the mechanisms of graptolite evolution and their pathways of descent. It is also expected that it will lead to improvements in the methods paleobiologists employ to study evolutionary pattern and process. Both of these outcomes are likely, it is thought, to positively effect the broader issue of testing the fossil record for evidence of progress in evolution and the means by which it might occur.