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

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"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.