Parsimony Trees, Best-Fit Fences, and Consensus Sequences: Integrating Cladistics and Biostratigraphy at High Resolution

9980372sadler树形图概括了物种或高级分类群之间的进化关系。在树枝的顶端有物种标签，树的其余部分描绘了祖先。计算机算法更倾向于树中的分支模式，这种模式最简单地解释了物种之间的大量形态和生化比较。相似性可能是从一个共同的祖先那里遗传下来的，或者它们可能代表着不太密切相关的分类群之间的外观趋同——这使搜索变得复杂。不同地点地层间的时间相关性用栅栏状图表示。每个地方的地层序列都画在自己的栅栏柱上，“钢丝线”将同一年代的地平线从一个地方连接到另一个地方。许多线代表了一个化石分类群的起源时间。由于化石的保存和收集不完善，各地在起源顺序的细节上往往相互矛盾。计算机算法搜索最能解决这些矛盾的围栏。寻找最好的篱笆和树通常会找到不止一个同样好的解决方案。搜查使用不同的证据；但是树木和篱笆都包含了关于形态特征出现顺序的推论。该项目将开发将两种搜索程序结合起来的方法，以便每一种程序都可以帮助减少另一种程序找到的同样好的解决方案的范围。

9980372SadlerTree-shaped diagrams summarize evolutionary relationships between species or higher taxa. With species labels at the tips of branches, the rest of the tree depicts ancestry. Computer algorithms much for a branching pattern in the tree that most simply explains a large array of morphological and biochemical comparisons between the species. Similarities may be inherited from a common ancestor, or they may represent convergence of appearance between less closely related taxa - this complicates the search.Time correlations between strata at different localities are represented by fence-like diagrams. With the sequence of strata at each locality drawn on its own fence post, "wire lines' connect horizons of the same age from locality to locality. Many of the wire lines represent the time of origination of a fossil taxon. Because of imperfect preservation and collection of fossils, the localities tend to contradict one another in detail concerning the order of originations. Computer algorithms search for the fence that best resolves these contradictions.Searches for the best fences and trees typically find more than one equally good solution. The searches use different evidence; but trees and fences both include inferences about the order of appearance of morphological traits. This project will develop ways to combine the two search procedures so that each can help reduce the range of equally good solutions found by the other.