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

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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.