PARSIMONY AND THE CHOICE BETWEEN DIFFERENT TRANSFORMATIONS FOR THE SAME CHARACTER SET.

Abstract- When phylogeneticists choose among alternative hypotheses, they choose the one that requires the fewest ad hoc assumptions, i.e. the one that is the most parsimonious. For some systematists, choosing among alternative transformation series for the same set of taxa is equivalent to attaining trees with shorter length and minimal homoplasy. Homoplasy is shown to be composed of hierarchical discordance and scattering, which are recognized and described for the first time. Neither the consistency nor retention indices can be used in assessing different theories of multistate character transformation because both are affected by the shape of the transformation series rather than the character state distribution on a tree. Fits of transformations to a tree are better assessed by comparing the transformation to the cladogram character and the nearest neighbor network. Nearest neighbor networks are graphical representations of the nearest neighbor matrix. Transformations with the closest greatest number of matches between cladogram characters and the least complexity in the nearest neighbor network are preferred. These transformations are shown to make the fewest number of ad hoc statements and hence to be the most parsimonious. A means for obtaining cladogram characters and nearest neighbor matrices using a widely distributed microcomputer program is presented.

CHARACTER DEFINITIONS AND CHARACTER STATE DELINEATION: THE BETE NOIRE OF PHYLOGENETIC INFERENCE.

Abstract- Currently characters are static concepts whose definition and state delineations seldom undergo any scrutiny. Common systematic practice tends to synthesize character slates by combining or dividing observed conditions, a situation most likely due to current theoretical limitations in phylogenetic inference, which tends to ignore problems of multistate characters. This process we refer to as the "synthetic" method for character definition. Character definitions derived for the genera of North American Cochylini (Lepidoptera: Tortricidae) using "synthetic" character states postulated that the cochylines were not monophyletic. The use of cladogram characters and nearest neighbor matrices in uncovering potential flaws in character state delineation is demonstrated. The "synthetic" set of character definitions proved deficient upon such analysis, principally due to its attempt to force highly variable features into a few states. The set of character definitions produced from this analysis is referred to as "reflective" because it does not ignore observed variation. It produces characters with many states and presents problems of setting up transformation series. Three means lor deriving transformations are applied to produce transformation series for the reflective set of character definitions: the unordered outgroup method, morphocline analysis and Transformation Series Analysis (TSA). All three data sets postulated the Cochylini as monophyletic. The three sets of phylogenies were compared. Consensus trees are ambiguous when analysing changes in hierarchy. In order to summarize these results in a manner which does not destroy the phylogenetic structure, positional subtrees, a new means for summarizing multiple solution cladograms, are introduced. It was found that all three sets of transformations produced very different cladograms which in turn were very different from the tree produced by the original, synthetic definitions. The results of each of these methods were assessed for their internal consistency. TSA gave the least contradictory results.

EVOLUTIONARY CHARACTER ANALYSIS: TRACING CHARACTER CHANGE ON A CLADOGRAM.

Abstract- There has been little formal discussion concerning character analysis in cladistics, even though characters and their character state trees are central to phylogenetic analyses. We refer to this field as Evolutionary Character Analysis. This paper defines the components of evolutionary character analysis: character state trees, transmodal characters, cladogram characters, attribute and character phylogenies; and the use of these components in phylogenetic inference and evolutionary studies. Character state trees and their effect on cladogram construction are discussed. A new method for numerically coding complex character state trees is described that further reduces the number of variables required to describe them. This method, ordinal coding, reduces the size of data matrices, and facilitates retrieval of state codes. This paper advocates the use of both biological evidence and evidence internal to the cladogram itself to construct character state trees (CSTs). We discuss general models of character evolution (morphocline analysis, Fitch minimum mutation model, etc.) and their role in forming CSTs. Character state trees formed with theories of character evolution are referred to as transmodal characters. These transmodal characters are contrasted with cladogram characters (Mickevich, 1982), and the place of each in a phylogenetic analysis is discussed. The method for determining cladogram characters is detailed with more complicated examples than found in previous publications. We advocate testing transmodal characters by comparing them with the resultant cladogram characters. This comparison involves transformation series analysis (TSA; Mickevich, 1982) which is viewed as an extension of reciprocal illumination. The TSA procedure and its place in hypothesis testing are reviewed. Tracing the evolution of characters interests both systematists and non-systematists alike. When character state trees (transmodal characters) are optimized on pre-existing phylogenies, character phylogenies and attribute phylogenies result. Attributes are defined as a feature that may or may not be homologous (i.e., ecological categories, plant hosts, etc.). We provide two illustrations of this approach, one involving the evolution of the anuran ear and another involving the coevolution of the butterfly Heliconius and its hostplants. Finally, the components of phylogenetic character analysis can be used to test more general evolutionary theories such as the biogenetic law and vicariance biogeography.

On the Information Content of Classifications.

Abstract- The best fit estimate of the retrospective information content of a classification is argued to be the proportion of the maximal sum of informative subgroups to which each included taxon is assigned. The best fit estimate of the prospective information content of a classification is argued to be the proportion of fully resolved dadograms prohibited by that classification. Those (wo proportions are multiplied to provide a general information index that is sensitive to both the degree of resolution and the contents of individual subgroups. That index and the best fit considerations supporting it have implications for congruence studies, consensus indices, and the choice between Adams and Nelson consensus trees.