The linguistic problem of morphology: structure versus homology and the standardization of morphological data

Abstract

The present article discusses the need for standardization in morphology in order to increase comparability and communicability of morphological data. We analyse why only morphological descriptions and not character matrices represent morphological data and why morphological terminology must be free of homology assumptions. We discuss why images only support and substantiate data but are not data themselves. By comparing morphological traits and DNA sequence data we reveal fundamental conceptual shortcomings of the former that result from their high average degree of individuality. We argue that the delimitation of morphological units, of datum units, and of evidence units must be distinguished, each of which involves its own specific problems. We conclude that morphology suffers from the linguistic problem of morphology that results from the lack of (i) a commonly accepted standardized morphological terminology, (ii) a commonly accepted standardized and formalized method of description, and (iii) a rationale for the delimitation of morphological traits. Although this is not problematic for standardizing metadata, it hinders standardizing morphological data. We provide the foundation for a solution to the linguistic problem of morphology, which is based on a morphological structure concept. We argue that this structure concept can be represented with knowledge representation languages such as the resource description framework (RDF) and that it can be applied for morphological descriptions. We conclude with a discussion of how online databases can improve morphological data documentation and how a controlled and formalized morphological vocabulary, i.e. a morphological RDF ontology, if it is based on a structure concept, can provide a possible solution to the linguistic problem of morphology.Ó The Willi Hennig Society 2009.Due to the fact that biology has to deal with a continuum of highly complex forms and structures, in which usually no two organisms are completely identical, the comparative approach takes a central role in biological methodology. Although the comparative approach originated in morphology and classification, today it is used in various biological disciplines, among others for the inference of function of very similar structures, thereby saving resources associated with expensive and time-consuming experiments. The comparative approach thus represents one of the most important approaches in biological research. Comparison requires data to be comparable. Moreover, in order to allow the sharing of data and the cooperation of biologists (collective empiricism), data must also be communicable. Communicability of data represents an indication of its objectivity-if a specific observation relies less on the particular scientist who described it than another observation, it is considered to be more objective (aperspectival objectivity sensu Daston, 1992Daston, , 1998Daston and Galison, 1992; procedural objectivity sensu Heintz, 2000).In order to guarantee comparability and communicability of data, each...

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