Format: ORAL

Tom Wells 1,2

1. Herbarium, Royal Botanic Gardens, Kew, UK 2. Biology Department, University of Oxford, UK

The rise of molecular phylogenetics and integrative taxonomy have led to a sense that disagreements about the fundamental nature of the species category are no longer an issue in contemporary systematics. The implicit consensus is that increases in the volume, type, and precision of data and methods available to contemporary researchers will automatically lead to more accurate and consistent species delimitations, without the need for a widely accepted definition of what species are and how they should be identified and used in biological research. The chief challenge to this triumphalist view of integrative taxonomy remains the heterogenous nature of speciation. Since speciation proceeds over extended periods of time and through different processes, it results in the inconsistent manifestation of different contingent properties for its recognition, depending on the taxa in question. Simply combining multiple forms of data or methods under an integrative approach cannot automatically overcome this fundamental obstacle because of the continued lack of an overarching theoretical framework for species delimitation and how to treat incongruence between different types of Systematic data. Deciding what properties to assess, how to do so, and which to prioritise in the event of incongruence remains an unresolved issue, requiring a theoretical framework within which to make those decisions. In this talk, I explore how treating species as a heuristic can provide the basis of just such a framework. Species delimitation inherently involves the use of heuristics through the study of representative specimens, the use of selected diagnostic characters, and strategic sampling of tree space. Meanwhile, species themselves are routinely used in a heuristic manner to investigate broader patterns of biodiversity and the processes underpinning them. Acknowledging these aspects of systematic resarch can therefore inform both operational ways of accurately and consistently delimiting species, and theoretical ideas about their nature.