Endemic butterflies of the Western Palaearctic: distribution patterns, and their analysis based on parsimony (Lepidoptera, Papilionoidea)

Abstract

The geographic distributions of the butterflies endemic to the Western Palaearctic are used to classify operative area units based on an index of association, and on parsimony analyses, and these results are compared. It is shown that the PAE-PCE method proposed by García-Barros et al. (2002) does not warrant detection of all subsets of area units characterised by endemic elements with identic distributions. However, satisfactory results can be achieved if Wager parsimony is subtituted by a method of cladogram construction that proscibes homoplasy, such as compatibility. When used as a classification procedure, the results of parsimony analysis can be broadly consistent with those derived from other procedures of hyerarchical classification. A distinction should be made between two different usages of parsimony, both of which represent ‘static’ (sensu Rosen, 1988) interpretations of area cladograms: PAE in a strict sense, aimed at detecting putative areas of endemicity. These are potentially overlapping entities, and hence the method may imply potentially multiple solutions. And, cladistic procedures applied as an agglomerative method (ideally with a single, most parsimonious solution). As far as the butterfly faunas are concered, the highest concentration of endemisms occur across the western circum-mediterranean mountain chains, and in the largest Mediterranean islands. The Iberian Peninsula is featured not just by a high concentration of endemic butterflies, but also by the coexistence of several distinc areas of endemism. Broad patterns derived from the endemic fauna fit well to those based on the whole butterfly fauna.