Inferring the patterns and causes of geographic variation in Ephippiger ephippiger (Orthoptera, Tettigoniidae) using geographical information systems (GIS)

Abstract

Ephippiger ephippiger is a tettigoniid cricket that is fairly widespread in Europe. In southern France, between the Alps and the Pyrenees, it is geographically highly variable for a number of different traits including morphology, allozymes, behaviour and genetic markers. This variation has resulted in considerable confusion over the taxonomic and evolutionary status of forms of the organism. Through the use of geographical information systems (GIS) it has been possible to integrate both trait and environmental data sets from a variety of sources. The GIS is used to interpolate trait and environmental surfaces that are then examined for coincidence. Four general spatial patterns are identified. These can be explained through a combination of secondary contact, environmental adaptation and drift. Covariance between trait and environmental surfaces point to patterns which are primary in origin, whereas other clines probably reflect secondary contact following divergence in refugiae. Multivariate statistics support the validity of a major subdivision identified by GIS. This study is an example of the considerable potential for GIS as an investigative tool in evolutionary studies. (C) 2000 The Linnean Society of London.