UNCERTAIN BRANCH LENGTHS, TAXONOMIC SAMPLING ERROR, AND THE EGG TO BODY-SIZE ALLOMETRY IN TEMPERATE BUTTERFLIES (LEPIDOPTERA)

The allometry of egg to body size in temperate butterflies, and the re lationships between egg size and lan al host structure, taxonomy, volt inism, and duration of the egg stage, are investigated using cross-spe cies analysis and the comparative analysis of independent contrasts. I n addition, the effect of two sources of uncertainty that may affect c ontinuous data when treated under a statistical, comparative, framewor k, is assessed: (1) unknown evolutionary distances, and (2) taxonomic representativity (proportion of species of a given taxon, from which d ata are available). It is suggested that the effects of taxonomic unde r-representation could be important in comparative, quantitative studi es, but this problem may be tempered by means of weighted regression. Under the assumption that taxonomy represents butterfly phylogeny, egg and adult body size are related by negative allometry (i.e. the slope of the line fitted to the logarithmically transformed data is lower t han 1.0). However, the precise slope (0.2-0.9) depends on the method u sed, branch lengths, and taxonomic sampling. There is evidence for a r elationship between a species' voltinism and the number of days it spe nds in the egg stage, as well as between adult butterfly size and the gross structure of the plants used as larval hosts (woody plants or he rbs). Egg size proves to be related to foodplant taxonomy, voltinism, and duration of the egg stage when the data are analysed using species means, but these relationships become non-significant when the compar ative method is employed. (C) 1997 The Linnean Society of London.