Allozyme variation in the butterfly, Maniola jurtina (Lepidoptera: Satyrinae) (L.): evidence for selection

Abstract

This paper describes patterns of allozyme variation in the butterfly, Maniola jurtina (L.). Twelve loci, of which four were polymorphic (PGM, PGI, IDH-1 and IDH-2), were screened across 14 populations in south-east England. The patterns described are not in agreement with expectation for a sedentary butterfly in which alleles are neutral to selection, for geographically distant populations differed very little in gene frequencies. Geographic homogeneity is compatible with either a higher degree of vagility than expected for this species or similar selection pressures maintaining allele frequencies across the area sampled. Associations between patterns of variation at two loci and behavioural, morphological and environmental variables suggested that selection may be acting upon them. In particular, the genotype at the locus for PGM affected the length of time for which individual butterflies could fly continuously, while PGM allozyme frequencies varied according to the altitude of the site. The frequency of allozymes at IDH-2 was correlated with the mean size of individuals in both sexes when comparing sites. Possible causes of these associations are discussed. I conclude that patterns of variation in the loci studied are probably not good estimators of population structuring, but are more likely to be the result of selection.