Genetic variation in a continuously breeding population of Danaus plexippus L. (Lepidoptera: Nymphalidae)

Abstract

Variation at 4 genetic loci (Pgm; Me; Idh; Hbdh) was studied in a population of monarchs (Danaus plexippus L.) not subject to migration to overwintering sites. Adult insects were sampled from 18 milkweed patches in 5 widely spaced locations in south-east Queensland (Australia). Genetic differentiation between sub-populations (patches) was high (FST= 0·032). For 2 loci (Me and Idh) both males and females showed significant differentiation between patches. Idh showed a significant cline with latitude in males only and Me showed no apparent geographic pattern in either sex. Both loci showed significant differences in gene frequencies between sexes. Possible mechanisms for maintaining these differences are discussed. © 1984, The Genetical Society of Great Britain.