THE EFFECT OF ANT ASSOCIATION ON THE POPULATION-GENETICS OF THE AUSTRALIAN BUTTERFLY JALMENUS-EVAGORAS (LEPIDOPTERA, LYCAENIDAE)

Populations of the myrmecophilous lycaenid Falmenus evagoras Donovan w ere assessed for genetic structure at three hierarchical spatial scale s: sites, geographically-defined subpopulations, and subpopulations de fined by species of mutualistic ant-associate. Estimates of Wright's F -ST generated from multilocus electrophoretic data revealed low, thoug h significant, amounts of genetic structure. Most structure was observ ed at the level of geographic subpopulations, suggesting that adult bu tterflies do not exhibit preferential mating and oviposition along the lines of ant associate. The genetic structure data, together with est imates of Nei's genetic distance (D) for pairwise site and subpopulati on comparisons, suggest that F. evagoras populations are spatially and temporally dynamic. These patterns are considered in the context of e xtinction and recolonization models. The extreme patchiness of F. evag oras populations stems from the stringent requirements of both host pl ant and host ant, contributing to an extinction/ recolonization proces s. We discuss the key parameters influencing genetic cohesion versus d ifferentiation under an extinction/recolonization regime, including mo de of butterfly dispersal, site turnover rate, and the effects of host dispersal and phenology. This system provides a model of population-l evel consequences of certain mutualistic interactions as well as of a class of patterns arising from an extinction/recolonization process. ( C) 1996 The Linnean Society of London