Genetic consequences of outcrossing in the cleistogamous annual, Impatiens capensis. III. Interlocus associations

Abstract

Electrophoresis was used to examine levels of association between alleles at different variable loci within eight natural populations of the annual plant, Impatiens capensis. This species produces both obligately self-fertilizing cleistogamous (CL) and strongly protandrous chasmogamous (CH) flowers. Values of gametic (Dij) and composite (∆ij) disequilibrium estimated for all pairs of covarying loci revealed significant levels of disequilibrium in most of the populations. A bootstrap technique was used to obtain weighted means and standard errors of normalized disequilibrium estimates and these were compared among populations and groups. Mean composite disequilibrium (∆′) spanned a remarkable range among populations (0·09–1·0, mean = 0·43), as did fixation indexes (f), but these were only weakly correlated with each other (r = 0·50). Levels of disequilibrium in the CL and CH progeny generally resembled those found in their maternal parents, but values for the CH group were more variable. A reduction in disequilibrium was sometimes associated with outcrossing, but it is unlikely that selection to reduce disequilibrium favours outcrossing in this species. © 1989, The Genetical Society of Great Britain.