CYTONUCLEAR DISEQUILIBRIA IN HYBRID ZONES

Cytonuclear disequilibria provide a new array of conceptual tools for the analysis of hybrid zone data. By measuring the associations of cytoplasmic genes with nuclear genes and genotypes within a hybrid zone, cytonuclear disequilibria provide fresh insights into: (i) levels of gene flow; (ii) age of reproductive barriers, (iii) directionality of crosses between hybridizing taxa; (iv) levels of assortative mating; (v) and mechanisms of selection on hybrids. The application of these cytonuclear disequilibria are illustrated in several hybrid zone studies.