Convergent evolution of flower polymorphism in Narcissus (Amaryllidaceae)

We present new results on morphological variation for style polymorphism and perianth features in the seven species of Narcissus sect. Apodanthi and in N. pallidulus (sect. Cyclaminei), which exhibits a wide array of flower conditions: heterostyly, style dimorphism of variable reciprocity, and style monomorphism. There is a significant association between perianth morphology and style polymorphism in the studied species. Among significant flower features, the two heterostylous species show pendulous flowers. Most style-dimorphic species have patent flowers, whereas monomorphic and one style-dimorphic species display erect flowers. Interpretation of a chloroplast (trnL-trnF) phylogeny of species representing most sections in the genus leads us to conclude that the two heterostylous species have independent origins, supporting previous hypothesis of convergence of heterostyly in Narcissus. Remarkable resemblance of flower features between both species indicates that pollinator activity might have driven flower convergence. A second chloroplast (trnT-trnL) phylogeny in sect. Apodanthi helps elucidate some evolutionary transitions in moulding heterostyly. Stylar dimorphism appears to precede distyly and style monomorphism. Population studies on style dimorphic and monomorphic species of Narcissus are congruent with a pollinator-mediated process also involved in a shift to monomorphism.