Herkogamy and mating patterns in the self-compatible daffodil Narcissus longispathus

Background and Aims Floral design in self-compatible plants can influence mating patterns. This study investigated Narcissus longispathus, a self-compatible bee-pollinated species with wide variation in anther-stigma separation (herkogamy), to determine the relationship between variation in this floral trait and the relative amounts of cross- and self-fertilization. Methods Anther-stigma separation was measured in the field in six populations of N. longispathus from southeastern Spain. Variation in herkogamy during the life of individual flowers was also quantified. Multilocus out-crossing rates were estimated from plants differing in herkogamy using allozyme markers. Key Results Anther-stigma separation varied considerably among flowers within the six populations studied (range= 1-10 mm). This variation was nearly one order of magnitude larger than the slight, statistically non-significant developmental variation during the lifespan of individual flowers. Estimates of multilocus outcrossing rate for different herkogamy classes (t(m) range = 0.49-0-76) failed to reveal a monotonic increase with increasing herkogamy. Conclusions It is suggested that the lack of a positive relationship between herkogamy and outcrossing rate, a result that has not been previously documented for other species, could be mostly related to details of the foraging behaviour of pollinators.