Herkogamy and mating patterns in the self-compatible daffodil Narcissus longispathus.
OBJECTIVE
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 south-eastern Spain. Variation in herkogamy during the life of individual flowers was also quantified. Multilocus outcrossing rates were estimated from plants differing in herkogamy using allozyme markers.


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.
Medrano
Mónica
M
Estación Biológica de Doñana, Consejo Superior de Investigaciones Científicas, E-41013 Sevilla, Spain. monica@ebd.csic.es
Herrera
Carlos M
CM
Barrett
Spencer C H
SC
D035264:Flowers / Q000033:anatomy & histology*; D014644:Genetic Variation; D007178:Inbreeding; D031427:Narcissus / Q000033:anatomy & histology* / Q000502:physiology*; D012098:Reproduction