Testing the ‘assortative mating’ hypothesis on a variation maintenance mechanism for flowering time within a forest‐floor population of Primula sieboldii

Abstract

AbstractFlowering phenology and allozyme variation were studied to test the existence of positive assortative mating for flowering time in a natural population of Primula sieboldii E. Morren, a heterostylous perennial herb, consisting of approximately 180 genets in a deciduous forest. There was significant variation in flowering date among genets, but not between heterostylous morphs. The temporal order of the flowering time of genets was fairly constant for the two years of the study. The spatial heterogeneity of light availability at the study site was small during the flowering season of the species. In order to analyze the extent of genetic differentiation between early‐ and late‐flowering genet groups, allozyme diversities were analyzed with 10 loci. The GST between the early‐ and late‐flowering groups was not significantly different from zero. Evidence of positive assortative mating for flowering time was not detected. Prolongation of flowering duration due to pollen limitation may be one important factor preventing the genetic differentiation of early‐ and late‐flowering groups by enhancing the overlap of flowering time among genets.