Outcrossing rates and correlated mating within a population of Eichhornia paniculata (Pontederiaceae)

Abstract

Measurements of mating patterns at the style morph and individual plant level within a population of tristylous Eichhornia paniculata from N.E. Brazil were made using allozyme and style morph marker loci. Application of a model of the mating system that incorporates the correlation of selling and of outcrossed paternal parentage indicated a high level of outcrossing at the population level (t=0·90±0·029). Parameter estimates from the model suggest that progeny from individual plants result from matings to a limited number of male parents. Thirty-two per cent of progeny within fruits were full sibs, compared to 24 per cent between fruits. Style morph segregation patterns in open-pollinated progenies indicated that most matings were between style morphs. Disassortative mating was significantly lower in the mid-styled morph in comparison with the long- and short-styled morphs. Significant variation in outcrossing rate among individuals was detected using two different multilocus procedures. Large statistical error associated with estimates of individual outcrossing rate will complicate attempts to correlate this variation with plant attributes.