Outcrossing rates of a natural population of Cryptocarya moschata Nees (Lauraceae)

Abstract

The mating system of the canopy Brazilian Atlantic rain forest tree Cryptocarya moschata was studied at Parque Estadual Carlos Botelho, São Miguel Arcanjo, São Paulo, Brazil. Outcrossing rates were determined through electrophoretic allozyme markers from seedlings germinated of seed cohorts collected from 35 trees. An indirect estimate of the outcrossing rate at equilibrium gave a mean of t^eq = 0.51. Direct single locus and multilocus outcrossing rate estimates were t^s = 0.725 ± 0.041 and t^m = 0.884 ± 0.034, respectively, indicating a predominant outcrossing mating system. Individual trees outcrossing rates ranged from 27 to 100 (x¯ = 87.8) percent, from t^m calculated by holding the population pollen allele frequency constant for each family. From Ritland's "sibling-pair" model (correlated mating model), correlation of selfing (r^s) and correlation of outcrossing paternity (r^p) were 35.7% and 99.0%, respectively. These results corroborate the fact that there is variation in selfing rates among different trees, but it may also have indicated that when there is inbreeding, most seeds in the trees are likely to be full-sibs.