Abstract
The multilocus mixed mating model and correlated mating model were used to analyze the mating system of a natural Hevea brasiliensis (Willd. Ex Adr. of Juss.) population from the State of Acre. Seeds of 37 mother trees were planted in a progeny test in Selviria, state of Mato Grosso do S ul. Six to 24 individuals per family were evaluated in allozyme electrophoretic analysis. Significant differences between pollen and ovule frequencies were detected in three loci, indicating that the pollen pool was heterogeneous among trees. The multilocus outcrossing rate was estimated at 0.962, indicating allogamy predominance in the population. The correlation of paternity was high (0.351), indicating that 34% of outcrossing progenies are full-sibs. The estimate of the mean coefficient of coancestry among plants within families was 0.177, confirming the mixture of different degrees of relatedness within families.
Highlights
The mating system of a species determines how genetic information is transmitted from one generation to the (Wright 1921) and partially determines the genetic structure of its populations
The model of inbreeding equilibrium assumes that the inbreeding coefficient does not change from one generation to another and that all inbreeding observed in a generation can be ascribed to selfing
These presuppositions are not likely to apply to tree species owing to the strong inbreeding depression these species are generally subjected to (Sorensen 1997, Wang et al 2004), altering the inbreeding coefficient between generations, and due to the frequently detected spatial genetic structure within populations, creating another form of inbreeding, biparental inbreeding
Summary
The mating system of a species determines how genetic information is transmitted from one generation to the (Wright 1921) and partially determines the genetic structure of its populations. Species with a mating type that spreads pollen over great distances maintain the greatest part of genetic diversity within populations, opposite to predominantly selfing species that spreads pollen over short distances and maintain the greatest part of diversity among populations (Hamrick 1989). Such information is fundamental in breeding and forest conservation programs for the selection of populations and the estimation of the coefficient of relatedness among plants within progenies in order to estimate genetic parameters, collect samples for ex situ conservation and collect seeds for environmental reforestation. These presuppositions are not likely to apply to tree species owing to the strong inbreeding depression these species are generally subjected to (Sorensen 1997, Wang et al 2004), altering the inbreeding coefficient between generations, and due to the frequently detected spatial genetic structure within populations, creating another form of inbreeding, biparental inbreeding
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