Mating System Estimation in Forest Trees: Models, Methods and Meanings

Isozyme markers have stimulated efforts to measure the mating system in natural and planted populations of forest trees. When open-pollinated progenies have been surveyed for allozyme variation, the arrays have usually been analyzed in terms of the model of mixed self-fertilization and random outcrossing. This procedure has encountered several problems of which the more difficult are due to heterogeneity in outcrossing rates or in pollen allele frequencies. Recent models which deal with these problems and enrich the study of plant mating systems include multilocus estimation, measurement of ’effective’ selfing and of differential male fertility. More reliable estimates of outcrossing, which these methods encourage, will be needed to predict selection gains, management practices and optimal conservation strategies in forest trees.