Male reproductive success in Pseudotsuga menziesii (Mirb.) Franco: the effects of spatial structure and flowering characteristics
1997
Burczyk, J.L. | Prat, D.
Reproductive patterns and effective pollen dispersal were investigated in a Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) clonal seed orchard using 11 isozyme loci as genetic markers. Progenies from 94 mother trees were analysed by the mixed-mating and the neighbourhood models and outcrossing rates were estimated as 0.96 and 0.97, respectively. The proportion of offspring resulting from pollination by males located outside the neighbourhood of each mother tree (30 m in radius) was estimated as 0.54, with approximately 43 per cent of matings resulting from outcrossing with nearby males (within neighbourhoods). The effects of distance and direction of individual males from mother trees, pollen fecundity and phenological synchronization were all significant in determining outcross mating patterns within neighbourhoods. Generally, male reproductive success increased with proximity and phenology overlap with mother tree and pollen fecundity. The effect of different factors influencing male reproductive success varied among the three groups of mother trees divided according to the time of female receptivity (early, intermediate and late). Phenology was important in the early and intermediate groups, whereas fecundity was important in the intermediate and late phenology groups. Both distance and directionality effects were significant in the early and late classes. The directionality effect could be partially explained by the wind patterns existing during the pollination period. The mean effective number of males mating with each female within neighbourhoods was 10.95 (49.31 per cent of males within neighbourhoods).
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