Life histories, neighbourhood sizes, and variance structure in some North American conifers

Neighourhood sizes and variance structure were determined for ten North American coniferous forest tree species, using information on seed dispersal, patterns of life history, and demography. A synthetic cohort of reproductive individuals belonging to a critical age group was constructed using normal yield tables. Data on reproductive individuals in a synthetic cohort were used to determine the neighbourhood sizes for each species. The neighbourhood sizes varied from 1244 to 50 118 individuals. Effective population sizes were calculated from data on neighbourhood sizes and replacement patterns of individuals in various species, the inter-deme differentiation, Fst ranged from 0.0002 to 0.007. The results suggest that large neighbourhood and effective population sizes, and hence panmixia, may be virtually common among the species examined. These conclusions are consistent with recent findings on population differentiation and estimates of gene flow in confers using allozyme markers.