Comparison of selection methods for optimizing genetic gain and gene diversity in a red pine (Pinus resinosa Ait.) seedling seed orchard

Four selection methods, individual selection (IS), family selection (FS), family plus within-family selection (FWFS) and combined selection (CS), were used to estimate genetic gain [E(g)] for stem volume and gene diversity (GD) for ten theoretical selection intensities in a 108-family, 12-year-old red pine seedling seed orchard. Estimated genetic gain for stem volume ranged from 4.6% to 11.8% across all selection methods and intensities with CS consistently having the highest gains and FS the lowest for any given selection intensity. Genetic diversity ranged from 0.9797 to 0.9954 across all selection methods and intensities. Individual selection was the best selection method for retaining GD, especially at the higher selection intensities, while FWFS was more efficient at the lowest selection intensity. An optimization point, which maximized E(g) and GD relative to each other, was calculated for each selection method. In all cases the optimization point indicated that both E(g) and GD would be favorably high when optimized relative to each other. The implications for volume gain, genetic diversity and potential inbreeding in red pine, a species with inherently low levels of genetic variation, are discussed.