Reproductive systems in conifer seed orchards : 2. Reproductive selection monitored at an LAP gene locus in Pinus sylvestris L.

In a Scots pine seed orchard the genetic structures at an enzyme gene locus active in pine seeds were compared among the parental clones and the allorchard seeds produced over a period of three years. The genotypes of the seeds were identified as ordered pairs consisting of the female and male contribution. The sexual reproductive function monitored at the studied locus differed significantly between the two sexes. This fact proves the necessity of taking sexual asymmetry into account in studies of reproductive selection. This is done by comparing the observed genotypic structures among the offspring with the corresponding multiplicative structure expected under random gametic fusion. Additionally, accounting for partial self-fertilization increased the conformity between the observed and the hypothesized model structures. The differences in female and male gametic contributions to the offspring were used to estimate female and male relative fitness components. Significant deviations between the allelic and/or genotypic structures of orchard clones and their seed, and between seed lots collected in different years, may reduce the efficiency of realizing breeding gains in seed orchards.