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Reproductive dynamics and fingerprinting effort in a Douglas-fir seed orchard Kess, Joseph Anthony

Abstract

Seed orchards are the tree improvement programs’ production populations used to predictably package genetic gain and diversity achieved during the breeding cycle. Genetic gain and diversity delivered by seed orchards is calculated under the assumption of reproductive randomness, equality, and synchrony. These ideal expectations are not fulfilled by any existent seed orchards and deviations in gametic contribution by orchard parents’ makes genetic gain and diversity unpredictable. In this study, five Douglas-fir (Pseudotsuga menziesii) microsatellite markers (Slavov et al 2004) were used to genotype 66 orchard parents, 14 of which were also supplemental mass pollination (SMP) pollen donors, and 396 bulk seeds from the 2009 seed crop of a wind-pollinated Douglas-fir seed orchard. Genotype data were analyzed using the likelihood based CERVUS parentage analysis program (Kalinowski et al 2007) for full pedigree reconstruction. In this orchard, 14% of paternal gametic contributions came from outside males. Parental balance curves showed that 80% of paternal, maternal, and gametic contributions were made by 38 (58%), 34 (52%) and 37 (56%) orchard parents, indicating that the greatest gametic contribution inequality was attributable to maternal gametic contribution. Differences in gametic contribution and common ancestry between orchard parents decreased the effective number of males, females, and population size to 42, 37, and 41, lower than the census number of 66 parents. Selfing was 24.24%, higher than that reported for many Douglas-fir seed orchards. High selfing may be attributed to reproductive asynchrony or differences in parental reproductive output. Supplemental mass pollination did not result in significantly higher paternal gametic contribution. Failure of SMP may be attributed to either incorrect timing of application or competition with ambient pollen. The minimum number of genotyped seeds required for accurate contamination estimate was 150, identified by jackknife sampling of the total genotyped seed sample.

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Attribution 3.0 Unported

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