Male reproductive success and pedigree error in red spruce open-pollinated and polycross mating systems

Open-pollinated and polycross mating systems are widely used in forest genetics and breeding to quickly, simply, and inexpensively generate progenies assumed to be related as half-sibs (coefficient of relationship, r = 0.25) from a random mating population. However, nonrandom mating, such as unequal male reproductive success (RS) or selfing, can increase the genetic correlation among offspring, and thus, genetic variance and heritability are overestimated. Conversely, pedigree errors will cause additive genetic variance and heritability to be underestimated. Unequal male reproductive success and three types of potential pedigree errors (volunteers, mishandled maternal identities, and foreign pollen) were detected in operational open-pollinated and polycross red spruce (Picea rubens Sarg.) progeny tests, through paternity testing using microsatellite (simple sequence repeat) DNA markers. The potential impact of unequal RS and pedigree errors on quantitative genetic parameters is discussed. Paternity and parentage analyses could be used to reconstruct the pedigree of any plantation consisting of sibships, where candidate parents (e.g., members of seed orchard) can be identified. This offers an alternative to traditional progeny testing for estimation of quantitative genetic parameters.