Multisite genetic parameter estimates from aCallitropsis nootkatensisdiallel study with clonally replicated progeny

Abstract

Clonally replicated Callitropsis nootkatensis (D. Don) D.P. Little progeny from partial diallels were established in nine trials on coastal British Columbia, Canada. The trials were assessed for height, diameter, and crown form at age 12 years. An individual-genotype, linear mixed model with spatially correlated residuals was used to estimate the variance components and related genetic parameters. The majority of the estimated genetic variance for all traits was additive, and nonadditive genetic variance was predominantly due to dominance effects. Narrow-sense heritabilities for height and diameter at individual sites varied from 0.07 to 0.39, whereas for crown form, they were all less than 0.1. Dominance and epistasis ratios were, for the most part, lower than narrow-sense heritabilities. Common across-site additive and nonadditive genetic correlations were strongly positive and not significantly different from 1.0 for the majority of traits across sites within a series. Significant levels of additive genetic variance, coupled with insignificant to low nonadditive genetic variance for growth and crown form, would seem to be contrary to developing a clonal testing and deployment program. However, the lack of viable orchard seed and the faster delivery of genetic gain to reforestation, as well as more accurate forward selections based on additive genetic effects, makes this strategy viable for C. nootkatensis.Résumé : Des descendances de Callitropsis nootkatensis (D. Don) D.P. Little provenant de croisements diallèles partiels ont été multipliées végétativement et établies dans neuf plantations comparatives dans la région côtière de la Colombie-Britannique, au Canada. La hauteur, le diamètre et la forme de la cime des arbres ont été mesurés à 12 ans. Un modèle linéaire mixte de génotypes individuels avec des résidus spatialement corrélés a été utilisé pour estimer les composantes de la variance et les paramètres génétiques connexes. La plus grande portion de la variance génétique estimée était de nature additive pour tous les caractères et la variance génétique non additive était surtout due à des effets de dominance. Les héritabilités au sens strict pour la hauteur et le diamètre pour chaque site variaient de 0,07 à 0,39, alors qu'elles étaient toutes inférieures à 0,1 dans le cas de la forme. Les rapports de dominance et d'épistasie étaient pour la plupart inférieurs aux héritabilités au sens strict. Les corrélations génétiques additives et non additives communes estimées entre les sites d'une même série étaient fortement positives et pas significativement différentes de 1,0 pour la majorité des caractères. Les niveaux significatifs de variance génétique additive, combinés à la variance génétique non additive non significative à faible pour la croissance et la forme, sembleraient aller à contresens de l'idée de développer un programme de tests clonaux et de déploiement de clones. Toutefois, cette stratégie est justifiée chez C. nootakatensis par l'absence de vergers à graines viables et le transfert plus rapide ...

Performance and Phenotypic Stability of Norway Spruce Provenances, Families, and Clones Growing under Diverse Climatic Conditions in Four Nordic Countries

“…In the analyses and presentations focus has been on the N × N and E × E family groups. The low number of parents and families is also the reason why no attempts were made to separate the total genetic variance into additive, dominance, and epistatic components, which can be done when measurements are available from trials with families and clones within families [9,18,19].…”

A climate adaptation strategy for conservation and management of yellowcedar in Alaska

“…Height: wk, yr 1, yr 2, yr 3 h 2 = 0.69, 0.64, 0.44, 0.31 Cherry and Lester (1992), Russell (1993), Russell and Krakowski (2012) Height: yr 12 h 2 = 0.07-0.45 Baltunis et al 2013, Russell et al (2015) Shoot growth, first-year growth H 2 = 0.58 Russell (1993) Index of injury to cold H 2 = 0.38 Russell (1993) Reproductive yellow-cedar plasticity H 2 = 0.36 El-Kassaby et al (1993) Root collar diameter: 32 wk, yr 2 h 2 = 0.30, 0.17 Russell (1993) Diameter at breast height: yr 12 h 2 = 0.06-0.27 Russell et al (2015) Total growth at growth cessation h 2 = 0.16 Russell (1993) Tree form: yr 12 h 2 = 0.02-0.05 Russell et al (2015) Trait heritabilities-The heritability of a trait is the proportion of the total population variation in that trait attributable to genetic effects. Heritability is key to understanding how readily a trait responds to natural selection in the environment or to selection in tree improvement programs.…”

“…Most have focused on the apportionment of variation within and across populations (Cherry and Lester 1992, El-Kassaby 1995, Russell 1993, and two studies explicitly evaluated this variation in a genecological framework (Russell 1993, Russell andKrakowski 2012). In addition, a more recent study evaluated how additive, dominant, and epistasic modes of inheritance contribute to total variability in yellow-cedar (Russell et al 2015). All studies were conducted in common gardens with hierarchical variation represented by clones, families, populations, and geographic provenances.…”

“…Traits showing heritabilities of this magnitude include seedling and young tree height, shoot growth during first-year growth, diameter at age 12, cold injury during acclimation, and maximum cold hardiness. Nonadditive inheritance due to dominance or epistasis is negligible in traits examined to date (height, diameter; Russell et al 2015), and the species shows minimal genotype × environment interactions (Baltunis et al 2013, Russell et al 2015.…”