Improving Genetic Analysis of Corymbia citriodora subsp. variegata with Single- and Multiple-Trait Spatial-Competition Models

Abstract

Environmental heterogeneity and/or genetic and environmental competition were quantified on two growth traits, diameter at breast height and total height, and wood density in a progeny trial of Corymbia citriodora subsp. variegata. Three single-trait mixed models with random spatial and/or competition effects were compared to a standard analysis by analyzing fit, dispersion parameters, accuracy of breeding values, genetic gains, and ranking of trees. In addition, a multiple-trait spatial-competition model was fitted to estimate correlations among direct and indirect additive genetic effects, and to explore relations between traits. Single-trait analyses with spatial and/or competition effects outperformed the standard model. However, the performance of these models depended on the sensitivity of each trait to detect each effect. Direct–indirect genetic correlations from the multiple-trait spatial-competition model showed inverse and strong relations among growth traits and wood density, suggesting that growth traits can be affected by competition and environmental heterogeneity, but also wood density might be influenced by these effects. The approach proposed was useful to improve the genetic analysis of the species as well as to gain an understanding of the genetic relations between traits under the influence of environmental heterogeneity and competition.

Accounting for competition in multi-environment tree genetic evaluations: a case study with hybrid pines

“…Our results showed that ignoring a strong inter-tree competition may downwardly the estimation of narrow-and broad-sense heritabilities. A similar tendency was observed by Cappa et al (2017) in Eucalyptus grandis (Hill ex Maiden) for the trait DBH, and by Hernández et al (2019) in Corymbia citriodora subsp. variegata (F.Muell.)…”

“…2), implying that the selection based only on the additive (or direct) breeding value could increase the level of competitiveness in DBH growth for the next population of improvement. As suggested by Hernández et al (2019), a breeding strategy based on selecting less competitive genotypes might reduce the number of suppressed individuals in forests, increasing yields per unit area of future commercial plantations.…”

“…Recent studies in forest tree breeding have used a univariate single-environment competition mixed model to investigate direct and indirect genetic relationships among trees (Cappa and Cantet 2008;; Costa e Silva and Kerr 2013; Cappa et al 2015Cappa et al , 2016. Also using a singleenvironment approach, Costa e Silva et al ( 2017) and Hernández et al (2019) fitted a multivariate competition mixed model to address the direct and indirect genetic correlations among traits.…”

Conservative or non-conservative strategy to advance breeding generation? A case study in Eucalyptus benthamii using spatial variation and competition model

“…Likewise, Araujo et al, (2021) reported similar results for a Eucalyptus dunnii. The DBH trait is more sensitive to competition effect whereas H is more favorable to detecting environmental heterogeneity, however less sensitive to competition, as previously described in other studies (Magnussen 1989, Hannrup et al 1998, Dutkowski et al 2006, Ye and Jayawickrama 2008, Cappa et al 2016, Hernández et al 2019.…”

“…Regarding narrow sense heritability and accuracy, these parameters basically did not change among the fitted models, but changes in the ranking were observed at the levels of families and individuals. The H trait is less important than DBH to determine the tree volume once after primary growth decrease or stops the secondary growth in trees continues (Gadow and Gangying Hui, 1999;Hernández et al, 2019). Therefore, similar to Eucalyptus dunnii (Araujo et al, 2021), DBH is the best growth field trait, regarding precision and accuracy, in the individuals selection in this trial with E. benthamii.…”