Open-nucleus breeding strategies compared with population-wide positive assortative mating

Lstibůrek, Milan; Mullin, T. J.; Lindgren, D.; Rosvall, Ola

doi:10.1007/s00122-004-1746-1

Cited by 8 publications

(5 citation statements)

References 14 publications

(9 reference statements)

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“…The enhancement of V A(BP) observed in this study exceeds the magnitude reported earlier under unbalanced mating schemes Lstibů rek et al 2004). This conclusion holds under infinitesimal model assumptions, as well as under the mixed-inheritance model with a single majorgene locus, contributing 10% of the additive genetic variance.…”

Section: Resultssupporting

confidence: 52%

“…In earlier investigations Lstibů rek et al 2004), parental contributions did not follow the actual distributional patterns of their predicted breeding values. The number of mating combinations assigned to each individual followed its rank, rather than its predicted breeding value, which imposed an unrealistic assumption that the correlation between rank and breeding value was one.…”

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confidence: 69%

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Positive Assortative Mating With Family Size as a Function of Predicted Parental Breeding Values

et al. 2005

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While other investigations have described benefits of positive assortative mating (PAM) for forest tree breeding, the allocation of resources among mates in these studies was either equal or varied, using schemes corresponding only to parental rank (i.e., more resources invested in higher-ranking parents). In this simulation study, family sizes were proportional to predicted midparent BLUP values. The distribution of midparent BLUP values was standardized by a constant, which was varied to study the range of distributions of family size. Redistributing progenies from lower-to higher-ranking families to a point where an equal number of progenies were still selected out of each family to the next generation caused minimal change in group coancestry and inbreeding in the breeding population (BP), while the additive genetic response and variance in the BP were both greatly enhanced. This generated additional genetic gains for forest plantations by selecting more superior genotypes from the BP (compared to PAM with equal family sizes) for production of improved regeneration materials. These conclusions were verified for a range of heritability under a polygenic model and under a mixed-inheritance model with a QTL contributing to the trait variation. E ARLIER studies by computer simulation have demonstrated that positive assortative mating (PAM) applied in a long-term forest tree breeding program has the potential to generate extra genetic improvement in forest plantations (e.g., dissertations by Mahalovich 1990; Rosvall 1999). This is due to the enhancement of the additive genetic response and variance in the breeding population (BP), enabling the selection of more extreme genotypes from the BP. These genotypes can be established in orchards to produce seeds for production of reforestation nursery stock or alternatively can be vegetatively propagated and directly planted as clones. When both genetic gain and diversity are considered in a single selection criterion, PAM does not much alter the effective population size compared with that achieved under random mating, but increases the average inbreeding in the BP as a consequence of mating among more related individuals .Ideally, the contribution of individuals in the BP to the next generation should correlate with their breeding values (Lindgren 1986). Various weighting schemes have been proposed to assign mating frequencies to individuals in the BP. These are built on different assumptions about the distribution of breeding values and the function used to assign the corresponding mating frequencies Kang 1989;Wei and Lindgren 1995). Two approaches for controlling parental contributions during PAM were investigated by , using a stochastic model of a forest-tree breeding program. In the first approach, balanced mating (each individual involved in an equal number of combinations) was followed by unbalanced selection (more progenies selected from higher-ranking families and fewer from lower-ranking families). In the second, unbalanced mating (individuals of high...

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Section: Resultssupporting

confidence: 52%

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confidence: 69%

Positive Assortative Mating With Family Size as a Function of Predicted Parental Breeding Values

et al. 2005

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“…For long-term breeding, balanced within-family selection seems to be a near-optimal strategy, even considering possible gain in PPs drawn from the BP (DANUSEVICIUS and LINDGREN, 2002b;ROSVALL and MULLIN, 2003). Compared to the methods used in this study, there are advantages in creating a BP with assortative mating (i.e., positive assortative mating) and /or by allocating more resources to better parent trees (ROSVALL and MULLIN, 2003;LSTIBU°REK et al, 2004a, 2004b. Obviously, application of these modifications will result in changes in BP A and V A .…”

Section: Discussionmentioning

confidence: 96%

Efficiencies of Clonally Replicated and Seedling Testing for Spruce Breeding and Deployment Strategies

et al. 2009

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Genetic gains based on a genetic test using clonal replicates were compared to those based on a test using seedlings at the same gene diversity and testing effort levels using POPSIM™ Simulator. Three testing and deployment strategies targeting for white spruce (P. glauca [Moench] Voss) and black spruce (P. mariana (Mill.) B.S.P.) in New Brunswick were compared: seedling test with clonal seed orchard deployed as seedlings (CSO_ST), clonally replicated test with clonal seed orchard deployed as seedlings (CSO_CRT), and clonally replicated test deployed as a clone mix (MVF). The breeding populations (BP) were formed by balanced within-family selection and the production populations (PP) were selected by strong restriction on relatedness, i.e., no parent in common. Compared to the seedling test, the clonally replicated test resulted in faster accumulation of additive effects but quicker loss of additive variance in the BP, and this is particular true in the case of lower narrow-sense heritability or less non-additive genetic variance. The quicker loss in BP additive variance was overcompensated for by its faster accumulation in BP additive effect, resulting in higher gain in the clonally replicated test based PPs. Compared to the CSO_ST, the gain superiority of the CSO_CRT increased with generations, decreasing narrow-sense heritability or reducing the amount of non-additive variance. Implementing MVF was the most effective in terms of gain in most simulated cases and its superiority over the CSO_ST increased with generations, decreasing narrowsense heritability, or increasing non-additive genetic variance. Overall results demonstrated significant advantages of using clonally replicated test both for BP advancement and PP selection in most of the scenarios, suggesting that clonally replicated test should be incorporated into current spruce breeding strategies.

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“…The grandparent-balance can easily be combined with positive assortative mating (Lstibùrek et al, 2004a(Lstibùrek et al, , 2004bRosvall, 1999) or similar with stratified sublining (Ruotsalainen, 2002). The positive assortative mating increases the range of the genetic values so the genotypes used for mass multiplication in seed orchards become better, even if the average breeding stock is not improved.…”

Section: Possible Improvements Of the Grandparent-balance Strategymentioning

confidence: 99%

Efficiency of breeding strategy where grandparents — but not parents — contribute equally to the breeding population

Danusevičius¹,

Lindgren²

2010

Ann. For. Sci.

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Abstract• The objective was to optimise the strategy for maintaining the genetic balance in long-term breeding where the grandparents contribute equally to the breeding population, but the parents do not.• The annual genetic progress under a budget constraint was compared for a number of scenarios. The factors considered were: genetic parameters, recruitment population size, mating number per grandparent, cost of plants and parents, selection age and time components. Phenotypic selection forward was assumed. Using more parents than grandparents affects the testing population only, thus, gene diversity loss and breeding population size remain constant.• Using larger number of parents than grandparents was a superior strategy at all scenarios tested. The strategy with 6 parents per grandparent and 1% of the tested plants selected on their phenotype at age 15 for further mating is recommendable. The strategy to choose 6 parents per grandparent was robust over a heritability range 0.05 to 0.2. At a higher heritability, the optimum number of parents per grandparent was 2 to 4.• Using larger number of parents than grandparents has the potential to improve annual genetic gain in the magnitude of 50% compared to the strategies currently used for Scots pine in Sweden. Mots-clés :sélection équilibrée / sélection à long terme / diversité génétique / optimisation / Pinus sylvestris Résumé -Efficacité de la stratégie de sélection où les grands-parents -mais pas les parentscontribuent également à l'amélioration de la population.• L'objectif était d'optimiser la stratégie pour le maintien de l'équilibre génétique dans une sélection à long terme où les grands-parents, mais pas les parents, contribuent également à l'amélioration de la population.• Le progrès génétique annuel sous une contrainte budgétaire a été comparé pour un certain nombre de scénarios. Les facteurs considérés sont les suivants : les paramètres génétiques, la taille de la population de recrutement, le nombre de croisements par grand-parent, le coût des plants et des parents, l'âge de sélection et les composantes temporelles. La sélection phénotypique précoce a été prise en charge. Utiliser plus de parents que de grands-parents a seulement un effet sur la population d'essai, donc, la perte de la diversité génétique et la taille de la population améliorée restent constantes.• L'utilisation d'un plus grand nombre de parents que de grands-parents est une stratégie supérieure pour tous les scénarios testés. La stratégie avec 6 parents par grands-parents et par 1 % des plants testés sur leur phénotype à l'âge de 15 ans par croisement supplémentaire est recommandable. La stratégie du choix de 6 parents par grand-parent a été robuste sur une échelle d'héritabilité de 0,05 à 0,2. Lors d'une héritabilité plus élevée, le nombre optimal de parents par grand-parent était de 2 à 4.• L'utilisation d'un plus grand nombre de parents que de grands-parents a le potentiel d'améliorer le gain génétique annuel de l'ordre de 50 % par rapport aux stratégies utilisées actuellement pou...

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Open-nucleus breeding strategies compared with population-wide positive assortative mating

Cited by 8 publications

References 14 publications

Positive Assortative Mating With Family Size as a Function of Predicted Parental Breeding Values

Positive Assortative Mating With Family Size as a Function of Predicted Parental Breeding Values

Efficiencies of Clonally Replicated and Seedling Testing for Spruce Breeding and Deployment Strategies

Efficiency of breeding strategy where grandparents — but not parents — contribute equally to the breeding population

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