Effect of different mating designs on inbreeding, genetic variance and response to selection when applying individual selection in fish breeding programs

A genetic improvement project for black spruce (Piceamariana (Mill.) B.S.P.) was initiated in Minnesota in 1974, with an objective of improving the inherent growth rate of the local population. This study reports some field results from the initial phase of the project. Study objectives were to (i) estimate genetic and environmental variance components of early (age 10 years) tree height, (ii) estimate expected genetic gains from various selection methods in three seedling seed orchards and a clonal seed orchard, and (iii) evaluate the effect that these selection methods have on inbreeding levels in the rogued seedling orchards. Additive genetic variance accounted for 15 to 22% of the phenotypic variance in three wind-pollinated family tests and 10% of the phenotypic variance across the tests. Expected gains from combined-index (family and individual) selection in the family test - seed orchards (selection of 22 to 27%) ranged from 4.6 to 6.1%. Family + within-family selection and individual selection were 18 and 32% less efficient, respectively. Index selection resulted in the highest estimated levels of inbreeding in the rogued orchards. However, the largest difference between the various selection methods resulted in a difference in the average inbreeding coefficient of less than 0.15%. Based on this small difference, index selection could be used in roguing similarly designed seedling seed orchards with minimal risk of elevated inbreeding levels.

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Response to Selection Under Non-Random Mating I. Partitioning Genetic Variance

Biometrical Journal ◽

10.1002/bimj.4710340204 ◽

1992 ◽

Vol 34 (2) ◽

pp. 147-152 ◽

Cited By ~ 2

Author(s):

K. Muralidharan ◽

J. P. Jain

Keyword(s):

Genetic Variance ◽

Random Mating ◽

Response To Selection

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Improved methodology for analyzing survival data in fish breeding programs

Aquaculture ◽

10.1016/j.aquaculture.2007.07.110 ◽

2007 ◽

Vol 272 ◽

pp. S278-S279

Author(s):

K. Kolstad ◽

J. Ødegård ◽

L. Tran ◽

D. Nguyen ◽

I. Olesen

Keyword(s):

Survival Data ◽

Breeding Programs ◽

Fish Breeding

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Using known QTLs to detect directional epistatic interactions

Genetics Research ◽

10.1017/s0016672312000043 ◽

2012 ◽

Vol 94 (1) ◽

pp. 39-48 ◽

Cited By ~ 2

Author(s):

MONTGOMERY SLATKIN ◽

MARK KIRKPATRICK

Keyword(s):

Genetic Variance ◽

Additive Model ◽

Quantitative Character ◽

Gene Interactions ◽

Ratio Test ◽

Linkage Equilibrium ◽

Response To Selection ◽

Epistatic Interactions ◽

New Strategy ◽

Trait Locus

SummaryEpistasis plays important roles in evolution, for example in the evolution of recombination, but each of the current methods to study epistasis has limitations. Here, we propose a new strategy. If a quantitative trait locus (QTL) affecting a quantitative character has been identified, individuals who have the same genotype at that QTL can be regarded as comprising a subpopulation whose response to selection depends in part on interactions with other loci affecting the character. We define the marginal differences to be the differences in the average phenotypes of individuals with different genotypes of that QTL. We show that the response of the marginal differences to directional selection on the quantitative character depends on epistatic gene interactions. For a model with no interactions, the marginal differences do not differ on average from their starting values once linkage equilibrium has been re-established. If there is directional epistasis, meaning that interactions between the QTL and other loci tend to increase or decrease the character more than under an additive model, then the marginal differences will tend to increase or decrease accordingly when larger values of the character are selected for. We develop a likelihood ratio test for significant changes in the marginal differences and show that it has some power to detect directional epistasis for realistic sample sizes. We also show that epistatic interactions which affect the evolution of the marginal differences do not necessarily result in a substantial epistatic component of the genetic variance.

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Heritability estimation in early generations of two-way crosses in soybean

Bragantia ◽

10.1590/s0006-87052008000100012 ◽

2008 ◽

Vol 67 (1) ◽

pp. 101-108 ◽

Cited By ~ 1

Author(s):

Marcelo Marchi Costa ◽

Antonio Orlando Di Mauro ◽

Sandra Helena Unêda-Trevisoli ◽

Nair Helena Castro Arriel ◽

Ivana Marino Bárbaro ◽

...

Keyword(s):

Genetic Parameters ◽

Genetic Variance ◽

Selection Process ◽

Broad Sense ◽

Selection Methods ◽

Narrow Sense ◽

Breeding Programs ◽

Heritability Estimation ◽

The Family ◽

Simple Selection

The estimation of genetic parameters, especially in early generations, is very useful for directing the selection process in breeding programs. The present research was undertaken to estimate heritabilities in the broad sense, narrow sense and using parent-offspring regression in F3 soybean populations from six two-way crosses, originated from the Soybean Breeding Program of Faculdade de Ciências Agrárias e Veterinárias (UNESP), Jaboticabal campus. It was used the family design with common checks located ten plots apart. It was observed highly significant differences among families. The experimental coefficient of variation (CVe), the CVg/CVe ratio and the heritability showed wide variation among traits, being the highest values found for number of pods, number of seeds and grain yield, making evident the existence of variance to be exploited by breeding. The estimation of the heritability coefficients in the broad sense, narrow sense and by regression were close in most of the situations, showing that the largest part of genetic variance is of additive nature, in which simple selection methods can lead to satisfactory genetic gains.

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THEORETICAL VARIANCE OF RESPONSE TO MODIFIED PEDIGREE SELECTION

Canadian Journal of Plant Science ◽

10.4141/cjps71-092 ◽

1971 ◽

Vol 51 (6) ◽

pp. 463-468 ◽

Cited By ~ 5

Author(s):

R. J. BAKER

Keyword(s):

Population Size ◽

Genetic Variance ◽

Selection Intensity ◽

Environmental Variance ◽

Breeding Programs ◽

Selection Experiments ◽

Pedigree Selection

Modified pedigree selection was proposed as a method for improving self-pollinated species. The theoretical variance of response to this type of selection is developed in this paper. Response is expected to be more variable with higher selection intensity or greater genetic variance, and less variable with larger population size or decreased environmental variance. Ways of using the theory for planning breeding programs and for assessing the results of selection experiments are discussed by considering examples.

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Testing limits to adaptation along altitudinal gradients in rainforest Drosophila

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2008.1601 ◽

2009 ◽

Vol 276 (1661) ◽

pp. 1507-1515 ◽

Cited By ~ 52

Author(s):

Jon R Bridle ◽

Sedef Gavaz ◽

W. Jason Kennington

Keyword(s):

Gene Flow ◽

Genetic Variance ◽

Local Density ◽

Theoretical Models ◽

Rate Of Change ◽

Adaptive Divergence ◽

Local Optimum ◽

Response To Selection ◽

Costs And Benefits ◽

The One

Given that evolution can generate rapid and dramatic shifts in the ecological tolerance of a species, what prevents populations adapting to expand into new habitat at the edge of their distributions? Recent population genetic models have focused on the relative costs and benefits of migration between populations. On the one hand, migration may limit adaptive divergence by preventing local populations from matching their local selective optima. On the other hand, migration may also contribute to the genetic variance necessary to allow populations to track these changing optima. Empirical evidence for these contrasting effects of gene flow in natural situations are lacking, largely because it remains difficult to acquire. Here, we develop a way to explore theoretical models by estimating genetic divergence in traits that confer stress resistance along similar ecological gradients in rainforest Drosophila . This approach allows testing for the coupling of clinal divergence with local density, and the effects of genetic variance and the rate of change of the optimum on the response to selection. In support of a swamping effect of migration on phenotypic divergence, our data show no evidence for a cline in stress-related traits where the altitudinal gradient is steep, but significant clinal divergence where it is shallow. However, where clinal divergence is detected, sites showing trait means closer to the presumed local optimum have more genetic variation than sites with trait means distant from their local optimum. This pattern suggests that gene flow also aids a sustained response to selection.

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