scholarly journals Long-term comparison between index selection and optimal independent culling in plant breeding programs with genomic prediction

PLoS ONE ◽  
2021 ◽  
Vol 16 (5) ◽  
pp. e0235554
Author(s):  
Lorena G. Batista ◽  
Robert Chris Gaynor ◽  
Gabriel R. A. Margarido ◽  
Tim Byrne ◽  
Peter Amer ◽  
...  
Keyword(s):  
Recurrent Selection ◽  
Genetic Correlations ◽  
Economic Importance ◽  
Index Selection ◽  
Selection Intensity ◽  
Crop Breeding ◽  
Breeding Programs ◽  
Independent Culling ◽  
Selection Of

In the context of genomic selection, we evaluated and compared breeding programs using either index selection or independent culling for recurrent selection of parents. We simulated a clonally propagated crop breeding program for 20 cycles using either independent culling or an economic index with two unfavourably correlated traits under selection. Cycle time from crossing to selection of parents was kept the same for both strategies. Both methods led to increasingly unfavourable genetic correlations between traits and, compared to independent culling, index selection led to larger changes in the genetic correlation between the two traits. When linkage disequilibrium was not considered, the two methods had similar losses of genetic diversity. Two independent culling approaches were evaluated, one using optimal culling levels and one using the same selection intensity for both traits. Optimal culling levels outperformed the same selection intensity even when traits had the same economic importance. Therefore, accurately estimating optimal culling levels is essential for maximizing gains when independent culling is performed. Once optimal culling levels are achieved, independent culling and index selection lead to comparable genetic gains.

scholarly journals Plant breeders should be determining economic weights for a selection index instead of using independent culling for choosing parents in breeding programs with genomic selection

2018 ◽  
Author(s):  
Lorena G. Batista ◽  
R. Chris Gaynor ◽  
Gabriel R. A. Margarido ◽  
Tim Byrne ◽  
Peter Amer ◽  
...  
Keyword(s):  
Genomic Selection ◽  
Genetic Gain ◽  
Recurrent Selection ◽  
Selection Index ◽  
Economic Importance ◽  
Index Selection ◽  
Breeding Programs ◽  
Independent Culling ◽  
Economic Selection ◽  
Selection Of

AbstractIn the context of genomic selection, we evaluated and compared recurrent selection breeding programs using either index selection or independent culling for selection of parents. We simulated a clonally propagated crop breeding program for 20 cycles of selection using either independent culling or an economic selection index with two unfavourably correlated traits under selection. Cycle time from crossing to selection of parents was kept the same for both strategies. Our results demonstrate that accurate knowledge of the economic importance of traits is essential even when performing independent culling. This is because independent culling achieved its optimum genetic gain when the culling threshold for each trait varied accordingly to the economic importance of the traits. When gains from independent culling were maximised, the efficiency of converting genetic diversity into genetic gain of both selection methods were equivalent. When the same proportion selected of 10% for each trait was used instead of optimal culling levels, index selection was 10%, 128% and 310% more efficient than independent culling when T2 had a relative economic importance of 1.0, 2.5 and 5.0, respectively. Given the complexity of estimating optimal culling levels and the fact that the gains achieved with independent culling are, at most, equivalent to index selection, the use of an economic selection index is recommended for multi-trait genomic selection.

scholarly journals GENETIC GAINS AND SELECTION ADVANCES OF THE UENF-14 POPCORN POPULATION

2018 ◽  
Vol 31 (2) ◽  
pp. 271-278 ◽  
Author(s):  
AMANDA GONÇALVES GUIMARÃES ◽  
ANTÔNIO TEIXEIRA DO AMARAL JÚNIOR ◽  
VALTER JÁRIO DE LIMA ◽  
JHEAN TORRES LEITE ◽  
CARLOS ALBERTO SCAPIM ◽  
...  
Keyword(s):  
Grain Yield ◽  
Genetic Gain ◽  
Recurrent Selection ◽  
Selection Index ◽  
Economic Importance ◽  
Average Height ◽  
Breeding Programs ◽  
Genetic Gains ◽  
Full Sibling ◽  
Selection Of

ABSTRACT Recurrent selection can generate successive gains for characters of economic interest without causing genetic narrowing in the population. However, it has rarely been used in breeding programs in popcorn, especially when using full-sibling progenies to generate more expressive gains. The objective of this study was to estimate the genetic gain of the UENF-14 popcorn population through recurrent selection, and verify the evolution of the gains between the selection cycles four and eight. A total of 200 full-sibling progenies were evaluated in randomized blocks arranged in eight sets within three replicates in two environments; each set containing twenty-five progenies and six controls (selection cycles 4, 5, 6 and 7 of the UENF-14, BRS-Angela and IAC-125). The average height, prolificacy, 100-grain weight, ear weight, grain yield, and grain popping expansion of the plants were evaluated. In the selection of the thirty superior progenies for the eighth cycle, the Mulamba and Mock selection index was used, which generated estimated genetic gains of 4.60 for grain yield and 3.61% for popping expansion. The grain yield increased 111.99 kg ha-1 and the popping expansion increased 1.75 mL g-1 per cycle. The evolution of the cycles resulted in an accumulated genetic gain for the main characters of economic importance, allowing the prediction of success in the continuity of the recurrent selection.

scholarly journals Selection gains for the palm oil production from progenies of American oil palm with oil palm

2021 ◽  
Vol 56 ◽  
Author(s):  
Rui Alberto Gomes Junior ◽  
Alessandra Ferraiolo de Freitas ◽  
Raimundo Nonato Vieira da Cunha ◽  
Antônio José de Abreu Pina ◽  
Higo Otávio Brochado Campos ◽  
...  
Keyword(s):  
Palm Oil ◽  
Oil Palm ◽  
Genetic Parameters ◽  
Recurrent Selection ◽  
Oil Production ◽  
Reciprocal Recurrent Selection ◽  
Fresh Fruit Bunches ◽  
Favorable Conditions ◽  
Selection Of

Abstract The objective of this work was to estimate the genetic parameters, correlations, and selection gains for the oil production of interspecific hybrids progenies between American oil palm, of ‘Manicoré’ origin, and oil palm, of ‘La Mé’ origin. Thirty-nine progenies were evaluated from the sixth to the ninth year after planting, for the productivity of fresh fruit bunches (PROD_FFB), oil content in the bunch (OCB), and palm oil productivity (PROD_OP). The genetic parameters and gains from direct (GDS) and indirect (GIS) selection were estimated for PROD_OP. High values of heritability for the CVg/CVe ratio indicated favorable conditions for the selection. With the selection of 20% of the progenies (selection in both sexes), the following estimates were obtained: 11.15% GDS for PROD_OP, 9.1% GIS for OCB, and 8.1% GIS for PROD_FFB. The PROD_OP of the progenies was of 6,175, 6,057, and 5,995 kg ha-1 per year with GDS and GIS for OCB and PROD_FFB, respectively. The restricted selection of the LM2T male genitor offspring resulted in 5.1% estimated GSD and in a mean of 5,800 kg ha-1 per year for PROD_OP. Selection gains for PROD_OP can be achieved immediately through the selection restricted to oil palm male genitors, and, in the medium and long term, through the interspecific reciprocal recurrent selection between American oil palm and oil palm populations.

scholarly journals Optimum selection intensities in artificial selection programmes: an experimental evaluation

1977 ◽  
Vol 30 (2) ◽  
pp. 115-119 ◽  
Author(s):  
R. Frankham
Keyword(s):  
Experimental Evaluation ◽  
Selection Intensity ◽  
Effective Population ◽  
Term Selection ◽  
Optimum Selection ◽  
Selection For ◽  
Selection Intensities ◽  
Selection Of ◽  
Better Than

SUMMARYAn experimental evaluation of Robertson's (1970) theory concerning optimum intensities of selection for selection of varying durations has been carried out using published results from a long term selection study in Drosophila. Agreement of predicted rankings of treatments with expectations was excellent for low values of t/T (generations/total number scored) but poor for larger values of t/T. This was due to the 20% selection intensity treatments responding worse than expected and the 40% treatments relatively better than expected. Several possible reasons for the discrepancies exist but the most likely explanation is considered to be the greater reduction in effective population size due to selection in treatments with more intense selection.

scholarly journals SELECTION IN HEREFORD CATTLE I. SELECTION INTENSITY, GENERATION INTERVAL AND INDEXES IN RETROSPECT

2021 ◽  
Vol 8 (2) ◽  
pp. 97-111
Author(s):  
L. N. Nwakalor ◽  
J. S. Brinks ◽  
G. V. Richardson
Keyword(s):  
Feed Efficiency ◽  
Inbred Lines ◽  
Index Selection ◽  
Selection Intensity ◽  
Weaning Weight ◽  
Generation Interval ◽  
Hereford Cattle ◽  
Selection Indexes ◽  
Selection Differentials ◽  
Selection Of

Selection intensity and generation interval were evaluated in a Hereford cattle herd of 14 inbred lines and 14 linecross groups corresponding to the lines of inbred sire at the San Juan Basin Research Centre, Hesperus, Colorado. Selection indexes practised were calculated in retrospect. The records analysed were weaning weight and postweaning traits in males and females collected from 1946 through 1973. Analyses were performed by line for the inbreds and pooled analyses for the inbred and linecross populations. From records of 1,239 calves weaned, age of sire averaged 3.75 years compared with 4.52 years for age of dam, showing faster generation turnover for sires than for dams. Generation interval determined 98 actual age of midparent was 4.13 years.Selection applied, evaluated as annual selection differentials within inbred lines and then pooled over all lines, averaged .55 standard deviations per generation for sires for weaning weight. Selection of females was much less. Midparent selection differential amounted to .33 standard deviations per generation. Pooled standardized selection differentials per generation over all lines for sires were .49, .46, 40, -.20, -.10, and .69, respectively, for initial weight, final weight, feed consumption, unadjusted feed efficiency, adjusted feed efficiency, and average daily gain. Selection of females for postweaning traits was not intense. Selection Indexes actually practiced in retrospect were: for sires, IS = .4661(WW) -.0092(FE) + .6126(ADG); for inbred dams, ID = .1824(WW) -.0284 (12W) + .0736 (18W) - 1097 (SPW) -.1097 (FAW); for linecross dams, ID= .2693 (WW) - 2960 (12W) + .0147 (18W) + 1185 (SPW) -.0354 (FAW). The corresponding index selection differentials were .818, 203, and .209. Sire index selection differentials represent about 79 percent of the total selection differentials. 

scholarly journals Direct selection for phenotypic traits in carrot genotypes

2019 ◽  
Vol 37 (3) ◽  
pp. 354-358
Author(s):  
Agnaldo DF de Carvalho ◽  
Giovani O da Silva ◽  
Gabriel E Pereira
Keyword(s):  
Agronomic Traits ◽  
Block Design ◽  
Direct Selection ◽  
Phenotypic Traits ◽  
Crop Breeding ◽  
Breeding Programs ◽  
Randomized Block Design ◽  
Increase Productivity ◽  
Abstract Selection ◽  
Selection Of

ABSTRACT Selection of more productive carrot genotypes is fundamental for crop breeding programs aiming to increase productivity and reduce cost production. Thus, the aim of this work was to evaluate gains from direct selection and to measure its effects on other agronomic traits of interest in carrots. Thirty six carrot genotypes were evaluated in two experiments: the first, sown in the second half of November 2016 and the second one in the first week of March 2017. The experimental plots covered a useful area of 1.5 m2, in transversal rows and 0.10-m double spacing between single rows x 0.20-m between double rows in a randomized block design with 3 replicates. At 90 days, the incidence of leaf blight was evaluated using a note scale and 100 days after sowing, roots were harvested measuring the number and mass of total, commercial and non-commercial roots of each plot. The direct selection of commercial root mass allowed to estimate indirect and expressive gains for most evaluated traits, allowing to select seven genotypes (populations 758, 751, 737, 736, 735, 744 and 742) which can be released as cultivar or for the formation of a broader genetic-based population.

scholarly journals POPULATION SIZE AND SELECTION INTENSITY EFFECTS ON LONG-TERM SELECTION RESPONSE IN MICE

Genetics ◽  
1975 ◽  
Vol 79 (2) ◽  
pp. 305-323
Author(s):  
E J Eisen
Keyword(s):  
Inbreeding Depression ◽  
Genetic Correlations ◽  
Selection Response ◽  
Second Phase ◽  
Selection Intensity ◽  
Total Response ◽  
Family Selection ◽  
Effective Population ◽  
The Difference

ABSTRACT Long-term response to within full-sib family selection for increased postweaning gain was evaluated in lines having different effective population sizes (Ne) and selection intensities (i). Line designations were I4(4), I8(2), I16(2), M4(4), M8(2) and M16(2), where I and M indicate selection of the top 50% and 25%, respectively; 4, 8 and 16 represent the number of parental pairs per replicate and number of replicates is given in parentheses. Realized within full-sib family heritabilities (hR  2) in the first phase of selection (0-14 generations) were larger in 16-pair lines than in 4- and 8-pair lines. In the second phase of selection (>14 generations), hR  2 declined significantly (P<.01) in all lines, and only the I16 and M16 lines had hR  2 values significantly (P<.01) greater than zero. Realized genetic correlations involving number born, 12-day litter weight, weaning weight and six-week weight tended to decline in the second phase of selection. The I16, M16 and control (C16) replicates were crossed in all combinations at generation 14. Crosses were then selected within litters for high postweaning gain. The hR  2 values in the crossbred lines were all larger than those in the second selection phase for M16-1, M16-2 and I16-1, but not for I16-2. Within each Ne level, total response was significantly (P<.01) less for I lines compared with M lines. Total response increased as Ne increased, within each level of i. Relatively small differences in realized i values among Ne lines could not account for this result. The difference in total response among the Ne lines at a given selection intensity may be due to inbreeding depression and a combination of interactions involving "drift" and selection. By crossing replicates of the M lines with the C16 control, the effects of inbreeding depression were removed. Inbreeding depression and genetic drift, as defined herein, were equally important in accounting for differences among Ne lines in total response.

scholarly journals Agronomic evaluation and clonal selection of ginger genotypes (Zingiber officinale Roseoe) in Brazil

2017 ◽  
Vol 35 (3) ◽  
pp. 275-284
Author(s):  
Eleonora Zambrano Blanco ◽  
José Baldin Pinheiro
Keyword(s):  
Agronomic Traits ◽  
Clonal Selection ◽  
Phenotypic Variability ◽  
Block Design ◽  
Genetic Correlations ◽  
Phenotypic Expression ◽  
Germplasm Collection ◽  
Environmental Variance ◽  
Breeding Programs ◽  
Selection Of

The analysis of the genetic diversity of ginger based on agronomic traits is essential to know its performance and to design breeding programs. In this study, we analyzed the phenotypic variability of 61 accessions of the ginger germplasm collection of the "Luiz de Queiroz" College of Agriculture at the University of Sao Paulo (ESALQ/USP) in a complete randomized block design with four replications. An analysis of variance test was performed and genetic parameters such as heritability, genetic variance, environmental variance, genetic-environmental variation ratio (CVg/CVe) and genetic correlations were estimated. There were highly significant differences (P≤0.01) among the accessions for all the agronomic traits analyzed. The CVg/CVe ratio (>1), along with the high heritability (>80%), showed a significant contribution of genetic factors on the phenotypic expression of plant height, rhizome thickness and yield traits, favoring the clonal selection of genotypes. Accessions Gen-29, Gen-29, Gen-32, Gen-36, Gen-37, Gen-40, Gen-41, Gen-42, Gen-50 were selected due to the best agronomic performance when compared to the rest of the germplasm. The results obtained may be useful in future breeding programs in Brazil.

scholarly journals Estimativas de parâmetros genéticos, correlações e índices de seleção para seis caracteres agronômicos em linhagens F8 de soja

2016 ◽  
Vol 7 (3) ◽  
pp. 302 ◽  
Author(s):  
Wallace De Sousa Leite ◽  
Bruno Ettore Pavan ◽  
Carlos Humberto Aires Matos Filho ◽  
Francisco De Alcantara Neto ◽  
Cleidismar Barbosa de Oliveira ◽  
...  
Keyword(s):  
Grain Yield ◽  
Block Design ◽  
Genetic Correlations ◽  
Phenotypic Selection ◽  
Breeding Programs ◽  
Randomized Block Design ◽  
High Heritability ◽  
High Degree ◽  
Prospect Of Success ◽  
Selection Of

This study aimed to estimate genetic and phenotypic parameters and provide knowledge for breeding programs aiming at the selection of the main characters of assessment in soybeans. The experiment was installed in Sabia farm, located at ‘Serra das Laranjeiras” , in the municipality of Currais, Piaui, Brazil, during the 2011/2012 crop year using a randomized block design with 27 genotypes and three repetitions. The evaluated variables were: height at flowering (APF), height at maturity (APM), pod insertion height (AIV), grain yield (PG), number of nodes (NN) and number of pods (NV). The obtained heritability coefficients were from medium to high, for all evaluated characters, ranging from 0.53 to 0.94, for grain yield and plant height at flowering, respectively. These high heritability were confirmed by the high degree of genetic variation and the CVg/CVe ratio, indicating a high prospect of success for the phenotypic selection. The higher positive genetic correlations and the significant (P <0.01) were observed between grain yield and the variables number of nodes (0.807**) and number of pods (0.781**), indicating that the selection of plants with higher number of nodes and pods could result in more productive plants. The Williams-based index presented the highest percentage of gain with the selection offor the grain yield (21.84%) variable.

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