Limits in recurrent selection. I. Factors affecting the increment in allelic frequencies
Autor(a) principal: | |
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Data de Publicação: | 2014 |
Outros Autores: | |
Tipo de documento: | Artigo |
Idioma: | por |
Título da fonte: | Pesquisa Agropecuária Brasileira (Online) |
Texto Completo: | https://seer.sct.embrapa.br/index.php/pab/article/view/13961 |
Resumo: | The limit of intrapopulational recurrent selection and the main factors affecting it were investigated, through the total change in allelic frequency, until total depletion of genetic variability, and was computed through the probability of ultimate fixation of favorable alleles. Half mass selection was considered as reference selection scheme, in a panmitic species. For different combinations of the main factors 360 values of the total change were calculated. Despite the restrictions, it was concluded that selection limit is strongly unfavored when we combine: a low coefficient of heritability (h2), small effective population size (Ne), weak selection intensity, low initial frequency of favorable alleles and a trait controlled by loci with small effects. When one of these factors is at an inadequate level, it can be compensated through changes in the others. High Ne values, during selection cycles, can be chosen for such compensation, provided k is not reduced correspondingly, since, in this case, immediate progress will be reduced. Low experimental precision reduces h2, so a high Ne is needed. The product Neh is a good measure of how much Ne a should be increased if h2 is reduced. The model was applied to corn yield data, and the use of local populations for breeding purposes, which have as only advantage its adaptations, was commented. It was also verified that 80% to 85% of the total change in allelic frequency variation is due to factors under the control of the breeder. This indicates that schemes can be chosen not only to assure adequate immediate progress but also appropriate selection limits. |
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Limits in recurrent selection. I. Factors affecting the increment in allelic frequenciesLimites da seleção recorrente. I. Fatores que afetam o acréscimo das frequências alélicasselection limits; gene fixation; effective size; maize; Zea mayslimites da seleção; fixação de genes; tamanho efetivo; milho; Zea maysThe limit of intrapopulational recurrent selection and the main factors affecting it were investigated, through the total change in allelic frequency, until total depletion of genetic variability, and was computed through the probability of ultimate fixation of favorable alleles. Half mass selection was considered as reference selection scheme, in a panmitic species. For different combinations of the main factors 360 values of the total change were calculated. Despite the restrictions, it was concluded that selection limit is strongly unfavored when we combine: a low coefficient of heritability (h2), small effective population size (Ne), weak selection intensity, low initial frequency of favorable alleles and a trait controlled by loci with small effects. When one of these factors is at an inadequate level, it can be compensated through changes in the others. High Ne values, during selection cycles, can be chosen for such compensation, provided k is not reduced correspondingly, since, in this case, immediate progress will be reduced. Low experimental precision reduces h2, so a high Ne is needed. The product Neh is a good measure of how much Ne a should be increased if h2 is reduced. The model was applied to corn yield data, and the use of local populations for breeding purposes, which have as only advantage its adaptations, was commented. It was also verified that 80% to 85% of the total change in allelic frequency variation is due to factors under the control of the breeder. This indicates that schemes can be chosen not only to assure adequate immediate progress but also appropriate selection limits. Investigou-se o limite da seleção recorrente e os principais fatores que o afetam, por meio do acréscimo esperado na frequência dos alelos favoráveis, até o esgotamento da variabilidade genética, calculado a partir da probabilidade de fixação destes alelos. Como referência, considerou-se uma seleção fenotípica, feita num só sexo, em espécie alógama. Calcularam-se 360 valores do acréscimo, fazendo variar os principais fatores determinantes do limite seletivo. Apesar das restrições, concluiu-se, de modo geral que: o limite da seleção é extremamente prejudicado quando se combinam baixa herdabilidade (h2), pequeno tamanho efetivo (Ne), fraca intensidade de seleção (K), baixas frequências iniciais dos alelos favoráveis e um caráter governado por genes de efeitos pequenos. Estando um desses fatores em condições desfavoráveis é possível compensá-lo adequando os demais. Manter alto Ne tende a compensar a inadequação dos demais; isto porém, só é recomendável se não prejudicar a intensidade de seleção (k), pois desta depende o progresso imediato. A baixa precisão experimental reduz h2, exigindo maiores Ne. O produto Neh é indicador de quanto se deve aumentar Ne quando h2 diminui. Discute-se a adaptação do modelo a dados de milho (Zea mays L.) e o uso de populações locais, que só têm a vantagem da adaptação. Verificou-se que 80% a 85% da variação dos acréscimos nas frequências gênicas é devido a fatores que podem ser manipulados pelo melhorista, podendo ser escolhidos esquemas que garantam não só o progresso imediato como um elevado platô seletivo. Pesquisa Agropecuaria BrasileiraPesquisa Agropecuária BrasileiraPereira, Mauricio B.Vencovski, Roland2014-04-17info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionapplication/pdfhttps://seer.sct.embrapa.br/index.php/pab/article/view/13961Pesquisa Agropecuaria Brasileira; v.23, n.7, jul. 1988; 769-780Pesquisa Agropecuária Brasileira; v.23, n.7, jul. 1988; 769-7801678-39210100-104xreponame:Pesquisa Agropecuária Brasileira (Online)instname:Empresa Brasileira de Pesquisa Agropecuária (Embrapa)instacron:EMBRAPAporhttps://seer.sct.embrapa.br/index.php/pab/article/view/13961/7932info:eu-repo/semantics/openAccess2014-09-15T19:39:17Zoai:ojs.seer.sct.embrapa.br:article/13961Revistahttp://seer.sct.embrapa.br/index.php/pabPRIhttps://old.scielo.br/oai/scielo-oai.phppab@sct.embrapa.br || sct.pab@embrapa.br1678-39210100-204Xopendoar:2014-09-15T19:39:17Pesquisa Agropecuária Brasileira (Online) - Empresa Brasileira de Pesquisa Agropecuária (Embrapa)false |
dc.title.none.fl_str_mv |
Limits in recurrent selection. I. Factors affecting the increment in allelic frequencies Limites da seleção recorrente. I. Fatores que afetam o acréscimo das frequências alélicas |
title |
Limits in recurrent selection. I. Factors affecting the increment in allelic frequencies |
spellingShingle |
Limits in recurrent selection. I. Factors affecting the increment in allelic frequencies Pereira, Mauricio B. selection limits; gene fixation; effective size; maize; Zea mays limites da seleção; fixação de genes; tamanho efetivo; milho; Zea mays |
title_short |
Limits in recurrent selection. I. Factors affecting the increment in allelic frequencies |
title_full |
Limits in recurrent selection. I. Factors affecting the increment in allelic frequencies |
title_fullStr |
Limits in recurrent selection. I. Factors affecting the increment in allelic frequencies |
title_full_unstemmed |
Limits in recurrent selection. I. Factors affecting the increment in allelic frequencies |
title_sort |
Limits in recurrent selection. I. Factors affecting the increment in allelic frequencies |
author |
Pereira, Mauricio B. |
author_facet |
Pereira, Mauricio B. Vencovski, Roland |
author_role |
author |
author2 |
Vencovski, Roland |
author2_role |
author |
dc.contributor.none.fl_str_mv |
|
dc.contributor.author.fl_str_mv |
Pereira, Mauricio B. Vencovski, Roland |
dc.subject.por.fl_str_mv |
selection limits; gene fixation; effective size; maize; Zea mays limites da seleção; fixação de genes; tamanho efetivo; milho; Zea mays |
topic |
selection limits; gene fixation; effective size; maize; Zea mays limites da seleção; fixação de genes; tamanho efetivo; milho; Zea mays |
description |
The limit of intrapopulational recurrent selection and the main factors affecting it were investigated, through the total change in allelic frequency, until total depletion of genetic variability, and was computed through the probability of ultimate fixation of favorable alleles. Half mass selection was considered as reference selection scheme, in a panmitic species. For different combinations of the main factors 360 values of the total change were calculated. Despite the restrictions, it was concluded that selection limit is strongly unfavored when we combine: a low coefficient of heritability (h2), small effective population size (Ne), weak selection intensity, low initial frequency of favorable alleles and a trait controlled by loci with small effects. When one of these factors is at an inadequate level, it can be compensated through changes in the others. High Ne values, during selection cycles, can be chosen for such compensation, provided k is not reduced correspondingly, since, in this case, immediate progress will be reduced. Low experimental precision reduces h2, so a high Ne is needed. The product Neh is a good measure of how much Ne a should be increased if h2 is reduced. The model was applied to corn yield data, and the use of local populations for breeding purposes, which have as only advantage its adaptations, was commented. It was also verified that 80% to 85% of the total change in allelic frequency variation is due to factors under the control of the breeder. This indicates that schemes can be chosen not only to assure adequate immediate progress but also appropriate selection limits. |
publishDate |
2014 |
dc.date.none.fl_str_mv |
2014-04-17 |
dc.type.none.fl_str_mv |
|
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion |
format |
article |
status_str |
publishedVersion |
dc.identifier.uri.fl_str_mv |
https://seer.sct.embrapa.br/index.php/pab/article/view/13961 |
url |
https://seer.sct.embrapa.br/index.php/pab/article/view/13961 |
dc.language.iso.fl_str_mv |
por |
language |
por |
dc.relation.none.fl_str_mv |
https://seer.sct.embrapa.br/index.php/pab/article/view/13961/7932 |
dc.rights.driver.fl_str_mv |
info:eu-repo/semantics/openAccess |
eu_rights_str_mv |
openAccess |
dc.format.none.fl_str_mv |
application/pdf |
dc.publisher.none.fl_str_mv |
Pesquisa Agropecuaria Brasileira Pesquisa Agropecuária Brasileira |
publisher.none.fl_str_mv |
Pesquisa Agropecuaria Brasileira Pesquisa Agropecuária Brasileira |
dc.source.none.fl_str_mv |
Pesquisa Agropecuaria Brasileira; v.23, n.7, jul. 1988; 769-780 Pesquisa Agropecuária Brasileira; v.23, n.7, jul. 1988; 769-780 1678-3921 0100-104x reponame:Pesquisa Agropecuária Brasileira (Online) instname:Empresa Brasileira de Pesquisa Agropecuária (Embrapa) instacron:EMBRAPA |
instname_str |
Empresa Brasileira de Pesquisa Agropecuária (Embrapa) |
instacron_str |
EMBRAPA |
institution |
EMBRAPA |
reponame_str |
Pesquisa Agropecuária Brasileira (Online) |
collection |
Pesquisa Agropecuária Brasileira (Online) |
repository.name.fl_str_mv |
Pesquisa Agropecuária Brasileira (Online) - Empresa Brasileira de Pesquisa Agropecuária (Embrapa) |
repository.mail.fl_str_mv |
pab@sct.embrapa.br || sct.pab@embrapa.br |
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1793416698160742400 |