Fixation, Segregation and Linkage of Allozyme Loci in Inbred Families of the Pacific Oyster Crassostrea Gigas (Thunberg): Implications for the Causes of Inbreeding Depression
The effect that inbreeding has on the fixation and segregation of genes has rarely been confirmed by direct observation. Here, fixation, segregation, and linkage of allozymes is investigated in the progeny of self-fertilized hermaphrodites of the normally outcrossing Pacific oyster Crassostrea gigas...
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ftpubmed:oai:pubmedcentral.nih.gov:1207947 2023-05-15T15:58:06+02:00 Fixation, Segregation and Linkage of Allozyme Loci in Inbred Families of the Pacific Oyster Crassostrea Gigas (Thunberg): Implications for the Causes of Inbreeding Depression McGoldrick, D. J. Hedgecock, D. 1997-05 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1207947 http://www.ncbi.nlm.nih.gov/pubmed/9136021 en eng http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1207947 http://www.ncbi.nlm.nih.gov/pubmed/9136021 Investigations Text 1997 ftpubmed 2013-08-30T13:27:45Z The effect that inbreeding has on the fixation and segregation of genes has rarely been confirmed by direct observation. Here, fixation, segregation, and linkage of allozymes is investigated in the progeny of self-fertilized hermaphrodites of the normally outcrossing Pacific oyster Crassostrea gigas. The estimate of fixation pooled over loci, individuals, and families, F = 0.462, is significantly lower than the expected value of 0.5. Log-likelihood ratios reveal significant heterogeneity in fixation among individuals, among families, and among loci. In addition, the grand pooled segregation ratio, 127:243:54, deviates significantly from 1:2:1, with a bias against homozygotes for alleles of lesser frequency in the natural population. Segregation ratios for 11 of 14 loci are significantly heterogeneous among families, and exact tests for segregation within families reveal 16 significant results out of 51 tests. Thus, fixation and segregation of allozyme markers in inbred oyster families deviates from the expectations of neutral inbreeding theory. Di-genic disequilibria are significant for four of 74 di-locus pairs revealing two linkage groups. Strong viability selection is apparently conditional on the genotype of the hermaphrodite-founders and is largely focused on these two linkage groups. These genetic effects are explained by interaction between cis-linked factors and polymorphic regulatory backgrounds. Text Crassostrea gigas Pacific oyster PubMed Central (PMC) Pacific |
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Investigations McGoldrick, D. J. Hedgecock, D. Fixation, Segregation and Linkage of Allozyme Loci in Inbred Families of the Pacific Oyster Crassostrea Gigas (Thunberg): Implications for the Causes of Inbreeding Depression |
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Investigations |
description |
The effect that inbreeding has on the fixation and segregation of genes has rarely been confirmed by direct observation. Here, fixation, segregation, and linkage of allozymes is investigated in the progeny of self-fertilized hermaphrodites of the normally outcrossing Pacific oyster Crassostrea gigas. The estimate of fixation pooled over loci, individuals, and families, F = 0.462, is significantly lower than the expected value of 0.5. Log-likelihood ratios reveal significant heterogeneity in fixation among individuals, among families, and among loci. In addition, the grand pooled segregation ratio, 127:243:54, deviates significantly from 1:2:1, with a bias against homozygotes for alleles of lesser frequency in the natural population. Segregation ratios for 11 of 14 loci are significantly heterogeneous among families, and exact tests for segregation within families reveal 16 significant results out of 51 tests. Thus, fixation and segregation of allozyme markers in inbred oyster families deviates from the expectations of neutral inbreeding theory. Di-genic disequilibria are significant for four of 74 di-locus pairs revealing two linkage groups. Strong viability selection is apparently conditional on the genotype of the hermaphrodite-founders and is largely focused on these two linkage groups. These genetic effects are explained by interaction between cis-linked factors and polymorphic regulatory backgrounds. |
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Text |
author |
McGoldrick, D. J. Hedgecock, D. |
author_facet |
McGoldrick, D. J. Hedgecock, D. |
author_sort |
McGoldrick, D. J. |
title |
Fixation, Segregation and Linkage of Allozyme Loci in Inbred Families of the Pacific Oyster Crassostrea Gigas (Thunberg): Implications for the Causes of Inbreeding Depression |
title_short |
Fixation, Segregation and Linkage of Allozyme Loci in Inbred Families of the Pacific Oyster Crassostrea Gigas (Thunberg): Implications for the Causes of Inbreeding Depression |
title_full |
Fixation, Segregation and Linkage of Allozyme Loci in Inbred Families of the Pacific Oyster Crassostrea Gigas (Thunberg): Implications for the Causes of Inbreeding Depression |
title_fullStr |
Fixation, Segregation and Linkage of Allozyme Loci in Inbred Families of the Pacific Oyster Crassostrea Gigas (Thunberg): Implications for the Causes of Inbreeding Depression |
title_full_unstemmed |
Fixation, Segregation and Linkage of Allozyme Loci in Inbred Families of the Pacific Oyster Crassostrea Gigas (Thunberg): Implications for the Causes of Inbreeding Depression |
title_sort |
fixation, segregation and linkage of allozyme loci in inbred families of the pacific oyster crassostrea gigas (thunberg): implications for the causes of inbreeding depression |
publishDate |
1997 |
url |
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1207947 http://www.ncbi.nlm.nih.gov/pubmed/9136021 |
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Pacific |
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Pacific |
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Crassostrea gigas Pacific oyster |
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Crassostrea gigas Pacific oyster |
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1207947 http://www.ncbi.nlm.nih.gov/pubmed/9136021 |
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1766393823245631488 |