Quantitative Trait Locus Analysis of Stage-Specific Inbreeding Depression in the Pacific Oyster Crassostrea gigas
Abstract Inbreeding depression and genetic load have been widely observed, but their genetic basis and effects on fitness during the life cycle remain poorly understood, especially for marine animals with high fecundity and high, early mortality (type-III survivorship). A high load of recessive muta...
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Language: | English |
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Oxford University Press (OUP)
2011
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Online Access: | http://dx.doi.org/10.1534/genetics.111.131854 https://academic.oup.com/genetics/article-pdf/189/4/1473/46858168/genetics1473.pdf |
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croxfordunivpr:10.1534/genetics.111.131854 2024-06-23T07:52:16+00:00 Quantitative Trait Locus Analysis of Stage-Specific Inbreeding Depression in the Pacific Oyster Crassostrea gigas Plough, Louis V Hedgecock, Dennis 2011 http://dx.doi.org/10.1534/genetics.111.131854 https://academic.oup.com/genetics/article-pdf/189/4/1473/46858168/genetics1473.pdf en eng Oxford University Press (OUP) https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model Genetics volume 189, issue 4, page 1473-1486 ISSN 1943-2631 journal-article 2011 croxfordunivpr https://doi.org/10.1534/genetics.111.131854 2024-06-11T04:18:08Z Abstract Inbreeding depression and genetic load have been widely observed, but their genetic basis and effects on fitness during the life cycle remain poorly understood, especially for marine animals with high fecundity and high, early mortality (type-III survivorship). A high load of recessive mutations was previously inferred for the Pacific oyster Crassostrea gigas, from massive distortions of zygotic, marker segregation ratios in F2 families. However, the number, genomic location, and stage-specific onset of mutations affecting viability have not been thoroughly investigated. Here, we again report massive distortions of microsatellite-marker segregation ratios in two F2 hybrid families, but we now locate the causative deleterious mutations, using a quantitative trait locus (QTL) interval-mapping model, and we characterize their mode of gene action. We find 14–15 viability QTL (vQTL) in the two families. Genotypic frequencies at vQTL generally suggest selection against recessive or partially recessive alleles, supporting the dominance theory of inbreeding depression. No epistasis was detected among vQTL, so unlinked vQTL presumably have independent effects on survival. For the first time, we track segregation ratios of vQTL-linked markers through the life cycle, to determine their stage-specific expression. Almost all vQTL are absent in the earliest life stages examined, confirming zygotic viability selection; vQTL are predominantly expressed before the juvenile stage (90%), mostly at metamorphosis (50%). We estimate that, altogether, selection on vQTL caused 96% mortality in these families, accounting for nearly all of the actual mortality. Thus, genetic load causes substantial mortality in inbred Pacific oysters, particularly during metamorphosis, a critical developmental transition warranting further investigation. Article in Journal/Newspaper Crassostrea gigas Pacific oyster Oxford University Press Pacific Genetics 189 4 1473 1486 |
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Oxford University Press |
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croxfordunivpr |
language |
English |
description |
Abstract Inbreeding depression and genetic load have been widely observed, but their genetic basis and effects on fitness during the life cycle remain poorly understood, especially for marine animals with high fecundity and high, early mortality (type-III survivorship). A high load of recessive mutations was previously inferred for the Pacific oyster Crassostrea gigas, from massive distortions of zygotic, marker segregation ratios in F2 families. However, the number, genomic location, and stage-specific onset of mutations affecting viability have not been thoroughly investigated. Here, we again report massive distortions of microsatellite-marker segregation ratios in two F2 hybrid families, but we now locate the causative deleterious mutations, using a quantitative trait locus (QTL) interval-mapping model, and we characterize their mode of gene action. We find 14–15 viability QTL (vQTL) in the two families. Genotypic frequencies at vQTL generally suggest selection against recessive or partially recessive alleles, supporting the dominance theory of inbreeding depression. No epistasis was detected among vQTL, so unlinked vQTL presumably have independent effects on survival. For the first time, we track segregation ratios of vQTL-linked markers through the life cycle, to determine their stage-specific expression. Almost all vQTL are absent in the earliest life stages examined, confirming zygotic viability selection; vQTL are predominantly expressed before the juvenile stage (90%), mostly at metamorphosis (50%). We estimate that, altogether, selection on vQTL caused 96% mortality in these families, accounting for nearly all of the actual mortality. Thus, genetic load causes substantial mortality in inbred Pacific oysters, particularly during metamorphosis, a critical developmental transition warranting further investigation. |
format |
Article in Journal/Newspaper |
author |
Plough, Louis V Hedgecock, Dennis |
spellingShingle |
Plough, Louis V Hedgecock, Dennis Quantitative Trait Locus Analysis of Stage-Specific Inbreeding Depression in the Pacific Oyster Crassostrea gigas |
author_facet |
Plough, Louis V Hedgecock, Dennis |
author_sort |
Plough, Louis V |
title |
Quantitative Trait Locus Analysis of Stage-Specific Inbreeding Depression in the Pacific Oyster Crassostrea gigas |
title_short |
Quantitative Trait Locus Analysis of Stage-Specific Inbreeding Depression in the Pacific Oyster Crassostrea gigas |
title_full |
Quantitative Trait Locus Analysis of Stage-Specific Inbreeding Depression in the Pacific Oyster Crassostrea gigas |
title_fullStr |
Quantitative Trait Locus Analysis of Stage-Specific Inbreeding Depression in the Pacific Oyster Crassostrea gigas |
title_full_unstemmed |
Quantitative Trait Locus Analysis of Stage-Specific Inbreeding Depression in the Pacific Oyster Crassostrea gigas |
title_sort |
quantitative trait locus analysis of stage-specific inbreeding depression in the pacific oyster crassostrea gigas |
publisher |
Oxford University Press (OUP) |
publishDate |
2011 |
url |
http://dx.doi.org/10.1534/genetics.111.131854 https://academic.oup.com/genetics/article-pdf/189/4/1473/46858168/genetics1473.pdf |
geographic |
Pacific |
geographic_facet |
Pacific |
genre |
Crassostrea gigas Pacific oyster |
genre_facet |
Crassostrea gigas Pacific oyster |
op_source |
Genetics volume 189, issue 4, page 1473-1486 ISSN 1943-2631 |
op_rights |
https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model |
op_doi |
https://doi.org/10.1534/genetics.111.131854 |
container_title |
Genetics |
container_volume |
189 |
container_issue |
4 |
container_start_page |
1473 |
op_container_end_page |
1486 |
_version_ |
1802643527391248384 |