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| Registros recuperados: 11 | |
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| BACH,JEAN-FRANÇOIS. |
| Abstract: Genetic drift is the fortuitous occurrence of genetic events that when they become fixed modify the genome of populations. They can take the form of mutations of single nucleotides (SNPs), the insertion or deletion of short sequences (Indels) or the repetitions of short sequences (CNV i.e. copy number variants) or long insertions or deletion (structural modifications). Their frequency is 10-9 to 10-8 depending on the species, or 50 to 100 per birth in humans. The incidence of these de novo mutations is higher when the father is old at conception. It thus appears that genetic drift, which constitutes the initial element of evolution, has a very strong dynamics. Its intervention in the appearance or disappearance of some major phenotypes is... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Genetic drift; Genome of populations; De novo mutations; Inbred mouse strains. |
| Ano: 2019 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652019000600613 |
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| Ghafouri-Kesbi,Farhad. |
| The aim of this study was to monitor changes in genetic size of a small-closed population of Iranian Zandi sheep, by using pedigree information from animals born between 1991 and 2005. The genetic size was assessed by using measures based on the probability of identity-by-descend of genes (coancestry, f, and effective population size, Ne), as well as measures based on probability of gene origin (effective number of founders, f e, effective number of founder genomes, f g, and effective number of non-founder genomes, f ne). Average coancestry, or the degree of genetic similarity of individuals, increased from 0.81% to 1.44% during the period 1993 to 2005, at the same time that Ne decreased from 263 to 93. The observed trend for f e was irregular throughout... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Pedigree; Effective size; Genetic drift; Genetic diversity; Genetic similarity; Sheep. |
| Ano: 2010 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572010000400011 |
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| Santos,Silvana; Kok,Fernando; Weller,Mathias; Paiva,Francisco Rennan Lopes de; Otto,Paulo A.. |
| A new autosomal recessive genetic condition, the SPOAN syndrome (an acronym for spastic paraplegia, optic atrophy and neuropathy syndrome), was recently discovered in an isolated region of the State of Rio Grande do Norte in Northeast Brazil, in a population that was identified by the IBGE (Brazilian Institute of Geography and Statistics) as belonging to the Brazilian communities with the highest rates of "deficiencies" (Neri, 2003), a term used to describe diseases, malformations, and handicaps in general. This prompted us to conduct a study of consanguinity levels in five of its municipal districts by directly interviewing their inhabitants. Information on 7,639 couples (corresponding to about 40% of the whole population of the studied districts) was... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Inbreeding levels; Genetic drift; Geographic isolation. |
| Ano: 2010 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572010000200003 |
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| Taris, Nicolas; Sauvage, Christopher; Ernande, Bruno; Batista, Frederico; Boudry, Pierre. |
| Hatchery techniques are now well handled in an increasing number of aquaculture species. However, unintentional effects of domestication often remain poorly documented. In this context, we studied how current hatchery practices may genetically influence larval traits for which significant genetic variation had previously been reported in the Pacific oyster. Two main factors were studied: culling (i.e. discarding the smallest larvae) and rearing temperature (26°C versus 20°C). In parallel, we estimated genetic diversity of broodstock populations sampled in French hatcheries. Finally, we compared larval development and settlement success in the progeny of one of these hatchery broodstock, which had been selected for seven generations, with those of wild... |
| Tipo: Text |
Palavras-chave: Genetic drift; Selection; Genetic; Crassostrea gigas; Oysters; Hatchery techniques. |
| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/2006/acte-3362.pdf |
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| Taris, Nicolas; Sauvage, Christopher; Boudry, Pierre. |
| Oysters, like many marine bivalves, are characterized by very high fecundity and low survival rate at early stages of life. Rearing conditions in hatcheries (i.e. density, feeding, temperature...) are different from those observed in the wild. Additionally, slow growing larvae are culled by sieving. As previous studies have shown that genetic variability exists for several early development traits, we aimed to assess if common hatchery rearing practices exert specific selective processes at the larval stage. In order to avoid possible bias and to increase the number of families studied, we used a mixed-family approach with subsequent parentage analysis using a recently developed set of three multiplexed microsatellite markers. We studied the variance in... |
| Tipo: Text |
Palavras-chave: Hatcheries; Selection; Genetic drift; Genetic; Crassotrea gigas; Pacific oysters. |
| Ano: 2004 |
URL: http://archimer.ifremer.fr/doc/2004/acte-3483.pdf |
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| Guinand, B; Rolland, Jean-luc; Bonhomme, Francois. |
| Coastal and estuarine areas in the Bay of Biscay are essential nursery habitats for sole (Solea solea). Using three intronic markers, we investigated patterns of genetic differentiation among cohorts of juveniles (0+, 1+, sub-adults) inhabiting four major nurseries in the Vilaine and Loire river estuaries, the Pertuis d' Antioche strait, and the Gironde estuary. Genetic differentiation was not significant for the age 0- and 1-groups, but was among sub-adult samples (theta(WC) = 0.017; P = 0.031). Hierarchical analyses of genotypic frequencies by nested multivariate ANOVA using redundancy analysis indicated that northern nurseries of Loire and Vilaine rivers had different patterns of genotypic variation with age than southern nurseries of the Pertuis d'... |
| Tipo: Text |
Palavras-chave: Selection; Genetic drift; EPIC PCR; Population genetics; Coastal nurseries; Juveniles; Flatfish. |
| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-4299.pdf |
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| Brito,Daniel. |
| Habitat fragmentation may cause population subdivision, affecting genetic variation, leading to heterozygosity loss and increased inbreeding, and contributing to population extinction. However, some genetic models have shown that under some conditions, population subdivision can favor heterozygosity and allelic diversity, and small populations may adapt to inbreeding. Here I investigate the relationship between population subdivision and genetic diversity for the marsupial Micoureus paraguayanus (Tate, 1931) using the program Vortex. Hypothetical populations of 100 and 2000 individuals were partitioned into 1, 2, 5 or 10 populations that were linked by varying rates of dispersal and also by sex-biased dispersal. Results suggested that heterozygosity and... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Genetic drift; Genetic load; Habitat fragmentation; Inbreeding; Metapopulation; Population viability analysis. |
| Ano: 2009 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1984-46702009000400013 |
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| Registros recuperados: 11 | |
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