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Registros recuperados: 10
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Change in genetic size of small-closed populations: lessons from a domestic mammal population Genet. Mol. Biol.
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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Changements adaptatifs induits par la pêche chez les populations halieutiques ArchiMer
Marty, Lise.
Fishing is an important source of mortality in harvested populations and therefore may induce adaptive responses. These responses affect life-history traits in particular, which have consequences for stocks’ dynamics, and thus can alter the demographic direct effect of fishing (i.e. the reduction in stock’s biomass). Fishing-induced adaptive changes depend, non-exclusively, on two processes: evolution and phenotypic plasticity. These two components are observed at the phenotypic level because functional genes coding for the traits undergoing adaptive changes have not yet been identified. These two origins are confounded in individual phenotypes, and the impact of adaptive changes in the long run remains therefore unclear: evolutionary changes are expected...
Tipo: Text Palavras-chave: : Pêche; Évolution adaptative; Plasticité phénotypique; Norme de réaction; Dérive génétique; Érosion génétique; Age et taille à maturation; Croissance; Survie; Trade-offs; Densité-dépendance; Gadidées de mer du nord; Fishing; Adaptive evolution; Phenotypic plasticity; Reaction norm; Genetic drift; Genetic erosion; Age and size at maturation; Growth; Survival; Trade-offs; Density-dependence; North sea Gadoids.
Ano: 2011 URL: http://archimer.ifremer.fr/doc/00079/19013/16591.pdf
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Effects of genetic drift and selection at larval stage resulting from hatchery practices in the Pacific oyster (Crassostrea gigas) ArchiMer
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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Fisheries-induced neutral and adaptive evolution in exploited fish populations and consequences for their adaptive potential ArchiMer
Marty, Lise; Dieckmann, Ulf; Ernande, Bruno.
Fishing may induce neutral and adaptive evolution affecting life-history traits, and molecular evidence has shown that neutral genetic diversity has declined in some exploited populations. Here we theoretically study the interplay between neutral and adaptive evolution caused by fishing. An individual-based eco-genetic model is devised that includes neutral and functional loci in a realistic ecological setting. In line with theoretical expectations, we find that fishing induces evolution towards slow growth, early maturation at small size, and higher reproductive investment. We show, first, that the choice of genetic model (based on either quantitative genetics or gametic inheritance) influences the evolutionary recovery of traits after fishing ceases....
Tipo: Text Palavras-chave: Eco-genetic model; Effective population size; Fisheries-induced evolution; Genetic drift; Genetic erosion; Genetic markers; Life-history traits; Natural selection and contemporary evolution.
Ano: 2015 URL: http://archimer.ifremer.fr/doc/00228/33964/33473.pdf
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Genetic consequences of population subdivision: the marsupial Micoureus paraguayanus (Mammalia: Didelphimorphia) as a case study Rev. Bras. Zool.
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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Genetic structure of the common sole (Solea solea) in the Bay of Biscay: Nurseries as units of selection? ArchiMer
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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Impact of intensive larval rearing practices in oyster hatcheries : selective processes and loss of genetic variability (slides) ArchiMer
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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Inbreeding depression in maize populations of reduced size Scientia Agricola
Maldonado,Félix Alonso Astete; Miranda Filho,José Branco de.
Inbreeding is a well known phenomenon in living beings and its immediate consequence is the decrease in the expression of quantitative traits, known as inbreeding depression. Selfing is the most common system of inbreeding in plant species; however, little has been studied with other less severe inbreeding systems, such that resulting from small population sizes. The present work consisted of the study of the inbreeding effect on quantitative traits as a consequence of reduced population size under panmixy. Three maize (Zea mays L.) populations were used in this study: P1 -- ITA, population derived from the variety IAC-Taiúba; P2 -- represented by 30 subpopulations already submmited to reduced size (N = 5); and P3 - population derived from the...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Zea mays; Genetic drift; Effective size.
Ano: 2002 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162002000200020
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Inbreeding levels in Northeast Brazil: strategies for the prospecting of new genetic disorders Genet. Mol. Biol.
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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Structure and genetic variability in Nellore (Bos indicus) cattle by pedigree analysis Genet. Mol. Biol.
Vozzi,Pedro Alejandro; Marcondes,Cíntia Righetti; Magnabosco,Cláudio de Ulhôa; Bezerra,Luiz Antonio Framartino; Lôbo,Raysildo Barbosa.
Parameters based on the probability of gene origin were used to describe the genetic variability in strains of Nellore and polled Nellore (Bos indicus) cattle that participated in the Program for Genetic Improvement of the Nellore Breed (Programa de Melhoramento Genético da Raça Nelore). The effective number of founders was 87.2 for Nellore and 107.9 for polled Nellore, while the number of ancestors was 59.8 for Nellore and 61.5 for polled Nellore and the remaining genomes were 39.4 for Nellore and 34.5 for polled Nellore cattle. The results indicate an intense use (by artificial insemination) of some sires and the absence of subdivisions in the population. The family structure in the two breeds was mainly caused by the genetic contribution of the same...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Genetic drift; Genetic variability matings; Nellore; Pedigree analysis; Probability of gene origin.
Ano: 2006 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572006000300014
Registros recuperados: 10
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