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Variabilidade e base genética da pungência e de caracteres do fruto: implicações no melhoramento de uma população de Capsicum annuum L..; Variability and genetic basis of pungency and fruit characters: implications in the breeding of a capsicum annuum l. population.

Wagner, Caroline Moor
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 10/04/2003 PT
Relevância na Pesquisa
46.08%
Este trabalho está inserido no programa de melhoramento genético de Capsicum da Embrapa Hortaliças. Teve como principal objetivo investigar a base genética e a variabilidade de uma população segregante de Capsicum em relação à pungência e a alguns caracteres do fruto para, fornecer informações úteis ao programa. Os genótipos utilizados compreenderam dois genitores homozigóticos contrastantes para o caráter principal, a pungência, bem como as respectivas gerações F1, RC11 e progênies F4.3. Estas últimas num total de 100, foram obtidas pelo método SSD (single seed descent). Empregou-se delineamento em blocos casualizados com três repetições e dez plantas por parcela. As análises biométricas foram feitas com base em médias de parcelas. Os caracteres avaliados foram: pungência, produtividade, largura, comprimento, número e peso médio dos frutos e espessura da polpa. Investigou-se a segregação fenotípica das progênies F4.3, classificando-as em pungentes e doces. Estimou-se o coeficiente de herdabilidade na base de médias de progênies em todos os caracteres. Simulando uma seleção entre progênies somente para a pungência, tanto para aumento como redução deste caráter, estimou-se o ganho esperado (Gs) sob intensidades de 20%...

"Abordagem genética para seleção de um conjunto reduzido de características para construção de ensembles de redes neurais: aplicação à língua eletrônica" ; A genetic approach to feature subset selection for construction of neural network ensembles: an application to gustative sensors

Ferreira, Ednaldo José
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 10/08/2005 PT
Relevância na Pesquisa
46.08%
As características irrelevantes, presentes em bases de dados de diversos domínios, deterioram a acurácia de predição de classificadores induzidos por algoritmos de aprendizado de máquina. As bases de dados geradas por uma língua eletrônica são exemplos típicos onde a demasiada quantidade de características irrelevantes e redundantes prejudicam a acurácia dos classificadores induzidos. Para lidar com este problema, duas abordagens podem ser utilizadas. A primeira é a utilização de métodos para seleção de subconjuntos de características. A segunda abordagem é por meio de ensemble de classificadores. Um ensemble deve ser constituído por classificadores diversos e acurados. Uma forma efetiva para construção de ensembles de classificadores é por meio de seleção de características. A seleção de características para ensemble tem o objetivo adicional de encontrar subconjuntos de características que promovam acurácia e diversidade de predição nos classificadores do ensemble. Algoritmos genéticos são técnicas promissoras para seleção de características para ensemble. No entanto, a busca genética, assim como outras estratégias de busca, geralmente visam somente a construção do ensemble, permitindo que todas as características (relevantes...

Avaliação de progênies F2:4 de uma população de soja e perspectivas de melhoramento; Evaluation of F2:4 progenies of a soybean population and breeding perspectives

Farias, Guilherme José
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 21/01/2009 PT
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Os objetivos do presente trabalho compreenderam a obtenção de estimativas de parâmetros genéticos e fenotípicos, como variâncias, correlações, herdabilidades e respostas à seleção, em uma população derivada do cruzamento entre as linhagens 14 e 56 de soja, contrastantes para produção de grãos. Os tratamentos consistiram de uma amostra de 89 progênies F2:4 e 11 testemunhas comerciais, que foram avaliadas em experimentos em látice triplo 10 x 10 no ano agrícola 2007/08 na Estação Experimental Anhembi do Departamento de Genética da ESALQ/USP, localizada em Piracicaba, SP. A parcela experimental foi constituída de uma linha de 2 m de comprimento, espaçada de 0,5 m, contendo 35 plantas no estande ideal, após o desbaste. Foram avaliados os seguintes caracteres: dias até a maturação (DM), altura das plantas na maturação (AM), acamamento (AC) e produção de grãos (PG). As estimativas dos coeficientes de herdabilidade entre médias de progênies foram: elevada para AM (77,4%), mediana para DM (32,3%) e baixas para AC e PG (18,1% e 19,0%, respectivamente). Entretanto, os coeficientes de variação genética foram muito baixos para DM e AC (0,37% e 1,61%, respectivamente), e mais altos para AM e PG (6,80% e 6,83%...

Seleção de características por meio de algoritmos genéticos para aprimoramento de rankings e de modelos de classificação; Feature selection by genetic algorithms to improve ranking and classification models

Silva, Sérgio Francisco da
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 25/04/2011 PT
Relevância na Pesquisa
46.13%
Sistemas de recuperação de imagens por conteúdo (Content-based image retrieval { CBIR) e de classificação dependem fortemente de vetores de características que são extraídos das imagens considerando critérios visuais específicos. É comum que o tamanho dos vetores de características seja da ordem de centenas de elementos. Conforme se aumenta o tamanho (dimensionalidade) do vetor de características, também se aumentam os graus de irrelevâncias e redundâncias, levando ao problema da "maldição da dimensionalidade". Desse modo, a seleção das características relevantes é um passo primordial para o bom funcionamento de sistemas CBIR e de classificação. Nesta tese são apresentados novos métodos de seleção de características baseados em algoritmos genéticos (do inglês genetic algorithms - GA), visando o aprimoramento de consultas por similaridade e modelos de classificação. A família Fc ("Fitness coach") de funções de avaliação proposta vale-se de funções de avaliação de ranking, para desenvolver uma nova abordagem de seleção de características baseada em GA que visa aprimorar a acurácia de sistemas CBIR. A habilidade de busca de GA considerando os critérios de avaliação propostos (família Fc) trouxe uma melhora de precisão de consultas por similaridade de até 22% quando comparado com métodos wrapper tradicionais para seleção de características baseados em decision-trees (C4.5)...

Genome-Wide Analysis Reveals Selection for Important Traits in Domestic Horse Breeds

Petersen, Jessica L.; Mickelson, James R.; Rendahl, Aaron K.; Valberg, Stephanie J.; Andersson, Lisa S.; Axelsson, Jeanette; Bailey, Ernie; Bannasch, Danika; Binns, Matthew M.; Borges, Alexandre S.; Brama, Pieter; da Câmara Machado, Artur; Capomaccio, St
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica
ENG
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Intense selective pressures applied over short evolutionary time have resulted in homogeneity within, but substantial variation among, horse breeds. Utilizing this population structure, 744 individuals from 33 breeds, and a 54,000 SNP genotyping array, breed-specific targets of selection were identified using an FST-based statistic calculated in 500-kb windows across the genome. A 5.5-Mb region of ECA18, in which the myostatin (MSTN) gene was centered, contained the highest signature of selection in both the Paint and Quarter Horse. Gene sequencing and histological analysis of gluteal muscle biopsies showed a promoter variant and intronic SNP of MSTN were each significantly associated with higher Type 2B and lower Type 1 muscle fiber proportions in the Quarter Horse, demonstrating a functional consequence of selection at this locus. Signatures of selection on ECA23 in all gaited breeds in the sample led to the identification of a shared, 186-kb haplotype including two doublesex related mab transcription factor genes (DMRT2 and 3). The recent identification of a DMRT3 mutation within this haplotype, which appears necessary for the ability to perform alternative gaits, provides further evidence for selection at this locus. Finally, putative loci for the determination of size were identified in the draft breeds and the Miniature horse on ECA11...

Evaluation of mature cow weight: Genetic correlations with traits used in selection indices, correlated responses, and genetic trends in Nelore cattle

Boligon, A. A.; Carvalheiro, R.; Albuquerque, L. G.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 20-28
ENG
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Genetic correlations of selection indices and the traits considered in these indices with mature weight (MW) of Nelore females and correlated responses were estimated to determine whether current selection practices will result in an undesired correlated response in MW. Genetic trends for weaning and yearling indices and MW were also estimated. Data from 612,244 Nelore animals born between 1984 and 2010, belonging to different beef cattle evaluation programs from Brazil and Paraguay, were used. The following traits were studied: weaning conformation (WC), weaning precocity (WP), weaning muscling (WM), yearling conformation (YC), yearling precocity (YP), yearling muscling (YM), weaning and yearling indices, BW gain from birth to weaning (BWG), postweaning BW gain (PWG), scrotal circumference (SC), and MW. The variance and covariance components were estimated by Bayesian inference in a multitrait analysis, including all traits in the same analysis, using a nonlinear (threshold) animal model for visual scores and a linear animal model for the other traits. The mean direct heritabilities were 0.21 ± 0.007 (WC), 0.22 ± 0.007 (WP), 0.20 ± 0.007 (WM), 0.43 ± 0.005 (YC), 0.40 ± 0.005 (YP), 0.40 ± 0.005 (YM), 0.17 ± 0.003 (BWG), 0.21 ± 0.004 (PWG)...

Genetic Diversity in the Modern Horse Illustrated from Genome-Wide SNP Data

Petersen, Jessica L.; Mickelson, James R.; Cothran, E. Gus; Andersson, Lisa S.; Axelsson, Jeanette; Bailey, Ernie; Bannasch, Danika; Binns, Matthew M.; Borges, Alexandre S.; Brama, Pieter; da Câmara Machado, Artur; Distl, Ottmar; Felicetti, Michela; Fox-
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
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Horses were domesticated from the Eurasian steppes 5,000-6,000 years ago. Since then, the use of horses for transportation, warfare, and agriculture, as well as selection for desired traits and fitness, has resulted in diverse populations distributed across the world, many of which have become or are in the process of becoming formally organized into closed, breeding populations (breeds). This report describes the use of a genome-wide set of autosomal SNPs and 814 horses from 36 breeds to provide the first detailed description of equine breed diversity. FST calculations, parsimony, and distance analysis demonstrated relationships among the breeds that largely reflect geographic origins and known breed histories. Low levels of population divergence were observed between breeds that are relatively early on in the process of breed development, and between those with high levels of within-breed diversity, whether due to large population size, ongoing outcrossing, or large within-breed phenotypic diversity. Populations with low within-breed diversity included those which have experienced population bottlenecks, have been under intense selective pressure, or are closed populations with long breed histories. These results provide new insights into the relationships among and the diversity within breeds of horses. In addition these results will facilitate future genome-wide association studies and investigations into genomic targets of selection. © 2013 Petersen et al.

Evolução do gene da esterase E3 : avaliação dos efeitos da seleção e distribuição geográfica de mutações associadas à resistência a inseticidas em Cochliomyia hominivorax (Diptera: Calliphoridae); Esterase E3 gene evolution : selection effects and geographic distribution of mutations associated to insecticide resistance in Cochliomyia hominivorax (Diptera: Calliphoridae)

Luana Walravens Bergamo
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 25/03/2014 PT
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A pecuária é uma importante atividade econômica do Brasil, mas tem sofrido perdas significativas devido ao impacto de parasitas. Neste cenário destaca-se a mosca-da-bicheira, Cochliomyia hominivorax, que é um importante ectoparasita causador de miíase primária e endêmico das Américas. Sua distribuição geográfica sofreu redução a partir da implementação da técnica do inseto estéril (SIT), sendo considerada erradicada nos Estados Unidos e países continentais da América Central. Na América do Sul, o controle desta espécie é realizado através de inseticidas, cujo uso indiscriminado pode acarretar na seleção de indivíduos resistentes. Em estudos anteriores, as mutações denominadas Gly137Asp e Trp251Leu foram observadas no sítio ativo da enzima carboxilesterase E3 e associadas à resistência a inseticidas dietil e dimetil-organofosforados, respectivamente. A caracterização molecular da região desse gene que compreende desde o final do éxon 2 até o final do éxon 4 para C. hominivorax revelou que o íntron I2 apresenta um tamanho maior que em outras espécies de Muscomorpha. A análise da composição nucleotídica e comparações por métodos estatísticos entre modelos de mutação-seleção de sequências do cDNA da carboxilesterase E3 de C. hominivorax e outros Muscomorpha mostraram sinais de seleção restritiva sobre as substituições sinônimas. Porém...

Prediction of genetic gain from selection indices for disease resistance in papaya hybrids

Vivas,Marcelo; Silveira,Silvaldo Felipe da; Pereira,Messias Gonzaga
Fonte: Universidade Federal de Viçosa Publicador: Universidade Federal de Viçosa
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2012 EN
Relevância na Pesquisa
46.01%
In order to select superior hybrids for the concentration of favorable alleles for resistance to papaya black spot, powdery mildew and phoma spot, 67 hybrids were evaluated in two seasons, in 2007, in a randomized block design with two replications. Genetic gains were estimated from the selection indices of Smith & Hazel, Pesek & Baker, Williams, Mulamba & Mock, with selection intensity of 22.39%, corresponding to 15 hybrids. The index of Mulamba & Mock showed gains more suitable for the five traits assessed when it was used the criterion of economic weight tentatively assigned. Together, severity of black spot on leaves and on fruits, characteristics considered most relevant to the selection of resistant materials, expressed percentage gain of -44.15%. In addition, there were gains for other characteristics, with negative predicted selective percentage gain. The results showed that the index of Mulamba & Mock is the most efficient procedure for simultaneous selection of papaya hybrid resistant to black spot, powdery mildew and phoma spot.

Breeding strategies for recurrent selection of maize

Viana,José Marcelo Soriano
Fonte: Embrapa Informação Tecnológica; Pesquisa Agropecuária Brasileira Publicador: Embrapa Informação Tecnológica; Pesquisa Agropecuária Brasileira
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/2007 EN
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The objectives of this work were to analyze theoretical genetic gains of maize due to recurrent selection among full-sib and half-sib families, obtained by Design I, Full-Sib Design and Half-Sib Design, and genotypic variability and gene loss with long term selection. The designs were evaluated by simulation, based on average estimated gains after ten selection cycles. The simulation process was based on seven gene systems with ten genes (with distinct degrees of dominance), three population classes (with different gene frequencies), under three environmental conditions (heritability values), and four selection strategies. Each combination was repeated ten times, amounting to 25, 200 simulations. Full-sib selection is generally more efficient than half-sib selection, mainly with favorable dominant genes. The use of full-sib families derived by Design I is generally more efficient than using progenies obtained by Full-Sib Design. Using Design I with 50 males and 200 females (effective size of 160) did not result in improved populations with minimum genotypic variability. In the populations with lower effective size (160 and 400) the loss of favorable genes was restricted to recessive genes with reduced frequencies.

Responses to reciprocal recurrent selection and changes in genetic variability in IG-1 and IG-2 maize populations

Santos,Mateus Figueiredo; Moro,Gustavo Vitti; Aguiar,Aurélio Mendes; Souza Jr.,Cláudio Lopes de
Fonte: Sociedade Brasileira de Genética Publicador: Sociedade Brasileira de Genética
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2005 EN
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46.07%
This paper reports the effects of three cycles of reciprocal recurrent selection (RRS) on the means, genetic variances, and on the genetic correlations for several traits in the IG-1 and IG-2 maize (Zea mays L.) populations. Interpopulation full-sib progenies from cycle zero (C0) and from cycle 3 (C3) of RRS were evaluated in two locations. RRS was highly effective to improve the traits according the objectives of the program: grain yield and prolificacy increased significantly, while plant height, ear height, and ear placement decreased significantly. Genetic variances for all traits decreased significantly from C0 to C3, but the genetic correlations did not change consistently across the cycles of selection. The expected responses to the fourth cycle of RRS and the probability of selecting double-crosses from C3 that outperform those from C0 showed that the decreases in the genetic variances were not great enough to limit the continued improvement of the populations as well as the use of the improved populations as sources of inbred lines to develop commercial hybrids. However, if the magnitudes of the genetic variances continue to decrease, new sources of improved germplasm should be incorporated into both populations to allow the continued improvement of the interpopulation by RRS.

Artificial family selection based on growth rate in cultivated lines of Litopenaeus vannamei (Decapoda, Penaeidae) from Venezuela

De Donato,Marcos; Ramirez,Raúl; Howell,Chris; Verginelli,Roberto; Orta,Tomás; Cabrera,Saúl; Mata,Enrique; Manrique,Ramón
Fonte: Sociedade Brasileira de Genética Publicador: Sociedade Brasileira de Genética
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2008 EN
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45.97%
We investigated the effects of family selection on the growth rates of four genetic lines of Litopenaeus vannamei, the Pacific white shrimp, from Venezuela. The mean family weight at selection was 16.79 g and the mean growth rate was 0.169 g d-1 at a mean age of 138 days. The mean growth rates per generation were 0.141 g d-1 for the parental generation (P0), 0.173 g d-1 for the F1 and 0.191 g d-1 for the F2. Survival varied from 83.3% to 94.4%. There were statistically significant differences between lines, with lines B and C, growing at higher temperatures and lower salinities, showing the fastest growth. Regression analysis between growth rate and age for each genetic line showed high r² values, but smaller than those shown between growth rate and generation. The mean heritability (h²) estimated for growth rate was 0.25 ± 0.04, with line per generation values ranging from 0.18 to 0.38. The mean heritability for growth rate per line showed some variation but there was no correlation between heritability and growth rate. Females showed a greater gain in growth rate per generation than males due to their faster growth when they were older. This study shows the high potential of these L. vannamei populations for the future of shrimp culture in the Americas.

Determinação da variabilidade genética nas populações de seleção recorrente de arroz CNA-IRAT 4 e CNA 12 utilizando marcadores microssatélites; Determination of the genetic variability in rice populations of recurrent selection CNA-IRAT 4 and CNA 12 using microssatellites markers

PINHEIRO, Letícia da Silveira
Fonte: Universidade Federal de Goiás; BR; UFG; Mestrado em Agronomia; Ciências Agrárias Publicador: Universidade Federal de Goiás; BR; UFG; Mestrado em Agronomia; Ciências Agrárias
Tipo: Dissertação Formato: application/pdf
POR
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Recurrent Selection is a population inbreed method that is not traditionally used in autogamous species as rice. However, it is still an interesting methodology to the implementation of recurrent selection populations, due to the possibility of obtaining genotypes with wide genetic base and adequate agronomical traits. It is even more attractive when a great genetic variability is easily available, as it is for rice and could be largely used in the development of more productive elite cultivars and with a better production stability even under low input agricultural systems. Two recurrent selection irrigated rice populations, developed by Embrapa Arroz e Feijão, were synthetized using different recombination methods. The CNA-IRAT 4 population was developed in field conditions using male-sterelity, while the CNA 12 population originated from manual crosses in a circulant partial diallel scheme. The aim of this work was the evaluation of the genetic variability among cycles of the two recurrent selection populations using fourteen SSR markers. Hundred and eighty genotypes of the cycles 1, 2 and 5 of CNA-IRAT 4 population and cycles 1 and 2 of CNA 12, were evaluated. The AMOVA did not indicate any genetic structure among the cycles of selection...

Genetic control of traits associated with maize seed quality

Fonte: Consiglio per la Ricerca e la sperimentazione in Agricoltura, Unità di Ricerca per la Valorizzazione qualitativa dei cereali (CRA-QCE) Publicador: Consiglio per la Ricerca e la sperimentazione in Agricoltura, Unità di Ricerca per la Valorizzazione qualitativa dei cereali (CRA-QCE)
Tipo: Artigo de Revista Científica
EN_US
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46.02%
The aim of this work was to estimate genetic parameters for traits associated with maize seed quality of two populations in an interpopulational recurrent selection for this trait. Two populations derived from singlecross commercial hybrids and currently in Hardy-Weinberg equilibrium (1 and 2) were used for these experiments. Initially 169 half-sib progenies were obtained from each population. All progenies were sown in two isolated fields. The pollinator from one field was population 1 and the pollinator was the opposite population on the other field, all developed under similar conditions. The ears harvested by hand, in both isolated fields were bulked, resulting in a “half-sib progeny bulk”. This seed production method produced an adequate quantity of same-ageseed of each intra and inter progenies to use in the seed quality tests. The seed produced was initially separated using screens and were evaluated seeds of the same size in the germination test (GT), speed of germination index (SGI) and the accelerated aging test (AAT). Each plot consisted of 25 seeds and the design was completely randomized (one way classification) with four replications. The genetic and phenotypic parameters were estimated based on the mean square expectations of variance and covariance analyses. The populations of intra and interpopulational half-sibs differed in seed quality. The heterosis estimates were of low magnitude 4.5% in the GT...

Impairment of organ-specific T cell negative selection by diabetes susceptibility genes: genomic analysis by mRNA profiling

Liston, Adrian; Hardy, Kristine; Pittelkow, Yvonne; Wilson, Susan R; Makaroff, Lydia E; Fahrer, Aude M; Goodnow, Christopher C
Fonte: BioMed Central Publicador: BioMed Central
Tipo: Artigo de Revista Científica
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BACKGROUND T cells in the thymus undergo opposing positive and negative selection processes so that the only T cells entering circulation are those bearing a T cell receptor (TCR) with a low affinity for self. The mechanism differentiating negative from positive selection is poorly understood, despite the fact that inherited defects in negative selection underlie organ-specific autoimmune disease in AIRE-deficient people and the non-obese diabetic (NOD) mouse strain RESULTS Here we use homogeneous populations of T cells undergoing either positive or negative selection in vivo together with genome-wide transcription profiling on microarrays to identify the gene expression differences underlying negative selection to an Aire-dependent organ-specific antigen, including the upregulation of a genomic cluster in the cytogenetic band 2F. Analysis of defective negative selection in the autoimmune-prone NOD strain demonstrates a global impairment in the induction of the negative selection response gene set, but little difference in positive selection response genes. Combining expression differences with genetic linkage data, we identify differentially expressed candidate genes, including Bim, Bnip3, Smox, Pdrg1, Id1, Pdcd1, Ly6c, Pdia3, Trim30 and Trim12. CONCLUSION The data provide a molecular map of the negative selection response in vivo and...

Divergent patterns of selection on the DAB and DXB MHC class II loci in Xiphophorus fishes

Summers, K.; Roney, K.; Da Silva, J.; Capraro, G.; Cuthbertson, B.; Kazianis, S.; Rosenthal, G.; Ryan, M.; McConnell, T.
Fonte: Kluwer Academic Publ Publicador: Kluwer Academic Publ
Tipo: Artigo de Revista Científica
Publicado em //2009 EN
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Two MHC class II loci, DAB (a classical class II locus) and DXB (putatively a non-classical class II locus), were sequenced in samples of individuals from two populations of swordtail fish, Xiphophorus multilineatus and X. pygmaeus. The DAB locus showed higher levels of genetic variation in the B1-encoding region, (putative binding region) than the DXB locus. We used two methods to investigate dN/dS ratios. The results from a maximum likelihood method based on phylogenetic relationships indicated positive selection on the B1 region of DAB (this method could not be used on DXB). Results from a coalescent-based method also showed evidence for positive selection in the B1 region of DAB, but only weak evidence for selection on the DXB. Further analyses indicated that recombination is an important source of variation in the B1 region of DAB, but has a relatively small effect on DXB. Overall, our results were consistent with the hypothesis that the DAB locus is under positive selection driven by antagonistic coevolution, and that the DXB locus plays the role of a non-classical MHC II locus. We also used simulations to investigate the presence of an elevated synonymous substitution rate in the binding region. The simulations revealed that the elevated rate could be caused by an interaction between positive selection and codon bias.; Copyright © Springer Science+Business Media B.V. 2008

One cycle of phenotypic selection combined with marker assisted selection for improving yield and quality in cucumber

Behera, T.K.; Staub, J.E.; Behera, S.; Rao, A.R.; Mason, S.
Fonte: INRA. Centre de Recherche d'Avignon. Unité Génétique et Amélioration des Fruits et Légumes, Montfavet (France) Publicador: INRA. Centre de Recherche d'Avignon. Unité Génétique et Amélioration des Fruits et Légumes, Montfavet (France)
Tipo: Conference Paper
EN; ENG
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45.96%
Estimation of response to marker-assisted selection (MAS) is critical to breeding programs. To investigate MAS for line development, two cucumber recombinant inbred lines (RILs) (7026B76 and 7022C8) differing in plant habit were mated, and F4 and F5 progeny were MAS selected to improve both yield and quality. The broad-sense heritability (h2B) ranged from 0.22 to 0.45 for yield (fruits per plant), and from 0.09 to 0.20 for fruit length:diamter ratio (L:D). Selection was effective in maintaining phenotypic performance in F4 progeny, but not after advanced generation (F5) progeny selection (i.e., yield decreased, but fruit quality was maintained). The lack of response may be due to low trait heritability.; Cucurbitaceae 2008. IX EUCARPIA Meeting. Avignon (France), May 21-24th, 2008

Mate choice for genetic quality when environments vary: suggestions for empirical progress

Bussiere, Luc F; Hunt, J.; Stolting, K N; Jennions, Michael; Brooks, Rob
Fonte: Kluwer Academic Publishers Publicador: Kluwer Academic Publishers
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
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Mate choice for good-genes remains one of the most controversial evolutionary processes ever proposed. This is partly because strong directional choice should theoretically deplete the genetic variation that explains the evolution of this type of female m

Speeding up microevolution: the effects of increasing temperature on selection and genetic variance in a wild bird population

Husby, Arild; Visser, Marcel E.; Kruuk, Loeske E. B.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica Formato: 9 pages
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46.1%
The amount of genetic variance underlying a phenotypic trait and the strength of selection acting on that trait are two key parameters that determine any evolutionary response to selection. Despite substantial evidence that, in natural populations, both parameters may vary across environmental conditions, very little is known about the extent to which they may covary in response to environmental heterogeneity. Here we show that, in a wild population of great tits (Parus major), the strength of the directional selection gradients on timing of breeding increased with increasing spring temperatures, and that genotype-by-environment interactions also predicted an increase in additive genetic variance, and heritability, of timing of breeding with increasing spring temperature. Consequently, we therefore tested for an association between the annual selection gradients and levels of additive genetic variance expressed each year; this association was positive, but non-significant. However, there was a significant positive association between the annual selection differentials and the corresponding heritability. Such associations could potentially speed up the rate of micro-evolution and offer a largely ignored mechanism by which natural populations may adapt to environmental changes.; This work was conducted as part of a GENACT Project studentship to AH...

Assessing the potential for an ongoing arms race within and between the sexes: selection and heritable variation

Friberg, Urban; Lew, Timothy; Byrne, Phillip G; Rice, William
Fonte: Society for the Study of Evolution Publicador: Society for the Study of Evolution
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
45.99%
In promiscuous species, sexual selection generates two opposing male traits: offense (acquiring new mates and supplanting stored sperm) and defense (enforcing fidelity on one's mates and preventing sperm displacement when this fails). Coevolution between