Manioc : Portail | resultats 81 - 100 pour la recherche: Cooperative Extension

Une histoire des colonies anglaises aux Antilles: de 1649 à 1660 : thèse présentée à la faculté des lettres de l'Université de Paris
Auteur(s) : Watts, Arthur Pryor (18..-19..)
Auteurs secondaires : Université de Paris (1896-1968). Faculté des lettres
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Reports from committees : eighteen volumes. Sugar and coffee planting. Session 18 november 1847 - 5 september 1848. Part. 2
Auteur(s) : Grande Bretagne. House of commons. Library
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Le pacte de famille et l'Amérique : la politique coloniale franco-espagnole de 1760 à 1792
Auteur(s) : Renaut d'Oultre-Seille, Francis-Paul (1893-19..)
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L'abolitioniste français
Auteur(s) : Société française pour l'abolition de l'esclavage
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Histoire générale des Antilles T.4
Auteur(s) : Dessalles, Adrien (1809-1870)
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Avec les orpailleurs de Guyane
Auteur(s) : Quris, Bernard
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Genomic patterns of adaptive divergence between chromosomally differentiated sunflower species
Auteur(s) : Strasburg, Jared L SCOTTI-SAINTAGNE, Caroline Scotti, Ivan Lai, Zhao Rieseberg, Loren H.
Auteurs secondaires : Department of Biology ; Indiana University [Bloomington] Ecologie des forêts de Guyane (ECOFOG) ; Centre de Coopération Internationale en Recherche Agronomique pour le Développement (CIRAD) - Institut National de la Recherche Agronomique (INRA) - Université des Antilles et de la Guyane (UAG) - AgroParisTech - Centre National de la Recherche Scientifique (CNRS) Center for Genomics and Bioinformatics ; Indiana University [Bloomington] Department of Botany ; University of British Columbia (UBC) National Institutes of Health ( 5F32GM07240902 GM059065 ) ; National Science Foundation (DEB-0314654 DBI0421630)

Éditeur(s) : HAL CCSD Oxford University Press (OUP)
Résumé : Understanding the genetic mechanisms of speciation and basis of species differences is among the most important challenges in evolutionary biology. Two questions of particular interest are what roles divergent selection and chromosomal differentiation play in these processes. A number of recently proposed theories argue that chromosomal rearrangements can facilitate the development and maintenance of reproductive isolation and species differences by suppressing recombination within rearranged regions. Reduced recombination permits the accumulation of alleles contributing to isolation and adaptive differentiation and protects existing differences from the homogenizing effects of introgression between incipient species. Here, we examine patterns of genetic diversity and divergence in rearranged versus collinear regions in two widespread, extensively hybridizing sunflower species, Helianthus annuus and Helianthus petiolaris, using sequence data from 77 loci distributed throughout the genomes of the two species. We find weak evidence for increased genetic divergence near chromosomal break points but not within rearranged regions overall. We find no evidence for increased rates of adaptive divergence on rearranged chromosomes; in fact, collinear chromosomes show a far greater excess of fixed amino acid differences between the two species. A comparison with a third sunflower species indicates that much of the nonsynonymous divergence between H. annuus and H. petiolaris probably occurred during or soon after their formation. Our results suggest a limited role for chromosomal rearrangements in genetic divergence, but they do document substantial adaptive divergence and provide further evidence of how species integrity and genetic identity can be maintained at many loci in the face of extensive hybridization and gene flow.
ISSN: 0737-4038

hal-01032153
https://hal.archives-ouvertes.fr/hal-01032153
DOI : 10.1093/molbev/msp043

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