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Gene genealogies and population variation in plants / Barbara A. Schaal in Proceedings of the National Academy of Sciences of the United States of America, 97 (13) (June 2000) 

Public Citation [article]  inProceedings of the National Academy of Sciences of the United States of America > 97 (13) (June 2000) . - 235-251 Titre : Gene genealogies and population variation in plants Type de document : Imprimé Auteurs : Barbara A. Schaal ; Kenneth M. Olsen Année de publication : 2000 Article en page(s) : 235-251 Langues : Anglais (eng) Catégories : [CBNPMP-Thématique] Génétique et écologie (dynamique, démographique, sélection) [CBNPMP-Thématique] Revégétalisation Résumé : Early in the development of plant evolutionary biology, genetic drift, fluctuations in population size, and isolation were identified as critical processes that affect the course of evolution in plant species. Attempts to assess these processes in natural populations became possible only with the development of neutral genetic markers in the 1960s. More recently, the application of historically ordered neutral molecular variation (within the conceptual framework of coalescent theory) has allowed a reevaluation of these microevolutionary processes. Gene genealogies trace the evolutionary relationships among haplotypes (alleles) with populations. Processes such as selection, fluctuation in population size, and population substructuring affect the geographical and genealogical relationships among these alleles. Therefore, examination of these genealogical data can provide insights into the evolutionary history of a species. For example, studies of Arabidopsis thaliana have suggested that this species underwent rapid expansion, with populations showing little genetic differentiation. The new discipline of phylogeography examines the distribution of allele genealogies in an explicit geographical context. Phylogeographic studies of plants have documented the recolonization of European tree species from refugia subsequent to Pleistocene glaciation, and such studies have been instructive in understanding the origin and domestication of the crop cassava. Currently, several technical limitations hinder the widespread application of a genealogical approach to plant evolutionary studies. However, as these technical issues are solved, a genealogical approach holds great promise for understanding these previously elusive processes in plant evolution. Lien pérenne : DOI : 10.1073/pnas.97.13.7024 Permalink : https://biblio.cbnpmp.fr/index.php?lvl=notice_display&id=149010 Schaal, Barbara A., Olsen, Kenneth M. 2000 Gene genealogies and population variation in plants. Proceedings of the National Academy of Sciences of the United States of America, 97(13): 235-251.

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Reproductive systems and evolution in vascular plants / Kent E. Holsinger in Proceedings of the National Academy of Sciences of the United States of America, 97 (13) (June 2000) 

Public Citation [article]  inProceedings of the National Academy of Sciences of the United States of America > 97 (13) (June 2000) . - 271-288 Titre : Reproductive systems and evolution in vascular plants Type de document : Imprimé Auteurs : Kent E. Holsinger Année de publication : 2000 Article en page(s) : 271-288 Langues : Anglais (eng) Catégories : [CBNPMP-Thématique] Génétique et écologie (dynamique, démographique, sélection) [CBNPMP-Thématique] Revégétalisation Résumé : Differences in the frequency with which offspring are produced asexually, through self-fertilization and through sexual outcrossing, are a predominant influence on the genetic structure of plant populations. Selfers and asexuals have fewer genotypes within populations than outcrossers with similar allele frequencies, and more genetic diversity in selfers and asexuals is a result of differences among populations than in sexual outcrossers. As a result of reduced levels of diversity, selfers and asexuals may be less able to respond adaptively to changing environments, and because genotypes are not mixed across family lineages, their populations may accumulate deleterious mutations more rapidly. Such differences suggest that selfing and asexual lineages may be evolutionarily short-lived and could explain why they often seem to be of recent origin. Nonetheless, the origin and maintenance of different reproductive modes must be linked to individual-level properties of survival and reproduction. Sexual outcrossers suffer from a cost of outcrossing that arises because they do not contribute to selfed or asexual progeny, whereas selfers and asexuals may contribute to outcrossed progeny. Selfing and asexual reproduction also may allow reproduction when circumstances reduce opportunities for a union of gametes produced by different individuals, a phenomenon known as reproductive assurance. Both the cost of outcrossing and reproductive assurance lead to an over-representation of selfers and asexuals in newly formed progeny, and unless sexual outcrossers are more likely to survive and reproduce, they eventually will be displaced from populations in which a selfing or asexual variant arises. Lien pérenne : DOI : 10.1073/pnas.97.13.7037 Permalink : https://biblio.cbnpmp.fr/index.php?lvl=notice_display&id=149011 Holsinger, Kent E. 2000 Reproductive systems and evolution in vascular plants. Proceedings of the National Academy of Sciences of the United States of America, 97(13): 271-288.

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The role of genetic and genomic attributes in the success of polyploids / Pamela S. Soltis in Proceedings of the National Academy of Sciences of the United States of America, 97 (13) (June 2000) 

Public Citation [article]  inProceedings of the National Academy of Sciences of the United States of America > 97 (13) (June 2000) . - 310-329 Titre : The role of genetic and genomic attributes in the success of polyploids Type de document : Imprimé Auteurs : Pamela S. Soltis (1957-) ; Douglas E. Soltis (1953-) Année de publication : 2000 Article en page(s) : 310-329 Langues : Anglais (eng) Catégories : [CBNPMP-Thématique] Génétique et écologie (dynamique, démographique, sélection) [CBNPMP-Thématique] Revégétalisation Résumé : In 1950, G. Ledyard Stebbins devoted two chapters of his book Variation and Evolution in Plants (Columbia Univ. Press, New York) to polyploidy, one on occurrence and nature and one on distribution and significance. Fifty years later, many of the questions Stebbins posed have not been answered, and many new questions have arisen. In this paper, we review some of the genetic attributes of polyploids that have been suggested to account for the tremendous success of polyploid plants. Based on a limited number of studies, we conclude: (i) Polyploids, both individuals and populations, generally maintain higher levels of heterozygosity than do their diploid progenitors. (ii) Polyploids exhibit less inbreeding depression than do their diploid parents and can therefore tolerate higher levels of selfing; polyploid ferns indeed have higher levels of selfing than do their diploid parents, but polyploid angiosperms do not differ in outcrossing rates from their diploid parents. (iii) Most polyploid species are polyphyletic, having formed recurrently from genetically different diploid parents. This mode of formation incorporates genetic diversity from multiple progenitor populations into the polyploid “species”; thus, genetic diversity in polyploid species is much higher than expected by models of polyploid formation involving a single origin. (iv) Genome rearrangement may be a common attribute of polyploids, based on evidence from genome in situ hybridization (GISH), restriction fragment length polymorphism (RFLP) analysis, and chromosome mapping. (v) Several groups of plants may be ancient polyploids, with large regions of homologous DNA. These duplicated genes and genomes can undergo divergent evolution and evolve new functions. These genetic and genomic attributes of polyploids may have both biochemical and ecological benefits that contribute to the success of polyploids in nature. Lien pérenne : DOI : 10.1073/pnas.97.13.7051 Permalink : https://biblio.cbnpmp.fr/index.php?lvl=notice_display&id=149012 Soltis, Pamela S. (1957-), Soltis, Douglas E. (1953-) 2000 The role of genetic and genomic attributes in the success of polyploids. Proceedings of the National Academy of Sciences of the United States of America, 97(13): 310-329.

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Consultable Article (2000) URL