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Auteur Norman Carl Ellstrand (1952-)
Documents disponibles écrits par cet auteur (2)
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Hybridization as a stimulus for the evolution of invasiveness in plants / Norman Carl Ellstrand (2000)
est un tiré à part de 97 (13) - June 2000 (Proceedings of the National Academy of Sciences of the United States of America)
Titre : Hybridization as a stimulus for the evolution of invasiveness in plants Type de document : Tiré à part d'ouvrage Auteurs : Norman Carl Ellstrand (1952-) ; Kristina A. Schierenbeck Année de publication : 2000 Importance : p. 289-309 Langues : Anglais (eng) Catégories : [Thématique] Diversité génétique
[Thématique] Hybridations interspécifiques et intergénériques, introgression (ét. cytogén. & appl. amélior. pl.)
[Thématique] Plantes subspontanées, naturalisées, envahissantes
[Thématique] Pollution génétique
Résumé : Invasive species are of great interest to evolutionary biologists and ecologists because they represent historical examples of dramatic evolutionary and ecological change. Likewise, they are increasingly important economically and environmentally as pests. Obtaining generalizations about the tiny fraction of immigrant taxa that become successful invaders has been frustrated by two enigmatic phenomena. Many of those species that become successful only do so (i) after an unusually long lag time after initial arrival, and/or (ii) after multiple introductions. We propose an evolutionary mechanism that may account for these observations. Hybridization between species or between disparate source populations may serve as a stimulus for the evolution of invasiveness. We present and review a remarkable number of cases in which hybridization preceded the emergence of successful invasive populations. Progeny with a history of hybridization may enjoy one or more potential genetic benefits relative to their progenitors. The observed lag times and multiple introductions that seem a prerequisite for certain species to evolve invasiveness may be a correlate of the time necessary for previously isolated populations to come into contact and for hybridization to occur. Our examples demonstrate that invasiveness can evolve. Our model does not represent the only evolutionary pathway to invasiveness, but is clearly an underappreciated mechanism worthy of more consideration in explaining the evolution of invasiveness in plants. Lien pérenne : DOI : 10.1073/pnas.97.13.7043Ellstrand, N.C., Schierenbeck, KA. 2000. Hybridization as a stimulus for the evolution of invasiveness in plants. In: 97 (13) - June 2000 (Proceedings of the National Academy of Sciences of the United States of America, 97 (13) [01/06/2013]). National Academy of Sciences, Washington, D.C.: 289-309.
Nonlocal transplantation and outbreeding depression in the subshrub Lotus scoparius (Fabaceae) / Arlee M. Montalvo (2001)
est un tiré à part de 88 (2) - 2001 (American Journal of Botany)
Titre : Nonlocal transplantation and outbreeding depression in the subshrub Lotus scoparius (Fabaceae) Type de document : Tiré à part de revue Auteurs : Arlee M. Montalvo ; Norman Carl Ellstrand (1952-) Année de publication : 2001 Importance : 258-269 Langues : Anglais (eng) Catégories : [Thématique] Revégétalisation Mots-clés : Lotus scoparius Résumé : The genetic background of transplants used to create or augment wild populations may affect the long-term success of restored populations. If seed sources are from differently adapted populations, then the relative performance of progeny from crosses among populations may decrease with an increase in genetic differences of parents and in the differences of parental environments to the transplant location. We evaluated the potential for such outbreeding depression by hybridizing individuals from six different populations of Lotus scoparius var. scoparius and L. s. var. brevialatus. We used allozyme data to calculate genetic distances between source populations, and compiled climatic data and measured soil traits to estimate environmental distances between source populations. We found significant outbreeding depression following controlled crosses. In the greenhouse, the success of crosses (seeds/flower × seedlings/seed) decreased with increasing genetic distance between populations revealing genetically based outbreeding depression unrelated to local adaptation. After outplanting to one native site (in situ common garden), field cumulative fitness of progeny (survival × fruit production) decreased significantly with mean environmental distance of the parental populations to the transplant site, but not with genetic distance between the crossed populations. This result is consistent with a disruption of local adaptation. At the second, ecologically contrasting common garden, where low survival reduced statistical power, field cumulative fitness (survival × progeny height) did not decrease significantly with either environmental distance or genetic distance. Overall, intervariety crosses were 40 and 50% as fit (seeds/flower × seedlings/seed × survival × fruits at the first garden or × height at the second) as intravariety crosses. These results suggest that the cumulative outbreeding depression was caused by a combination of genetically based ecological differences among populations and other genomic coadaptation. We conclude that mixing genetically differentiated seed sources of Lotus scoparius may significantly lower the fitness of augmented or restored populations. Genetic and environmental similarities of source populations relative to the transplant site should be considered when choosing source materials, a practice recommended by recent seed transfer policies. Geographic separation was not a good surrogate for either of these measures. Lien pérenne : DOI : 10.2307/2657017Montalvo, AM., Ellstrand, N.C. 2001. Nonlocal transplantation and outbreeding depression in the subshrub Lotus scoparius (Fabaceae). American Journal of Botany, 88(2) : 258-269.
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