Mention de date : 09/2011
Plos One . 6 (9)
Paru le : 01/09/2011
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Alien plants introduced by different pathways differ in invasion success : unintentional introductions as a threat to natural areas / Petr Pyšek in Plos One, 6 (9) (09/2011)
Titre : Alien plants introduced by different pathways differ in invasion success : unintentional introductions as a threat to natural areas Type de document : Électronique Auteurs : Petr Pyšek ; Vojtěch Jarošík (1958-2013) ; Jan Pergl (1977-) Année de publication : 2011 Article en page(s) : 1-11 Langues : Anglais (eng) Catégories : [Thématique] Plantes subspontanées, naturalisées, envahissantes Résumé : Background : Understanding the dimensions of pathways of introduction of alien plants is important for regulating species invasions, but how particular pathways differ in terms of post-invasion success of species they deliver has never been rigorously tested. We asked whether invasion status, distribution and habitat range of 1,007 alien plant species introduced after 1500 A.D. to the Czech Republic differ among four basic pathways of introduction recognized for plants. Principal Findings : Pathways introducing alien species deliberately as commodities (direct release into the wild; escape from cultivation) result in easier naturalization and invasion than pathways of unintentional introduction (contaminant of a commodity; stowaway arriving without association with it). The proportion of naturalized and invasive species among all introductions delivered by a particular pathway decreases with a decreasing level of direct assistance from humans associated with that pathway, from release and escape to contaminant and stowaway. However, those species that are introduced via unintentional pathways and become invasive are as widely distributed as deliberately introduced species, and those introduced as contaminants invade an even wider range of seminatural habitats. Conclusions : Pathways associated with deliberate species introductions with commodities and pathways whereby species are unintentionally introduced are contrasting modes of introductions in terms of invasion success. However, various measures of the outcome of the invasion process, in terms of species' invasion success, need to be considered to accurately evaluate the role of and threat imposed by individual pathways. By employing various measures we show that invasions by unintentionally introduced plant species need to be considered by management as seriously as those introduced by horticulture, because they invade a wide range of seminatural habitats, hence representing even a greater threat to natural areas. Identifiant pérenne : DOI : 10.1371/journal.pone.0024890
in Plos One > 6 (9) (09/2011) . - 1-11Pyšek, P., Jarošík, V., Pergl, J., 2011 - Alien plants introduced by different pathways differ in invasion success : unintentional introductions as a threat to natural areas ; Plos One, 6 (9) : 1-11.
Article (2011)Adobe Acrobat PDF
Population genetic diversity and structure of a naturally isolated plant species, Rhodiola dumulosa (Crassulaceae) / Yan Hou in Plos One, 6 (9) (09/2011)
Titre : Population genetic diversity and structure of a naturally isolated plant species, Rhodiola dumulosa (Crassulaceae) Type de document : Électronique Auteurs : Yan Hou ; Anru Lou Année de publication : 2011 Article en page(s) : 6(9) Langues : Anglais (eng) Catégories : [Thématique] Diversité génétique Mots-clés : Rhodiola dumulosa Résumé : Aims : Rhodiola dumulosa (Crassulaceae) is a perennial diploid species found in high-montane areas. It is distributed in fragmented populations across northern, central and northwestern China. In this study, we aimed to (i) measure the genetic diversity of this species and that of its populations; (ii) describe the genetic structure of these populations across the entire distribution range in China; and (iii) evaluate the extent of gene flow among the naturally fragmented populations. Methods : Samples from 1089 individuals within 35 populations of R. dumulosa were collected, covering as much of the entire distribution range of this species within China as possible. Population genetic diversity and structure were analyzed using AFLP molecular markers. Gene flow among populations was estimated according to the level of population differentiation. Important Findings : The total genetic diversity of R. dumulosa was high but decreased with increasing altitude. Population-structure analysis indicated that the most closely related populations were geographically restricted and occurred in close proximity to each other. A significant isolation-by-distance pattern, caused by the naturally fragmented population distribution, was observed. At least two distinct gene pools were found in the 35 sampled populations, one composed of populations in northern China and the other composed of populations in central and northwestern China. The calculation of Nei's gene diversity index revealed that the genetic diversity in the northern China pool (0.1972) was lower than that in the central and northwestern China pool (0.2216). The populations were significantly isolated, and gene flow was restricted throughout the entire distribution. However, gene flow among populations on the same mountain appears to be unrestricted, as indicated by the weak genetic isolation among these populations. Identifiant pérenne : DOI : 10.1371/journal.pone.0024497
in Plos One > 6 (9) (09/2011) . - 6(9)Hou, Y., Lou, A., 2011 - Population genetic diversity and structure of a naturally isolated plant species, Rhodiola dumulosa (Crassulaceae) ; Plos One, 6 (9) : 6(9).
Article (2011)Adobe Acrobat PDF