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Saint-Leu-la-Forêt, France

Hornoy B.,University of Rennes 1 | Tarayre M.,University of Rennes 1 | Herve M.,French National Institute for Agricultural Research | Gigord L.,Conservatoire Botanique National de Mascarin | Atlan A.,University of Rennes 1
PLoS ONE | Year: 2011

Several hypotheses that attempt to explain invasive processes are based on the fact that plants have been introduced without their natural enemies. Among them, the EICA (Evolution of Increased Competitive Ability) hypothesis is the most influential. It states that, due to enemy release, exotic plants evolve a shift in resource allocation from defence to reproduction or growth. In the native range of the invasive species Ulex europaeus, traits involved in reproduction and growth have been shown to be highly variable and genetically correlated. Thus, in order to explore the joint evolution of life history traits and susceptibility to seed predation in this species, we investigated changes in both trait means and trait correlations. To do so, we compared plants from native and invaded regions grown in a common garden. According to the expectations of the EICA hypothesis, we observed an increase in seedling height. However, there was little change in other trait means. By contrast, correlations exhibited a clear pattern: the correlations between life history traits and infestation rate by seed predators were always weaker in the invaded range than in the native range. In U. europaeus, the role of enemy release in shaping life history traits thus appeared to imply trait correlations rather than trait means. In the invaded regions studied, the correlations involving infestation rates and key life history traits such as flowering phenology, growth and pod density were reduced, enabling more independent evolution of these key traits and potentially facilitating local adaptation to a wide range of environments. These results led us to hypothesise that a relaxation of genetic correlations may be implied in the expansion of invasive species. © 2011 Hornoy et al. Source


Ranghoo-Sanmukhiya M.,University of Mauritius | Govinden-Soulange J.,University of Mauritius | Lavergne C.,Conservatoire Botanique National de Mascarin | Khoyratty S.,University of Mauritius | And 3 more authors.
Phytochemical Analysis | Year: 2010

Introduction - Aloe tormentorii, A. purpurea and A. macra are used as multipurpose folk medicines in Réunion and Mauritius Islands and are mistaken for the introduced Aloe vera.Objective - To compare the phytochemical, antimicrobial and DNA profiles of Aloe endemic to Mauritius and Réunion with the profiles of A. vera.Methodology - Leaf extracts of these Aloe species were analysed using standard phytochemical screening techniques, TLC and by HPLC. These extracts were also assayed for antimicrobial activity using microdilution techniques. Genetic diversity was studied using RAPD markers.Results - Phytochemical and antimicrobial assays and RAPD analysis showed that Mascarene Aloe species were very different from A. vera.Conclusion - This study is the first report highlighting the differences between Aloe sp.p from Mascarene and Aloe vera at the metabolic and genomic level. Copyright © 2010 John Wiley & Sons, Ltd. Copyright © 2010 John Wiley & Sons, Ltd. Source


Soubeyran Y.,Comite francais de lUICN | Meyer J.-Y.,British Petroleum | Lebouvier M.,French National Center for Scientific Research | De Thoisy B.,Association Kwata | And 3 more authors.
Biological Invasions | Year: 2014

Invasive alien species (IAS) are one of the most serious threats to the rich and unique biodiversity of the 13 French overseas territories (FOTs) scattered across three oceans and two continents. To address this critical issue, a dedicated Initiative has been conducted since 2005, with the support of a large panel of national and local experts and stakeholders. This paper summarizes the main results and benefits of this project after 7 years. As a first phase, an unprecedented overview of IAS and their impacts in all the FOTs was achieved. A total of 630 alien taxa were recorded, among which 258 plants, 52 terrestrial vertebrates and 32 invertebrates were identified as a threat, or a potential threat, to native species and/or natural habitats. Gaps in the knowledge about invasive species were also highlighted and a comprehensive set of recommendations was developed. Using a range of targeted collaborative actions and promoting the exchange of information and regional cooperation, the Initiative raised awareness of invasive species issues, improved access to information and strengthened local and regional capacities. In this paper, we report on the outcomes of the Initiative and what remains to be done with regards to the prevention of new introductions, early detection, rapid response and public awareness, as well as future challenges. © 2014 Springer International Publishing Switzerland. Source


Pechon T.L.,CAS Chengdu Institute of Biology | Pechon T.L.,University of Reunion Island | Pause J.-B.,rue Allemagne | Dubuisson J.-Y.,University Pierre and Marie Curie | And 4 more authors.
Systematic Botany | Year: 2013

Dombeya formosa (Malvaceae s. l. or Dombeyaceae), a new species endemic to La Réunion, is described and illustrated. The species is distinguishable by its ovate leaves with round or slightly cordate bases, round to lightly acute apices and glabrescent abaxial surfaces, subulate and persistent stipules, umbellate inflorescences, and acute apices of floral bracts. Dombeya formosa is morphologically close to Dombeya punctata Cav. but differs from it in having ovate leaves and acute apices on floral bracts. Dombeya formosa is also morphologically similar to D. ficulnea Baill. but can be distinguished from it by its persistent and subulate stipules as well as the glabrescent adaxial surface of its leaves. Our study, focusing on 16 quantitative floral characters, demonstrates that there is a clear morphological distinction between D. formosa, D. punctata, and D. ficulnea. In comparison to the other two species, Dombeya formosa possesses smaller flowers and additionally shows cryptic dioecy along with flower-size dimorphism between sexes. Amongst the Mascarene Dombeyoideae, it is the only species distributed up to an altitude of 2,100 m. The phylogenetic position of Dombeya formosa is consistent with the morphological features and locates the species within the clade endemic to La Réunion characterized by umbellate inflorescences. © Copyright 2013 by the American Society of Plant Taxonomists. Source


Pellissier L.,University of Lausanne | Vittoz P.,University of Lausanne | Internicola A.I.,University of Lausanne | Internicola A.I.,University of Calgary | Gigord L.D.B.,Conservatoire Botanique National de Mascarin
Journal of Plant Ecology | Year: 2010

Aims Food-deceptive pollination, in which plants do not offer any food reward to their pollinators, is common within the Orchidaceae. As food-deceptive orchids are poorer competitors for pollinator visitation than rewarding orchids, their occurrence in a given habitat may be more constrained than that of rewarding orchids. In particular, the success of deceptive orchids strongly relies on several biotic factors such as interactions with co-flowering rewarding species and pollinators, which may vary with altitude and over time. Our study compares generalized food-deceptive (i.e. excluding sexually deceptive) and rewarding orchids to test whether (i) deceptive orchids flower earlier compared to their rewarding counterparts and whether (ii) the relative occurrence of deceptive orchids decreases with increasing altitude.Methods To compare the flowering phenology of rewarding and deceptive orchids, we analysed data compiled from the literature at the species level over the occidental Palaearctic area. Since flowering phenology can be constrained by the latitudinal distribution of the species and by their phylogenetic relationships, we accounted for these factors in our analysis. To compare the altitudinal distribution of rewarding and deceptive orchids, we used field observations made over the entire Swiss territory and over two Swiss mountain ranges.Important FindingsWe found that deceptive orchid species start flowering earlier than rewarding orchids do, which is in accordance with the hypotheses of exploitation of naive pollinators and/or avoidance of competition with rewarding co-occurring species. Also, the relative frequency of deceptive orchids decreases with altitude, suggesting that deception may be less profitable at high compared to low altitude. © 2009 The Author. Published by Oxford University Press on behalf of the Institute of Botany, Chinese Academy of Sciences and the Botanical Society of China. All rights reserved. Source

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