Conservatoire Botanique National de Mascarin

Saint-Leu, France

Conservatoire Botanique National de Mascarin

Saint-Leu, France

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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.


Kueffer C.,University of Hawaii at Manoa | Kueffer C.,ETH Zurich | Daehler C.C.,University of Hawaii at Manoa | Torres-Santana C.W.,University of Hawaii at Manoa | And 4 more authors.
Perspectives in Plant Ecology, Evolution and Systematics | Year: 2010

Oceanic islands have long been considered to be particularly vulnerable to biotic invasions, and much research has focused on invasive plants on oceanic islands. However, findings from individual islands have rarely been compared between islands within or between biogeographic regions. We present in this study the most comprehensive, standardized dataset to date on the global distribution of invasive plant species in natural areas of oceanic islands. We compiled lists of moderate (5-25% cover) and dominant (>25% cover) invasive plant species for 30 island groups from four oceanic regions (Atlantic, Caribbean, Pacific, and Western Indian Ocean). To assess consistency of plant behaviour across island groups, we also recorded present but not invasive species in each island group. We tested the importance of different factors discussed in the literature in predicting the number of invasive plant species per island group, including island area and isolation, habitat diversity, native species diversity, and human development. Further we investigated whether particular invasive species are consistently and predictably invasive across island archipelagos or whether island-specific factors are more important than species traits in explaining the invasion success of particular species. We found in total 383 non-native spermatophyte plants that were invasive in natural areas on at least one of the 30 studied island groups, with between 3 and 74 invaders per island group. Of these invaders about 50% (181 species) were dominants or co-dominants of a habitat in at least one island group. An extrapolation from species accumulation curves across the 30 island groups indicates that the total current flora of invasive plants on oceanic islands at latitudes between c. 35°N and 35°S may eventually consist of 500-800 spermatophyte species, with 250-350 of these being dominant invaders in at least one island group. The number of invaders per island group was well predicted by a combination of human development (measured by the gross domestic product (GDP) per capita), habitat diversity (number of habitat types), island age, and oceanic region (87% of variation explained). Island area, latitude, isolation from continents, number of present, non-native species with a known invasion history, and native species richness were not retained as significant factors in the multivariate models. Among 259 invaders present in at least five island groups, only 9 species were dominant invaders in at least 50% of island groups where they were present. Most species were invasive only in one to a few island groups although they were typically present in many more island groups. Consequently, similarity between island groups was low for invader floras but considerably higher for introduced (but not necessarily invasive) species - especially in pairs of island groups that are spatially close or similar in latitude. Hence, for invasive plants of natural areas, biotic homogenization among oceanic islands may be driven by the recurrent deliberate human introduction of the same species to different islands, while post-introduction processes during establishment and spread in natural areas tend to reduce similarity in invader composition between oceanic islands. We discuss a number of possible mechanisms, including time lags, propagule pressure, local biotic and abiotic factors, invader community assembly history, and genotypic differences that may explain the inconsistent performance of particular invasive species in different island groups. © 2009 Rübel Foundation, ETH Zürich.


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.


Le Pechon T.,CAS Chengdu Institute of Biology | Gigord L.D.B.,Conservatoire Botanique National de Mascarin
Methods in Molecular Biology | Year: 2014

In this article, we present an overview of changes to the taxonomy of Malvales. In traditional classifications, this order was variously circumscribed as including four main families (i.e., Malvaceae, Bombacaceae, Sterculiaceae, and Tiliaceae, also known now as "Core Malvales"), but major disagreements existed between different taxonomic treatments. Contributions from molecular data, new morpho-anatomical data, and progress in methodological approaches have recently led to a new broader concept of this order (namely, "expanded Malvales"). Now, expanded Malvales includes ten families (Neuradaceae, Thymelaeaceae, Sphaerosepalaceae, Bixaceae, Cistaceae, Sarcolaenaceae, Dipterocarpaceae, Cytinaceae, Muntingiaceae, Malvaceae s.L.) distributed among seven monophyletic lineages. All these families were previously considered to have malvalean affinities in some traditional treatments, except the holoparasitic and highly modified Cytinaceae. Although molecular evidence has clarified the Malvales taxonomy, the phylogenetic positions of Sarcolaenaceae, Thymelaeaceae, and Sphaerosepalaceae are still controversial and need new analyses focusing specifically on these families to assess their phylogenetic placement and their morphological evolution. In a phylogenetic context, molecular data combined with recent examination of morphological characters supported the hypothesis of a common origin of "core Malvales." However, these analyses also showed that the former families but Malvaceae s.s. were paraphyletic or polyphyletic. As a consequence, recent taxonomic treatments grouped taxa formerly included in "Core Malvales" in a broader concept of Malvaceae s.L. Additionally, the intrafamilial taxonomy has been deeply modified, and in its present circumscription, Malvaceae includes nine subfamilies (Grewioideae, Byttnerioideae, Sterculioideae, Dombeyoideae, Brownlowioideae, Tilioideae, Bombacoideae, Malvoideae, Helicteroideae) in two main lineages. Phylogenetic studies on subfamilial rearrangements have focused on the relationships between emblematic taxa such as Bombacoideae and Malvoideae (which form together the /Malvatheca lineage). However, our understanding of the phylogenetic relationships among and within taxa of the other subfamilies (e.g., Dombeyoideae, Tilioideae, and Sterculioideae) has not followed at the same pace. Despite recent investigations, the relationships between the subfamilies of Malvaceae s.L. remain controversial. As an example of these taxonomic issues, we review the systematic studies on Dombeyoideae, with special emphasis on taxa endemic to the Mascarene archipelago (Indian Ocean). Recent investigations have shown that several island endemic genera such as Trochetia, Ruizia, and Astiria (endemic to the Mascarenes) are nested within the mega-genus Dombeya. Consequently, the current taxonomy of this genus does not match the phylogeny and should be modified. Therefore, we propose three possible taxonomic schemes as part of an ongoing revision of the Mascarene Dombeyoideae. However, these taxonomic rearrangements should only be made after a broader study of the diversity in Madagascar and adjacent areas. This broader approach shall avoid possibly multiple and contradictory taxonomic revisions of restricted regions if they were each studied in isolation. © 2014 Springer Science+Business Media New York.


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.


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.


Barthelat F.,Union Internationale pour la Conservation de la Nature | Viscardi G.,Conservatoire Botanique National de Mascarin
Revue d'Ecologie (La Terre et la Vie) | Year: 2012

This paper deals with the natural history and the flora of Mayotte by presenting some of its characteristics and providing an assessment of its conservation status. Mayotte is a French islands group belonging to the Comoros archipelago (Indian Ocean), located between Madagascar and East Africa. Its geological history, its geographical position and multiple human influences have shaped some remarkable landscapes composed by unique ecosystems and habitats, with an extraordinary biodiversity for a small territory. Since the first inhabitants, via the colonial centuries to the contemporary era, natural vegetation is restricted to the bare minimum but nevertheless it houses most of the plant biodiversity in Mayotte. As sanctuaries these small natural areas are unfortunately still poorly known and highly threatened. The flora of Mayotte was not well studied in the past because the naturalists' attention was probably drawn by Madagascar. Most of the discoveries were made during the two main periods of investigation that took place during the second half of the nineteenth century and the late twentieth to date. The vascular flora of Mayotte is composed by 681 species that have been recently evaluated by using the categories and criteria of the IUCN Red List. To illustrate the need and urgency to ensure the conservation of this unique heritage, a "Top fourteen" of the critically endangered species is proposed and suggestions for conservation measures are discussed.


Soubeyran Y.,Comite francais de l'UICN | 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.


Le Pechon T.,University Pierre and Marie Curie | Le Pechon T.,University of Reunion Island | Dubuisson J.-Y.,University Pierre and Marie Curie | Haevermans T.,CNRS Systematics, Biodiversity and Evolution Institute | And 3 more authors.
Annals of Botany | Year: 2010

Background and Aims In the Mascarenes, a young oceanic archipelago composed of three main islands, the Dombeyoideae (Malvaceae) have diversified extensively with a high endemism rate. With the exception of the genus Trochetia, Mascarene Dombeyoideae are described as dioecious whereas Malagasy and African species are considered to be monocline, species with individuals bearing hermaphrodite/perfect flowers. In this study, the phylogenetic relationships were reconstructed to clarify the taxonomy, understand the phylogeographic pattern of relationships and infer the evolution of the breeding systems for the Mascarenes Dombeyoideae. Methods Parsimony and Bayesian analysis of four DNA markers (ITS, rpl16 intron and two intergenic spacers trnQ-rsp16 and psbM-trnD) was used. The molecular matrix comprised 2985 characters and 48 taxa. The Bayesian phylogeny was used to infer phylogeographical hypotheses and the evolution of breeding systems. Key ResultsParsimony and Bayesian trees produced similar results. The Dombeyoideae from the Mascarenes are polyphyletic and distributed among four clades. Species of Dombeya, Trochetia and Ruizia are nested in the same clade, which implies the paraphyly of Dombeya. Additionally, it is shown that each of the four clades has an independent Malagasy origin. Two adaptive radiation events have occurred within two endemic lineages of the Mascarenes. The polyphyly of the Mascarene Dombeyoideae suggests at least three independent acquisitions of dioecy.Conclusions This molecular phylogeny highlights the taxonomic issues within the Dombeyoideae. Indeed, the limits and distinctions of the genera Dombeya, Trochetia and Ruizia should be reconsidered. The close phylogeographic relationships between the flora of the Mascarenes and Madagascar are confirmed. Despite their independent origins and a distinct evolutionary history, each endemic clade has developed a different breeding systems (dioecy) compared with the Malagasy Dombeyoideae. Sex separation appears as an evolutionary convergence and may be the consequence of selective pressures particular to insular environments. © The Author 2010. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved.


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.

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