42 research outputs found

    Morphological differences and identification of Jumellea rossii and Jumellea fragrans (Orchidaceae) in Reunion Island: implications for conservation

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    Conservation strategies are not possible when there is confusion in the taxonomic status of a group of plants. Such confusion makes difficult for systematic biologists to identify functional biological entities. This is particularly true in the case of species that diversified fast due to adaptive radiation particularly plants from the oceanic islands. It is the case of certain orchids from Reunion Island. Among them, the ‚ÄúFaham‚ÄĚ complex includes several taxa whose populations are situated at various elevations with morphological and reproductive variations. These taxa are actually merged into one name: Jumellea fragrans causing confusion in their taxonomic status. This confusion has caused numerous problems of identification and errors hindering the protection status of the species. In this study, we suggest to clarify the systematic position of the taxa composing complex Jumellea fragrans using a biometric approach at population scale. The objective is to identify morphological characters that allow distinguishing the taxa of the J. fragrans complex. Morphological characters (vegetative and floral) are measured on individuals from three natural populations representative of altitudinal range of the complex. Principal component analysis made on the characters show a separation of the individuals in two groups (Mare-Longue vs Basse-Vall√©e and Cilaos). Nine characters (on 14 measured) are significantly different between Mare-Longue population and the populations of Basse-Vall√©e and Cilaos and allow identifying both groups. Population of Mare-Longue belongs to the species Jumellea fragrans (Thouars) Schltr. and populations of Basse-Vall√©e and Cilaos belongs to the species Jumellea rossii Senghas. In terms of conservation, the first recommendation is to recognize two different species: J. rossii and J. fragrans. Moreover, putting J. fragrans into the ¬ę vulnerable ¬Ľ IUCN Red List category and the adoption of a protection status are recommended. Concerning J. rossii, more studies on geographical range and population dynamics are necessary to estimate the risk of extinction. In the same way, studies on genetic variability of both species would generate useful data for implementation of conservation strategiesLa clarification du statut taxinomique des esp√®ces constitue un pr√©ambule n√©cessaire √† la mise en place de mesures de conservation appropri√©es et efficaces, particuli√®rement dans les √ģles oc√©aniques o√Ļ la radiation adaptative rend difficile la reconnaissance des entit√©s biologiques fonctionnelles. C‚Äôest le cas de certaines orchid√©es de La R√©union comme le ¬ę Faham ¬Ľ (Jumellea spp.) qui regroupe plusieurs taxons dont les populations se situent √† diff√©rentes altitudes et semblent pr√©senter des variations morphologiques et reproductives. Dans cette √©tude, nous proposons d‚Äô√©claircir la position syst√©matique des taxons composant le complexe d‚Äôesp√®ces regroup√©es sous le nom de ¬ę Faham ¬Ľ par le biais d‚Äôune approche morphom√©trique √† l‚Äô√©chelle populationnelle et d‚Äôidentifier des caract√®res morphologiques permettant de distinguer les diff√©rents taxons. Quatorze caract√®res (v√©g√©tatifs et floraux) ont √©t√© mesur√©s sur 51 individus issus de trois populations naturelles repr√©sentatives de la distribution altitudinale du complexe. Des analyses multivari√©es effectu√©es sur ces caract√®res ont montr√© une s√©paration des individus en deux groupes (Mare-Longue d‚Äôune part, Basse-Vall√©e et Cilaos d‚Äôautre part). Neuf caract√®res sont significativement diff√©rents entre la population de Mare-Longue et les populations de Basse-Vall√©e et Cilaos et permettent de distinguer les deux groupes. La population de Mare-Longue appartiendrait √† l‚Äôesp√®ce Jumellea fragrans (Thouars) Schltr. et les populations de Basse-Vall√©e et Cilaos √† l‚Äôesp√®ce Jumellea rossii Senghas. En termes de conservation, la premi√®re recommandation est de reconna√ģtre deux esp√®ces bien distinctes : J. rossii et J. fragrans. D‚Äôautre part, l‚Äôinscription dans la cat√©gorie ¬ę vuln√©rable ¬Ľ de la Liste Rouge de l‚ÄôUICN et l‚Äôadoption d‚Äôun statut de protection semblent fortement recommand√©es pour J. fragrans. Concernant J. rossii, des connaissances approfondies sur la distribution g√©ographique et la dynamique des populations de l‚Äôesp√®ce s‚Äôav√®rent n√©cessaires afin d‚Äô√©valuer le risque d‚Äôextinction. Parall√®lement, l‚Äô√©tude de la diversit√© g√©n√©tique des deux esp√®ces fournirait des donn√©es utiles pour la mise en oeuvre de plans de conservatio

    A review of the dodo and its ecosystem: insights from a vertebrate concentration Lagerstätte in Mauritius

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    The dodo Raphus cucullatus Linnaeus,1758, an extinct and flightless, giant pigeon endemic to Mauritius, has fascinated people since its discovery, yet has remained surprisingly poorly known. Until the mid-19th century, almost all that was known about the dodo was based on illustrations and written accounts by 17th century mariners, often of questionable accuracy. Furthermore, only a few fragmentary remains of dodos collected prior to the bird's extinction exist. Our understanding of the dodo's anatomy was substantially enhanced by the discovery in 1865 of subfossil bones in a marsh called the Mare aux Songes, situated in southeastern Mauritius. However, no contextual information was recorded during early excavation efforts, and the majority of excavated material comprised larger dodo bones, almost all of which were unassociated. Here we present a modern interdisciplinary analysis of the Mare aux Songes, a 4200-year-old multitaxic vertebrate concentration Lagerstätte. Our analysis of the deposits at this site provides the first detailed overview of the ecosystem inhabited by the dodo. The interplay of climatic and geological conditions led to the exceptional preservation of the animal and associated plant remains at the Mare aux Songes and provides a window into the past ecosystem of Mauritius. This interdisciplinary research approach provides an ecological framework for the dodo, complementing insights on its anatomy derived from the only associated dodo skeletons known, both of which were collected by Etienne Thirioux and are the primary subject of this memoir.Additional co-authors: Anneke H. Van Heteren, Vikash Rupear, Gorah Beebeejaun, Alan Grihault, J. (Hans) Van Der Plicht, Marijke Besselink, Juli√ęn K. Lubeek, Max Jansen, Hege Hollund, Beth Shapiro, Matthew Collins, Mike Buckley, Ranjith M. Jayasena, Nicolas Porch, Rene Floore, Frans Bunnik, Andrew Biedlingmaier, Jennifer Leavitt, Gregory Monfette, Anna Kimelblatt, Adrienne Randall, Pieter Floore & Leon P. A. M. Claessen

    Estimating the global conservation status of more than 15,000 Amazonian tree species

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    Estimates of extinction risk for Amazonian plant and animal species are rare and not often incorporated into land-use policy and conservation planning. We overlay spatial distribution models with historical and projected deforestation to show that at least 36% and up to 57% of all Amazonian tree species are likely to qualify as globally threatened under International Union for Conservation of Nature (IUCN) Red List criteria. If confirmed, these results would increase the number of threatened plant species on Earth by 22%. We show that the trends observed in Amazonia apply to trees throughout the tropics, and we predict thatmost of the world’s >40,000 tropical tree species now qualify as globally threatened. A gap analysis suggests that existing Amazonian protected areas and indigenous territories will protect viable populations of most threatened species if these areas suffer no further degradation, highlighting the key roles that protected areas, indigenous peoples, and improved governance can play in preventing large-scale extinctions in the tropics in this century

    Local hydrological conditions influence tree diversity and composition across the Amazon basin

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    Tree diversity and composition in Amazonia are known to be strongly determined by the water supplied by precipitation. Nevertheless, within the same climatic regime, water availability is modulated by local topography and soil characteristics (hereafter referred to as local hydrological conditions), varying from saturated and poorly drained to well-drained and potentially dry areas. While these conditions may be expected to influence species distribution, the impacts of local hydrological conditions on tree diversity and composition remain poorly understood at the whole Amazon basin scale. Using a dataset of 443 1-ha non-flooded forest plots distributed across the basin, we investigate how local hydrological conditions influence 1) tree alpha diversity, 2) the community-weighted wood density mean (CWM-wd) ‚Äď a proxy for hydraulic resistance and 3) tree species composition. We find that the effect of local hydrological conditions on tree diversity depends on climate, being more evident in wetter forests, where diversity increases towards locations with well-drained soils. CWM-wd increased towards better drained soils in Southern and Western Amazonia. Tree species composition changed along local soil hydrological gradients in Central-Eastern, Western and Southern Amazonia, and those changes were correlated with changes in the mean wood density of plots. Our results suggest that local hydrological gradients filter species, influencing the diversity and composition of Amazonian forests. Overall, this study shows that the effect of local hydrological conditions is pervasive, extending over wide Amazonian regions, and reinforces the importance of accounting for local topography and hydrology to better understand the likely response and resilience of forests to increased frequency of extreme climate events and rising temperatures

    Estimating the global conservation status of more than 15,000 Amazonian tree species

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    Pervasive gaps in Amazonian ecological research

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    Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5‚Äď7 vast areas of the tropics remain understudied.8‚Äď11 In the American tropics, Amazonia stands out as the world‚Äôs most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13‚Äď15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon‚Äôs biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region‚Äôs vulnerability to environmental change. 15%‚Äď18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio

    Pervasive gaps in Amazonian ecological research

    Get PDF

    Pervasive gaps in Amazonian ecological research

    Get PDF
    Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%‚Äď18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost
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