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  1. Article ; Online: Forests Without Frugivores and Frugivores Without Forests – An Investigation Into the Causes of a Paradox in One of the Last Archipelagos Colonized by Humans

    Sébastien Albert / Olivier Flores / Claudine Ah-Peng / Dominique Strasberg

    Frontiers in Ecology and Evolution, Vol

    2021  Volume 9

    Abstract: The Mascarenes are sadly famous worldwide for the massive extinction of their native vertebrates since recent human colonization. However, extinction patterns show astonishing disparities between the two main islands and between lineages of forest ... ...

    Abstract The Mascarenes are sadly famous worldwide for the massive extinction of their native vertebrates since recent human colonization. However, extinction patterns show astonishing disparities between the two main islands and between lineages of forest vertebrates. On Réunion (2,512 km2, 3,070 m) where about a third of native habitats remains, most large-bodied vertebrates, especially frugivores, collapsed by the first half of the 18th century, while several have survived longer and some still exist on Mauritius (1,865 km2, 828 m) where more than 95% of native habitats have been transformed. Considering lineages of forest vertebrates shared by both islands (23 genera, 53 species), we test the hypothesis that differing patterns of lowland suitable habitat destruction is the main cause behind this paradox. Before that, we assess the potential impact of other major drivers of extinctions since first contact with humans. Firstly, Mauritius shows earlier and more numerous introductions of mammal predators known for their devastating impact (except northern islets which have thus become important sanctuaries for several squamates). Secondly, settlers were inveterate hunters on both islands, but while Réunion was overhunted before Mauritius, the burst of human population in the latter in late 18th century has not led to the rapid extinction of all large native vertebrates. These two factors alone therefore cannot explain the observed paradox. Rather, the early destruction of lowland habitats (<400 m) on Réunion is concomitant with most extinctions of forest vertebrate, notably frugivores that rapidly lost most lowland habitats dominated by large fleshy-fruited plants. Moreover, landform-induced fragmentation has likely decreased the ability of adjacent habitats to act as effective refuges. Conversely, Mauritius retained suitable low-fragmented habitats until the late 19th which probably allowed, at least for a time, several native vertebrates to escape from multiple human-induced disturbances. Despite the almost total ...
    Keywords biodiversity loss ; biological invasion ; elevational gradients ; habitat destruction and fragmentation ; Mascarene archipelago ; overhunting ; Evolution ; QH359-425 ; Ecology ; QH540-549.5
    Subject code 333
    Language English
    Publishing date 2021-08-01T00:00:00Z
    Publisher Frontiers Media S.A.
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: Do Native and Alien Species Differ in Their Ecological Strategies? A Test with Woody Plants in Tropical Rainforests on Réunion Island (Mascarene Archipelago, Indian Ocean)

    Lyse Heymans / Jean-Yves Meyer / Claudine Ah-Peng / Quentin Ethève / Olivier Flores / Christophe Lavergne / Bertrand Mallet / Hilde Parlevliet / Dominique Strasberg / Robin Pouteau

    Plants, Vol 12, Iss 23, p

    2023  Volume 3990

    Abstract: Understanding the mechanisms of biological invasions (e.g., competitive exclusion) is a key conservation challenge, especially on islands. Many mechanisms have been tested by comparing the characteristics of native and alien species, but few studies have ...

    Abstract Understanding the mechanisms of biological invasions (e.g., competitive exclusion) is a key conservation challenge, especially on islands. Many mechanisms have been tested by comparing the characteristics of native and alien species, but few studies have considered ecological strategies. Here we aim at comparing the competitive ability, stress tolerance, and ruderalism (CSR) of native and alien trees in the tropical rainforests of Réunion Island. A total of sixteen 100 m 2 plots (eight ‘near-trail’ and eight ‘off-trail’, at less disturbed sites) were established over a 2100 m elevational gradient. Three traits were measured in 1093 leaves from 237 trees: leaf area, leaf dry matter content and specific leaf area. They were converted into a CSR score assigned to each of the 80 surveyed tree species (70 native and 10 alien) using the ‘Stratefy’ ordination approach. C scores increased with basal area and S scores with elevation, but R scores were not higher along the trail, thus only partially validating Stratefy. Native and alien trees had similar CS strategies, thus challenging invasion hypotheses predicting a difference in ecological strategies and rather demonstrating the importance of environmental filtering. However, other differences falling outside the CSR theory may also explain the success of alien species on Réunion.
    Keywords biological invasion ; elevational gradient ; functional ecology ; Grime’s CSR theory ; Réunion ; leaf trait ; Botany ; QK1-989
    Subject code 580
    Language English
    Publishing date 2023-11-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article: Community assembly and diversification in a species‐rich radiation of island weevils (Coleoptera: Cratopini)

    Kitson, James J. N / Ben H. Warren / Brent C. Emerson / Christophe Thébaud / Dominique Strasberg

    Journal of biogeography. 2018 Sept., v. 45, no. 9

    2018  

    Abstract: AIM: To test a prediction derived from island biogeographical theory that in situ speciation should make an increasingly important contribution to community assembly as islands age. This prediction is tested on estimated biogeographical histories from ... ...

    Abstract AIM: To test a prediction derived from island biogeographical theory that in situ speciation should make an increasingly important contribution to community assembly as islands age. This prediction is tested on estimated biogeographical histories from Mauritius (approximately 9 Myr) and Reunion (approximately 5 Myr). We additionally investigate the evolutionary dynamics of insect flight loss, as the loss of flight in island lineages can influence patterns of diversification. LOCATION: Mascarene Islands; Southwest Indian Ocean. TAXON: Weevils. METHODS: Up to five individuals of each taxonomically described species sampled within each sampling site were sequenced for the mitochondrial gene Cytochrome Oxidase II to delimit operational taxonomic units (OTUs). OTUs were further sequenced for the nuclear genes Arginine Kinase, Histone 3 and ribosomal 28s, to reconstruct the phylogenetic history of the group. Timings of colonization and in situ speciation events were estimated with beast2. RESULTS: Our results support the hypothesis that present‐day species richness on the older island of Mauritius is largely the result of in situ speciation, with few colonization events, of which all but the most basal are recent. In contrast, Reunion presents a more uniform temporal spectrum of colonization times. Flight loss has evolved convergently at least five times, and speciation events associated with flight loss are significantly younger than speciation events that have not resulted in flight loss. MAIN CONCLUSIONS: Patterns of community assembly on the islands of Mauritius and Reunion fit a model where the addition of new species and species turnover is increasingly dominated by in situ speciation as an island community matures. Repeated flight loss indicates selection for flightlessness, with the young age of flightless lineages suggesting higher extinction rates over longer evolutionary time‐scales and little influence on present‐day species richness.
    Keywords arginine kinase ; biogeography ; Curculionidae ; cytochrome-c oxidase ; extinction ; flight ; histones ; insect flight ; islands ; mitochondrial genes ; models ; new species ; phylogeny ; prediction ; species diversity ; Indian Ocean ; Mauritius ; Reunion
    Language English
    Dates of publication 2018-09
    Size p. 2016-2026.
    Publishing place John Wiley & Sons, Ltd
    Document type Article
    Note JOURNAL ARTICLE
    ZDB-ID 188963-1
    ISSN 0305-0270
    ISSN 0305-0270
    DOI 10.1111/jbi.13393
    Database NAL-Catalogue (AGRICOLA)

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  4. Article: Why are woody plants fleshy‐fruited at low elevations? Evidence from a high‐elevation oceanic island

    Albert, Sébastien / Olivier Flores / Mathieu Rouget / Nicholas Wilding / Dominique Strasberg

    Journal of vegetation science. 2018 Sept., v. 29, no. 5

    2018  

    Abstract: QUESTION: The composition of fruit types, fleshy vs dry fruits, greatly influences the functioning of plant communities. Literature documenting spatial patterns of fruit types at fine scale is abundant. However, studies at larger geographical scale ... ...

    Abstract QUESTION: The composition of fruit types, fleshy vs dry fruits, greatly influences the functioning of plant communities. Literature documenting spatial patterns of fruit types at fine scale is abundant. However, studies at larger geographical scale remain scarce, especially on high‐elevation oceanic islands that provide a great environmental heterogeneity. Here, we investigated how abiotic factors explained the proportion of fleshy‐fruited species (pFF) on Réunion. We asked (a) which abiotic factors were most related to pFF, (b) if fleshy‐fruited canopy species were more sensitive than fleshy‐fruited shrubs to harsh climatic conditions and (c) what are the relationships between pFF, endemism and phylogenetic relatedness. LOCATION: Réunion (3,070 m a.s.l), Mascarene archipelago, South‐West Indian Ocean. METHODS: We used a dataset of 429 vegetation plots and assigned fruit types, growth forms and geographical distribution to 213 native woody species. Phylogenetic trees were constructed for each plot. We used GLMs to measure the relationship between pFF and abiotic factors, controlling for spatial autocorrelation. We then assessed the relationship between pFF, the standardized net relatedness index and the proportion of endemic species. RESULTS: The top model explained 78% of the variation in pFF. Elevation was by far the best predictor, with pFF decreasing from 81% at 50 m a.s.l to 0% at 3,000 m a.s.l. At low elevations, pFF was higher on the wet windward (81%) than on the leeward (70%) where phylogenetic clustering was evident. Almost half (48%) of woody plants was fleshy‐fruited trees at low elevations. The proportion of fleshy‐fruited trees declined sharply with elevation and was significantly related to precipitation of the driest month contrary to the proportion of fleshy‐fruited shrubs that showed a hump shaped pattern along elevational gradient and no correlation with precipitation of the driest month. At high elevations, most plant assemblages were phylogenetically clustered and strongly dominated by single‐island endemic dry‐fruited plants. CONCLUSIONS: The striking relationship between pFF and elevation, the shift among fleshy‐fruited growth forms along climatic gradients and the phylogenetic clustering of assemblages subjected to harsh climatic conditions, suggested that climatic factors were the main drivers of the distribution of fruit types on Réunion. To explain the absence of fleshy‐fruited species at high elevations, we hypothesized that native fleshy‐fruited lineages lacked the evolutionary potential to adapt and fleshy‐fruited cold‐adapted lineages had major difficulties reaching Réunion.
    Keywords altitude ; autocorrelation ; canopy ; climatic factors ; data collection ; fruit composition ; fruits ; geographical distribution ; indigenous species ; islands ; models ; phylogeny ; shrubs ; trees ; vegetation ; woody plants ; Indian Ocean
    Language English
    Dates of publication 2018-09
    Size p. 847-858.
    Publishing place John Wiley & Sons, Ltd
    Document type Article
    Note JOURNAL ARTICLE
    ZDB-ID 1053769-7
    ISSN 1100-9233
    ISSN 1100-9233
    DOI 10.1111/jvs.12676
    Database NAL-Catalogue (AGRICOLA)

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  5. Article ; Online: Correction

    Ben H Warren / Rémy Baudin / Antoine Franck / Sylvain Hugel / Dominique Strasberg

    PLoS ONE, Vol 11, Iss 4, p e

    Predicting Where a Radiation Will Occur: Acoustic and Molecular Surveys Reveal Overlooked Diversity in Indian Ocean Island Crickets (Mogoplistinae: Ornebius).

    2016  Volume 0153504

    Keywords Medicine ; R ; Science ; Q
    Language English
    Publishing date 2016-01-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  6. Article ; Online: Predicting Where a Radiation Will Occur

    Ben H Warren / Rémy Baudin / Antoine Franck / Sylvain Hugel / Dominique Strasberg

    PLoS ONE, Vol 11, Iss 2, p e

    Acoustic and Molecular Surveys Reveal Overlooked Diversity in Indian Ocean Island Crickets (Mogoplistinae: Ornebius).

    2016  Volume 0148971

    Abstract: Recent theory suggests that the geographic location of island radiations (local accumulation of species diversity due to cladogenesis) can be predicted based on island area and isolation. Crickets are a suitable group for testing these predictions, as ... ...

    Abstract Recent theory suggests that the geographic location of island radiations (local accumulation of species diversity due to cladogenesis) can be predicted based on island area and isolation. Crickets are a suitable group for testing these predictions, as they show both the ability to reach some of the most isolated islands in the world, and to speciate at small spatial scales. Despite substantial song variation between closely related species in many island cricket lineages worldwide, to date this characteristic has not received attention in the western Indian Ocean islands; existing species descriptions are based on morphology alone. Here we use a combination of acoustics and DNA sequencing to survey these islands for Ornebius crickets. We uncover a small but previously unknown radiation in the Mascarenes, constituting a three-fold increase in the Ornebius species diversity of this archipelago (from two to six species). A further new species is detected in the Comoros. Although double archipelago colonisation is the best explanation for species diversity in the Seychelles, in situ cladogenesis is the best explanation for the six species in the Mascarenes and two species of the Comoros. Whether the radiation of Mascarene Ornebius results from intra- or purely inter- island speciation cannot be determined on the basis of the phylogenetic data alone. However, the existence of genetic, song and ecological divergence at the intra-island scale is suggestive of an intra-island speciation scenario in which ecological and mating traits diverge hand-in-hand. Our results suggest that the geographic location of Ornebius radiations is partially but not fully explained by island area and isolation. A notable anomaly is Madagascar, where our surveys are consistent with existing accounts in finding no Ornebius species present. Possible explanations are discussed, invoking ecological differences between species and differences in environmental history between islands.
    Keywords Medicine ; R ; Science ; Q
    Subject code 590
    Language English
    Publishing date 2016-01-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  7. Article ; Online: Artemisia annua , a Traditional Plant Brought to Light

    Axelle Septembre-Malaterre / Mahary Lalarizo Rakoto / Claude Marodon / Yosra Bedoui / Jessica Nakab / Elisabeth Simon / Ludovic Hoarau / Stephane Savriama / Dominique Strasberg / Pascale Guiraud / Jimmy Selambarom / Philippe Gasque

    International Journal of Molecular Sciences, Vol 21, Iss 4986, p

    2020  Volume 4986

    Abstract: Traditional remedies have been used for thousand years for the prevention and treatment of infectious diseases, particularly in developing countries. Of growing interest, the plant Artemisia annua , known for its malarial properties, has been studied for ...

    Abstract Traditional remedies have been used for thousand years for the prevention and treatment of infectious diseases, particularly in developing countries. Of growing interest, the plant Artemisia annua , known for its malarial properties, has been studied for its numerous biological activities including metabolic, anti-tumor, anti-microbial and immunomodulatory properties. Artemisia annua is very rich in secondary metabolites such as monoterpenes, sesquiterpenes and phenolic compounds, of which the biological properties have been extensively studied. The purpose of this review is to gather and describe the data concerning the main chemical components produced by Artemisia annua and to describe the state of the art about the biological activities reported for this plant and its compounds beyond malaria.
    Keywords Artemisia annua ; Asteraceae ; biological properties ; secondary metabolites ; Biology (General) ; QH301-705.5 ; Chemistry ; QD1-999
    Language English
    Publishing date 2020-07-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  8. Article: Long‐term declines of native trees in an oceanic island's tropical forests invaded by alien plants

    Florens, F.B. Vincent / Cláudia Baider / Nooshruth B. Seegoolam / Zeyn Zmanay / Dominique Strasberg

    Applied vegetation science. 2017 Jan., v. 20, no. 1

    2017  

    Abstract: QUESTION: How did the native and alien woody plant communities of protected lowland wet forests of a tropical oceanic island change in the presence of understorey invasive alien plants over the medium (21–27 yrs) and longer term (68 yrs)? LOCATION: ... ...

    Abstract QUESTION: How did the native and alien woody plant communities of protected lowland wet forests of a tropical oceanic island change in the presence of understorey invasive alien plants over the medium (21–27 yrs) and longer term (68 yrs)? LOCATION: Bel Ombre, Brise Fer and Macchabé forests in the Black River Gorges National Park (BRGNP), Mauritius (20°22′10″–20°28′17″ S, 57°24′45″–57°27′12″ E). METHODS: Random and replicated vegetation plots were sampled in two protected forest areas whose communities of woody plants were surveyed 21 and 27 yrs previously, and in another protected and similar forest that was surveyed 68 yrs earlier, to identify species and measure stem diameters so as to permit comparisons at the three sites over these time periods. RESULTS: Invasion by woody alien plants has progressed through time at all three sites, comprised mostly of the understorey and shade‐tolerant Strawberry guava (Psidium cattleianum). Concomitantly, although reductions in native woody plant species richness of large trees (≥10 cm DBH) were not statistically significant at the community level, their densities and basal area had roughly halved in 68 yrs. Comparisons with the studies 21–27 yrs previously confirmed the tendency towards a reduction in density of larger trees, besides indicating a trend towards decline in species richness of smaller understorey trees. CONCLUSION: An unabated replacement of native by alien trees over the longer term is occurring in protected areas of the lowland wet forests of the BRGNP and presumably in other similarly invaded areas. Our work stresses the importance of long‐term monitoring in elucidating impacts of invasive alien plants at the community level, particularly when dealing with slow‐growing and long‐lived species. Plausible mechanisms bringing about the observed changes and that have been found at the same or similar sites, include reduced regeneration, growth, production of flowers and fruits and increased mortality of native trees when these grow among invasive alien plants. The control of invasive alien plants, where they invade tropical forests, should be a central conservation objective even in better preserved and well protected areas.
    Keywords Psidium cattleyanum ; basal area ; conservation areas ; flowers ; forest reserves ; fruits ; indigenous species ; introduced plants ; invasive species ; monitoring ; mortality ; national parks ; rivers ; shade tolerance ; species diversity ; trees ; tropical forests ; understory ; woody plants ; Mauritius
    Language English
    Dates of publication 2017-01
    Size p. 94-105.
    Publishing place John Wiley & Sons, Ltd
    Document type Article
    Note JOURNAL ARTICLE
    ZDB-ID 1445659-x
    ISSN 1402-2001
    ISSN 1402-2001
    DOI 10.1111/avsc.12273
    Database NAL-Catalogue (AGRICOLA)

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  9. Article ; Online: Tropical Forests of Réunion Island Classified from Airborne Full-Waveform LiDAR Measurements

    Xiaoxia Shang / Patrick Chazette / Julien Totems / Elsa Dieudonné / Eric Hamonou / Valentin Duflot / Dominique Strasberg / Olivier Flores / Jacques Fournel / Pierre Tulet

    Remote Sensing, Vol 8, Iss 1, p

    2016  Volume 43

    Abstract: From an unprecedented experiment using airborne measurements performed over the rich forests of Réunion Island, this paper aims to present a methodology for the classification of diverse tropical forest biomes as retrieved from vertical profiles measured ...

    Abstract From an unprecedented experiment using airborne measurements performed over the rich forests of Réunion Island, this paper aims to present a methodology for the classification of diverse tropical forest biomes as retrieved from vertical profiles measured using a full-waveform LiDAR. This objective is met through the retrieval of both the canopy height and the Leaf Area Index (LAI), obtained as an integral of the foliage profile. The campaign involved sites ranging from coastal to rain forest, including tropical montane cloud forest, as found on the Bélouve plateau. The mean values of estimated LAI retrieved from the apparent foliage profile are between ~5 and 8 m2/m2, and the mean canopy height values are ~15 m for both tropical montane cloud and rain forests. Good agreement is found between LiDAR- and MODIS-derived LAI for moderate LAI (~5 m2/m2), but the LAI retrieved from LiDAR is larger than MODIS on thick rain forest sites (~8 against ~6 m2/m2 from MODIS). Regarding the characterization of tropical forest biomes, we show that the rain and montane tropical forests can be well distinguished from planted forests by the use of the parameters directly retrieved from LiDAR measurements.
    Keywords tropical forest ; airborne LiDAR ; canopy height ; Leaf Area Index ; apparent foliage ; Science ; Q
    Subject code 333
    Language English
    Publishing date 2016-01-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  10. Article: Invasive alien plants progress to dominate protected and best-preserved wet forests of an oceanic island

    Florens, F.B.Vincent / Cláudia Baider / Dominique Strasberg / Geneviève M.N. Martin / Nooshruth B. Seegoolam / Zeyn Zmanay

    Journal for nature conservation. 2016 Dec., v. 34

    2016  

    Abstract: Invasive alien plants pose a threat to biodiversity in particular on oceanic islands, where endemism tends to be high. In this context, it matters to characterise invasions in-situ and in particular to document how far invasive plants may invade ... ...

    Abstract Invasive alien plants pose a threat to biodiversity in particular on oceanic islands, where endemism tends to be high. In this context, it matters to characterise invasions in-situ and in particular to document how far invasive plants may invade protected areas devoid of major human disturbances. We explore this question on the tropical island of Mauritius, which provides an interesting case study because it possesses several attributes of human impacts, which are increasingly being encountered by most tropical oceanic islands worldwide. Mauritius today may thus serve as a “window” into the future of many other islands. We assess woody invasive alien plant abundance in the island’s wet native forests by sampling five of the currently best-preserved sites. We chose only protected areas that have benefitted from long-term legal protection. All woody alien plants reaching at least 1cm of diameter at breast height (dbh) were identified and their dbh measured in a series of fifteen 100m2 quadrats randomly placed in each forest. All sites are today dominated by woody invasive alien plants, which comprised 78.5% of the 27868 sampled plants ≥1cm dbh. Density-wise, the alien shade tolerant strawberry guava (Psidium cattleianum) dominates all forests sampled. In terms of Importance Value (as percent relative dominance and percent relative density), P. cattleianum dominates four sites and another alien, Cinnamomum verum, dominates one site. Our study shows that even though relatively diverse, the native plant communities of an oceanic island cannot resist the encroachment of understory invasive alien plants, even in better preserved, least disturbed forests that have been receiving long-term formal legal protection.
    Keywords anthropogenic activities ; biodiversity ; case studies ; Cinnamomum verum ; conservation areas ; forests ; humans ; indigenous species ; introduced plants ; invasive species ; islands ; plant communities ; Psidium cattleyanum ; shade tolerance ; tree and stand measurements ; understory ; Mauritius
    Language English
    Dates of publication 2016-12
    Size p. 93-100.
    Publishing place Elsevier GmbH
    Document type Article
    ZDB-ID 2077553-2
    ISSN 1618-1093 ; 1617-1381
    ISSN (online) 1618-1093
    ISSN 1617-1381
    DOI 10.1016/j.jnc.2016.09.006
    Database NAL-Catalogue (AGRICOLA)

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