Éditeur(s) : HAL CCSD BioMed Central
Résumé : International audience
BACKGROUND: Sampling design is a key issue when establishing species inventories and characterizing habitats within highly heterogeneous landscapes. Sampling efforts in such environments may be constrained and many field studies only rely on subjective and/or qualitative approaches to design collection strategy. The region of Cacao, in French Guiana, provides an excellent study site to understand the presence and abundance of Anopheles mosquitoes, their species dynamics and the transmission risk of malaria across various environments. We propose an objective methodology to define a stratified sampling design. Following thorough environmental characterization, a factorial analysis of mixed groups allows the data to be reduced and non-collinear principal components to be identified while balancing the influences of the different environmental factors. Such components defined new variables which could then be used in a robust k-means clustering procedure. Then, we identified five clusters that corresponded to our sampling strata and selected sampling sites in each stratum. RESULTS: We validated our method by comparing the species overlap of entomological collections from selected sites and the environmental similarities of the same sites. The Morisita index was significantly correlated (Pearson linear correlation) with environmental similarity based on i) the balanced environmental variable groups considered jointly (p = 0.001) and ii) land cover/use (p-value<0.001). The Jaccard index was significantly correlated with land cover/use-based environmental similarity (p-value = 0.001). CONCLUSIONS: The results validate our sampling approach. Land cover/use maps (based on high spatial resolution satellite images) were shown to be particularly useful when studying the presence, density and diversity of Anopheles mosquitoes at local scales and in very heterogeneous landscapes.
BMC Ecology

pasteur-00914104
https://hal-riip.archives-ouvertes.fr/pasteur-00914104
https://hal-riip.archives-ouvertes.fr/pasteur-00914104/document
DOI : 10.1186/1472-6785-13-45
PUBMED : 24289184

Éditeur(s) : HAL CCSD Springer Verlag/EDP Sciences
Résumé : Le développement de modèles de dynamique forestière adaptés aux forêts tropicales humides est compliqué par la très grande diversité spécifique caractérisant ces forêts. Les modélisateurs ont souvent eu recours, pour simplifier le problème, à des techniques de regroupement d'espèces. Il existe des méthodes diverses de regroupement, qui relèvent de trois grands types de stratégie : (i) stratégie écologique subjective, (ii) stratégie écologique basée sur l'analyse de données, (iii) stratégie des processus de dynamique populationnelle. Dans le cadre des deux premières stratégies, une espèce est affectée à un groupe et un seul alors que dans le cadre de la troisième, des groupes d'espèces sont définis pour chacun des processus de dynamique (recrutement, croissance, mortalité) pris séparément, et chaque espèce est affectée à trois groupes. Dans la littérature, on trouve peu d'exemples de congruence ou de convergence entre les groupes définis par ces différentes méthodes. Ceci peut être expliqué par l'indépendance existant entre les caractères utilisés pour fabriquer tel ou tel groupe, ou encore par la grande variabilité intra-spécifique de ces caractères. Nous argumentons et concluons sur le fait que le recours à la stratégie des processus de dynamique paraît être la meilleure pour construire des groupes d'espèces adaptés à la prédiction de la dynamique des forêts tropicales.
ISSN: 1286-4560

hal-01032060
https://hal.archives-ouvertes.fr/hal-01032060
DOI : 10.1051/forest:2005084

Éditeur(s) : HAL CCSD Royal Society, The
Résumé : There is broad consensus that the diversity of functional traits within species assemblages drives several ecological processes. It is also widely recognized that rare species are the first to become extinct following human-induced disturbances. Surprisingly, however, the functional importance of rare species is still poorly understood, particularly in tropical species-rich assemblages where the majority of species are rare, and the rate of species extinction can be high. Here, we investigated the consequences of local and regional extinctions on the functional structure of species assemblages. We used three extensive datasets (stream fish from the Brazilian Amazon, rainforest trees from French Guiana, and birds from the Australian Wet Tropics) and built an integrative measure of species rarity versus commonness, combining local abundance, geographical range, and habitat breadth. Using different scenarios of species loss, we found a disproportionate impact of rare species extinction for the three groups, with significant reductions in levels of functional richness, specialization, and originality of assemblages, which may severely undermine the integrity of ecological processes. The whole breadth of functional abilities within species assemblages, which is disproportionately supported by rare species, is certainly critical in maintaining ecosystems particularly under the ongoing rapid environmental transitions.
ISSN: 0962-8452

hal-01532639
https://hal.archives-ouvertes.fr/hal-01532639
DOI : 10.1098/rspb.2016.0084
PRODINRA : 384617

Éditeur(s) : HAL CCSD
Résumé :  Diffusion du document : INRA Antilles-Guyane, UMR ECOFOG, F97387 Kourou, Guyane (France)Diplôme : Master Recherche
il s'agit d'un type de produit dont les métadonnées ne correspondent pas aux métadonnées attendues dans les autres types de produit : DISSERTATION
Origin and maintenance of species diversity is one of the main questions in evolutive biology. Species complexes, ie sister species still exchanging genes, are common in tropical forests and contribute to this diversity. This poster describes the organization of the genetic diversity in two closely related tree species, Carapa guianensis and C. procera, which are in sympatry in French Guiana. By using a clustering method based on nuclear markers (Pritchard et al. 2000), 506 trees sampled in French Guiana have been assigned to a species. Interestingly, many individuals harbored intermediate genome and we assigned to an hybrid group. The geographic distribution of these individuals revealed the presence of a contact zone between the two carapa species in the Eastern part of French Guiana. We then analysed genetic diversity at cholroplast genome and revealed a symmetrical gene flow between the two sister species. In addition, hybridization between hybrids and parental species ar likely possible but still need validations thanks to control crosses. Within species, we finally revealed the presence of a departure from the neutral equilibrium in thedirection of a population expansion likely related to Holocene perturbations. This expansion may have contributed to the hybrid zone formation in French Guiana.
L'origine et le maintien de la diversité spécifique des forêts tropicales humides est une question clé en biologie évolutive. Ce travail contribue à améliorer la compréhension de ces mécanismes à travers l'étude de la distribution de la diversité génétique de deux espèces sœurs interfertiles, le Carapa procera et C. guianensis en Guyane. L'assignation botanique des arbres échantillonnés (506) a été effectuée en adoptant une approche moléculaire qui repose sur l'analyse de la répartition des fréquences alléliques de six microsatellites nucléaires (Pritchard et al. 2000). Chaque locus présente des allèles dont les différences de fréquences entre espèces sont importantes, permettant ainsi d'envisager des outils simples de reconnaissances pour ces espèces difficilement identifiables sur la seule base de leurs caractères phénotypiques. Une zone de contact des deux espèces où les phénomènes d'hybridations sont fréquents a par ailleurs été localisée. En associant une analyse de la diversité au niveau du génome chloroplastique sur un sous ensemble d'individus (244), j'ai pu montrer que l'introgression est bidirectionnelle et que les backcross sont possibles. Les flux de gènes entre les deux espèces sont fréquents, et à l'intérieur des espèces, les populations sont peu structurées bien que la différenciation soit significative entre les sites les plus éloignés. Enfin, ce travail met en évidence que les populations de chacune des deux espèces présentent un signal d'expansion de population, avec un signal plus fort pour le C. procera, qui laisse présager une expansion récente, vraisemblablement à l'origine de la zone de contact. L'impact des évènements climatiques et/ou des activités amérindiennes des 10 000 dernières années pourrait expliquer la restriction puis l'expansion de ce genre post pionnier.
https://hal.archives-ouvertes.fr/hal-01189488

hal-01189488
https://hal.archives-ouvertes.fr/hal-01189488
PRODINRA : 42333

Éditeur(s) : HAL CCSD
Résumé : International audience
Over the past decade, much attention has been devoted to the development of forest biomass estimation methods at a stand scale, leading to the establishment of allometric models (Chave et al., 2014). These allometric equations use a unique wood specific gravity value (WSG) per species, but neglect the within tree variations of WSG found by others (Wiemann & Williamson, 1989).The main objectives of this study are (1) to illustrate the diversity of radial (from pith to bark) and longitudinal (from bottom to top) patterns of WSG variation within and between species, (2) to highlight different trends of WSG radial variations and the possible misinterpretations of these trends due to the effect of heartwood and (3) to link these variations and patterns to the successional status of the species (from pioneer to sciaphilic species).We sampled 33 small trees (10 Wood sciences underpinning tropical ecology and management. International closing symposium of the XYLAREDD project.
Tervuren, Belgium

hal-01188894
https://hal-sde.archives-ouvertes.fr/hal-01188894

Éditeur(s) : HAL CCSD Ecological Society of America
Résumé : Line transect surveys are widely used in neotropical rainforests to estimate the population abundance of medium- and large-sized vertebrates. The use of indices such as Encounter Rate has been criticized because the probability of animal detection may fluctuate due to the heterogeneity of environmental conditions among sites. In addition, the morphological and behavioral characteristics (biological traits) of species affect their detectability. In this study, we compared the extent to which environmental conditions and species' biological traits bias abundance estimates in terra firme rainforests in French Guiana. The selected environmental conditions included both physical conditions and forest structure covariates, while the selected biological traits included the morphological and behavioral characteristics of species. We used the distance sampling method to model the detection probability as an explicit function of environmental conditions and biological traits and implemented a model selection process to determine the relative importance of each group of covariates. Biological traits contributed to the variability of animal detectability more than environmental conditions, which had only a marginal effect. Detectability was best for large animals with uniform or disruptive markings that live in groups in the canopy top. Detectability was worst for small, solitary, terrestrial animals with mottled markings. In the terra firme rainforests which represent ~80% of the Amazonia and Guianas regions, our findings support the use of relative indices such as the encounter rate to compare population abundance between sites in species-specific studies. Even though terra firme rainforests may appear similar between regions of Amazonia and the Guianas, comparability must be ensured, especially in forests disturbed by human activity. The detection probability can be used as an indicator of species' vulnerability to hunting and, thus, to the risk of local extinction. Only a few biological trait covariates are required to correctly estimate the detectability of the majority of medium- and large-sized vertebrates. Thus, a biological trait model could be useful in predicting the detection probabilities of rare, uncommon or localized species for which few data are available to fit the detection function.
ISSN: 1051-0761

hal-01555267
https://hal.archives-ouvertes.fr/hal-01555267
DOI : 10.1002/eap.1549
PRODINRA : 396614
PUBMED : 28419598

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : Functional aspects of biodiversity were investigated in a lowland tropical rainforest in French Guyana (5°2'N, annual precipitation 2200 mm). We assessed leaf '15N as a presumptive indicator of symbiotic N2 fixation, and leaf and wood cellulose '13C as an indicator of leaf intrinsic water-use efficiency (CO2 assimilation rate/leaf conductance for water vapour) in dominant trees of 21 species selected for their representativeness in the forest cover, their ecological strategy (pioneers or late successional stage species, shade tolerance) or their potential ability for N2 fixation. Similar measurements were made in trees of native species growing in a nearby plantation after severe perturbation (clear cutting, mechanical soil disturbance). Bulk soil '15N was spatially quite uniform in the forest (range 3-5‰), whereas average leaf '15N ranged from m0.3‰ to 3.5‰ in the different species. Three species only, Diplotropis purpurea, Recordoxylon speciosum (Fabaceae), and Sclerolobium melinonii (Caesalpiniaceae), had root bacterial nodules, which was also associated with leaf N concentrations higher than 20 mg gm1. Although nodulated trees displayed significantly lower leaf '15N values than non-nodulated trees, leaf '15N did not prove a straightforward indicator of symbiotic fixation, since there was a clear overlap of '15N values for nodulated and non-nodulated species at the lower end of the '15N range. Perturbation did not markedly affect the difference '15Nsoil m '15Nleaf, and thus the isotopic data provide no evidence of an alteration in the different N acquisition patterns. Extremely large interspecific differences in sunlit leaf '13C were observed in the forest (average values from m31.4 to m26.7‰), corresponding to intrinsic water-use efficiencies (ratio CO2 assimilation rate/leaf conductance for water vapour) varying over a threefold range. Wood cellulose '13C was positively related to total leaf '13C, the former values being 2-3‰ higher than the latter ones. Leaf '13C was not related to leaf '15N at either intraspecific or interspecific levels. '13C of sunlit leaves was highest in shade hemitolerant emergent species and was lower in heliophilic, but also in shade-tolerant species. For a given species, leaf '13C did not differ between the pristine forest and the disturbed plantation conditions. Our results are not in accord with the concept of existence of functional types of species characterized by common suites of traits underlying niche differentiation; rather, they support the hypothesis that each trait leads to a separate grouping of species.
ISSN: 0029-8549

hal-01032378
https://hal.archives-ouvertes.fr/hal-01032378
DOI : 10.1007/s004420050593

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : Intraguild predation (IGP) is a type of biological interaction involving the killing and consuming of competing species that exploit similar and often limited resources. This phenomenon is widespread among a great variety of taxonomic groups and has already been reported for mosquito (Diptera: Culicidae) larvae. Moreover, the larvae of certain mosquito species of the tribe Sabethini have evolved modified mouthparts ending in rigid apical structures signaling their capacity to be effective intraguild predators. We assumed that IGP confers a selective advantage under severe competitive conditions by both providing an immediate energetic gain and reducing potential competition. Because potential competition is likely to increase with decreasing habitat size, we hypothesized that the proportion of species with modified mouthparts would increase in smaller aquatic habitats. We tested this hypothesis by examining the mosquito species naturally associated with phytotelmata of decreasing sizes in French Guiana. We show that the degree of specialization in mosquito-phytotelm associations is high, suggesting a long coevolutive process. Indeed, short-term interaction experiments confirmed that species with modified mouthparts are able to prey upon similarly-sized intraguild prey and are, thus, effective intraguild predators. In addition, these species are larger and associated with smaller phytotelmata than those with typical mouthparts. Moreover, below a certain threshold of phytotelm size, only species with modified mouthparts were present. These results show that IGP confers a selective advantage under severe competitive conditions and results from the coadaptation of mosquito species to their specific phytotelm habitat. The presence of functionally analogous structures in different mosquito genera also implies that IGP has emerged from convergent evolution in small phytotelmata.
ISSN: 0269-7653

hal-01603304
https://hal.archives-ouvertes.fr/hal-01603304
DOI : 10.1007/s10682-016-9862-3
PRODINRA : 405771

Éditeur(s) : HAL CCSD Paris : Muséum national d'histoire naturelle
Résumé : International audience
Coral reefs are one of the most diverse ecosystems on Earth and sustain millions of people worldwide.However, coral reefs are temporally dynamic and fragile systems subject to ever increasing disturbancesof anthoropogenic and natural origins. Understanding the patterns and trajectories of changes through time isurgently needed to estimate the resilience of coral reefs. To ascertain these patterns, we depend on the availabilityof long-term datasets, which are seldom available. In this study, we present the data set which allowed us to analysethe long-term trends of coral and fish assemblages for the island of Moorea (French Polynesia) from 1983to 2014, a dataset spanning 32 years, comprising two Acanthaster planci outbreaks (1987 and 2006) and severalhurricanes (1982, 1983, 1991 and 2010), on three permanent monitoring sites (quadrats of 50 × 2 m2) located onboth fringing and barrier reefs as well as on the outer slope. Coral cover oscillated significantly over time, particularlyon the outer slope where it suffered greatly from the effects of A. planci outbreaks and hurricanes. Totalfish and commercial fish abundances varied significantly across the three habitats. Prior to 2000, both total fishand herbivorous fish abundances increased on the barrier reef while after this time, numbers began to drop significantlyalong the outer slope. Species richness for total, commercialized and herbivorous fish increased over thesampling period for all three habitats. There were varied responses amongst species to disturbances on the outerslope over the sampling period: while some tended to disappear for a while before reappearing, others showed apeak in abundance in the middle of the sampling period, and still others increased or decreased continuously orwere stable over time. Our results support the view that coral reefs are highly dynamic systems and that differentfunctional groups show different temporal trajectories. While disturbance is probably the major driver for coralcover dynamics, its impact is less obvious for fish, possibly due to their mobility and population dynamics whichmay mask the effect of disturbance.
Les récifs coralliens sont des systèmes dynamiques et diversifiés régulièrement soumis à des perturbationsnaturelles et anthropiques, sources d’hétérogénéité spatiale et temporelle dans la structure et la dynamique deces communautés d’organismes que sont, entre autres, les poissons et les coraux. Récemment, il a été démontréque les activités humaines pouvaient modifier les régimes naturels de perturbations des récifs coralliens en transformantles événements ponctuels en perturbations persistantes ou en stress chronique, soit en introduisant denouveaux types de perturbations, soit en ajoutant ou altérant certaines perturbations naturelles nécessaires au bonmaintien de la dynamique inhérente aux récifs. Dans cette étude, nous présentons la base de données qui nouspermettra d’analyser les tendances à long-terme des assemblages de poissons et de coraux de l’île de Moorea(Polynésie française) entre 1983 et 2014 sur une période de 32 ans, comprenant deux proliférations d’Acanthasterplanci (1987 et 2006) et plusieurs cyclones (1982, 1983, 1991 et 2010), sur trois sites de suivi permanents(quadrats de 50 × 2 m2) sur les récifs barrière et frangeant ainsi que sur la pente externe. La couverture corallienneprésente de fortes oscillations, en particulier sur la pente externe où elle a répondu fortement à la proliférationd’A. planci et des cyclones. Les abondances des poissons totaux et des poissons commercialisés montrent destendances contrastées sur les trois habitats, avec, plus particulièrement, une augmentation sur le récif barrière etune diminution sur la pente externe après 2000. Ces tendances se retrouvent chez les poissons herbivores dansces deux habitats. La richesse spécifique des poissons totaux, commerciaux et herbivores, augmente de façoncontinue au cours de la période d’étude dans les trois habitats. Des groupes particuliers d’espèces répondentdifféremment aux perturbations de la pente externe au cours du suivi : alors que certaines espèces ont tendanceà disparaître pendant quelques années avant de réapparaître, d’autres présentent un pic en terme d’abondanceen milieu de suivi ; d’autres espèces ont des abondances qui augmentent ou diminuent de façon continue, etd’autres encore montrent des abondances stables. Ceci indique que les récifs coralliens sont des systèmes trèsdynamiques dans lesquels les perturbations naturelles peuvent affecter les espèces de façon différente. Alors quele régime de perturbations naturelles semble être important pour la dynamique de la couverture corallienne danscertains habitats, cela se retrouve beaucoup moins pour les poissons. Cette atténuation des fluctuations spatialeset temporelles peut être due aux aptitudes de dispersion de nombreuses espèces de poissons, capables de chercherun autre habitat favorable en cas de perturbation de l’habitat corallien d’origine.
ISSN: 0399-0974

hal-01282378
https://hal-univ-perp.archives-ouvertes.fr/hal-01282378

Éditeur(s) : HAL CCSD Wiley
Résumé : Question: To establish a habitat classification based on functional group co-occurrence that may help the drawing up of conservation plans. Location: Riverine forest fragments in the Grand-duché de Luxembourg, Europe. Methods: Forest fragments were surveyed for their abundance of vascular plants. These were clustered into emergent groups according to 14 life-traits related 10 plant dispersal, establishment and persistence. Forest fragments were classified according to similar distribution of the identified emergent groups. Environmental factors were related to the emergent group richness in each forest type using generalized linear models. Results: Contrary to former species centred classification, only two groups of forests, each with clearly different emergent group composition and conservation requirements. Were detected: (1) swamp forests characterized by anemogamous perennials, annuals and hydrochorous perennials and (2) moist forests characterized by barochorous perennials, small geophytes and zoochorous phanerophytes. From a conservation point of view, priority should he given to large swamp forest with intact flooding regimes his is in accordance with the high wind and water dispersal capacities of their typical emergent groups. For the moist forests. conservation priorities should he high forest connectivity and historical continuity since dispersal and establishment of their characteristic emergent groups arc highly limited. Conclusions: The described methodology, situated at an intermediate integration level between the individual species and whole community descriptors. takes advantage of both conservation plans built for single species and the synthetic power of bread ecological measures.
ISSN: 1402-2001

hal-01031884
https://hal.archives-ouvertes.fr/hal-01031884

Éditeur(s) : HAL CCSD Oxford University Press (OUP)
Résumé : International audience
Background and Aims: In rain forests, sapling survival is highly dependent on the regulation of trunk slenderness (height/diameter ratio): shade-intolerant species have to grow in height as fast as possible to reach the canopy but also have to withstand mechanical loadings (wind and their own weight) to avoid buckling. Recent studies suggest that mechanosensing is essential to control tree dimensions and stability-related morphogenesis. Differences in species slenderness have been observed among rainforest trees; the present study thus investigates whether species with different slenderness and growth habits exhibit differences in mechanosensitivity. Methods: Recent studies have led to a model of mechanosensing (sum-of-strains model) that predicts a quantitative relationship between the applied sum of longitudinal strains and the plant's responses in the case of a single bending. Saplings of five different neotropical species (Eperua falcata, E. grandiflora, Tachigali melinonii, Symphonia globulifera and Bauhinia guianensis) were subjected to a regimen of controlled mechanical loading phases (bending) alternating with still phases over a period of 2 months. Mechanical loading was controlled in terms of strains and the five species were subjected to the same range of sum of strains. The application of the sum-of-strain model led to a dose-response curve for each species. Dose-response curves were then compared between tested species. Key Results: The model of mechanosensing (sum-of-strain model) applied in the case of multiple bending as long as the bending frequency was low. A comparison of dose-response curves for each species demonstrated differences in the stimulus threshold, suggesting two groups of responses among the species. Interestingly, the liana species B. guianensis exhibited a higher threshold than other Leguminosae species tested. Conclusions: This study provides a conceptual framework to study variability in plant mechanosensing and demonstrated interspecific variability in mechanosensing.
ISSN: 0305-7364

halsde-00454145
https://hal.archives-ouvertes.fr/halsde-00454145
DOI : 10.1093/aob/mcp286

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Aim of the study: A knowledge attitude and practice study centred on leishmaniasis and its treatment was performed among the Chayahuita, an Amazonian Peruvian ethnic group living in an endemic area. This study documents traditional Chayahuita plant's use and disease concepts. Also, activty of some medicinal plants used by the Chayahuita is highlighted and discussed. Materials and methods: Ninety-three Chayahuita people were interviewed, following a semi-structured questionnaire focussed on disease knowledge and perception, personal attitude and healing practices. Simultaneously, a collection of plants was performed in different ecotopes, in order to make an extensive inventory of the pharmacopoeia. Results: For the Chayahuita, cutaneous (CL) and muco-cutaneous leishmaniasis (MCL) are considered as diseases of their own, with specific names, aetiologies, mode of transmission. Regarding CL, Chayahuita people consider that the humid characteristic of the skin ulcer is a discriminative fact orienting the diagnostic forTa'ta' (leishmaniasis). Forty-six different species were designated useful against LC and /or MCL (29 species by means of the questionnaire and 27 species when collecting in different ecotopes). Thirty-seven extracts corresponding to 31 species used medicinally were screened in vitro against Leishmania amnzonensis axenic amastigotes, assessing their viability by the reduction of tetrazolium salt (MTT). Six species displayed a good activity ( 10 μg/ml < IC50 < 20 μg/ml): an undetermined hemi-epiphytic Clusiaceae, Cyhianthus anthuriophyllus Pipoly (Myrsinaceae), two Piper, Piper sanguineispicum Trel., and Piper loretoanum Trel. (Piperaceae), Desmodium axillare Sw. DC. (Fabaceae), and Clibadium sylvestre (Aubl.) Baill. (Asteraceae). Conclusion: Perception of leishmaniasis, attitude, treatments and diet prohibitions still largely reflects traditional Chayahuita cosmovision, even if some tentative of bio-medical re-interpretation is arising.
ISSN: 0378-8741

hal-01087667
https://hal-agroparistech.archives-ouvertes.fr/hal-01087667
DOI : 10.1016/j.jep.2009.07.015

Éditeur(s) : HAL CCSD Magnolia Press
Résumé : International audience
Hydroporus rifensis sp. n. is described from Central Rif in northern Morocco. The new species is the first member of the Hydroporus tristis-group to be recorded from the African continent. Analyses of cytochrome oxydase 1 (CO1) and 16S rRNA partial sequences indicate unambiguously that H. rifensis sp. n. is a geographical vicariant of the widespread and common European species Hydroporus gyllenhalii Schiodte, 1841, whose closest Iberian populations are known from southern Spain and southern Portugal. Genetically the two species are very close, but in terms of morphology they differ considerably, to the extent that in several respects H. rifensis sp. n. is more similar to some species of the H. striola-group, the sister clade of the H. tristis-group. The new species differs from H. gyllenhalii notably by its larger size, lighter elytra, stronger pubescence, much finer elytral punctation, morphology of the median prosternum area, and marked differentiation of protarsal claws in male. Hydroporus rifensis sp. n. is the first dytiscid species endemic to the Rif and the second Hydroporus species endemic to Morocco.
ISSN: 1175-5326

hal-01544481
https://hal.archives-ouvertes.fr/hal-01544481
DOI : 10.11646/zootaxa.3841.1.4

Éditeur(s) : HAL CCSD
Résumé : One of the major challenges in forest ecology is to understand the ecology, physiology and potential responses of the> 250000 species of vascular plants of the planet through the categorization of this diversity into functional groups. This approach is essentially based on functional traits analysis, but few investigations were made in tropical areas. The aim of this study was to determine functional groups in two contrasted tropical ecosystems, dry (DF) and mountain rain (MRF) forest (respectively rainfall of 1 200 mm/year and 10 000 mm/year). Guadeloupe Island in FWI presents both these ecosystems spread over less 100 km. In a first time, we developed an original species typology based on 7 "soft" traits, easy to measure (stomatal density, leaf trichom density, chlorophyll content, leaf nitrogen content, specific leaf area, wood density, leaf area, plant height). The method was based on principal component analysis (PCA) and agglomerative hierarchical clustering (AHC) applied to these traits measured at the individual level (Blazy et al., 2009). In a second time, we evaluated the relevance of these soft trait-based groups compared to a typology based on 5 "hard" ecophysiological traits, more costly to quantify but with higher functional significance (difference between predawn and minimum leaf water potential, stomatal conductance, maximal carbon assimilation rate, leaf water potential at 90% of loss of stem hydraulic conductivity). When performed on the dominant canopy species in DF and MRF (a total of 13 species and 60 mature individuals), the typological approach based on soft traits seems relevant to discriminate groups with a distinct functional reality. Through both ecosystems, we obtained 4 homogenous groups. Two were exclusively composed by DF's or MRF's species, indicating that a functional strategy can be linked to specific environmental conditions. The two other groups showed a mix of DF and MRF species indicating that different functional strategies can coexist in the same environment. These mixed groups seem distinct by their ecophysiological features, particularly in term of hydraulic characteristics. One group was composed by drought tolerant species, water spender species, with a high xylem embolism resistance, whereas the second one was composed by water saver species, less resistant to embolism. Therefore, a determination of functional groups based on soft traits could be useful to model ecosystem's responses to environmental changes on a global scale.
Book of Abstracts - isem 2013 - Ecological Modelling for Ecosystem Sustainability
Toulouse, France

hal-00964668
https://hal.archives-ouvertes.fr/hal-00964668

Éditeur(s) : HAL CCSD Elsevier
Résumé :  
Classifying species by shared life-history traits is important if common ecological response groups are to be identified among different species. We investigated how habitat area, local and regional factors shape plant communities in small isolated closed depressions, and how the species richness is related to the interplay between environmental factors and specific life-history trait combinations. In Central-Western Europe, 169 closed depressions were completely Surveyed for plant presence in two highly contrasted landscapes (forested and open landscapes). All species were clustered into 9 Emergent Groups based oil 10 life-history traits related to plant dispersal, establishment and persistence. Habitat areas were related to species presence using logistic regressions. Most Emergent Groups were more area-dependent in open than in forested landscapes, owing to heterogeneous light levels in forest weakening the species-area relationship. In open landscapes, Floating Hydrophytes were severely underrepresented in very small depressions, owing to the absence of waterfowl poulation. Local environmental and regional factors were related to species richness using Generalized Linear Models. In open landscapes, local environmental factors such as water conductivity or soil productivity are respectively the main predictors. In forested landscapes, the abundance of most Emergent Groups Was better predicted by regional factors, i.e., habitat connectivity and distance to the forest edge. Forested landscapes strongly impeded the closed depressions' colonization by the less mobile Emergent Groups Such as Large-seeded Perennials.
ISSN: 1146-609X

hal-01032144
https://hal.archives-ouvertes.fr/hal-01032144
DOI : 10.1016/j.actao.2009.02.002

Éditeur(s) : HAL CCSD
Résumé : International audience
Fish is a rich source of essential nutrients for fetal development, but in contrast, it is also a well-known route of exposure to environmental pollutants. We assessed whether fish intake during pregnancy is associated with fetal growth and the length of gestation in a panel of European birth cohort studies. The study sample of 151,880 mother-child pairs was derived from 19 population-based European birth cohort studies. Individual data from cohorts were pooled and harmonized. Adjusted cohort-specific effect estimates were combined by using a random- and fixed-effects meta-analysis. Women who ate fish >1 time/wk during pregnancy had lower risk of preterm birth than did women who rarely ate fish (≤ 1 time/wk); the adjusted RR of fish intake >1 but <3 times/wk was 0.87 (95% CI: 0.82, 0.92), and for intake ≥ 3 times/wk, the adjusted RR was 0.89 (95% CI: 0.84, 0.96). Women with a higher intake of fish during pregnancy gave birth to neonates with a higher birth weight by 8.9 g (95% CI: 3.3, 14.6 g) for >1 but <3 times/wk and 15.2 g (95% CI: 8.9, 21.5 g) for ≥ 3 times/wk independent of gestational age. The association was greater in smokers and in overweight or obese women. Findings were consistent across cohorts. This large, international study indicates that moderate fish intake during pregnancy is associated with lower risk of preterm birth and a small but significant increase in birth weight.
The American Journal of Clinical Nutrition

hal-01118513
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01118513
PUBMED : 24335057
DOI : 10.3945/ajcn.113.067421

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
Ants figure prominently among the worst invasive species because of their enormous ecological and economic impacts. However, it remains to be investigated which species would be behaviourally dominant when confronted with another invasive ant species, should two species be introduced in the same area. In the future, many regions might have suitable environmental conditions for several invasive ant species, as predicted under climate change scenarios. Here, we explored interactions among several highly invasive ant species, which have been shown to have overlapping suitable areas. The aim of this study was to evaluate the performance in interference competition of seven of the world's worst invasive ant species (Anoplolepis gracilipes, Paratrechina longicornis, Myrmica rubra, Linepithema humile, Lasius neglectus, Wasmannia auropunctata and Pheidole megacephala). We conducted pairwise confrontations, testing the behaviour of each species against each of the six other species (in total 21 dyadic confrontations). We used single worker confrontations and group interactions of 10 versus 10 individuals to establish a dominance hierarchy among these invasive ant species. We discovered two different behavioural strategies among these invasive ants: three species displayed evasive or indifferent behaviour when individuals or groups were confronted (A. gracilipes, Pa. longicornis, M. rubra), while the four remaining species were highly aggressive during encounters and formed a linear dominance hierarchy. These findings contrast with the widespread view that invasive ants form a homogeneous group of species displaying the `invasive syndrome', which includes generally aggressive behaviour. The dominance hierarchy among the four aggressive species may be used to predict the outcome of future competitive interactions under some circumstances. Yet, the existence of several behavioural strategies renders such a prediction less straightforward.
ISSN: 1387-3547

hal-01444816
https://hal.archives-ouvertes.fr/hal-01444816
DOI : 10.1007/s10530-015-0892-5

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Ctenophores are a phylum of non-bilaterian marine (mostly planktonic) animals, characterised by several unique synapomorphies (e.g., comb rows, apical organ). Relationships between and within the nine recognised ctenophore orders are far from understood, notably due to a paucity of phylogenetically informative anatomical characters. Previous attempts to address ctenophore phylogeny using molecular data (18S rRNA) led to poorly resolved trees but demonstrated the paraphyly of the order Cydippida. Here we compiled an updated 18S rRNA data set, notably including a few newly sequenced species representing previously unsampled families (Lampeidae, Euryhamphaeidae), and we constructed an additional more rapidly evolving ITS1 + 5.8S rRNA + ITS2 alignment. These data sets were analysed separately and in combination under a probabilistic framework, using different methods (maximum likelihood, Bayesian inference) and models (e.g., doublet model to accommodate secondary structure; data partitioning). An important lesson from our exploration of these datasets is that the fast-evolving internal transcribed spacer (ITS) regions are useful markers for reconstructing high-level relationships within ctenophores. Our results confirm the paraphyly of the order Cydippida (and thus a ``cydippid-like'' ctenophore common ancestor) and suggest that the family Mertensiidae could be the sister group of all other ctenophores. The family Lampeidae (also part of the former ``Cydippida'') is probably the sister group of the order Platyctenida (benthic ctenophores). The order Beroida might not be monophyletic, due to the position of Beroe abyssicola outside of a clade grouping the other Beroe species and members of the ``Cydippida'' family Haeckeliidae. Many relationships (e.g. between Pleurobrachiidae, Beroida, Cestida, Lobata, Thalassocalycida) remain unresolved. Future progress in understanding ctenophore phylogeny will come from the use of additional rapidly evolving markers and improvement of taxonomic sampling.
ISSN: 0944-2006

hal-01544475
https://hal.archives-ouvertes.fr/hal-01544475
DOI : 10.1016/j.zool.2014.06.004

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
We sought transversotrematid trematodes from French Polynesian fishes by examining 304 individual scaled fishes of 53 species from seven families known to harbour the family elsewhere. A single species was found at two locations in the Tuamotus Archipelago on two species of Chaetodontidae (Chaetodon auriga and Chaetodon ephippium) and one species of Lutjanidae (Lutjanus gibbus). The species closely resembles Transversotrema borboleta Hunter & Cribb, 2012 from chaetodontids and lutjanids of the northern Great Barrier Reef (GBR) but differs from it consistently in 8 base positions of ITS2 rDNA. This level of variation exceeds that between some clearly morphologically distinct pairs of species of Transversotrema and the form from French Polynesia is thus interpreted as a distinct, though cryptic, species and named Transversotrema polynesiae n. sp. The new species forms part of a complex of species, here characterised as the T. borboleta complex, associated with chaetodontids and lutjanids in the tropical Indo-West Pacific. Most of the putative species within this complex are yet to be described. Comparison of identical numbers of matched samples of fishes from French Polynesia, Heron Island (southern GBR) and Lizard Island (northern GBR) revealed 1, 4 and 10 species of Transversotrema respectively suggesting that the French Polynesian fauna is depauperate for this family. In addition to those species apparently missing from suitable hosts in French Polynesia, several species from further west infect fishes (especially Nemipteridae) that are themselves absent from French Polynesia. This dramatic east–west decline in richness contrasts strongly with what is known for monogeneans, which appear to maintain their richness over the same scale, and is more precipitate than is known for other groups of trematodes. The decline might be explained in part by the absence of the as yet unknown first intermediate hosts in French Polynesia. However, we predict that it is explained by other life cycle traits. We hypothesise that the characters of large short-lived cercariae, short-lived miracidia, the absence in the life-cycle of second intermediate hosts that are capable of transporting the species, and definitive and first intermediate hosts that have limited vagility combine to give marine Transversotrematidae limited dispersal capacity and a propensity for localised speciation.
ISSN: 1383-5769

hal-01333467
https://hal-univ-perp.archives-ouvertes.fr/hal-01333467
DOI : 10.1016/j.parint.2013.11.009

Éditeur(s) : HAL CCSD
Résumé : Ctenophores are one of the four animal phyla positioned outside from the Bilateria. Most ctenophore species are planktonic and gelatinous, and are easily recognisable by their eight comb rows used for swimming. Ctenophore systematics remains nowadays poorly understood. Anatomical characters do not help much in placing them within the animal tree, and similarly the grounds for establishment of their internal phylogeny as well as delimitation of species are notoriously weak due to a paucity of informative morpho-anatomical characters. Until now, the use of molecular data has failed to improve significantly this situation. The aim of this PhD thesis was to bring a contribution to our understanding of ctenophore evolution at different taxonomic scales. At the metazoan level, the position of ctenophores was addressed using a phylogenomic approach. Taxonomic sampling was significantly improved through sequencing and assembly of transcriptomes of 22 non-bilaterian species (belonging to ctenophores, cnidarians and sponges). Two independent datasets were analysed, one consisting in an update of an existing supermatrix of 128 genes, the other one (4235 genes) having been entirely built de novo, thanks to a newly-devised semi-automated protocol intended to eliminate all major potential causes of artefacts (contaminations, paralogies, missing data). Results clearly contradict recent phylogenomic studies which claimed Ctenophora to be the most early-diverging animal lineage, our analyses instead supporting Porifera as the sister-group to other metazoans. The exact position of ctenophores remains however uncertain at this stage, different conditions of analyses yielding three contradictory hypotheses as open possibilities. At the intra-phyletic level, analyses of a ADNr 18S and ITS (internal transcribed spacers) dataset, together with study of duplicated genes and the results of phylogenomic analyses, allowed resolving most phylogenetic relationships between ctenophore orders and families, including the placement of the ctenophore tree root. Finally, at smaller taxonomic scale, in-depth comparison between two species of the genus Pleurobrachia using immunohistochemistry demonstrates the potential of these techniques for uncovering new structural “micro-anatomical” characters useful for diagnosis and identification of ctenophore species. It is our hope that this work will contribute to improving the systematics of a poorly known phylum of great importance for understanding early animal evolution.
Les cténophores représentent l’un des quatre embranchements animaux extérieurs aux Bilateria. La majoritédes espèces sont planctoniques et gélatineuses, et sont reconnaissables à leurs huit rangées de peignes dont lebattement permet la nage. Leur systématique est encore de nos jours mal comprise. L'anatomie descténophores offre peu de caractères aussi bien pour placer la lignée dans l’arbre des métazoaires, que pourétablir les relations de parenté au sein de l’embranchement et délimiter les espèces, et jusqu’à présent lesdonnées moléculaires n’ont pas permis de résoudre ces problèmes de manière satisfaisante. L’objectif de cetravail de thèse est de contribuer à améliorer notre compréhension de l'évolution des cténophores àdifférentes échelles taxonomiques. A l’échelle des métazoaires, la position phylogénétique des cténophores aété abordée par une approche phylogénomique. Un effort significatif a été réalisé pour améliorerl’échantillonnage taxonomique à travers le séquençage et l’assemblage des transcriptomes de 22 espèces denon-Bilateria (cténophores, cnidaires, spongiaires). Deux jeux de données indépendants ont été analysés, lepremier représentant une mise à jour d’une supermatrice existante de 128 gènes ; le second (4235 gènes)ayant été entièrement construit de novo via un protocole original comportant la mise au point de nouvellesméthodes pour traiter de manière semi-automatisée les principales sources potentielles d’artéfact(contaminations, paralogies, données manquantes). Les résultats contredisent certaines études récentes enmontrant que les spongiaires et non les cténophores représentent le groupe-frère des autres métazoaires. Laposition exacte de ces derniers reste à ce stade incertaine (trois options se présentant suivant les analyses). Al’échelle intra-phylétique, l'analyse d'un jeu de données comprenant les marqueurs ADNr 18S et InternalTranscribed Spacers (ITS), associée à des analyses de gènes dupliqués chez les cténophores et aux analysesphylogénomiques précédentes, a permis de résoudre une grande partie des relations phylogénétiques entre lesordres et les familles de cténophores, tout en permettant de préciser la position de la racine. Enfin, à uneéchelle taxonomique plus fine, une comparaison approfondie entre deux espèces du genre Pleurobrachia aumoyen de marquages immunohistochimiques montre le potentiel de ces techniques comme source denouveaux caractères structuraux « micro-anatomiques » à valeur diagnostique pour la délimitation etl’identification des espèces de cténophores. En conclusion, ce travail se veut une contribution au progrès dela systématique d’un embranchement encore méconnu et d’une grande importance pour la compréhensiondes évènements anciens de l’évolution animale.
https://tel.archives-ouvertes.fr/tel-01165014

NNT : 2014PA066448
tel-01165014
https://tel.archives-ouvertes.fr/tel-01165014
https://tel.archives-ouvertes.fr/tel-01165014/document
https://tel.archives-ouvertes.fr/tel-01165014/file/these_archivage_3158995o.pdf