9 research outputs found
Code and data: "Body size and trophic position determine the outcomes of species invasions along temperature and productivity gradients."
No full textCode and data to synthesize the influences of invading species traits (trophic position and body size) on simple communities under temperature and productivity gradients
Community structure and collapses in multichannel food webs: Role of consumer body sizes and mesohabitat productivities
No full textReproducible codes for the published study: Dijoux, S. and Boukal, D.S. (2021), Community structure and collapses in multichannel food webs: Role of consumer body sizes and mesohabitat productivities. Ecology Letters, 24: 1607-1618. https://doi.org/10.1111/ele.1377
Code: "Tri-trophic community responses to temperature-dependent vital rates, thermal niche (mis)matches and temperature-size rule"
No full text<p>Codes to reproduce our PSPMs accounting for the influences of temperature-dependent vital rates, temperature-size rule and thermal niche (mis)match between top-predator and consumer species.</p>
Stability and dynamics of size-structured freshwater communities along environmental gradients
No full textThis thesis focuses on the dynamics and stability of size-structured communities in freshwater in response to environmental stressors. It reviews the influences of anthropogenic stressors on the stability, structure and diversity of freshwater communities, with a particular focus on the multiscale influences of rising temperature and nutrient enrichment. The three main chapters use recent advances in food web theory to explore the dynamics, stability and structure of communities under multiple threats (species invasions, nutrient enrichment and warming). The theoretical outcomes provide robust predictions for ecologists to link individual-level responses to global patterns observed at community scale. This thesis demonstrates the importance of considering species traits (body size, trophic position, performance of vital rates) and life histories to improve predictions on future responses to environmental stressors and to develop appropriate conservation measures
Body size and trophic position determine the outcomes of species invasions along temperature and productivity gradients
No full textAbstract
Species invasions are predicted to increase in frequency with global change, but quantitative predictions of how environmental filters and species traits influence the success and consequences of invasions for local communities are lacking. Here we investigate how invaders alter the structure, diversity and stability regime of simple communities across environmental gradients (habitat productivity, temperature) and community size structure. We simulate all three-species trophic modules (apparent and exploitative competition, trophic chain and intraguild predation). We predict that invasions most often succeed in warm and productive habitats and that successful invaders include smaller competitors, intraguild predators and comparatively small top predators. This suggests that species invasions and global change may facilitate the downsizing of food webs. Furthermore, we show that successful invasions leading to species substitutions rarely alter system stability, while invasions leading to increased diversity can destabilize or stabilize community dynamics depending on the environmental conditions and invader's trophic position.Abstract
Species invasions are predicted to increase in frequency with global change, but quantitative predictions of how environmental filters and species traits influence the success and consequences of invasions for local communities are lacking. Here we investigate how invaders alter the structure, diversity and stability regime of simple communities across environmental gradients (habitat productivity, temperature) and community size structure. We simulate all three-species trophic modules (apparent and exploitative competition, trophic chain and intraguild predation). We predict that invasions most often succeed in warm and productive habitats and that successful invaders include smaller competitors, intraguild predators and comparatively small top predators. This suggests that species invasions and global change may facilitate the downsizing of food webs. Furthermore, we show that successful invasions leading to species substitutions rarely alter system stability, while invasions leading to increased diversity can destabilize or stabilize community dynamics depending on the environmental conditions and invader's trophic position
Body size and trophic position determine the outcomes of species invasions along temperature and productivity gradients
No full textInternational audienceSpecies invasions are predicted to increase in frequency with global change, but quantitative predictions of how environmental filters and species traits influence the success and consequences of invasions for local communities are lacking. Here we investigate how invaders alter the structure, diversity and stability regime of simple communities across environmental gradients (habitat productivity, temperature) and community size structure. We simulate all three‐species trophic modules (apparent and exploitative competition, trophic chain and intraguild predation). We predict that invasions most often succeed in warm and productive habitats and that successful invaders include smaller competitors, intraguild predators and comparatively small top predators. This suggests that species invasions and global change may facilitate the downsizing of food webs. Furthermore, we show that successful invasions leading to species substitutions rarely alter system stability, while invasions leading to increased diversity can destabilize or stabilize community dynamics depending on the environmental conditions and invader's trophic position
Photoprotective potential of emulsions formulated with Buriti oil (Mauritia flexuosa) and Vitamin E against UV irradiation on human keratinocytes and fibroblasts cell lines
No full textConsidering the belief that natural lipids and edible substances are safer for topical applications and that carotenoids are able to protect cells against photooxidative damage, wea have investigated whether topical creams and lotions, produced with Buriti oil and commercial surfactants, can exert photoprotective effect of against UVA and UVB irradiation. Emulsions and plain Buriti oil were diluted in DMEM medium supplemented with 10% FBS. Cell treatment was divided in two stages, prior and after being exposed to 30 minutes of UVA plus UVB radiation or 60 minutes to UVA radiation. Emulsions prepared with ethoxylated fatty alcohols as surfactants and containing α-tocopherol caused phototoxic damage to the cells, especially when applied prior to UV exposure. Damage reported was due to prooxidant activity and phototoxic effect of the surfactant. Emulsions prepared with Sorbitan Monooleate and PEG-40 castor oil and containing panthenol as active ingredient, were able to reduce the damages caused by radiation when compared to non-treated cells. When the different cells lines used in the study were compared, keratinocytes showed an increase in cell viability higher than fibroblasts. The Buriti oil emulsions can be considered potential vehicles to transport antioxidants precursors and also be used as adjuvant in sun protection
De l'intime au social : l'écriture de l'enfance dans le roman francophone contemporain de Maurice et de la Réunion
No full textDans cette thèse, qui interroge la mise en écriture de l’enfance dans le roman contemporain de Maurice et de la Réunion, il s’agit d’analyser les dimensions suivantes : les modalités narratives, la construction, l’évolution et les fonctions du personnage enfant dans l’économie des textes, les rapports qu’il entretient avec les membres de sa famille et de son entourage immédiat, ainsi que la relation entre ces œuvres et leur contexte social et discursif.
Notre corpus inclut quatorze récits d’enfance fictionnels de dix écrivains et écrivaines des Mascareignes, publiés de 1987 à 2012 : du côté mauricien, Nathacha Appanah, Ananda Devi, Marie-Thérèse Humbert, Shenaz Patel, Amal Sewtohul et Carl de Souza; du côté réunionnais, Danielle Dambreville, François Dijoux, Axel Gauvin et Jean-François Samlong.
Dans ces romans, si la diversité et l’hybridité narratives, discursives et symboliques témoignent de l’imaginaire pluriel de ces sociétés hétérogènes, l’on retrouve néanmoins certaines grandes tendances, comme une écriture axée sur la mémoire du narrateur adulte ou sur l’expérience immédiate de l’enfant; des personnages enfants principalement souffrants, mal-aimés, subalternes et révoltés; ainsi que des familles et des sociétés dont le fonctionnement, les discours et les idéologies paraissent inappropriés, voire tout à fait néfastes.
Si certains de ces choix esthétiques reconduisent certaines conventions, d’autres incarnent une perspective tout à fait nouvelle, voire transgressive. Par exemple, les emprunts à d’autres formes génériques comme le conte ou le théâtre, certaines écritures tout à fait singulières, ainsi que le fréquent mélange des voix et des langages se distinguent clairement des normes établies. La maltraitance extrême des petites et jeunes filles et l’apparition de la figure de l’enfant violent semblent également inédites. Le point de vue et l’expérience de l’enfant jettent enfin un regard global, approfondi et foncièrement critique sur les sociétés mauricienne et réunionnaise du présent (surtout dans le cas mauricien) comme du passé (années 1930 à 1970), procédant ainsi à un contre-discours s’opposant aux images exotiques et bucoliques de l’île paradisiaque. Du statut de témoin à celui d’acteur, l’enfant permet à l’auteur d’aborder une série de motifs et de problématiques distinctifs de l’imaginaire et des littératures de l’océan Indien, tels que l’altérité, l’identité, l’histoire, la mémoire, etc.In this doctoral dissertation, which deals with childhood narratives in contemporary novels of Mauritius and Reunion Islands, we will examine the following dimensions: the narrative modalities, the construction, evolution and functions of the child protagonist within the texts, his relationship with different members of his family and the people around him, and the connection between these works and their social and discursive context.
Our corpus includes fourteen works of fiction from ten different Mascareignes writers, published from 1987 to 2012 : from Mauritius, Nathacha Appanah, Ananda Devi, Marie-Thérèse Humbert, Shenaz Patel, Amal Sewtohul et Carl de Souza; and from Reunion, Danielle Dambreville, François Dijoux, Axel Gauvin et Jean-François Samlong.
In these novels, if the narrative, discursive and symbolic diversity corresponds to the plural imaginative world of these heterogeneous societies, we can still find some significant trends, including narratives based on the adult’s memory or the child’s immediate experience; suffering, ill-treated, subaltern and rebellious child protagonists; families and societies whose general functioning, discourses and ideologies seem inappropriate, even harmful.
If some of these aesthetic choices partake of certain conventions, others embody a new and even transgressive approach. For example, borrowings from other generic forms like tales, theatre, etc., particular styles of writing and the frequent mixing of different voices and languages distinguish those texts from established norms. The extreme abuse of little girls and the appearance of violent children also seem original. The child’s experience and perspective provides a global, profound and inherently critical view of present-day and past societies of Mauritius and Reunion Islands, therefore providing a counter-discourse to the exotic and bucolic images of a paradise island. From being a witness to an actor, the child allows the author to explore a series of motives and issues distinct to the imaginative world and literatures of the Indian Ocean, like otherness, identity, history, memory, etc
A novel method to predict dark diversity using unconstrained ordination analysis
No full text[Questions] Species pools are the product of complex ecological and evolutionary mechanisms, operating over a range of spatial scales. Here, we focus on species absent from local sites but with the potential to establish within communities — known as dark diversity. Methods for estimating dark diversity are still being developed and need to be compared, as well as tested for the type, and amount, of reference data needed to calibrate these methods. [Location] South Bohemia (48°58′ N, 14°28′ E) and Železné Hory (49°52′ N, 15°34′ E), Czech Republic. [Method] We compared a widely accepted algorithm to estimate species pools (Beals smoothing index, based on species co-occurrence) against a novel method based on an unconstrained ordination (UNO). Following previous work, we used spatially nested sampling for target plots, with the dark diversity estimates computed from smaller plots validated against additional species present in larger plots, and a reference dataset (Czech National Phytosociological Database of >30,000 plots as global reference data). We determined which method provides the best estimate of dark diversity with an index termed the “Success Rate Index”. [Results] When using the whole reference dataset (national scale), both UNO and Beals provided comparable predictions of dark diversity that were better than null expectations based on species frequency. However, when predicting from regionally restricted spatial scales, UNO performed significantly better than Beals. UNO also tended to detect less common species better than Beals. The success rate of combining UNO and Beals slightly outperformed the results obtained from the single methods, but only with the largest reference dataset. [Conclusions] The UNO method provides a consistently reliable estimate of dark diversity, particularly when the reference dataset is size-limited. For future calculations, we urge caution regarding the choice of dark diversity methods with respect to the reference data available, and how different methods handle species of high, and low, occurrence frequency.Grant Agency of the Czech Republic grant (GA16‐15012S; to Francesco de Bello and Lars Götzenberger). Long‐term research development grant from the Czech Academy of Sciences (RVO 67985939; FdB and LG). Czech Science Foundation ‐ Centre of Excellence PLADIAS (14‐36079G; Petr Šmilauer and Jan Lepš)
