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Auteur Patino, J.; Guilhaumon, F.; Whittaker, R.J.; Triantis, K.A.; Gradstein, S.R.; Hedenas, L.; Gonzalez-Mancebo, J.M.; Vanderpoorten, A.
Titre Accounting for data heterogeneity in patterns of biodiversity: an application of linear mixed effect models to the oceanic island biogeography of spore-producing plants Type Article scientifique
Année (up) 2013 Publication Revue Abrégée Ecography
Volume 36 Numéro 8 Pages 904-913
Mots-Clés area; bryophytes; diversification; diversity; evolution; genetic-structure; moss; richness; scale; speciation
Résumé The general dynamic model of oceanic island biogeography describes the evolution of species diversity properties, including species richness (SR), through time. We investigate the hypothesis that SR in organisms with high dispersal capacities is better predicted by island area and elevation (as a surrogate of habitat diversity) than by time elapsed since island emergence and geographic isolation. Linear mixed effect models (LMMs) subjected to information theoretic model selection were employed to describe moss and liverwort SR patterns from 67 oceanic islands across 12 archipelagos. Random effects, which are used to modulate model parameters to take differences among archipelagos into account, included only a random intercept in the best-fit model for liverworts and in one of the two best-fit models for mosses. In this case, the other coefficients are constant across archipelagos, and we interpret the intercept as a measure of the intrinsic carrying capacity of islands within each archipelago, independently of their size, age, elevation and geographic isolation. The contribution of area and elevation to the models was substantially higher than that of time, with the least contribution made by measures of geographic isolation. This reinforces the idea that oceanic barriers are not a major impediment for migration in bryophytes and, together with the almost complete absence of in situ insular diversification, explains the comparatively limited importance of time in the models. We hence suggest that time per se has little independent role in explaining bryophyte SR and principally features as a variable accounting for the changing area and topographic complexity during the life-cycle of oceanic islands. Simple area models reflecting habitat availability and diversity might hence prevail over more complex temporal models reflecting in-situ speciation and dispersal (time, geographic connectivity) in explaining patterns of biodiversity for exceptionally mobile organisms.
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ISSN 0906-7590 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 432
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Auteur Ndiaye, W.; Thiaw, M.; Diouf, K.; Ndiaye, P.; Thiaw, O.T.; Panfili, J.
Titre Changes in population structure of the white grouper Epinephelus aeneus as a result of long-term overexploitation in Senegalese waters Type Article scientifique
Année (up) 2013 Publication Revue Abrégée African Journal of Marine Science
Volume 35 Numéro 4 Pages 465-472
Mots-Clés West Africa; africa; biological indicators; communities; diversity; evaluate; fishing pressure; hermaphroditism; indicators; length at maturity; management; reef fishes; serranidae; size; size spectra; spectrum
Résumé In Senegal, a significant decrease in catches indicates that many demersal fish stocks are being overexploited. The white grouper Epinephelus aeneus, locally known as the 'thiof', is exploited by both small-scale and industrial fisheries. A 28-year database of E. aeneus catches along the Senegalese coast provided by the Centre for Oceanographic Research of Dakar-Thiaroye, and size at maturity measured in Dakar (Senegal) from monthly samples in 2010, were used to analyse changes in population structure in the area over the past 37 years. Catches from the northern fishing areas were lower than those from the southern fishing areas, and decreased steadily during the period (Kolmogorov-Smirnov test, D = 0.243, p = 0.0002). The individual mean weight of catches decreased from 1974 to 2010 (linear regression, r(2) = 0.40, n = 37) and only 60% of the individuals were mature. The calculated sizes at maturity were 49 cm total length (TL) for females and 55 cm for males, and the optimal length of capture for a sustainable fishery was 96 cm, but only 0.03% of E. aeneus caught reached this length. Most of the catch consisted of juveniles; the larger reproductive individuals had disappeared. The number of individuals caught decreased significantly between 1974 and 2010 (1974-1983, r(2) = 0.98, n = 74 674; 1984-1993, r(2) = 0.95, n = 96 696; 1994-2003, r(2) = 0.93, n = 12 619; 2004-2010, r(2) = 0.91, n = 12 887), whereas the length range remained the same (10-110 cm TL). Biological indicators clearly showed that E. aeneus stocks in Senegal are overexploited and the species is now endangered. Immediate active management of fishing pressure is needed, therefore, to maintain E. aeneus populations in the area. Our results suggest a minimum size of <50 cm should be introduced and that fishing effort should be reduced.
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ISSN 1814-232x ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 484
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Auteur Maury, O.; Poggiale, J.-C.
Titre From individuals to populations to communities: A dynamic energy budget model of marine ecosystem size-spectrum including life history diversity Type Article scientifique
Année (up) 2013 Publication Revue Abrégée Journal of Theoretical Biology
Volume 324 Numéro Pages 52-71
Mots-Clés biodiversity; Dynamic Energy Budget theory; predation; Schooling; Size spectrum
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ISSN 0022-5193 ISBN Médium
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Notes <p>\textbackslashtextlessp\textbackslashtextgreaterIndividual metabolism, predator–prey relationships, and the role of biodiversity are major factors underlying the dynamics of food webs and their response to environmental variability. Despite their crucial, complementary and interacting influences, they are usually not considered simultaneously in current marine ecosystem models. In an attempt to fill this gap and determine if these factors and their interaction are sufficient to allow realistic community structure and dynamics to emerge, we formulate a mathematical model of the size-structured dynamics of marine communities which integrates mechanistically individual, population and community levels. The model represents the transfer of energy generated in both time and size by an infinite number of interacting fish species spanning from very small to very large species. It is based on standard individual level assumptions of the Dynamic Energy Budget theory (DEB) as well as important ecological processes such as opportunistic size-based predation and competition for food. Resting on the inter-specific body-size scaling relationships of the DEB theory, the diversity of life-history traits (i.e. biodiversity) is explicitly integrated. The stationary solutions of the model as well as the transient solutions arising when environmental signals (e.g. variability of primary production and temperature) propagate through the ecosystem are studied using numerical simulations. It is shown that in the absence of density-dependent feedback processes, the model exhibits unstable oscillations. Density-dependent schooling probability and schooling-dependent predatory and disease mortalities are proposed to be important stabilizing factors allowing stationary solutions to be reached. At the community level, the shape and slope of the obtained quasi-linear stationary spectrum matches well with empirical studies. When oscillations of primary production are simulated, the model predicts that the variability propagates along the spectrum in a given frequency-dependent size range before decreasing for larger sizes. At the species level, the simulations show that small and large species dominate the community successively (small species being more abundant at small sizes and large species being more abundant at large sizes) and that the total biomass of a species decreases with its maximal size which again corroborates empirical studies. Our results indicate that the simultaneous consideration of individual growth and reproduction, size-structured trophic interactions, the diversity of life-history traits and a density-dependent stabilizing process allow realistic community structure and dynamics to emerge without any arbitrary prescription. As a logical consequence of our model construction and a basis for future studies, we define the function Φ as the relative contribution of each species to the total biomass of the ecosystem, for any given size. We argue that this function is a measure of the functional role of biodiversity characterizing the impact of the structure of the community (its species composition) on its function (the relative proportions of losses, dissipation and biological work).\textbackslashtextless/p\textbackslashtextgreater</p> Approuvé pas de
Numéro d'Appel LL @ pixluser @ collection 245
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Auteur Villeger, S.; Grenouillet, G.; Brosse, S.
Titre Decomposing functional β-diversity reveals that low functional β-diversity is driven by low functional turnover in European fish assemblages Type Article scientifique
Année (up) 2013 Publication Revue Abrégée Global Ecology and Biogeography
Volume 22 Numéro 6 Pages 671-681
Mots-Clés Europe; Functional richness; beta-diversity; convex hull volume; freshwater fish; functional diversity; functional traits; overlap
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ISSN 1466-8238 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 507
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Auteur Pellissier, L.; Leprieur, F.; Parravicini, V.; Cowman, P.F.; Kulbicki, M.; Litsios, G.; Olsen, S.M.; Wisz, M.S.; Bellwood, D.R.; Mouillot, D.
Titre Quaternary coral reef refugia preserved fish diversity Type Article scientifique
Année (up) 2014 Publication Revue Abrégée Science
Volume 344 Numéro 6187 Pages 1016-1019
Mots-Clés abundance; areas; assembly rules; cradles; global patterns; gradient; hotspots; marine biodiversity; museums; species richness
Résumé The most prominent pattern in global marine biogeography is the biodiversity peak in the Indo-Australian Archipelago. Yet the processes that underpin this pattern are still actively debated. By reconstructing global marine paleoenvironments over the past 3 million years on the basis of sediment cores, we assessed the extent to which Quaternary climate fluctuations can explain global variation in current reef fish richness. Comparing global historical coral reef habitat availability with the present-day distribution of 6316 reef fish species, we find that distance from stable coral reef habitats during historical periods of habitat loss explains 62% of the variation in fish richness, outweighing present-day environmental factors. Our results highlight the importance of habitat persistence during periods of climate change for preserving marine biodiversity.
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ISSN 0036-8075 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 801
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