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Auteur Mouillot, D.; Villeger, S.; Parravicini, V.; Kulbicki, M.; Arias-González, J.E.; Bender, M.; Chabanet, P.; Floeter, S.R.; Friedlander, A.; Vigliola, L.; Bellwood, D.R.
Titre Functional over-redundancy and high functional vulnerability in global fish faunas on tropical reefs Type Article scientifique
Année 2014 Publication Revue Abrégée Proceedings of the National Academy of Sciences of the United States of America
Volume 111 Numéro 38 Pages 13757-13762
Mots-Clés
Résumé When tropical systems lose species, they are often assumed to be buffered against declines in functional diversity by the ability of the species-rich biota to display high functional redundancy: i.e., a high number of species performing similar functions. We tested this hypothesis using a ninefold richness gradient in global fish faunas on tropical reefs encompassing 6,316 species distributed among 646 functional entities (FEs): i.e., unique combinations of functional traits. We found that the highest functional redundancy is located in the Central Indo-Pacific with a mean of 7.9 species per FE. However, this overall level of redundancy is disproportionately packed into few FEs, a pattern termed functional over-redundancy (FOR). For instance, the most speciose FE in the Central Indo-Pacific contains 222 species (out of 3,689) whereas 38% of FEs (180 out of 468) have no functional insurance with only one species. Surprisingly, the level of FOR is consistent across the six fish faunas, meaning that, whatever the richness, over a third of the species may still be in overrepresented FEs whereas more than one third of the FEs are left without insurance, these levels all being significantly higher than expected by chance. Thus, our study shows that, even in high-diversity systems, such as tropical reefs, functional diversity remains highly vulnerable to species loss. Although further investigations are needed to specifically address the influence of redundant vs. vulnerable FEs on ecosystem functioning, our results suggest that the promised benefits from tropical biodiversity may not be as strong as previously thought.
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Auteur Zupan, L.; Cabeza, M.; Maiorano, L.; Roquet, C.; Devictor, V.; Lavergne, S.; Mouillot, D.; Mouquet, N.; Renaud, J.; Thuiller, W.
Titre Spatial mismatch of phylogenetic diversity across three vertebrate groups and protected areas in Europe Type Article scientifique
Année 2014 Publication Revue Abrégée Diversity and Distributions
Volume 20 Numéro 6 Pages 674-685
Mots-Clés Europe; Species diversity; approach; biodiversity; climate-change; communities; ecological; evolutionary diversity; functional diversity; global patterns; hotspots; nature conservation; phylogenetic diversity; protected areas; spatial biodiversity congruence; species richness; terrestrial vertebrates; unified
Résumé Aim We investigate patterns of phylogenetic diversity in relation to species diversity for European birds, mammals and amphibians to evaluate their congruence and highlight areas of particular evolutionary history. We estimate the extent to which the European network of protected areas (PAs) network retains interesting evolutionary history areas for the three groups separately and simultaneously. Location Europe Methods Phylogenetic (QE(PD)) and species diversity (SD) were estimated using the Rao's quadratic entropy at 10 ' resolution. We determined the regional relationship between QE(PD) and SD for each taxa with a spatial regression model and used the tails of the residuals (QE(RES)) distribution to identify areas of higher and lower QE(PD) than predicted. Spatial congruence of biodiversity between groups was assessed with Pearson correlation coefficient. A simple classification scheme allowed building a convergence map where a convergent pixel equalled to a QE(RES) value of the same sign for the three groups. This convergence map was overlaid to the current PAs network to estimate the level of protection in convergent pixels and compared it to a null expectation built on 1000 randomization of PAs over the landscape. Results QE(RES) patterns across vertebrates show a strong spatial mismatch highlighting different evolutionary histories. Convergent areas represent only 2.7% of the Western Palearctic, with only 8.4% of these areas being covered by the current PAs network while a random distribution would retain 10.4% of them. QE(RES) are unequally represented within PAs: areas with higher QE(PD) than predicted are better covered than expected, while low QE(PD) areas are undersampled. Main conclusions Patterns of diversity strongly diverge between groups of vertebrates in Europe. Although Europe has the world's most extensive PAs network, evolutionary history of terrestrial vertebrates is unequally protected. The challenge is now to reconcile effective conservation planning with a contemporary view of biodiversity integrating multiple facets.
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ISSN 1366-9516 ISBN Médium
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Numéro d'Appel (down) MARBEC @ isabelle.vidal-ayouba @ collection 856
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Auteur Killen, S.S.; Marras, S.; McKenzie, D.J.
Titre Fast growers sprint slower: effects of food deprivation and re-feeding on sprint swimming performance in individual juvenile European sea bass Type Article scientifique
Année 2014 Publication Revue Abrégée Journal of Experimental Biology
Volume 217 Numéro 6 Pages 859-865
Mots-Clés Compensatory growth; Ecophysiology; Food deprivation; Foraging; Locomotion; atlantic; catch-up growth; cod; dicentrarchus-labrax; ecological performance; gadus-morhua; long-term starvation; metabolic responses; salmon; teleost fish; trade-off; trade-offs; trout oncorhynchus-mykiss
Résumé While many ectothermic species can withstand prolonged fasting without mortality, food deprivation may have sublethal effects of ecological importance, including reductions in locomotor ability. Little is known about how such changes in performance in individual animals are related to either mass loss during food deprivation or growth rate during re-feeding. This study followed changes in the maximum sprint swimming performance of individual European sea bass, Dicentrarchus labrax, throughout 45 days of food deprivation and 30 days of re-feeding. Maximum sprint speed did not show a significant decline until 45 days of food deprivation. Among individuals, the reduction in sprinting speed at this time was not related to mass loss. After 30 days of re-feeding, mean sprinting speed had recovered to match that of control fish. Among individuals, however, maximum sprinting speed was negatively correlated with growth rate after the resumption of feeding. This suggests that the rapid compensatory growth that occurs during re-feeding after a prolonged fast carries a physiological cost in terms of reduced sprinting capacity, the extent of which shows continuous variation among individuals in relation to growth rate. The long-term repeatability of maximum sprint speed was low when fish were fasted or fed a maintenance ration, but was high among control fish fed to satiation. Fish that had been previously food deprived continued to show low repeatability in sprinting ability even after the initiation of ad libitum feeding, probably stemming from variation in compensatory growth among individuals and its associated negative effects on sprinting ability. Together, these results suggest that food limitation can disrupt hierarchies of maximum sprint performance within populations. In the wild, the cumulative effects on locomotor capacity of fasting and re-feeding could lead to variable survival among individuals with different growth trajectories following a period of food deprivation.
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ISSN 0022-0949 ISBN Médium
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Numéro d'Appel (down) MARBEC @ isabelle.vidal-ayouba @ collection 601
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Auteur Jeanmougin, M.; Leprieur, F.; Lois, G.; Clergeau, P.
Titre Fine-scale urbanization affects Odonata species diversity in ponds of a megacity (Paris, France) Type Article scientifique
Année 2014 Publication Revue Abrégée Acta Oecologica-International Journal of Ecology
Volume 59 Numéro Pages 26-34
Mots-Clés Evenness; Landscape composition; Model averaging; Ponds; Species diversity; Urban ecology; agricultural landscape; comparative biodiversity; conservation; dragonflies odonata; ecology; fresh-water habitat; patterns; richness; selection; urban
Résumé Current developments in urban ecology include very few studies focused on pond ecosystems, though ponds are recognized as biodiversity hotspots. Using Odonata as an indicator model, we explored changes in species composition in ponds localized along an urban gradient of a megacity (Paris, France). We then assessed the relative importance of local- and landscape-scale variables in shaping Odonata alpha-diversity patterns using a model-averaging approach. Analyses were performed for adult (A) and adult plus exuviae (AE) census data. At 26 ponds, we recorded 657 adults and 815 exuviae belonging to 17 Odonata species. The results showed that the Odonata species assemblage composition was not determined by pond localization along the urban gradient. Similarly, pond characteristics were found to be similar among urban, suburban and periurban ponds. The analyses of AE census data revealed that fine-scale urbanization (i.e., increased density of buildings surrounding ponds) negatively affects Odonata alpha-diversity. In contrast, pond localization along the urban gradient weakly explained the alpha-diversity patterns. Several local-scale variables, such as the coverage of submerged macrophytes, were found to be significant drivers of Odonata alpha-diversity. Together, these results show that the degree of urbanization around ponds must be considered instead of pond localization along the urban gradient when assessing the potential impacts of urbanization on Odonata species diversity This work also indicates the importance of exuviae sampling in understanding the response of Odonata to urbanization. (C) 2014 Elsevier Masson SAS. All rights reserved.
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ISSN 1146-609x ISBN Médium
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Numéro d'Appel (down) MARBEC @ isabelle.vidal-ayouba @ collection 602
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Auteur Miller, M.J.; Bonhommeau, S.; Munk, P.; Castonguay, M.; Hanel, R.; McCleave, J.D.
Titre A century of research on the larval distributions of the Atlantic eels: a re-examination of the data Type Article scientifique
Année 2014 Publication Revue Abrégée Biological Reviews
Volume Numéro Pages
Mots-Clés anguilla; freshwater eels; larval distribution; oceanic fronts.; Sargasso Sea; spawning area
Résumé The spawning areas of the Atlantic freshwater eels were discovered about a century ago by the Danish scientistJohannes Schmidt who after years of searching found newly hatched larvae of the European eel, Anguillaanguilla, and the American eel, Anguilla rostrata, in the southern Sargasso Sea. The discovery showed thatanguillid eels migrate thousands of kilometers to offshore spawning areas for reproduction, and that theirlarvae, called leptocephali, are transported equally long distances by ocean currents to their continentalrecruitment areas. The spawning sites were found to be related to oceanographic conditions several decadeslater by German and American surveys from 1979 to 1989 and by a Danish survey in 2007 and a Germansurvey in 2011. All these later surveys showed that spawning occurred within a restricted latitudinal range,between temperature fronts within the Subtropical Convergence Zone of the Sargasso Sea. New data andre-examinations of Schmidt’s data confirmed his original conclusions about the two species having someoverlap in spawning areas. Although there have been additional collections of leptocephali in various parts ofthe North Atlantic, and both otolith research and transport modelling studies have subsequently been carriedout, there is still a range of unresolved questions about the routes of larval transport and durations of migration.This paper reviews the history and basic findings of surveys for anguillid leptocephali in the North Atlantic andanalyses a new comprehensive database that includes 22612 A. anguilla and 9634 A. rostrata leptocephali, whichprovides a detailed view of the spatial and temporal distributions and size of the larvae across the Atlantic basinand in the Mediterranean Sea. The differences in distributions, maximum sizes, and growth rates of the twospecies of larvae are likely linked to the contrasting migration distances to their recruitment areas on eachside of the basin. Anguilla rostrata leptocephali originate from a more western spawning area, grow faster, andmetamorphose at smaller sizes of <70mm than the larvae of A. anguilla, which mostly are spawned further eastand can reach sizes of almost 90 mm. The larvae of A. rostrata spread west and northwest from the spawningarea as they grow larger, with some being present in the western Caribbean and eastern Gulf of Mexico. Larvaeof A. anguilla appear to be able to reach Europe by entering the Gulf Stream system or by being entrainedinto frontal countercurrents that transport them directly northeastward. The larval duration of A. anguillais suggested to be quite variable, but gaps in sampling effort prevent firm conclusions. Although knowledgeabout larval behaviour is lacking, some influences of directional swimming are implicated by the temporaldistributions of the largest larvae. Ocean–atmosphere changes have been hypothesized to affect the survivalof the larvae and cause reduced recruitment, so even after about a century following the discovery of theirspawning areas, mysteries still remain about the marine life histories of the Atlantic eels.
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ISSN 1464-7931 ISBN Médium
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