References of "Denoël, Mathieu"
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See detailConférence plénière. Le Triton alpestre : diversité, écologie, éthologie et conservation
Denoël, Mathieu ULg

Conference (2012, October 18)

La diversité biologique s’entend bien au-delà de la notion d’espèce. Elle englobe ainsi toutes les particularités du vivant, telles les adaptations locales, les voies de développement alternatives et les ... [more ▼]

La diversité biologique s’entend bien au-delà de la notion d’espèce. Elle englobe ainsi toutes les particularités du vivant, telles les adaptations locales, les voies de développement alternatives et les tactiques comportementales. Le Triton alpestre est une espèce d’amphibien largement répandue en Europe où il peut être rencontré dans une multitude d’habitats. Sa persistance dans un grand nombre de conditions environnementales lui confère le plus souvent un statut d’espèce apparemment non menacée. Mais au-delà de ce constat, cette espèce présente des spécialisations des plus intéressantes dont certaines pourraient être perdues suite aux pressions d’origine anthropique. Ainsi, le Triton alpestre requiert certaines compositions et configurations d’habitats, tant aquatiques que terrestres. Selon celles-ci, il peut montrer différents patrons de fidélité au site. Son régime alimentaire englobe une multitude de proies mais en fonction des opportunités présentes, il peut adopter des tactiques prédatrices ciblées. Au niveau des interactions sexuelles, les mâles adoptent des parades particulières en fonction des circonstances, telle une femelle peu réceptive par exemple. Dans la majorité des cas, les larves, issues d’œufs pondus dans le milieu aquatique, se métamorphosent en juvéniles qui mènent dès lors une vie terrestre. Mais dans diverses populations, en particulier au sud de l’Europe, il en est tout autrement. Ainsi, certaines larves continuent à grandir tout en conservant leurs branchies ; devenant dès lors aptes à la reproduction. Il en résulte une coexistence de deux formes alternatives : les métamorphes et les pédomorphes. Quoique d’une même espèce, ces deux formes présentent des différences qui sont d’une ampleur voisine voire supérieure à celles rencontrées entre espèces. Selon l’hétérogénéité spatiale et temporelle des habitats, les deux formes présentent des avantages particuliers pouvant expliquer le succès prépondérant de l’une sur l’autre. Les caractéristiques de développement sont aussi variées selon les environnements : acquisition précoce de la maturité sexuelle et métamorphose au stade adulte en fonction d’aléas environnementaux. Une menace particulière pèse cependant sur cette diversité intra-spécifique : l’introduction de poissons. Celle-ci pourrait amener à transformer ce polyphénisme en un monomorphisme où ne subsisterait que la forme métamorphosée, dispersante. En effet, les introductions répétées de poissons dans les environnements aquatiques, quels qu’ils soient, entrainent davantage la disparition des pédomorphes. Les métamorphes, quant à eux, sont également atteints mais peuvent subsister dans certaines conditions qu’il reste à déterminer. [less ▲]

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See detailVideo multitracking to study the fish behaviour
Delcourt, Johann ULg; Ylieff, Marc ULg; Bolliet, Valérie et al

Conference (2012, July 07)

With the development of digital imaging techniques over the last decade, there are now new opportunities to study complex behavioural patterns and rhythms in fish (from individual to collective group) and ... [more ▼]

With the development of digital imaging techniques over the last decade, there are now new opportunities to study complex behavioural patterns and rhythms in fish (from individual to collective group) and to track a very large number of individuals. These new technologies and methods provide valuable information to fundamental and applied science disciplines such as ethology, animal sociology, animal psychology, veterinary sciences, animal welfare sciences, statistical physics, pharmacology, as well as neuro- and ecotoxicology. Specifically in situations where a large number of individuals are involved, the use of video tracking data is essential, as manual analyses would be complicated, time-consuming and sometimes even impossible. Today, multitracking allows us to observe directly the behaviours of groups, and to determine the real interaction rules by sampling data collected in nature or in the laboratory, without any a posteriori rules as it was and is frequently the case in computer simulation of collective behaviours. With these technologies, the quantitative measures of collective behaviours is now easily accessible, and allow to define social behaviours with more accuracy than just qualitative criteria as is always the case for instance with the definition of shoaling and schooling behaviours. Firstly will be introduced a review of fish video multitracking techniques. This review describes the possibilities of tracking individuals and groups at different scales, but also outlines the advantages and limitations of the different detection methods. The problem of occlusions, during which errors of individual identifications are very frequent, will be discuss. Secondly, our recent contribution in colour-based multitracking will be introduced, notably the new application of fluorescent VIE (Visible Implant Elastomer) tags in automatic tracking technology to study the behaviour of transparent animals like glass eels (Anguilla anguilla) in dim light or in darkness. The method makes it possible to measure the activity (notably distance and speed) of four individuals as a function of tidal and nycthemeral rhythms in the same flume (circular aquarium simulating the river or estuarine conditions) across a wide time scale (from seconds to weeks) in the context of migration in estuary. [less ▲]

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See detailLarval growth in polyphenic salamanders: making the best of a bad lot
Whiteman, Howard; Wissinger, Scott A.; Denoël, Mathieu ULg et al

in Oecologia (2012), 168(1), 109-118

Polyphenisms are excellent models for studying phenotypic variation, yet few studies have focused on natural populations. Facultative paedomorphosis is a polyphenism in which salamanders either ... [more ▼]

Polyphenisms are excellent models for studying phenotypic variation, yet few studies have focused on natural populations. Facultative paedomorphosis is a polyphenism in which salamanders either metamorphose or retain their larval morphology and eventually become paedomorphic. Paedomorphosis can result from selection for capitalizing on favorable aquatic habitats (paedomorph advantage), but could also be a default strategy under poor aquatic conditions (best of a bad lot). We tested these alternatives by quantifying how the developmental environment influences the ontogeny of wild Arizona tiger salamanders (Ambystoma tigrinum nebulosum). Most paedomorphs in our study population arose from slow-growing larvae that developed under high density and size-structured conditions (best of a bad lot), although a few faster-growing larvae also became paedomorphic (paedomorph advantage). Males were more likely to become paedomorphs than females and did so under a greater range of body sizes than females, signifying a critical role for gender in this polyphenism. Our results emphasize that the same phenotype can be adaptive under different environmental and genetic contexts and that studies of phenotypic variation should consider multiple mechanisms of morph production. [less ▲]

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See detailNewt decline in Western Europe: highlights from relative distribution changes within guilds
Denoël, Mathieu ULg

in Biodiversity & Conservation (2012), 21(11), 2887-2898

The recent increase in the number of monitoring schemes has formed the basis for high quality distribution atlases. This provides the opportunity of estimating global and specific decline patterns across ... [more ▼]

The recent increase in the number of monitoring schemes has formed the basis for high quality distribution atlases. This provides the opportunity of estimating global and specific decline patterns across regional and national borders. In this framework, this study focused on four sympatric newt species—including the great crested newt (Triturus cristatus), an Annex 2 European Habitats Directive species, over six geographic areas (five countries) in Western Europe. A relative comparison of distribution maps across time is used here and is based on more than twelve thousands occupied grid cells. It benefits from the definition of a guild, as these species are simultaneously detectable in wetlands. T. cristatus and the alpine newt (Mesotriton alpestris) were the most and the least threatened newt species, respectively, whereas the palmate (Lissotriton helveticus) and smooth newt (Lissotriton vulgaris) had an intermediate decline level at both coarse and fine grain resolutions. However, regional variations across Europe and scale effects were also found. On one hand, these results show that T. cristatus is not only regionally threatened but suffers from a global decline in Western Europe. On another hand, the results indicate that patterns of decline are not uniform within Europe and that species often considered as common and not threatened are, in fact, declining more than others. Finally, the proposed methodology, i.e. using guilds to assess relative decline, would be useful as a complement to other standardized methods in correctly advising conservation managers and policy makers, particularly for species with more subtle declines. [less ▲]

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See detailEcologie des tritons au Pays de Herve: influence des habitats à plusieurs échelles
Denoël, Mathieu ULg; Perez, Amélie; Ficetola, G. Francesco

in Echo des Rainettes (2012), 10

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See detailUsing sets of behavioral biomarkers to assess short-term effects of pesticide: a study case with endosulfan on frog tadpoles
Denoël, Mathieu ULg; D'hooghe, Bastien; Ficetola, G. Francesco et al

in Ecotoxicology (2012), 21(4), 1240-1250

Pesticides and other chemicals often have detrimental effects at environmental concentrations. Many amphibian species are particularly threatened because of their susceptibility but also because wetlands ... [more ▼]

Pesticides and other chemicals often have detrimental effects at environmental concentrations. Many amphibian species are particularly threatened because of their susceptibility but also because wetlands are often polluted. Behavioral assessments of toxicity have the advantage of showing sublethal effects but quantitative measures at varied scales of integrations are rarely considered together. In this study, we aimed at showing that these behavioral endpoints could be differently affected across time and concentrations, and be biomarkers of toxicity. To this end, we tested the effects of an organochlorine pesticide (endosulfan) on amphibians during a standard 96 h test. We evaluated possible lag effects in continuing the analyses after removal of the pesticide. The study was based on 240 tadpoles (4 pesticide treatments: 0.4, 3, 22, and 282 lg/l, 1 control and 1 solvent-control). Abnormal behaviors such as lying and swirling rapidly were exhibited only in the presence of the pesticide. Essential functions such as breathing and feeding were deeply affected by the pesticide: contaminated tadpoles breathed and fed less than control tadpoles. They also moved less and occupied a more central position in the aquariums in the presence of the pesticide. A higher mortality was only found at the highest concentration. These results suggest that endosulfan is toxic to amphibians at environmental concentrations. Behavioral markers showed potential as early warning systems. They should thus be used in complement to other markers to detect sublethal effects only a few days after application of the pesticide and at concentrations where mortality does not occur. [less ▲]

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See detailEffective conservation of an endangered newt species (Triturus cristatus): determinants from local to landscape scales
Denoël, Mathieu ULg; Perez, Amélie; Ficetola, Francesco

Conference (2011, December 07)

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See detailBehavioural ecotoxicology in amphibians: development of biomarkers
Denoël, Mathieu ULg

Conference (2011, October 25)

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See detailEffeti comportamentali dell'endosulfan su girini di Rana dalmatina
Lavorato, Manuela; Bernabé, I.; Tripepi, S. et al

Poster (2011, September)

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See detailAmphibia-Reptilia - 8 years on board: main changes and last figures
Denoël, Mathieu ULg; Ursenbacher, Sylvain; Harris, D. james et al

Conference (2011)

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See detailSex-specific effect of pool desiccation on the movement of Alpine newts, Mesotriton alpestris (Laurenti, 1768), among breeding sites (Caudata: Salamandridae)
Kopecky, Oldrich; Vojar, Jiri; Denoël, Mathieu ULg

in Herpetozoa (2011), 24(3/4), 127-134

In unpredictable habitats, it is advantageous to amphibians to reduce the risk of weather-induced offspring mortality by utilization of several reproductive patches. In european deciduous forest ... [more ▼]

In unpredictable habitats, it is advantageous to amphibians to reduce the risk of weather-induced offspring mortality by utilization of several reproductive patches. In european deciduous forest landscapes, ruts caused by vehicular traffic, typically comprising small vernal or ephemeral pools with variable hydroperiod, are at times used as breeding habitats by some species of amphibians. Previous research shows that in such systems newts move between ruts within a single reproductive season. The aim was to characterize such movements by means of a capture-mark-recapture study of the alpine Newt Mesotriton alpestris (laureNti, 1768), during two years differing in water availability, and to detect possible sex-specific differences. Movement between ruts differed between years according to sex. In the year with higher pool drying frequency, more females changed ruts than in the year when stable conditions prevailed. Among the adults that moved between ruts, however, the mean number of aquatic patches visited was higher in males. These results show that the sexes can react differently to environmental correlates and that alpine Newts are well adapted to utilize networks of temporary pools. [less ▲]

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See detailAmphibia-Reptilia - Editorial report 2010
Denoël, Mathieu ULg; Ursenbacher, sylvain; Harris, D. James

in Amphibia-Reptilia (2011), 32(4), 575-576

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See detailThe use of visual and automatized behavioral markers to assess methodologies: a study case on PIT-tagging in the Alpine newt
Winandy, Laurane ULg; Denoël, Mathieu ULg

in Behavior Research Methods (2011), 43(2), 568-576

Biomarkers are now widely used as tools in various research fields to assess individual integrity. The recent advances in quantification methods of behavioral patterns, such as computerized video-tracking ... [more ▼]

Biomarkers are now widely used as tools in various research fields to assess individual integrity. The recent advances in quantification methods of behavioral patterns, such as computerized video-tracking procedures, make them valuable biomarkers. However, the corollary of these novelties is that they remain relatively unknown and unused. In this study, we show that such tools can assess the validity of research methods, such as individual recognition. To demonstrate this we employed as a model a marking method (Passive Integrate Transponders: PIT-tagging) widely used in amphibians. Both detailed visual observations and video-tracking methods were complementary in highlighting components at different behavioral scales: locomotion, feeding, and breeding. We illustrate the scientific and ethical adequacy of the targeted marking method but also suggest that more studies should integrate behavioral analyses. Such biomarkers are a powerful tool to assess conservation concerns when other techniques cannot detect detrimental effects. [less ▲]

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See detailAmphibia-Reptilia - Editorial Report 2009
Denoël, Mathieu ULg; Ursenbacher, Sylvain; Harris, D. James

in Amphibia-Reptilia (2011), 32(1), 143

Detailed reference viewed: 47 (3 ULg)