References of "Denoël, Mathieu"
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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

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See detailEcogeographical variation of body size in the newt Triturus carnifex: comparing the hypotheses using an information-theoretic approach
Ficetola, Gentile Francesco; Scali, Stefano; Denoël, Mathieu ULg et al

in Global Ecology & Biogeography (2010), 19(4), 485-495

Aim. Ecogeographical body size variation in vertebrates (e.g., Bergmann’s rule) has long been recognized. However, the patterns and causes of intraspecific ecogeographical body size variation in ... [more ▼]

Aim. Ecogeographical body size variation in vertebrates (e.g., Bergmann’s rule) has long been recognized. However, the patterns and causes of intraspecific ecogeographical body size variation in ectotherms, and in amphibians in particular, are strongly debated. We identified the relationship between bioclimatic variables and body size predicted a priori by alternative hypotheses (heat balance; endurance, seasonality, starvation resistance, water availability; primary productivity, parental investment) proposed to explain ecogeographical patterns of body size in ectotherms, and we evaluated the relative support of these hypotheses in explaining body size variation of the Italian crested newt, Triturus carnifex. Location Twenty-three populations covering the whole range of T. carnifex (Austria, Croatia, Italy and Slovenia) Methods. We obtained data on body size (SVL) of 2639 adult newts from direct measurements and the literature; we obtained high resolution environmental data for the sampled localities. We used an information-theoretic approach to evaluate the support of the different hypotheses, by the data. We also integrated information on population genetics in our models. Results. We observed strong geographic variation of body size. The best AIC models showed that populations with larger body size are associated with cold climates and secondarily with high primary productivity. Furthermore, sexual dimorphism increases in cold climates, as the increase in body size was stronger for females. When taking into account population genetics, we did not find support for relationships with the other variables. Main conclusion. Our results are consistent with three hypotheses proposed to explain ecogeographic variation in amphibians: heat balance, increased parental investment of females and productivity. Information theory provides the framework for comparing hypotheses rather than looking for patterns. We suggest that evaluating the support of mechanisms can provide better insights than simply assessing whether ecogeographical variation is in agreement with some ‘rule’. [less ▲]

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See detailMovements of Alpine newts (Mesotriton alpestris) between small aquatic habitats (ruts) during the breeding season
Kopecky, Oldrich; Vojar, Jiri; Denoël, Mathieu ULg

in Amphibia-Reptilia (2010), 31(1), 109-116

Many species with complex life cycles, such as caudate amphibians, migrate from terrestrial to aquatic habitats for reproduction. However, movements between reproductive ponds within a breeding season ... [more ▼]

Many species with complex life cycles, such as caudate amphibians, migrate from terrestrial to aquatic habitats for reproduction. However, movements between reproductive ponds within a breeding season have rarely been studied and are usually considered to be limited. Our aim was to determine whether this pattern occurs frequently in Alpine newts (Mesotriton alpestris) inhabiting complexes of small ruts on muddy forest tracks. We analysed capture-recapture data for individually marked newts as a function of locality, sex, body condition and hydroperiod throughout the breeding season. More than one third of the newts changed their ruts. Movements occurred more often towards ruts that did not dry during the breeding season. The body condition of males that changed ponds (but not that of females) was higher compared to that of resident newts in one of the studied populations. The relatively high frequency of movements between ruts can be seen as an adaptive strategy in unpredictable habitats which have a high probability of drying. The promiscuous pattern of newts also favours low site tenacity, because few sexual partners are available in each rut. Because of the broad occurrence of this kind of habitat, future studies should take into account these movements to better understand newt population dynamics and how to apply adequate conservation measures. [less ▲]

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See detailDermocystid infection and associated skin lesions in free-living palmate newts (Lissotriton helveticus) from Southern France
González-Hernández, M.; Denoël, Mathieu ULg; Duffus, A. J. L. et al

in Parasitology International (2010), 59(3), 344-350

Since the early 1900s, mesomycetozoan parasites have been reported in both European anuran and caudate species. These reports have primarily been descriptive, which has made assessing the impact of these ... [more ▼]

Since the early 1900s, mesomycetozoan parasites have been reported in both European anuran and caudate species. These reports have primarily been descriptive, which has made assessing the impact of these parasites on host populations difficult. Anecdotal reports of Dermocystidium-like parasites are becoming widespread across Europe, possibly indicating that these mesomycetozoan parasites are increasing in distribution and/or abundance. This highlights the need for further investigations into the occurrence, pathogenesis and effects on host health of these parasitic infections for free-living amphibian populations, particularly those which are already stressed or threatened by other factors. Here we report the results of pathological, microbiological and molecular investigations used to characterize unidentified skin lesions in palmate newts (Lissotriton helveticus) from Larzac, France. We confirm that the lesions are the result of infection with a novel dermocystidium-like parasite, which is related to Amphybiocystidium ranae. We also show that the same parasite is distributed across several newt breeding sites. The lesions that result from infection with this parasite range from single or few vesicular or nodular cutaneous lesions to multiple coalescing skin ulcers with extensive hemorrhages. The latter have not been previously described in amphibians due to mesomycetozoan parasitic infection. Dermocystid DNA was detected only in newts that showed lesions, providing comparative evidence of the parasite's pathogenicity. We discuss the potential significance of the presence of this pathogen in the context of the population health of palmate newts. [less ▲]

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See detailShort-term effects of an organochloride pesticide (endosulfan) on amphibian tadpoles
D'Hooghe, Bastien; Brasseur, Catherine ULg; Kestemont, Patrick et al

Poster (2010)

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See detailColour differentiation in a coral reef fish throughout ontogeny: habitat background and flexibility
Frederich, Bruno ULg; Mills, Suzanne C.; Denoël, Mathieu ULg et al

in Aquatic Biology (2010), 9(3), 271-277

Colour polymorphism is widespread in animals but, in contrast to other types of polymorphism, has been little explored during ontogeny. Among coral reef fish, the surge damselfish Chrysiptera leucopoma ... [more ▼]

Colour polymorphism is widespread in animals but, in contrast to other types of polymorphism, has been little explored during ontogeny. Among coral reef fish, the surge damselfish Chrysiptera leucopoma settles in the larval stage as a yellow morph, whereas 2 colour morphs (yellow and brown) are apparent in adults at Rangiroa Atoll, French Polynesia. To understand this dimorphism, we tested, under controlled conditions, the hypotheses that: (1) environmental cues (habitat background and conspecific density) play important roles in morph differentiation during ontogeny and (2) morph colouration is reversible. Our first experiment showed that a dark habitat background induced the formation of the brown morph, while C. leucopoma larvae kept their yellow morph when placed in aquaria with a bright habitat background. Colour change from yellow to brown also occurred within the bright habitat, but only at high conspecific densities. Our second experiment showed that colour change was reversible within 15 d post-settlement, but not at the adult stage. Overall, our results highlighted that the studied polymorphism may be environmentally induced and reversible during the first post-settlement days of this coral reef fish. [less ▲]

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See detailConsumptive and nonconsumptive effects of cannibalism in fluctuating age-structured populations
Wissinger, Scott A.; Whiteman, Howard H.; Denoël, Mathieu ULg et al

in Ecology (2010), 91(2), 549-599

Theory and empirical studies suggest that cannibalism in age-structured populations can regulate recruitment depending on the intensity of intraspecific competition between cannibals and victims and the ... [more ▼]

Theory and empirical studies suggest that cannibalism in age-structured populations can regulate recruitment depending on the intensity of intraspecific competition between cannibals and victims and the nature of the cannibalism window, i.e., which size classes interact as cannibals and victims. Here we report on a series of experiments that quantify that window for age-structured populations of salamander larvae and paedomorphic adults. We determined body size limits on cannibalism in microcosms and then the consumptive and nonconsumptive (injuries, foraging and activity, diet, growth) effects on victims in mesocosms with seminatural levels of habitat complexity and alternative prey. We found that cannibalism by the largest size classes (paedomorphs and >age 3+yr larvae) occurs mainly on young-of-the-year (YOY) victims. Surviving YOY and other small larvae had increased injuries, reduced activity levels, and reduced growth rates in the presence of cannibals. Data on YOY survival in an experiment in which we manipulated the density of paedomorphs combined with historical data on the number of cannibals in natural populations indicate that dominant cohorts of paedomorphs can cause observed recruitment failures. Dietary data indicate that ontogenetic shifts in diet should preclude strong intraspecific competition between YOY and cannibals in this species. Thus our results are consistent with previous empirical and theoretical work that suggests that recruitment regulation by cannibalism is most likely when YOY are vulnerable to cannibalism, but have low dietary overlap with cannibals. Understanding the role of cannibalism in regulating recruitment in salamander populations is timely given the widespread occurrences of amphibian decline. Previous studies have focused on extrinsic (including anthropogenic) factors that affect amphibian population dynamics, whereas the data presented here combined with long-term field observations suggest the potential for intrinsically driven population cycles. [less ▲]

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See detailDetrimental effect of temperature increase on the fitness of an amphibian (Lissotriton helveticus)
Galloy, Valérie ULg; Denoël, Mathieu ULg

in Acta Oecologica: International Journal of Ecology (2010), 36(2), 179-183

Increases of global temperatures have resulted in measurable shifts in the distribution, phenology and survival of some plant and animal species. However, the mechanisms showing links between global ... [more ▼]

Increases of global temperatures have resulted in measurable shifts in the distribution, phenology and survival of some plant and animal species. However, the mechanisms showing links between global warming and biodiversity declines remain unclear. The aim of this study was to examine whether a key parameter of fitness, i.e. offspring number, could be affected by a temperature increase. To this end, we compared egg-laying traits at naturally occurring temperatures (14 °C, 18 °C and 22 °C) in palmate newts, Lissotriton helveticus. Our study suggests that water temperature increase has a negative effect on the fecundity of female newts. Females lay half as many eggs at high temperatures as they do at low temperatures, which results in a lower number of hatchlings. This study shows that global warming would affect amphibian populations. It complements other studies in pointing out that changes in phenology may not be driven only by warmer earlier temperatures but also by counter-selection during late-breeding, particularly in long-term breeders such as newts. More experimental studies should be carried out to understand the complex consequences of global warming and the proximate mechanisms of amphibian decline. [less ▲]

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See detailDisplaying in the dark: light-dependent alternative mating tactics in the Alpine newt
Denoël, Mathieu ULg; Doellen, Joffrey

in Behavioral Ecology and Sociobiology (2010), 64(7), 1171-1175

Environment plays a major role for determining the kind of courtship behaviours or alternative mating tactics employed, but the effect of physical variables on fitness has received little attention. The ... [more ▼]

Environment plays a major role for determining the kind of courtship behaviours or alternative mating tactics employed, but the effect of physical variables on fitness has received little attention. The Alpine newt courts during both day and night times and exhibits a complex suite of behaviours involving olfactory, visual and tactile cues. Displaying in both dark and light conditions may increase the number of mating opportunities and alleviate predation risk, but the frequency and efficacy of the various tactics deployed may vary across light conditions, leading males to vary their use of these tactics across different light regimes. To test this hypothesis, we video-recorded sexual encounters at two light intensities in a controlled experimental design. When courting in the dark, males used comparatively more olfactory rather than visual displays. They also relied more on positive feedback from the female before releasing a spermatophore for her to pick up. The particular mix of tactics used under each light condition is likely to be adaptive because in the dark (1) visual communication is hampered, making olfactory displays possibly more effective and (2) males depositing spermatophores are more likely to lose fertilizations to competitors. Mating in light and dark conditions has similar reproductive payoffs, which shows that displaying in the dark is not detrimental and may even be advantageous if predation risk is reduced at night. These results confirm the importance of taking into account physical variables to understand the evolution of sexual communication in animals. [less ▲]

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See detailCumulative effects of road de-icing salt on amphibian behavior
Denoël, Mathieu ULg; Bichot, Marion; Ficetola, G. Francesco et al

in Aquatic Toxicology (2010), 99(2), 275-280

Despite growing evidence of the detrimental effect of chemical substances on organisms, limited research has focused on changes in behavioral patterns, in part due to the difficulties to obtain detailed ... [more ▼]

Despite growing evidence of the detrimental effect of chemical substances on organisms, limited research has focused on changes in behavioral patterns, in part due to the difficulties to obtain detailed quantitative data. Recent developments in efficient computer-based video analyses have allowed testing pesticide effects on model species such as the zebrafish. However, these new techniques have not yet been applied to amphibians and directly to conservation issues, i.e. to assess toxicological risks on threatened species. We used video tracking analyses to test a quantitative effect of an environmental contaminant on the locomotion of amphibian tadpoles (Rana temporaria) by taking into account cumulative effects. Because recent research has demonstrated effects of de-icing salts on survival and community structure, we used sodium chloride in our experimental design (25 replicates, 4 concentrations, 4 times) to test for an effect at the scale of behavior at environmentally relevant concentrations. Analysis of 372 1-hr video-tracks (5 samples per sec) showed a complex action of salts on behavioral patterns with a dose and cumulative response over time. Although no effects were found on mortality or growth, the highest salt concentrations reduced the speed and movement of tadpoles in comparison with control treatments. The reduced locomotor performance could have detrimental consequences in terms of tadpoles’ responses to competition and predation and may be an indicator of the low concentration effect of the contaminant. On one hand, this study demonstrates the usefulness of examining behavior to address conservation issues and understand the complex action of environmental factors and, more particularly, pollutants on organisms. On the other hand, our results highlight the need of new computerized techniques to quantitatively analyze these patterns. [less ▲]

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See detailEditorial Report 2008
Denoël, Mathieu ULg

in Amphibia-Reptilia (2010), 31(1), 151-152

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