References of "Denoël, Mathieu"
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See detailHeterochrony in a complex world: disentangling environmental processes of facultative paedomorphosis in an amphibian
Denoël, Mathieu ULg; Ficetola, Gentile Francesco

in Journal of Animal Ecology (in press)

1. Heterochrony, the change in the rate or timing of development between ancestors and their descendants, plays a major role in evolution. When heterochrony produces polymorphisms, it offers the ... [more ▼]

1. Heterochrony, the change in the rate or timing of development between ancestors and their descendants, plays a major role in evolution. When heterochrony produces polymorphisms, it offers the possibility to test hypotheses that could explain its success across environments. Amphibians are particularly suitable to exploring these questions because they express complex life cycles (i.e. metamorphosis) that have been disrupted by heterochronic processes (paedomorphosis: retention of larval traits in adults). The large phenotypic variation across populations suggests that more complex processes than expected are operating, but they remain to be investigated through multivariate analyses over a large range of natural populations across time. 2. In this study we compared the likelihood of multiple potential environmental determinants of heterochrony. We gathered data on the proportion of paedomorphic and metamorphic palmate newts (Lissotriton helveticus) across more than 150 populations during 10 years, and used an information-theoretic approach to compare the support of multiple potential processes. 3. Six environmental processes jointly explained the proportion of paedomorphs in populations: predation, water availability, dispersal limitation, aquatic breathing, terrestrial habitat suitability, and anti-predator refuges. Analyses of variation across space and time supported models based on the advantage of paedomorphosis in favourable aquatic habitats. 4. Paedomorphs were favoured in deep ponds, in conditions favourable to aquatic breathing (high oxygen content), with lack of fish, and surrounded by suitable terrestrial habitat. Metamorphs were favoured by banks allowing easy dispersal. 5. These results indicate that heterochrony relies on complex processes involving multiple ecological variables and exemplifies why heterochronic patterns occur in contrasted environments. On the other hand, the fast selection of alternative morphs shows that metamorphosis and paedomorphosis developmental modes could be easily disrupted in natural populations. [less ▲]

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See detailUpdated distribution and biogeography of amphibians and reptiles of Europe
Silero, Neftali; Campos, João; Bonardi, Anna et al

in Amphibia-Reptilia (2014), 35(1), 1-31

A precise knowledge of the spatial distribution of taxa is essential for decision-making processes in land management and biodiversity conservation, both for present and under future global change ... [more ▼]

A precise knowledge of the spatial distribution of taxa is essential for decision-making processes in land management and biodiversity conservation, both for present and under future global change scenarios. This is a key base for several scientific disciplines (e.g. macro-ecology, biogeography, evolutionary biology, spatial planning, or environmental impact assessment) that rely on species distribution maps. An atlas summarizing the distribution of European amphibians and reptiles with 50×50 km resolution maps based on ca. 85,000 grid records was published by the Societas Europaea Herpetologica (SEH) in 1997. Since then, more detailed species distribution maps covering large parts of Europe became available, while taxonomic progress has led to a plethora of taxonomic changes including new species descriptions. To account for these progresses, we compiled information from different data sources: published in books and websites, ongoing national atlases, personal data kindly provided to the SEH, the 1997 European Atlas, and the Global Biodiversity Information Facility (GBIF). Databases were homogenised, deleting all information except species names and coordinates, projected to the same coordinate system (WGS84) and transformed into a 50×50 km grid. The newly compiled database comprises more than 384,000 grid and locality records distributed across 40 countries. We calculated species richness maps as well as maps of Corrected Weighted Endemism and species distribution types (i.e. groups of species with similar distribution patterns) by hierarchical cluster analysis using Jaccard’s index as association measure. Our analysis serves as a preliminary step towards an interactive, dynamic and online distributed database system (NA2RE system) of the current spatial distribution of European amphibians and reptiles (see http://na2re.ismai.pt). The NA2RE system will serve as well to monitor potential temporal changes in their distributions. Grid maps of all species are made available along with this paper as a tool for decision-making and conservation-related studies and actions. We also identify taxonomic and geographic gaps of knowledge that need to be filled, and we highlight the need to add temporal and altitudinal data for all records, to allow tracking potential species distribution changes as well as detailed modelling of the impacts of land use and climate change on European amphibians and reptiles. [less ▲]

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See detailFacultative paedomorphosis and the pattern of intra- and interspecific variation in cranial skeleton: lessons from European newts (Ichthyosaura alpestris and Lissotriton vulgaris)
Ivanović, Ana; Cvijanović, Milena; Denoël, Mathieu ULg et al

in Zoomorphology (2014), 133(1), 99-109

Paedomorphosis, the presence of ancestral larval and juvenile traits that occur at the descendent adult stage, is an evolutionary phenomenon that shaped morphological evolution in many vertebrate lineages ... [more ▼]

Paedomorphosis, the presence of ancestral larval and juvenile traits that occur at the descendent adult stage, is an evolutionary phenomenon that shaped morphological evolution in many vertebrate lineages, including tailed amphibians. Among salamandrid species, paedomorphic and metamorphic phenotypes can be observed within single populations (facultative paedomorphosis). Despite wide interest in facultative paedomorphosis and polymorphism produced by heterochronic changes (heterochronic polymorphism), the studies that investigate intraspecific morphological variation in facultative paedomorphic species are largely missing. By quantifying the cranium size and development (bone development and remodeling), we investigated the variation at multiple levels (i.e., between sexes, populations and species) of two facultatively paedomorphic European newt species: the alpine and the smooth newt. The pattern of variation between paedomorphs (individuals keeping larval traits at the adult stage) and metamorphs (metamorphosed adult individuals) varied between species and among populations within a single species. The patterns of variation in size and skull formation appear to be more uniform in the alpine than in the smooth newt, indicating that developmental constraints differed between species (more pronounced in alpine than in smooth newt). Our study shows that the cranial skeleton provides detailed insight in the pattern of variation and divergence in heterochronic polymorphism within and between species and open new questions related to heterochronic polymorphism and evolution of cranial skeleton. [less ▲]

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See detailIntroduced goldfish affect amphibians through inhibition of sexual behaviour in risky habitats: an experimental approach
Winandy, Laurane ULg; Denoël, Mathieu ULg

in PLoS ONE (2013), 8(11), 82736

The introduction of alien species is one of the major causes of current and global biodiversity loss. The introduction of fish can be a particular threat to native amphibian populations, which are ... [more ▼]

The introduction of alien species is one of the major causes of current and global biodiversity loss. The introduction of fish can be a particular threat to native amphibian populations, which are declining worldwide. One way for amphibians to persist in such altered environments is to adopt anti-predator strategies especially at the behavioural level. However, although it has been shown that avoidance behaviour may decrease the probability of being detected by a potential predator, little is known on the consequences on sexual behaviour. In this study, we tested the hypothesis that adult Alpine newts (Ichthyosaura alpestris) use shelters more often and exhibit less sexual activity in the presence of goldfish (Carassius auratus) and that they reduce sexual activity more in risky micro-habitats than in safe environments. To this end, we assessed behavioural patterns of adult newts in a replicated laboratory design. Goldfish were present in direct contact with newts in half of the tanks. Consistently throughout the study period, significantly more newts used shelter in the presence of fish than in their absence. Newts also significantly decreased their sexual activity level overall, but specially outside the shelter when they were in direct contact with fish. These results show that fish presence can affect newts in complex ways, such as through inhibition of their reproduction. Our work highlights that integrating behaviour in conservation studies is essential to understanding the patterns of coexistence and exclusion between introduced fish and amphibians. [less ▲]

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See detailDifferences in locomotor activity in two syntopic spadefoot toad species (genus Pelobates)
Székely, Diana; Denoël, Mathieu ULg; Székely, Paul et al

Poster (2013, August 25)

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See detailNA2RE Project—The new atlas of amphibians and reptiles: new compilation and online system
Sillero, Neftalí; Campos, João; Oliveira, Marco Amaro et al

Conference (2013, August 24)

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See detailDoes foraging plasticity favours adaptation to new habitats in fire salamanders? Preliminary data
Manenti, Raoul; Denoël, Mathieu ULg; Ficetola, Gentile Francesco

Conference (2013, August 23)

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See detailEnvironmental correlates of paedomorphosis and metamorphosis in palmate newts
Denoël, Mathieu ULg; Ficetola, G. Francesco

Conference (2013, August 23)

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See detailEcology and evolution of facultative paedomorphosis in newts and salamanders
Denoël, Mathieu ULg

Scientific conference (2013, February 21)

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See detailSimilar local and landscape processes affect both a common and a rare newt species
Denoël, Mathieu ULg; Perez, Amélie; Cornet, Yves ULg et al

in PLoS ONE (2013), 8(5), 62727

Although rare species are often the focus of conservation measures, more common species may experience similar decline and suffer from the same threatening processes. We tested this hypothesis by ... [more ▼]

Although rare species are often the focus of conservation measures, more common species may experience similar decline and suffer from the same threatening processes. We tested this hypothesis by examining, through an information-theoretic approach, the importance of ecological processes at multiple scales in the great crested newt Triturus cristatus, regionally endangered and protected in Europe, and the more common smooth newt, Lissotriton vulgaris. Both species were similarly affected by the same processes, i.e. suitability of aquatic and terrestrial components of their habitat at different scales, connectivity among breeding sites, and the presence of introduced fish. T. cristatus depended more on water depth and aquatic vegetation than L. vulgaris. The results show that environmental pressures threaten both common and rare species, and therefore the more widespread species should not be neglected in conservation programs. Because environmental trends are leading to a deterioration of aquatic and terrestrial habitat features required by newt populations, populations of the common species may follow the fate of the rarest species. This could have substantial conservation implications because of the numerical importance of common species in ecosystems and because commonness could be a transient state moving towards rarity. On the other hand, in agreement with the umbrella species concept, targeting conservation efforts on the most demanding species would also protect part of the populations of the most common species. [less ▲]

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See detailCues from introduced fish alter shelter use and feeding behaviour in adult alpine newts
Winandy, Laurane ULg; Denoël, Mathieu ULg

in Ethology (2013), 119(2), 121-129

Amphibians are particularly affected by alien fish introductions and are declining worldwide. However, the behavioural mechanisms behind the observed cases of coexistence and exclusion patterns between ... [more ▼]

Amphibians are particularly affected by alien fish introductions and are declining worldwide. However, the behavioural mechanisms behind the observed cases of coexistence and exclusion patterns between adult amphibians and fish are poorly understood. In the present study, we aimed at testing the hypothesis that adult newts display different feeding and space use behaviour in the presence of fish cues (i.e. access less food resources and use more shelters than when fish cues are absent). To achieve this we measured behavioural patterns in 100 adult Alpine newts (Mesotriton alpestris) in a replicated laboratory design (20 tanks × 7 replicates across time). Half of trials involved individuals in indirect (visual and olfactory) contact with goldfish (Carassius auratus), a non-predatory species for adult newts. In the presence of fish, significantly more newts hid under shelters than in their absence, but this difference decreased over time. A lower number of newts fed in comparison with controls. These results show that newts responded to fish presence even in the absence of direct contact, but the differences were small. Newts decreased vital activities such as exploration of open areas and feeding. They also adjusted shelter use over time, suggesting a process of habituation or a risk assessment in the absence of direct risk. These results reveal that exploring behavioural patterns can aid in understanding the causes of exclusion and coexistence patterns between fish and amphibians. [less ▲]

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See detailWhat remains from a 454 run: estimation of success rates of microsatellite loci development in selected newt species (Calotriton asper, Lissotriton helveticus, and Triturus cristatus) and comparison with Illumina-based approaches
Drechsler, Axel; Geller, Daniel; Freund, Katharina et al

in Ecology and Evolution (2013), 3(11), 3947-3957

The development of microsatellite loci has become more efficient using next-generation sequencing (NGS) approaches, and many studies imply that the amount of applicable loci is large. However, few studies ... [more ▼]

The development of microsatellite loci has become more efficient using next-generation sequencing (NGS) approaches, and many studies imply that the amount of applicable loci is large. However, few studies have sought to quantify the number of loci that are retained for use out of the thousands of sequence reads initially obtained. We analyzed the success rate of microsatellite loci development for three amphibian species using a 454 NGS approach on tetra-nucleotide motif-enriched species-specific libraries. The number of sequence reads obtained differed strongly between species and ranged from 19,562 for Triturus cristatus to 55,626 for Lissotriton helveticus, with 52,075 reads obtained for Calotriton asper. PHOBOS was used to identify sequences with tetra-nucleotide repeat motifs with a minimum repeat number of ten and high quality primer binding sites. Of 107 sequences for T. cristatus, 316 for C. asper and 319 for L. helveticus, we tested the amplification success, polymorphism, and degree of heterozygosity for 41 primer combinations each for C. asper and T. cristatus, and 22 for L. helveticus. We found 11 polymorphic loci for T. cristatus, 20 loci for C. asper, and 15 loci for L. helveticus. Extrapolated, the number of potentially amplifiable loci (PALs) resulted in estimated species-specific success rates of 0.15% (T. cristatus), 0.30% (C. asper), and 0.39% (L. helveticus). Compared with representative Illumina NGS approaches, our applied 454-sequencing approach on specifically enriched sublibraries proved to be quite competitive in terms of success rates and number of finally applicable loci. [less ▲]

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See detailEndosulfan effects on Rana dalmatina tadpoles: Quantitative developmental and behavioural analysis
Lavorato, Manuela; Bernabo, Ilaria; Crescente, Antonio et al

in Archives of Environmental Contamination & Toxicology (2013), 64(2), 253-262

Endosulfan is an organochlorine pesticide that was recently labeled as a persistent organic pollutant, but it is still widely employed, particularly in developing countries. The goal of this study is to ... [more ▼]

Endosulfan is an organochlorine pesticide that was recently labeled as a persistent organic pollutant, but it is still widely employed, particularly in developing countries. The goal of this study is to evaluate the acute (LC50) and chronic effects (developmental and behavioural traits) of this insecticide on Rana dalmatina tadpoles after exposure to ecologically relevant concentrations (0.005, 0.01, and 0.05 mg/L) by applying video-tracking techniques to evaluate the quantitative effect of endosulfan on amphibian behavioural patterns. The 96 h LC50 value was 0.074 mg endosulfan/L. Tadpoles chronically exposed to 0.01 and 0.05 mg endosulfan/L underwent high mortality rate, decreased larval growth, delayed development, and increased incidence of malformations, and they did not reach metamorphosis by the end of the experiment. Moreover, tadpoles exposed to these concentrations exhibited several abnormalities in swimming patterns, such as shorter distance moved, swirling, resting, and unusual use of space. The exposure to 0.005 mg endosulfan/L did not cause any significant effects on behaviour, larval growth, or development, but we observed a significant decrease in both survival and time to metamorphosis. We showed that developmental abnormalities are dose-dependent and that the pesticide effects could differ depending on the endosulfan concentration and the species tested. We also validated the hypothesis that behavioural analysis, along with the use of new analytical methods, could be a useful tool in amphibian ecotoxicological studies. [less ▲]

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See detailEffects of a sublethal pesticide exposure on locomotor behavior: A video-tracking analysis in larval amphibians
Denoël, Mathieu ULg; Libon, Sylvie; Kestemont, Patrick et al

in Chemosphere (2013), 90(3), 945-951

Organochlorine pesticides such as endosulfan have been shown to have both lethal and sublethal effects on amphibians. In this context, behavioral endpoints have proved their usefulness in evidencing ... [more ▼]

Organochlorine pesticides such as endosulfan have been shown to have both lethal and sublethal effects on amphibians. In this context, behavioral endpoints have proved their usefulness in evidencing impacts of such chemicals at environmental concentrations that do not necessarily cause mortality. The recent development of video-tracking technologies now offers the possibility of accurately quantifying locomotor behaviors. However, these techniques have not yet been applied to evaluating the toxicity of pesticides in amphibians. We therefore aimed at determining the potential toxicity of endosulfan on endpoints associated with locomotion after short-term environmental endosulfan exposure in Rana temporaria tadpoles and at using these data as warning systems for survival alterations after a longer exposure. To this end, we analyzed video-tracks of 64 tadpoles (two pesticide treatments: 5 and 50 μg L−1, one control and one solvent-control) with Ethovision XT 7 software. The highest endosulfan concentration had a significant effect on all four behavioral endpoints. Contaminated tadpoles traveled shorter distances, swam less often, at a lower mean speed, and occupied a less peripherical position than control tadpoles. The lowest endosulfan concentration had similar but lower effects, and did not affect mean speed during swimming. Survival was reduced only after a long-term exposure to endosulfan and was associated with short-term behavioral dysfunctions. These results show that endosulfan strongly affects the behavioral repertory of amphibian tadpoles, but in different ways depending on concentration, thus suggesting that the pesticide has complex modes of action. Given the importance of locomotion and space use in tadpole success in their aquatic environment, these results confirm the toxic action of endosulfan. By highlighting effects before mortality markers, video-tracking systems also show their potential as sentinels of sublethal effects of pesticides. [less ▲]

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See detailForaging plasticity favours adaptation to new habitats in fire salamanders
Manenti, Raoul; Denoël, Mathieu ULg; Ficetola, Gentile Francesco

in Animal Behaviour (2013), 86(2), 375-382

Predators often show strong plasticity of optimal foraging strategies. A major difference in foraging strategies occurs between sit-and-wait and active predators. Models predict that the efficiency of ... [more ▼]

Predators often show strong plasticity of optimal foraging strategies. A major difference in foraging strategies occurs between sit-and-wait and active predators. Models predict that the efficiency of these strategies is affected by environmental conditions, active predators being favoured when prey are scarce and their detection difficult. The shift between the two strategies may occur through both phenotypic plasticity and local adaptations. Larvae of the fire salamander, Salamandra salamandra, are typically stream-dwelling sit-and-wait predators, but some populations breed in caves. We evaluated whether local adaptations or phenotypic plasticity determine shifts in foraging strategy between stream and cave populations. The foraging behaviour of salamander larvae was evaluated under all combinations of three test conditions during trials: light versus darkness, prey presence versus absence and food deprived versus fed; larvae originated from caves and streams and were reared in epigeous photoperiod or in darkness. Observations and video tracking showed that salamander larvae modified their behaviour in response to environmental conditions. In the darkness, larvae showed higher average velocity and moved longer distances. Movements were higher in food-deprived larvae and in the presence of prey compared to fed larvae and prey absent conditions. Furthermore, larvae from cave populations showed higher behavioural plasticity than stream larvae, and better exploited the available space in test environments. Variation in foraging behaviour was strong, and involved complex interactions between plasticity and local adaptations. Larvae from cave populations showed higher behavioural plasticity, supporting the hypothesis that this trait may be important for the exploitation of novel environments, such as caves. [less ▲]

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See detailVideo multitracking of fish behaviour: a review and future perspectives
Delcourt, Johann ULg; Denoël, Mathieu ULg; Ylieff, Marc ULg et al

in Fish & Fisheries (2013), 14(2), 186-204

With the development of digital imaging techniques over the last decade, there are now new opportunities to study complex behavioural patterns in fish (e.g. schooling behaviour) and to track a very large ... [more ▼]

With the development of digital imaging techniques over the last decade, there are now new opportunities to study complex behavioural patterns in fish (e.g. schooling behaviour) 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. This paper presents a review of fish video multitracking techniques. It describes the possibilities of tracking individuals and groups at different scales, but also outlines the advantages and limitations of the detection methods. The problem of occlusions, during which errors of individual identifications are very frequent, is underlined. This paper summarises different approaches to improving the quality of individual identification, notably by the development of three-dimensional tracking, image analysis and probabilistic applications. Finally, implications for fish research and future directions are presented. [less ▲]

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See detailBehaviours Associated with Acoustic Communication in Nile Tilapia (Oreochromis niloticus)
Longrie, Nicolas; Poncin, Pascal ULg; Denoël, Mathieu ULg et al

in PLoS ONE (2013), 8(4), 61467

Detailed reference viewed: 49 (14 ULg)