References of "Denoël, Mathieu"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailOn the identification of paedomorphic and overwintering larval newts based on cloacal shape: review and guidelines
Denoël, Mathieu ULg

in Current Zoology (in press)

Paedomorphosis is an alternative process to metamorphosis in which adults retain larval traits at the adult stage. It is frequent in newts and salamanders, where larvae reach sexual maturity without ... [more ▼]

Paedomorphosis is an alternative process to metamorphosis in which adults retain larval traits at the adult stage. It is frequent in newts and salamanders, where larvae reach sexual maturity without losing their gills. However, in some populations, larvae overwinter in water, while remaining immature. These alternative ontogenetic processes are of particular interest in various research fields, but have different causes and consequences, as only paedomorphosis allows metamorphosis to be bypassed before maturity. It is thus relevant to efficiently identify paedomorphs versus overwintering larvae. In this context, the aim of this paper was threefold: firstly, to perform a meta-analysis of the identification procedures carried out in the literature; secondly, to determine the effectiveness of body size to make inferences about adulthood by surveying natural newt populations of Lissotriton helveticus and Ichthyosaura alpestris, and thirdly, to propose easy guidelines for an accurate distinction between large larvae and paedomorphs based on an external sexual trait, which is essential for reproduction — the cloaca. More than half of the studies in the literature do not mention the diagnostic criteria used for determining adulthood. The criteria mentioned were the presence of mature gonads (10%), eggs laid (4%), courtship behaviour (10%), and external morphological sexual traits (39%) including the cloaca (24%). Body-size thresholds should not be used as a proxy for paedomorphosis, because overwintering larvae can reach a larger size than paedomorphs within the same populations. In contrast, diagnosis based on cloacal external morphology is recommended, as it can be processed by the rapid visual assessment of all caught specimens, thus providing straightforward data at the individual level for both sexes. [less ▲]

Detailed reference viewed: 22 (2 ULg)
Full Text
Peer Reviewed
See detailTemporal habitat shift of a polymorphic newt species under predation risk
Winandy, Laurane ULg; Colin, Mélanie; Denoël, Mathieu ULg

in Behavioral Ecology (in press)

The temporal partitioning hypothesis suggests that the evolution of different diel activity rhythms in animals might facilitate the coexistence between prey and predators. However, the temporal shift of ... [more ▼]

The temporal partitioning hypothesis suggests that the evolution of different diel activity rhythms in animals might facilitate the coexistence between prey and predators. However, the temporal shift of habitat use induced by predation has rarely been observed. The study of such a mechanism is particularly relevant for introduced species because it might explain how native species can persist or decline in response to the presence of alien species. The introduction of fish into ponds inhabited by amphibians has severe consequences for their occurrence and abundance. Fish particularly affect an alternative newt phenotype, the paedomorph, which does not undergo metamorphosis and maintains larval traits such as gills at the adult stage. In a laboratory design, we assessed the diel patterns of habitat use in the 2 distinct morphological phenotypes of palmate newt (Lissotriton helveticus) in the presence or absence of goldfish (Carassius auratus). Both newt phenotypes avoided a risky habitat more in the presence than in the absence of fish. This habitat shift was more pronounced during the daytime (i.e., when the risk could be considered higher for the newts) than during nighttime. However, in contrast to metamorphs, paedomorphs showed less adaptive changes according to temporal risk and remained in their shelter for most of the time. Temporal and habitat partitioning at the diel scale between native and alien species might promote their coexistence, but diel change can also imply a cost in the overall reduction of the time allocated to essential activities, showing that species interactions remain complex. [less ▲]

Detailed reference viewed: 22 (2 ULg)
Full Text
Peer Reviewed
See detailCollective vortex behaviors: diversity, proximate, and ultimate causes of circular animal group movements
Delcourt, Johann ULg; Bode, W.F. Nikolaï; Denoël, Mathieu ULg

in Quarterly Review of Biology (2016), 91(1), 1-24

Ant mill, caterpillar circle, bat doughnut, amphibian vortex, duck swirl, and fish torus are different names for rotating circular animal formations, where individuals turn around a common center. These ... [more ▼]

Ant mill, caterpillar circle, bat doughnut, amphibian vortex, duck swirl, and fish torus are different names for rotating circular animal formations, where individuals turn around a common center. These “collective vortex behaviors” occur at different group sizes from pairs to several million individuals and have been reported in a large number of organisms, from bacteria to vertebrates, including humans. However, to date, no comprehensive review and synthesis of the literature on vortex behaviors has been conducted. Here, we review the state of the art of the proximate and ultimate causes of vortex behaviors. The ubiquity of this behavioral phenomenon could suggest common causes or fundamental underlying principles across contexts. However, we find that a variety of proximate mechanisms give rise to vortex behaviors. We highlight the potential benefits of collective vortex behaviors to individuals involved in them. For example, in some species, vortices increase feeding efficiency and could give protection against predators. It has also been argued that vortices could improve collective decision making and information transfer. We highlight gaps in our understanding of these ubiquitous behavioral phenomena and discuss future directions for research in vortex studies. [less ▲]

Detailed reference viewed: 165 (24 ULg)
Full Text
Peer Reviewed
See detailProvenance of Ichthyosaura alpestris (Caudata: Salamandridae) introductions to France and New Zealand assessed by mitochondrial DNA analysis
Arntzen, Jan W.; King, Tania M.; Denoël, Mathieu ULg et al

in The Herpetological Journal (2016), 26(1), 49-56

The last century has seen an unparalleled movement of species around the planet as a direct result of human activity, which has been a major contributor to the biodiversity crisis. Amphibians represent a ... [more ▼]

The last century has seen an unparalleled movement of species around the planet as a direct result of human activity, which has been a major contributor to the biodiversity crisis. Amphibians represent a particularly vulnerable group, exacerbated by the devastating effects of chytrid fungi. We report the malicious translocation and establishment of the alpine newt (Ichthyosaura alpestris) to its virtual antipode in North Island of New Zealand. We use network analysis of mitochondrial DNA haplotypes to identify the original source population as I. a. apuana from Tuscany, Italy. Additionally, a population in southern France, presumed to be introduced, is identified as I. a. alpestris from western Europe. However, the presence of two differentiated haplotypes suggests a mixed origin. This type of analysis is made possible by the recent availability of a phylogenetic analysis of the species throughout its natural range. We discuss the particulars of both introductions. [less ▲]

Detailed reference viewed: 376 (24 ULg)
Full Text
Peer Reviewed
See detailNewt life after fish introduction: extirpation of paedomorphosis in a mountain fish lake and newt use of satellite pools
Denoël, Mathieu ULg; Scime, Patrick; Zambelli, Nicola

in Current Zoology (2016), 62(1), 61-69

Fish introduction is one of the main causes of amphibian decline worldwide. It affects particularly rare aquatic phenotypes such as paedomorphs, which retain gills during the adult stage. In this context ... [more ▼]

Fish introduction is one of the main causes of amphibian decline worldwide. It affects particularly rare aquatic phenotypes such as paedomorphs, which retain gills during the adult stage. In this context, we determined whether small wetlands, such as pools surrounding fished and fishless lakes, could sustain paedomorphic and metamorphic newts. To this end, we surveyed lakes known historically to sustain Alpine newts (Ichthyosaura alpestris) as well as 35 nearby pools. On the basis of the published records, the only known population exhibiting paedomorphosis in the Swiss Alps was found to be extirpated by salmonid introductions. However, the metamorphs persisted in peripheral pools, paedomorphosis was discovered at a new locality, and overwintering larvae were still present in one of the lakes. These results show the importance of conserving varied aquatic habitats such as pools in mountainous environments where the main resources can become unsuitable for amphibians because of fish introductions. Pools may also function as reservoirs in maintaining newt populations until programs to remove fish from lakes can be carried out. It is not known if paedomorphs could reappear after fish removal. However, the combined resilience of amphibians after fish removal and the genetic basis for paedomorphosis highlighted in other taxa by previous studies suggest that there is the potential to maintain this intraspecific case of diversity even after its disappearance. [less ▲]

Detailed reference viewed: 205 (27 ULg)
Full Text
Peer Reviewed
See detailThe importance of phenotypic diversity in conservation: Resilience of palmate newt morphotypes after fish removal in Larzac ponds (France)
Denoël, Mathieu ULg; Winandy, Laurane ULg

in Biological Conservation (2015), 192

Resilience of organisms after threat removal is an essential feature to justify conservation efforts. Amphibians are particularly threatened with a worldwide decline, showing a low resistance to invaders ... [more ▼]

Resilience of organisms after threat removal is an essential feature to justify conservation efforts. Amphibians are particularly threatened with a worldwide decline, showing a low resistance to invaders such as fish. Previous research has shown that they could recover after fish extirpation due to metamorphosed colonizers. However, not all amphibian phenotypes are able to persist to fish introduction and disperse. In many species of newts and salamanders, paedomorphs retain gills in the adult stage, which makes them fully aquatic. A proposed way to conserve this phenotype would be to remove introduced fish from their habitats. However, because paedomorphosis is usually not expressed in the presence of fish, it is unknown whether fish removal could allow the resilience of paedomorphs. This would be possible only if progenies of metamorphosed individuals could become paedomorphic in restored habitats. Through a quantitative survey in three types of ponds, including control ponds without fish, ponds in which fish were extirpated, and fish ponds, we determined abundances of paedomorphic and metamorphic palmate newts (Lissotriton helveticus). The results show that paedomorphosis resilience is possible and even highly frequent, as paedomorphs were found in 80% of ponds where fish disappeared. Abundances were similar between these ponds and control ponds whereas fish ponds had almost no newts, indicating a very low resistance to invaders. This shows that conserving common phenotypes can help to preserve endangered phenotypes, as paedomorphs were produced through the reproduction of metamorphs. There is thus hope of maintaining intraspecific biodiversity though conservation action involving threat removal. [less ▲]

Detailed reference viewed: 58 (21 ULg)
Full Text
Peer Reviewed
See detailThe aggressive personality of an introduced fish affects foraging behavior in a polymorphic newt
Winandy, Laurane ULg; Denoël, Mathieu ULg

in Behavioral Ecology (2015), 26(6), 1528-1536

The study of personality has aroused much interest and has provided insight into the understanding of animal behavior. Nevertheless, the study of the ecological consequences of personality is a newer ... [more ▼]

The study of personality has aroused much interest and has provided insight into the understanding of animal behavior. Nevertheless, the study of the ecological consequences of personality is a newer field that could shed light on cases of alien species introductions. The goldfish (Carassius auratus) is frequently introduced worldwide and affects the abundance of newts, having an especially negative impact on an alternative phenotype, the paedomorph, which maintains larval traits at the adult stage, unlike the other phenotype, the metamorph, which has undergone metamorphosis. We experimentally assessed the impact of goldfish on the foraging behavior of both phenotypes of palmate newts (Lissotriton helveticus). More particularly, we assessed fish personality by analyzing the foraging activity and the aggressiveness toward newts, and newt personality by analyzing individual difference in boldness. In the presence of fish, fewer newts foraged than in their absence, and paedomorphs were more affected than metamorphs. We found strong personality differences in fish and fewer newts foraged in the presence of a more aggressive fish. Newts differed in boldness, but fish aggressiveness remains a key factor to explain newt behavior. Studying behavioral interactions between native and alien species helps to understand the mechanisms of coexistence and exclusion and why different phenotypes might be affected differently by the same threat. To a great extent, not only the presence of fish alters the foraging opportunities of newts but also the personality of the invader; integrating personality patterns of invaders is therefore a key to understanding the ecological consequences of alien species introduction. [less ▲]

Detailed reference viewed: 176 (82 ULg)
Full Text
Peer Reviewed
See detailAmphibians forgo aquatic life in response to alien fish introduction
Winandy, Laurane ULg; Darnet, Elodie; Denoël, Mathieu ULg

in Animal Behaviour (2015), 109

Species with complex life cycles are good models to understand trade-offs between life in hostile and favourable habitats. Newts remain in breeding wetlands for a long period and are strongly affected by ... [more ▼]

Species with complex life cycles are good models to understand trade-offs between life in hostile and favourable habitats. Newts remain in breeding wetlands for a long period and are strongly affected by fish introduction; however, mechanisms of the exclusion observed in the field are still not well known. In particular, whether newts skip breeding and leave water for land in response to fish introduction and how aquatic shelter may influence their choice remain open questions. To investigate these questions, we experimentally studied the use of aquatic and terrestrial habitats during the breeding season of palmate newts, Lissotriton helveticus, in the presence and absence of goldfish, Carassius auratus. We determined the consequences of habitat choice on newt fitness by assessing sexual activity and number of eggs. There was a strong, significant avoidance of the aquatic environment in the presence of fish, particularly when no aquatic shelter was available. This escape from the water had an impact on reproduction: newts decreased their sexual activity and laid fewer eggs. The availability of shelters favoured coexistence but did not prevent a large proportion of the newts from leaving water and skipping reproduction. This study shows how the presence of fish and the absence of aquatic shelters can lead to newts forgoing aquatic life, thus improving our understanding of the mechanisms behind the coexistence and exclusion patterns found in the wild. More broadly, these data contribute to explaining aquatic versus terrestrial life in favourable and unfavourable environments. [less ▲]

Detailed reference viewed: 221 (45 ULg)
Full Text
Peer Reviewed
See detailUsing kernels and ecological niche modeling to delineate conservation areas in an endangered patch-breeding phenotype
Denoël, Mathieu ULg; Ficetola, Francesco

in Ecological Applications (2015), 25(7), 1922-1931

Efficient delineation of conservation areas is a great challenge in maintaining biodiversity. Kernel density estimators (KDEs) are a powerful tool in this perspective, but they have not been applied at ... [more ▼]

Efficient delineation of conservation areas is a great challenge in maintaining biodiversity. Kernel density estimators (KDEs) are a powerful tool in this perspective, but they have not been applied at the population level on patch-distributed organisms. This would be particularly worthy for species that need broad habitats beyond those where they can be sampled; such as terrestrial lands for pond-breeding amphibians. The aim of this study was to compare different approaches for the identification of suitable areas for conservation: KDE, ecological niche modelling, and a combination of KDE and niche models. Paedomorphosis was chosen as a model system because this is an important form of intraspecific variation that is present in numerous taxa, but geographically localized within species and globally endangered. 277 ponds were sampled in one of the hotspots of paedomorphosis to determine the abundance and distribution of paedomorphs (i.e. individuals retaining gills at the adult stage) of the palmate newt (Lissotriton helveticus), with emphasis on the connections between the most valuable populations. KDEs gave insights into the surface areas required to balance the maintenance of certain number of connected ponds and the respective number of disjoint areas in which the whole population is divided. The inclusion of barriers in the models helped in accurately designing the limits of the areas to protect. Alone, habitat models were not able to successfully delineate the area to protect, but the integration between terrestrial suitable areas or barriers and KDE allowed an objective identification of areas required for conservation. Overall, the best performance was observed by the KDE integrating ecological barriers, and by the combination between KDE and niche modelling. In a broader perspective, KDEs are thus a pertinent tool in providing quantitative spatial measurements to delineate conservation areas based on patch-abundance data with a specific focus to connectivity. [less ▲]

Detailed reference viewed: 165 (72 ULg)
Peer Reviewed
See detailPredator cues and risky habitats affect foraging activity in salamanders
Melotto, Andrea; Ficetola, Gentile Francesco; Denoël, Mathieu ULg et al

Conference (2015, September 11)

Detailed reference viewed: 14 (0 ULg)
Peer Reviewed
See detailNewts skip aquatic life and forego reproduction in response to alien fish introduction
Winandy, Laurane ULg; Darnet, Elodie; Denoël, Mathieu ULg

Conference (2015, September 10)

Detailed reference viewed: 17 (1 ULg)
Peer Reviewed
See detailReevaluating IUCN Red List assesment on European amphibians
Crnobrnja-Isailović, Jelka; Cogalniceanu, Dan; Denoël, Mathieu ULg et al

Conference (2015, September 09)

Detailed reference viewed: 28 (0 ULg)
Peer Reviewed
See detailBehavioral effects of exposure to salinity on tadpoles of two syntopic species of spadefoot toads (genus Pelobates)
Székely, Diana ULg; Stanescu, Floriana; Székely, Paul et al

Poster (2015, September)

Detailed reference viewed: 19 (0 ULg)
Full Text
Peer Reviewed
See detailExpression of sexual ornaments in a polymorphic species: phenotypic variation in response to environmental risk
Winandy, Laurane ULg; Denoël, Mathieu ULg

in Journal of Evolutionary Biology (2015), 28(5), 1049-1056

Secondary sexual traits may evolve under the antagonistic context of sexual and natural selection. In some polymorphic species, these traits are only expressed during the breeding period and are ... [more ▼]

Secondary sexual traits may evolve under the antagonistic context of sexual and natural selection. In some polymorphic species, these traits are only expressed during the breeding period and are differently expressed in alternative phenotypes. However, it is unknown whether such phenotypes exhibit phenotypic plasticity of seasonal ornamentations in response to environmental pressures such as in the presence of fish (predation risk). This is an important question to understand the evolution of polyphenisms. We used facultative paedomorphosis in newts as a model system because it involves the coexistence of paedomorphs that retain gills in the adult stage with metamorphs that have undergone metamorphosis, but also because newts exhibit seasonal sexual traits. Our aim was therefore to determine the influence of fish on the development of seasonal ornamentation in the two phenotypes of the palmate newt (Lissotriton helveticus). During the entire newt breeding period, we assessed the importance of phenotype and fish presence with an information-theoretic approach. Our results showed that paedomorphs presented much less developed ornamentation than metamorphs and those ornamentations varied over time. Fish inhibited the development of sexual traits but differently between phenotypes: in contrast to metamorphs, paedomorphs lack the phenotypic plasticity of sexual traits to environmental risk. This study points out that internal and external parameters act in complex ways in the expression of seasonal sexual ornamentations and that similar environmental pressure can induce a contrasted evolution in alternative phenotypes. [less ▲]

Detailed reference viewed: 100 (31 ULg)
Full Text
Peer Reviewed
See detailEffects of low dose endosulfan exposure on brain neurotransmitter levels in the African clawed frog Xenopus laevis
Preud'Homme, Valérie; Milla, Sylvain; Gillardin, Virginie et al

in Chemosphere (2015), 120(2), 357-364

Understanding the impact of pesticides in amphibians is of growing concern to assess the causes of their decline. Among pesticides, endosulfan belongs to one of the potential sources of danger because of ... [more ▼]

Understanding the impact of pesticides in amphibians is of growing concern to assess the causes of their decline. Among pesticides, endosulfan belongs to one of the potential sources of danger because of its wide use and known effects, particularly neurotoxic, on a variety of organisms. However, the effect of endosulfan was not yet evaluated on amphibians at levels encompassing simultaneously brain neurotransmitters and behavioural endpoints. In this context, tadpoles of the African clawed frog Xenopus laevis were submitted to four treatments during 27 d: one control, one ethanol control, and two low environmental concentrations of endosulfan (0.1 and 1 μg L−1). Endosulfan induced a significant increase of brain serotonin level at both concentrations and a significant increase of brain dopamine and GABA levels at the lower exposure but acetylcholinesterase activity was not modified by the treatment. The gene coding for the GABA transporter 1 was up-regulated in endosulfan contaminated tadpoles while the expression of other genes coding for the neurotransmitter receptors or for the enzymes involved in their metabolic pathways was not significantly modified by endosulfan exposure. Endosulfan also affected foraging, and locomotion in links with the results of the physiological assays, but no effects were seen on growth. These results show that low environmental concentrations of endosulfan can induce adverse responses in X. laevis tadpoles. At a broader perspective, this suggests that more research using and linking multiple markers should be used to understand the complex mode of action of pollutants. [less ▲]

Detailed reference viewed: 115 (31 ULg)