References of "Denoël, Mathieu"
     in
Bookmark and Share    
Full Text
See detailLe Triton palmé, Triturus helveticus (Razoumowski, 1789)
Denoël, Mathieu ULg

in Jacob, Jean-Paul; Percsy, Christiane; de Wavrin, Hellin (Eds.) et al Amphibiens et Reptiles de Wallonie (2007)

Detailed reference viewed: 143 (11 ULg)
Full Text
See detailLe Triton crêté, Triturus cristatus (Laurenti, 1768)
Jacob, Jean-Paul; Denoël, Mathieu ULg

in Jacob, Jean-Paul; Percsy, Christiane; de Wavrin, Hellin (Eds.) et al Amphibiens et Reptiles de Wallonie (2007)

Detailed reference viewed: 185 (14 ULg)
Full Text
See detailLe Crapaud calamite, Bufo calamita Laurenti, 1768
Graitson, Eric ULg; Denoël, Mathieu ULg

in Jacob, Jean-Paul; Percsy, Christiane; de Wavrin, Hellin (Eds.) et al Amphibiens et Reptiles de Wallonie (2007)

Detailed reference viewed: 224 (14 ULg)
Full Text
See detailLe Triton ponctué, Triturus vulgaris (Linnaeus, 1758)
Denoël, Mathieu ULg

in Jacob, Jean-Paul; Percsy, Christiane; de Wavrin, Hellin (Eds.) et al Amphibiens et Reptiles de Wallonie (2007)

Detailed reference viewed: 134 (9 ULg)
Full Text
See detailLe Triton alpestre, Triturus alpestris (Laurenti, 1768)
Denoël, Mathieu ULg

in Jacob, Jean-Paul; Percsy, Christiane; de Wavrin, Hellin (Eds.) et al Amphibiens et Reptiles de WAllonie (2007)

Detailed reference viewed: 210 (12 ULg)
See detailAmphibiens et Reptiles de Wallonie
Jacob, Jean-Paul; Percsy, Christiane; de Wavrin, Hellin et al

Book published by Aves-Raînne et Centre de Recherche de la Nature, des Forêts et du Bois (MRW - DGRNE) (2007)

Detailed reference viewed: 117 (13 ULg)
Full Text
Peer Reviewed
See detailL’évolution du peuplement herpétologique en Région wallonne (Belgique)
Jacob, Jean-Paul; Percsy, Christiane; De Wavrin, Hellin et al

Conference (2007)

Detailed reference viewed: 22 (0 ULg)
Full Text
Peer Reviewed
See detailEcological thresholds and estimates of breaking points in newt populations: a useful tool to categorise habitat use and apply conservation measures
Denoël, Mathieu ULg; Ficetola, Gentile

Poster (2007)

Ecological thresholds are defined as points at which a rapid change occurs from one ecological condition to another. Their determination in species–habitat relationships has important implications because ... [more ▼]

Ecological thresholds are defined as points at which a rapid change occurs from one ecological condition to another. Their determination in species–habitat relationships has important implications because they allow to understand ecological requirements of species and to provide efficient conservation measures. However, there is a lack of concordance across studies and this method was not yet applied to newts. In this study, we sampled 371 ponds to gather occurrence data on the palmate newt Triturus heveticus and the Alpine newt Triturus alpestris. We tested for the existence of significant thresholds for three variables: distance to forest, forest and crop covers. We found significant thresholds for both landscape configuration and composition, with relationships between distance to forest and occurrence of Triturus alpestris and T. helveticus, and forest and crop cover and T. helveticus. Both species require breeding ponds within a given distance from the forest, but T. helveticus is more dependent on forest availability than T. alpestris: its ecological threshold is located at lower distance from forest edge, and requires also higher values of forest cover. Crops have a negative influence on palmate newt distribution with a significant breaking point, but not for T. alpestris in the studied area. These results indicate that thresholds can be a useful concept from which tools may be developed. They are particularly pertinent to focus conservation effort for threatened species and their habitats as quantitative measures of the most required habitats for species can be obtained from statistically determined breaking points [less ▲]

Detailed reference viewed: 22 (3 ULg)
Full Text
Peer Reviewed
See detailMetamorphosis rate of paedomorphs in a natural newt population
Denoël, Mathieu ULg; Lena, J. P.; Joly, Pierre

Poster (2007)

Facultative paedomorphis is a developmental process in which larvae opt for metamorphosis before maturity or reach sexual maturity while retaining larval traits (e.g., gills). Although metamorphosis is ... [more ▼]

Facultative paedomorphis is a developmental process in which larvae opt for metamorphosis before maturity or reach sexual maturity while retaining larval traits (e.g., gills). Although metamorphosis is not reversible, the paedomorphic state is not a dead end as branchiate adults are able to metamorphose. However, the extent of this process has never been quantified in the wild. Our aim was then to estimate switching rate by carrying out a 3-year monitoring survey of a population of Alpine newts (Triturus alpestris) inhabiting an alpine lake. The data were analysed using a multi-state capture-recapture model. While morph switching did occur in this population, it involved only 12% of the paedomorphs each year (i.e., 17% of recaptured individuals), suggesting that metamorphosis was not favoured in this population during the study period. This rate is lower than in laboratory experiments during which newts from the same population were placed in water drying conditions, but as shown previously paedomorphs can avoid metamorphosis in migrating to permanent water bodies when their pond dries out. These results are in agreement with other studies showing an advantage of a dimorphism in heterogeneous habitats. The ontogenetic pathway of wild Alpine newts is thus characterised by two forks in the developmental pathway. The first occurs during the larval stage, and the second occurs in paedomorphic adults. Such a two-level decision process may allow individuals to cope with environmental uncertainty. This may be particularly adaptive as aquatic conditions can deteriorate over time as shown by yearly changes in body condition of newts [less ▲]

Detailed reference viewed: 16 (1 ULg)
Full Text
Peer Reviewed
See detailStratégies comportementales de reproduction chez les animaux
Denoël, Mathieu ULg

in Bulletin de la Société Royale des Sciences de Liège (2007), 76

Biological diversity often refers to species counts but it also encompasses the amazing displayed reproductive strategies. Males and females exhibit adaptations which are not necessarily associated with ... [more ▼]

Biological diversity often refers to species counts but it also encompasses the amazing displayed reproductive strategies. Males and females exhibit adaptations which are not necessarily associated with the production of gametes. This sexual dimorphism is in part due to sexual selection, i.e. mate choice and competition within the sexes. The use of sometimes complex models allows to highlight the adaptive signification of strategies and then to explain their exhibition in varied situations. Each species is characterised by the existence of specific traits, but within each species, males and females are not constrained to exhibit a stereotyped strategy. In function of their phenotypic peculiarities and the surrounding environment, both sexes can opt for behavioural alternatives that optimize their reproductive success. This plasticity can lead to the exhibition of particular displays but also to the formation of monogamous or polygamous breeding systems. Selection does not stop at the reproductive act as varied strategies can favour a sexual partner over another one in a sexual conflict which can be pronounced, but which can also have bilateral advantages. Such a sperm competition – as acting at the gamete level – can result in sperm male precedence by the exhibition of guarding behaviour, physical or chemical manipulations and also by cryptic sperm choice. [less ▲]

Detailed reference viewed: 405 (10 ULg)
Full Text
Peer Reviewed
See detailTemporal shift of diet in alternative cannibalistic morphs of the tiger salamander
Denoël, Mathieu ULg; Whiteman, Howard H.; Wissinger, Scott A.

in Biological Journal of the Linnean Society (2006), 89(2), 373-382

Evolutionary theory predicts that alternative trophic morphologies are adaptive because they allow a broad use of resources in heterogeneous environments. The development of a cannibal morphology is ... [more ▼]

Evolutionary theory predicts that alternative trophic morphologies are adaptive because they allow a broad use of resources in heterogeneous environments. The development of a cannibal morphology is expected to result in cannibalism and high individual fitness, but conflicting results show that the situation is more complex. The goal of the present study was to increase our understanding of the ultimate benefits of a cannibalistic polyphenism by determining temporal changes in the feeding habits and biomass intake in a population of tiger salamanders (Ambystoma tigrinum nebulosum). Cannibals in this species develop a larger head than typicals and have prominent teeth, both useful for consuming large prey. Although cannibalism was only detected in cannibal morphs, large temporal variation in resource partitioning was found between morphs. The two morphs always differed in their foraging habits, but cannibalism mainly occurred immediately after the ontogenetic divergence between morphs. Cannibals shifted their foraging later to a more planktivorous diet (i.e. the primarily prey of the typical morph). Cannibals also obtained more prey biomass than typicals. These results indicate that the cannibalistic morph is advantageous over the typical development, but that these advantages vary ontogenetically. Although the results obtained are consistent with models predicting the maintenance of cannibalism polyphenism in natural populations, they show that the foraging tactics utilized by cannibal morphs, and the fitness consequences accrued by such tactics, are likely to be more complex and dynamic than previous studies have suggested. (c) 2006 The Linnean Society of London. [less ▲]

Detailed reference viewed: 106 (8 ULg)
Full Text
Peer Reviewed
See detailMulti-scale effect of landscape processes and habitat quality on newt abundance: Implications for conservation
Denoël, Mathieu ULg; Lehmann, Anthony

in Biological Conservation (2006), 130(4), 495-504

Recent studies in population dynamics suggest that landscape processes and habitat quality act at different scales on population abundances, but very few have modelled their simultaneous effects. However ... [more ▼]

Recent studies in population dynamics suggest that landscape processes and habitat quality act at different scales on population abundances, but very few have modelled their simultaneous effects. However, at a time of large declines in natural populations, it is essential to understand such multivariate components. We tested the hypothesis that natural populations of palmate newts (Triturus helveticus) are affected on three scales: breeding patch (pond), habitat complementation (terrestrial cover), and metapopulation. structure (density of ponds, surrounding populations). We conducted our survey in 130 ponds from southern France (Larzac) and analysed data with generalized additive models (GAM). Two main novel results emerge from these models: (1) the three landscape scales have significant effects on newt abundance, with more newts in deep, vegetated ponds, devoid of fish and surrounded by wooded areas and inhabited ponds; (2) the quality of the surrounding breeding patches is of primary importance in determining the abundance at core sites in a complex way: high abundances are associated positively with high densities of inhabited ponds, but negatively with the number of surrounding ponds. Deforestation, invasive species and abandonment of ponds all have negative impacts on the persistence of palmate newt populations. Future studies should encompass landscapes at different scales and incorporate the habitat quality in surrounding sites to better understand population dynamics and. provide adequate conservation measures. [less ▲]

Detailed reference viewed: 270 (12 ULg)
Full Text
Peer Reviewed
See detailSeasonal variation of morph ratio in facultatively paedomorphic populations of the palmate newt Triturus helveticus
Denoël, Mathieu ULg

in Acta Oecologica: International Journal of Ecology (2006), 29(2), 165-170

Facultative paedomorphosis is a polyphenism in which individuals may express one of two alternative ontogenetic pathways (metamorphosis vs. paedomorphosis) depending on environmental cues. Previous ... [more ▼]

Facultative paedomorphosis is a polyphenism in which individuals may express one of two alternative ontogenetic pathways (metamorphosis vs. paedomorphosis) depending on environmental cues. Previous laboratory experiments showed that drying can cause morph ratio change, suggesting that the maintenance of facultative paedomorphosis is highly dependent on environmental determinants. The aim of this study was to examine seasonal variation in morph ratios in eight ponds from Larzac (southern France) naturally inhabited by palmate newts and to relate it to pond drying. in some ponds, the relative proportion of paedomorphs (i.e. individuals retaining gills at the adult stage) increased after the breeding period, but it remained stable or decreased in other ponds. This seasonal variation in the abundance of the two morphs most probably reflects (1) the emigration of metamorphs leaving the pond to occupy terrestrial habitats and (2) metamorphosis of paedomorphic adults in response to drying of the ponds. This study shows that facultative paedomorphosis in palmate newts is a dynamic process that allows rapid change (i.e. within a single year) in morph ratio to fit environmental variation (i.e. risk of drying) within the aquatic habitats. Long-term studies are needed to model the evolution of the dimorphism according to environmental change. (c) 2005 Elsevier SAS. All rights reserved. [less ▲]

Detailed reference viewed: 86 (6 ULg)
Full Text
Peer Reviewed
See detailEditorial Report 2005
Denoël, Mathieu ULg

in Amphibia-Reptilia (2006), 27(3), 479

Detailed reference viewed: 8 (1 ULg)
Full Text
Peer Reviewed
See detailEffects of long-term population fluctuations of a top predator on invertebrate communities in subalpine ponds in Colorado
Wissinger, S.; Whiteman, H.; Denoël, Mathieu ULg et al

Conference (2006)

Experimental and comparative data from subalpine ponds with and without tiger salamanders (Ambystoma tigrinum nebulosum) suggest that this species is a keystone predator on benthic and planktonic prey ... [more ▼]

Experimental and comparative data from subalpine ponds with and without tiger salamanders (Ambystoma tigrinum nebulosum) suggest that this species is a keystone predator on benthic and planktonic prey communities. At our study site in central Colorado, the population size of salamanders has fluctuated cyclically over the past 20 years from fewer than 100 to over 5000 individuals. Here we present long-term benthic data that reveal taxon- and habitat-specific correlations with fluctuations in salamander populations. In temporary habitats, benthic biomass changed little during fluctuations in salamander abundance. In permanent ponds, we observed order-of-magnitude changes in benthic biomass that were negatively correlated with salamander abundance. Among the large-bodied and potentially most vulnerable taxa (odonates, caddisflies, beetles, water bugs), several species exhibited negatively coupled cycles, but others fluctuated little or out of phase with changes in salamander abundance. The absence of major shifts in benthic community composition in permanent ponds is probably a result of conflicting predation pressures exerted by different year classes of salamanders. Data on ontogenetic shifts in salamander diet help explain why cyclic fluctuations in the abundance of this predator had only minor impacts on benthic community composition despite having major effects on invertebrate biomass. [less ▲]

Detailed reference viewed: 8 (0 ULg)
Full Text
Peer Reviewed
See detailMechanisms of cohort suppression and population fluctuation in tiger salamanders
Whiteman, Howard; Wissinger, Scott; Denoël, Mathieu ULg

Conference (2006)

The mechanisms underlying population fluctuation have been well studied in mammals and insects but less research has focused on amphibians. Yet, the current global decline of amphibians equires that we ... [more ▼]

The mechanisms underlying population fluctuation have been well studied in mammals and insects but less research has focused on amphibians. Yet, the current global decline of amphibians equires that we understand these mechanisms, and be able to distinguish between anthropogenically induced declines and natural population fluctuations. We have followed a marked population of the Arizona tiger salamander, Ambystoma tigrinum nebulosum, for over 16 years during which time the population has completed two “boom and bust” cycles, generated by a dominant cohort that appears to suppress larval recruitment until it senesces. We tested two hypotheses for this suppression, cannibalism and resource depression, using a series of meso- and microcosm experiments. We found significant lethal and sublethal (behavior, diet, growth rates) effects of cannibalism by large larvae and paedomorphic adults on hatchling and 1st-year larvae, suggesting that both cannibalism and the threat of cannibalism are important in cohort suppression. Resource depression experiments revealed that paedomorphic adults did not affect larval survival, diet, or growth, despite reduced prey densities, because paedomorphs mainly reduced large bodied prey, whereas hatchlings fed primarily on smaller benthic and zooplanktonic invertebrates. Future experiments will determine how hatchlings are impacted by boom cohorts that are more similar in size and diet. Our results lend insight into the mechanisms underlying fluctuations in this population, and suggest that a better understanding of natural population fluctuations will aid amphibian conservation efforts. [less ▲]

Detailed reference viewed: 11 (0 ULg)