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International audience; Because it modulates the fitness returns of possible options of energy expenditure at each ontogenetic stage, environmental stochasticity is usually considered a selective force in driving or constraining possible life histories. Divergent regimes of envi- ronmental fluctuation experienced by populations are expected to generate differences in the resource allocation schedule between survival and reproductive effort and outputs. To our knowledge, no study has previously examined how different regimes of stochastic variation in environmental conditions could result in changes in both the temporal variation and mean of demographic parameters, which could then lead to intraspecific variation along the slow–fast continuum of life history tactics. To investigate these issues, we used capture–recapture data collected on five populations of a long-lived amphibian (Bombina variegata) experiencing two distinct levels of stochastic environmental variation: (1) constant availability of breeding sites in space and time (predictable environment), and (2) variable spatio-temporal availability of breeding sites (unpredictable environment). We found that female breeding propensity varied more from year to year in unpredictable than in pre- dictable environments. Although females in unpredictable environments produced on average more viable offspring per year, offspring production was more variable between years. Survival at each ontogenetic stage was slightly lower and varied significantly more from year to year in unpredictable environments. Taken together, these results confirm that increased environmental stochasticity can modify the resource allocation schedule between survival and reproductive effort and outputs and may lead to intraspecific variation along the slow–fast continuum of life history tactics.

Global biodiversity in freshwater and the oceans is declining at high rates. Reliable tools for assessing and monitoring aquatic biodiversity, especially for rare and secretive species, are important for efficient and timely management. Recent advances in DNA sequencing have provided a new tool for species detection from DNA present in the environment. In this study, we tested whether an environmental DNA (eDNA) metabarcoding approach, using water samples, can be used for addressing significant questions in ecology and conservation. Two key aquatic vertebrate groups were targeted: amphibians and bony fish. The reliability of this method was cautiously validated in silico, invitro and insitu. When compared with traditional surveys or historical data, eDNA metabarcoding showed a much better detection probability overall. For amphibians, the detection probability with eDNA metabarcoding was 0.97 (CI=0.90-0.99) vs. 0.58 (CI=0.50-0.63) for traditional surveys. For fish, in 89% of the studied sites, the number of taxa detected using the eDNA metabarcoding approach was higher or identical to the number detected using traditional methods. We argue that the proposed DNA-based approach has the potential to become the next-generation tool for ecological studies and standardized biodiversity monitoring in a wide range of aquatic ecosystems. see also the Perspective by Hoffmann, Schubert and Calvignac-Spencer.

International audience; In Western Europe, habitat loss and landscape fragmentation has led to significant population decline in various animal groups, including amphibians. The extinc- tion of the last natural populations of the yellow-bellied toad in Belgium, Luxembourg and several regions of southern and western France suggests a widespread decline. By using site-occupancy models and adding covariates corresponding to the human-influenced features of the landscape, we tried to identify the relative effects of different land-use types on the species’ distribution pattern in a man-made environment (the Alsatian Rhine floodplain in France). We recorded presence–absence data in 150 forest sample plots (300 9 300 m) and then modeled species distribution while taking into account detection errors in the field. Land-use was recorded on two spatial scales: within the forest sample plots and in a 1500 m radius buffer area around the forest plots. In the forest plots, toad occurrence was negatively correlated with loss of forest cover to agricultural land. In contrast, occurrence is positively correlated with the density of human-made rutted dirt paths and tracks, which provide semi-natural breeding sites. In the 1500 m radius buffer zones around forest plots, toad occurrence was negatively correlated with the density of urbanization and road net- works. These results can be used to plan conservation strategies for amphibians in human-dominated landscapes.

Amphibians are considered to be the most threatened group of vertebrates. Among the multiple factors involved in their decline, habitat loss and alteration as a result of human activities is a major threat. At the individual level the effects of habitat alteration are potentially multiple, including a range of morphological and physiological responses. Analysing and understanding these responses is therefore a critical challenge for amphibian conservation. We examined the influence of intensive vehicle traffic (motorbikes and trucks on unpaved pathways) on the body size and condition and on the production of glucocorticoids (i.e. corticosterone) in the yellow-bellied toad Bombina variegata. In particular, we tested the hypothesis that intensive vehicle traffic has a negative influence on body size and body condition, and postulated that it also increases corticosterone production. Using morphometric data and saliva samples collected from four populations in France, we found that intensive vehicle traffic is associated with a decrease in body size and body condition in both males and females. Furthermore, our analysis revealed that corticosterone production was lower in both sexes in populations experiencing intensive vehicle traffic. We suggest that measures should be applied to reduce vehicle traffic intensity on unpaved pathways during toad breeding activity. This is critical for B. variegata, for which man-made ruts and residual puddles could mitigate the loss of natural habitats.

Abstract The isolation of animal populations due to urban activities provides a useful framework for studying the consequences of landscape fragmentation. We studied a population of natterjack toads (Bufo calamita) in an urban park near Paris, France. In 2001 and 2002 we used radio-tracking to estimate the terrestrial movements of adults around their breeding sites. Twenty-four toads were equipped with internal transmitters in 2001 to record movements during and after the breeding period. In 2002, 19 males were released at 300 and 380 meters from their breeding ponds. Natterjack toad movements around and outside their breeding ponds were reduced compared to previous observations on this species. The only exchanges that were observed occurred between closely neighbouring breeding sites. During a translocation experiment in 2002, 58% of the displaced males returned to their site of capture and this happened mainly during the breeding period. The remaining 42% stayed close to the release site. There was no exchange of males between distant breeding sites. Natterjack toad conservation needs to take into account the high fidelity to a breeding site and the reduced breeding dispersal and homing ability of these animals. Conservation biology in urban landscapes constitutes a specific urban ecology with specific concepts such as 'population area'. Information from this study can assist land managers in establishing protected areas of high habitat quality around breeding ponds in urban areas, and managing parks for the protection of amphibian populations, particularly by facilitating exchanges between available areas.

International audience; We investigated the ontogeny of responses to scent marks in immature terrestrial salamanders (Salamandra lanzai) that inhabit the southwest Alps. In this species, sexual maturity is usually reached at about 8 years, and adults exhibit territoriality. One should expect territoriality to take place largely before the acquisition of sexual maturity if sexual competition is not the main force driving territoriality. However, both the difficulties for inexperienced animals to find a suitable territory and size-related competition may delay the acquisition of territoriality in juveniles. We performed choice tests with juveniles belonging to two age groups (1+/-1 years old versus 4+/-1 years old). Each focal animal was offered, in random order, the choice between two shelters, one without scent and the other containing one of the following scents: own, same-aged animal, a juvenile belonging to the other age group, or adult female. We also performed choice tests with adult females for which the scents of two juveniles belonging to a different age group were successively offered in a random order. Older juveniles were strongly attracted toward their own shelter and mostly avoided the shelters that contained the scent of juveniles of about the same age and of adult females. Adult females avoided the scents of older juveniles but not younger juveniles. These results therefore suggest that older juveniles use territorial marking. Conversely, young juveniles behaved randomly with respect to their own scents and to those of a same-aged juvenile, and they were significantly attracted towards the odor of an older animal, especially adult females. Both older juveniles and adult females displayed a random behavior toward the scents of young juveniles. Our results suggest that young juveniles do not defend territories but use spaces occupied by older individuals.

International audience

Conservation plans of European amphibians usually take into account: (1) species in dramatic decline due to a series of humaninduced factors, and (2) species with a narrow distribution area and/or particular ecological requirements. Salamandra lanzai belongs to the second group, being limited to the SW Alps. Furthermore, it is a high altitude amphibian, living in sites above 1200 m, and it is also a unique endemic vertebrate of the Alps. We here summarise information regarding its distribution and ecology to be interpreted for conservation. In this sense, we also provide new data regarding the age structure of a recently studied low altitude population in the Germanasca Valley. We then compare this population (exemplified as “low altitude population”) to a population living at 2200 m in the Guil Valley (example of a “high altitude population”). The knowledge obtained on these different life-history traits has allowed us to devise an age-structured model useful in identifying the main demographic parameter...

We studied age at maturity, longevity, and growth in a marbled newt (Triturus marmoratus) population in southwestern France. Parameters of the life cycle such as date of migration, reproductive period, and terrestrial activity were documented for three neighbouring temporary ponds. This Mediterranean marbled newt population was characterized by aestivation and hibernation periods, a prolonged aquatic phase in adults, and a presence of juveniles in water. Aestivation and hibernation lead to distinct growth periods as determined by skeletochronology. Minimum age at maturity was 2 and 3 years, whereas maximum age observed was 8 and 9 years in males and females, respectively. A higher growth rate and a lower survival rate were found in this Mediterranean population compared with other populations exposed to variable environmental conditions in western Europe.

Summary 1. This work aims to illustrating how it is possible to measure different modalities of adult dispersal in two subdivided populations of the alpine newt ( Triturus alpestris ). Recent developments in capture‐mark‐recapture methods make it possible to estimate transience rates from individuals captured only once. In the context of subdivided newt populations, transience is assumed to express nomadic behaviour that contribute to breeding dispersal. Skeletochronology and recaptures within each pond system also made it possible to estimate emigration rates and local dispersal. 2. Two subdivided populations of alpine newts were monitored over 4 and 5 years, respectively. Whereas population A is suspected to have been established for more than 100 years, population B was monitored when colonizing a newly created archipelago of ponds. 3. Transience was detected in each population at similar rates (37% in population A and 35% in the population B). Annual apparent survival rates were estimated as 82% in population A vs. 33% in population B. Similarity of age structures between populations leads us to consider such low survival rates in population B as resulting from emigration. Emigration was thus negligible in population A and was estimated to reach 57·3% in population B. Conversely, high local dispersal (movements within a pond system) was detected in population A, but not in population B. 4. Even though the causation of dispersal in newts (genetic polymorphism vs. phenotypic plasticity) remains unexplored, our study succeeded in identifying several dispersal components that could result from different selective pressures (habitat heterogeneity at different temporal scales). Experimental approaches are needed to investigate the causative bases of these traits.

International audience; Scent marking is often related to activities associated with the occupation of a home range or territory. It is widely agreed that when an animal sends signals, this influences the decisions made by the animal that receives them. Scent marks are mainly used as a warning, in order to decrease the cost of territorial behaviour. They are deposited directly on a substrate by rubbing them on but also through urination and defecation. European terrestrial salamanders show high site fidelity and move very little around their shelter. Risks and costs are compared before an animal decides whether or not to leave its shelter, and a rapidly detectable and unambiguous cue in the direction of the home shelter reduces risk. Furthermore, territoriality has also been observed in amphibians, both in Anurans (frogs and toads) and Urodela (newts and salamanders). We tested the use of faecal pellets in alpine salamanders in the laboratory (Salamandra lanzai and Salamandra atra) with regard to homing and territorial behaviour. Our experimental design allowed us to distinguish attraction to from avoidance of shelters containing varying olfactory information. Our results clearly argue for the role faecal pellets play in shelter recognition. Furthermore, contrary to the results observed in other terrestrial salamanders such as Plethodontids, the faecal pellets of S. lanzai and S. atra enable intruders to identify the residents, thus fulfilling the requirements of a genuine territorial warning, as observed in mammals. Excrement marking is used as an economic tactic to identify and warn about the occupation of a territory in these two species of alpine salamanders.

Fifty individuals of the endemic Alpine salamander, Salamandra atra, representing 13 populations throughout the range of the two currently recognized subspecies, atra and aurorae, were examined for sequence variation in a large portion (1050 bp) of the mitochondrial cytochrome b gene. We revealed a large number of mitochondrial DNA (mtDNA) haplotypes (10). Interpopulation sequence divergence was very low, ranging from 0 to 3.1%. The relationships among haplotypes were poorly resolved. The divergence time estimate between several mtDNA haplotypes suggested a pre-Pleistocene differentiation approximately 3 million years ago. Moreover, the impact of the Pleistocene glaciations on the phylogeographical patterns appears to have been secondary, although a somewhat reduced genetic variability was found in populations living in areas that were directly affected by the glaciation.

The black salamander, Salamandra lanzai, exists in isolated and fragmented populations in the Cottian Alps. To examine the degree of intra- and interpopulation divergence, mitochondrial cytochrome b sequences were obtained from samples representing all populations of S. lanzai. No genetic variation was observed either within or among populations. The presence of a single lineage suggests historical explanations closely related to Pleistocene events.

Les estimations des densités de grands singes dans la nature ne sont généralement possibles que par des méthodes indirectes. Une des méthodes les plus courantes consiste à estimer les densités des nids qui sont ensuite converties en densités d'individus. Cette conversion entre densité des nids et nombre d’individus nécessite deux paramètres : le taux de création et le taux de dégradation des nids. Le taux de création des nids est le nombre de nids créés par un individu de l’espèce étudiée par jour; il est caractéristique de l'espèce et varie avec les saisons. Le taux de dégradation de nids est le nombre total de jours qu'un nid d’une espèce peut être visible dans la nature. Il s’agit donc de la « durée de vie » des nids. Ce taux diffère non seulement entre espèces mais aussi entre saisons et surtout entre sites, selon le type de construction, le type d’habitat et l’espèce d’arbre support. Son estimation doit donc être réalisée sur la zone d’étude pour être fiable et ne peut être tirée de la bibliographie au risque de biaiser fortement les résultats des tailles de population. Cette étude a porté sur la détermination de la durée de vie de nids de bonobo dans la Réserve de faune de Lomako-Yokokala (RFLY) par la méthode de Marked Nest Count (MNC). Au total, 465 nids de bonobos ont été marqués et suivis régulièrement entre novembre 2011 et avril 2012. Nous avons utilisé deux méthodes différentes d’estimation de la longévité des nids dont l’une a été développée spécifiquement dans le cadre de cette étude en se basant sur des modèles de type Capture-Marquage-Recapture. Les estimations sont de 86 jours avec les méthodes de type Capture-Marquage-Recapture et de 79 jours avec la méthode usuelle des chaînes de Markov. Dans les deux cas les intervalles de confiance des estimations sont relativement larges et ne devraient pas être négligées dans l’estimation des tailles de population comme c’est fréquemment le cas.

International audience; Iteroparity is an adaptive response to uncer- tainty in reproductive success. However, spreading repro- ductive success over multiple reproduction events during a lifetime is constrained by adult mortality and the stochas- ticity associated with interactions between external factors and physiological states. The acquisition of information about environmental conditions during the growth of prog- eny and sufficient resources during the non-reproductive period are key factors for breeding success. Consequently, we hypothesized that long-lived animals may skip a breed- ing opportunity when information about unfavourable environmental conditions is available. In addition, nutri- tional constraints could prevent an animal from replenish- ing its reserves sufficiently to invest in the current breeding period. We investigated these questions using capture– recapture data from a 5-year study on a large population of yellow-bellied toads in a forest in north-eastern France. We took advantage of various advances in multi-state cap- ture–recapture models (e.g. unobservable states and mix- ture models) to test our hypotheses. Our results show that the combined effects of rainfall deficit and the breeding/ non-breeding state of individuals during the past breeding season affect breeding probability during the following breeding opportunity. We also found that females breed less frequently than males, suggesting that the overall energy cost of reproduction differs between genders. Finally, the results indicate that toad survival appears to be negatively influenced by rainfall deficits. We discuss the yellow-bel- lied toad’s reproductive behaviour in term of bet-hedging strategy and life history trait evolution.

International audience; We describe the life-history traits (body size, age at maturity, longevity, and survivorship) of a terrestrial salamander, Mertensiella luschani, from a population living in the Mediterranean environment of southwestern Turkey. We used phalangeal skeletochronology to estimate the age of juveniles and adults. Lines of arrested growth, deposited during the winter cessation of bone growth, allowed us to estimate the age at maturity to be 3 years old in both sexes. Males attained a maximum age of 8, whereas females attained a maximum age of 10. Juveniles ranged from 1 to 3 years old. Males were smaller than females. Growth curves fitted to von Bertalanffy's equation revealed similar growth coefficients in adults and larger average maximum body lengths in males. Adult annual survivorship and adult life expectancy were 0.79 and 5.4 years, respectively. Knowledge of age, growth, and survivorship in this species under the constraints of a seasonal Mediterranean climate, and a comparison of similar traits in other salamandrid species, allow us to test predictions regarding optimal timing of growth and reproduction in these species.

International audience; We describe the age structures of two neighbouring terrestrial salamander populations. The skeletochronological method was also used on larvae in utero and on new-born individuals. The age of adults was 8-24 years in population A, while males reached maturity at 3-5 years old and the youngest females were 6 years old in population B. Males and females from population B were also larger than those in population A. For the first time, lines of arrested growth (LAGs) were also found in the humerus of intra-uterine larvae and new-born individuals, indicating that young can spend up to 3 years in utero (population B) and up to 4 years (population A) before hatching. Growth of adults (fitted by the Bertalanffy model) also exhibited differences in growth coefficient (k) and mean asymptotic length (SVLmax) between sexes and populations. Local climatic conditions differed between the two areas of these populations and we hypothesize that the number of rainy days directly influences foraging during the short period of activity (< 3 months), leading to a delay in age at maturity, smaller length and growth rate, and increased gestation duration in the drier environment. The discussion is focused on proximate environmental influences on the variation of length and associated life-history traits in ectotherms, especially in terrestrial salamanders.

In farmlands, the population viability of many amphibians is suspected to depend on the resistance the matrix of crop fields presents to movements between ponds and terrestrial sites and movements among ponds. Over recent decades the increase in cereal growing at the expense of cattle breeding has caused a drastic change in habitat matrix in many European regions. We investigated the effect of such change on populations of three newt species ( Triturus helveticus, T. alpestris, and T. cristatus) by comparing their abundances in sites that varied in amount of cultivated ground. A multivariate regression analysis of the relationship of newt abundance to both pond and landscape variables demonstrated the negative influence of cultivated ground on abundance. The width of the uncultivated sector linking the pond to the forest was a good predictor of abundance after the influences of both pond area and fish presence were removed. Moreover, newt presence was positively related to the number of ponds within that 50-ha surrounding area, highlighting the role of metapopulation functioning in newt occupancy of ponds. The relationship between newt abundance and width of uncultivated sectors agrees with present knowledge of the orientation mechanisms that underlie migration movements in urodeles. Such a relationship between connectedness and sector width shows that narrow, linear corridors such as hedgerows may not be useful in newt conservation. Our study also highlights the need to incorporate a behavioral component of habitat use into models of connectivity in conservation biology. Resumen: Se considera que en tierras de cultivo la disponibilidad poblacional de muchos anfibios depende de la resistencia que la matriz de las tierras de cultivo presentan a los movimientos entre estanques y los sitios terrestres, y entre estanques. Durante las decadas recientes el incremento en la produccion de cereal a cambio de la cria de ganado ha ocasionado un cambio drastico en la matriz del habitat en muchas regiones de Europa. Investigamos los efectos de estos cambios en las poblaciones de tres especies de tritones ( Triturus helveticus, T. alpestris y T. cristatus) comparando sus abundancias en sitios que variaron en la cantidad de tierra cultivada. Un analisis de regresion multivariado de las relaciones entre la abundancia de tritones y las variables de los estanques y del paisaje demostro las influencias negativas de las tierras de cultivo sobre la abundancia. La amplitud de sectores sin cultivar que conecto a los estanques con el bosque fue un buen pronosticador de la abundancia despues de remover las influencias del area del estanque y la presencia de peces. Mas aun, la presencia de tritones estuvo positivamente relacionada con el numero de estanques dentro de un area adyacente de 50 ha, resaltando el papel del funcionamiento de la metapoblacion en la ocupacion de estanques. La relacion entre la abundancia de tritones y la amplitud de sectores sin cultivar concuerda con el conocimiento actual sobre los mecanismos de orientacion que delimitan los movimientos de migracion en urodelos. Esta relacion entre la conectividad y la amplitud del sector muestra que los corredores estrechos y lineales como lo son los cercos podrian no ser utiles para la conservacion de tritones. Nuestro estudio tambien resalta la necesidad de incorporar un componente conductual del uso del habitat cuando se modela la conectividad en estudios de conservacion biologica.

The movements of 19 natterjack toads (Bufo calamita) were monitored by telemetry in a semi-arid agricultural landscape in NE Spain. Toads reproduced in two water pools in fields of barley and an ancient clayquarrying zone filled by rainfall. Thirteen toads were followed during the breeding season (weeks 5-17 of 1997) and 11 toads were followed after reproduction (weeks 18 to 46). During the breeding season four toads moved distances of up to 500 m between breeding sites. No significant differences in movement patterns were found between the sexes, but a tendency was observed for males to show higher terrestrial site fidelity than females. Distances moved after the breeding season were substantial. The distance between the furthest positions recorded was from 164 to 1201 m, the maximum distance observed between daily recordings ranged from 125 to 353 m and the maximum overall distances ranged from 567 to 4411 m. No significant differences were observed between males and females or between small and large toads. The movements of these toads in a semi-arid agricultural landscape in Spain are compared with those observed in England and Germany.

Life-history traits of Rana temporaria were studied in an alpine French population and in the literature. In the living frogs, mean adult body length was greater in females than in males. Sexual dimorphism in body length was 0.109 using Lovich & Gibbon's (1992) formula, but tended to decrease with age. Age of adult frogs was assessed by skeletochronology, and age distribution was not significantly different between the sexes (range 4–15 years in males, 5–12 in females). Adult survival rate was about 0.80 in both sexes. Once maturity was reached, the total expected longevity was 6.1 years in males and 5.5 years in females. Age and body length were positively correlated in both sexes. The growth coefficient (K) was 0.47 in males, and 0.55 in females, mainly reflected as faster female growth between metamorphosis and maturation. Growth rate generally decreased before sexual maturity was reached. On average, females matured 1 year later than males. Newly metamorphosed froglets averaged 16.1 mm. When combined with published data from 12 European populations of R. temporaria, the following general patterns emerge. Mean adult body length is significantly greater in females than in males, and mean body length at maturity shows the same trend. Variation in mean age at maturity and in longevity are considerable among populations, but there is no consistent trend of difference between the sexes. Body length and age are correlated between males and females, i.e. populations with long and old males also have long and old females. Mean adult body length, mean body length at maturity, age at maturity, and longevity all increase with decreasing activity period. Adults exposed to a short activity period grow slower but attain a greater final length. Sexual dimorphism in body length generally increases as activity period gets shorter. Polygons describing norms of reaction for maturation in an age–body length space are similarly oriented in both sexes, but with a wider range in age for females. This is due to an older age at maturity for females in populations with a short activity season. Mean age and length at maturity are significantly correlated in females, but not in males, partly supporting the hypothesis that this species has a flexible pattern of development. Observed patterns are compared with predictions from life-history theory, paying attention to all life stages and environmental variation.

The way animals allocate resources to growth and reproduction is of major importance in understanding life-history trade-offs. Because the investment in reproduction of the two sexes differs, comparing the costs and the reproductive strategies adopted offers an insight into the evolutionary forces that shaped them. In the Eastern Spadefoot Toad, Pelobates syriacus the males are larger than females in body length, but not in body mass. We studied the reproductive effort and output in a population of P. syriacus from the Danube Delta Biosphere Reserve (Romania), during two consecutive years (2010 and 2011). Body mass loss during mating and egg deposition in females averaged 27%, while in males it was 3.9%. Body mass loss in females was proportional with size, with larger females losing more weight than smaller ones. Initial body mass and body mass loss during reproduction were significantly correlated with clutch size, but egg size was not correlated to female size or body mass loss. Year had a significant ...

Oviposition site selection in Triturus helveticus, T. alpestris and T. cristatus was studied both in natural and laboratory situations. In a natural breeding site, eggs of the three species were not laid equally on several plants: T. cristatus laid practically all their egges on only one plant (Nasturtium officinale) while T. helveticus eggs were collected on four plant species. In laboratory experiments, plastic and cotton fabric supports made it possible to test ovipositing female selectivity according to flexibility and shape of support and egg-laying distance below the surface. In all three species, a high proportion of eggs were laid on supports of linear shape (as opposed to arborescent shape) and egg frequency decreased as a function of depth (from 0 to 40 cm below the surface). Selection according to flexibility was also observed, the smallest species (T. helveticus) laying more eggs on the thinner supports. The role of support selectivity during oviposition in Triturus is discussed, in term of proximate (i.e. female protection against predators, breathing necessity) and ultimate (i.e. egg survival) factors, and related to new ecology.

International audience; The precise knowledge of species distribution is a key step in conservation biology. However, species detection can be extremely difficult in many environments, specific life stages and in populations at very low density. The aim of this study was to improve the knowledge on DNA persistence in water in order to confirm the presence of the focus species in freshwater ecosystems. Aquatic vertebrates (fish: Siberian sturgeon and amphibian: Bullfrog tadpoles) were used as target species. In control conditions (tanks) and in the field (ponds), the DNA detectability decreases with time after the removal of the species source of DNA. DNA was detectable for less than one month in both conditions. The density of individuals also influences the dynamics of DNA detectability in water samples. The dynamics of detectability reflects the persistence of DNA fragments in freshwater ecosystems. The short time persistence of detectable amounts of DNA opens perspectives in conservation biology, by allowing access to the presence or absence of species e.g. rare, secretive, potentially invasive, or at low density. This knowledge of DNA persistence will greatly influence planning of biodiversity inventories and biosecurity surveys.

A general consensus that an increased logK(ow) led to an increase in xenobiotic uptake and bioaccumulation is accepted. In this study we compared the toxicokinetics of two chemically different xenobiotics, i.e. benzo[a]pyrene and fipronil in female green frogs. Surprisingly, the uptake rates and the bioconcentration factors (BCF) of the two contaminants were not predicted by their logK(ow). The uptake rates obtained were of the same order of magnitude for the two contaminants and the BCFs measured for fipronil were about 3-fold higher than those obtained for benzo[a]pyrene. Fipronil appeared to be more recalcitrant than benzo[a]pyrene to detoxification processes leading to the accumulation of sulfone-fipronil especially in the ovaries. This phenomenon may explain reproductive influence of this contaminant described in other studies. Detoxification processes, including metabolism and the excretion of pollutants, are of importance when considering their persistence in aquatic organisms and trying to quantify their risks.

[Departement_IRSTEA]Territoires [TR1_IRSTEA]SEDYVIN; International audience; Graph-based analysis is a promising approach for analyzing the functional and structural connectivity of landscapes. In human-shaped landscapes, species have become vulnerable to land degradation and connectivity loss between habitat patches. Movement across the landscape is a key process for species survival that needs to be further investigated for heterogeneous human-dominated landscapes. The common frog (Rana temporaria) was used as a case study to explore and provide a graph connectivity analysis framework that integrates habitat suitability and dispersal responses to landscape permeability. The main habitat patches influencing habitat availability and connectivity were highlighted by using the software Conefor Sensinode 2. 2. One of the main advantages of the presented graph-theoretical approach is its ability to provide a large choice of variables to be used based on the study's assumptions and knowledge about target species. Based on dispersal simulation modelling in potential suitable habitat corridors, three distinct patterns of nodes connections of differing importance were revealed. These patterns are locally influenced by anthropogenic barriers, landscape permeability, and habitat suitability. And they are affected by different suitability and availability gradients to maximize the best possible settlement by the common frog within a terrestrial habitat continuum. The study determined the key role of landscape-based approaches for identifying the "availability-suitability-connectivity" patterns from a local to regional approach to provide an operational tool for landscape planning.

The fauna of the Aralkum has been studied only partly. But the lists of mammals of the Kazakhstan part of the Aral Sea region, the migratory breeding bird species and rare winter visitors, the resident breeding bird species, passage visitors (birds), vagrant birds, reptiles collected around Aral Sea in 2002–2004, and taxonomical diversity of insect orders and other groups are documented. The ecological disaster of the Aral Sea reduced the faunistic diversity of the area in a selective manner. Aquatic and semiaquatic animal species such as fish-eating birds, waterfowl, Amphibia, water snakes and aquatic insects suffered dramatic reductions in numbers. Some freshwater species and species of riverine forest died out or left the area completely. On the other hand, desert species and certain eurybionts were able to extend their ranges into the Aralkum. Further monitoring of the fauna of the Aralkum is strongly recommended to document the very active migrations to and invasions of the dynamic new ecosystems.

Anthropogenic sources of nitrogen that pollute bodies of water can have toxic and sub-lethal effects on amphibians. It has been hypothesized that such exposure may promote local adaptation, that is, selection for higher tolerance in individuals in populations exposed to pollutants. We tested this hypothesis with respect to the Natterjack toad (Bufo calamita Laurenti, 1768), by comparing the nitrate dose response of tadpoles from eight populations (doses: 0, 50, 100, 500 and 1000 mg/l nitrate) from relatively unpolluted and intensively farmed environments. We evaluated the effect of nitrate exposure by observing the behavior (movements) of tadpoles exposed to different concentrations of nitrates. Exposure to high nitrate levels did not cause tadpole mortality in the populations used in our experiments; however, we did observe changes in activity for all populations, with these changes being either dose-related responses (decreased activity after exposure to 500 or 1000 mg/l), or more complex responses (increased activity when exposed to 50 or 100 mg/l nitrate, followed by decreased activity at higher concentrations). Natterjack toad tadpoles exhibited variable behavioural responses among the tested populations. Although these populations were selected on the basis of their potential agrochemical contamination, the observed variation in population tolerance was not related to the parameters used to estimate this contamination in these breeding sites. Possible explanations for this apparent lack of local adaptation in B. calamita tadpoles include inadequate estimates of the toads’ actual nitrate exposure in the field, and the biological characteristics of B. calamita, which may limit the effects of exposure or favor phenotypic plasticity.

Predation on newt eggs (Triturus helveticus and T. alpestris) was studied in both natural (pond) and control (aquaria) conditions. Eggs were laid on artificial supports and set in a pond near Bourg-en-Bresse (south-east France). Survival from segmentation to pre-hatching stages was similar in these two species and estimated at 0·16 ± 0·07. Survival of eggs protected in a closed bag of plastic netting was significantly higher (0·79 ± 0·08), suggesting predation as the major mortality risk. Eggs of T. alpestris were offered to the following potential predators: newts Triturus alpestris and T. helveticus (males and females), adult aquatic insects (Dytiscus marginalis, Acilius suleatus. Notonecta glauca, Ranatra linearis. Ilyocoris hermanni). a snail (Lunnaea stugnalis) and a tadpole (Rana temporaria). Only the newts and water beetles were observed to cat the eggs. Females wrapped their eggs in a fold made with the support during oviposition. D. marginalis fed on wrapped eggs and those we unwrapped in the same proportion. but newts (especially females) and A. sulcatus clearly ate fewer wrapped than unwrapped eggs. These results are discussed in terms of mortality risk and antipredator adaptations.

Changes in age structure of local populations were analyzed to determine the migrations of adult crested newts (Triturus cristatus) in a network of ponds. An individual's age was estimated by applying a skeletochronological method to the phalanges. The local populations studied bred in four neighbouring cattle ponds, the distance between any two of which did not exceed 150 m. These ponds belong to the larger network. Though the size of the whole population doubled from one year to the next, one local population became extinct due to lack of recruitment of young breeders. The larger local population attracted not only young breeders but also older newts, which probably came from other ponds. In ponds inhabited by fish, the newts were mainly young animals (2–3 years old), suggesting that they leave such ponds after their first breeding season. The results are discussed with regard to the model proposed by Gill for metapopulations of Notophthalmus viridescens. In the crested newt, contrary to Gill's predictions, all the sites do not recruit young breeders, and fidelity to the breeding site may be broken. The two species differ in longevity and age at maturity, hence it is suggested that functional models of metapopulations must integrate life-history parameters.

The African clawed frog Xenopus laevis is by far the most widely used amphibian species in laboratories. In the wild, X. laevis is an asymptomatic carrier of an emerging infectious disease called chytridiomycosis. The vector is the chytrid fungus Batrachochytrium dendrobatidis ( Bd), which has devastating effects on wild amphibian populations around the world. The impact of Bd on the metabolism of X. laevis has not been comprehended yet. However, even if asymptomatic, an infection is likely to affect the individual's physiology, immunology, development, reproduction and overall response to stress from a purely medical point of view, which will introduce noise and therefore increase variance within experimental groups of X. laevis. This could have implications on the scientific results from studies using this species. Here, we review the current knowledge on treatments of infected amphibians and propose a hygiene protocol adapted to laboratory populations and amphibian husbandry. Following the presented sanitation guidelines could further prevent the spread of Bd and probably of other amphibian pathogens. The sanitation guidelines will help to reduce the impact of amphibian husbandry on natural populations and must be considered a crucial contribution to amphibian conservation, as today 32% of all amphibians are considered threatened.

Biological invasions and land-use changes are two major causes of the global modifications of biodiversity. Habitat suitability models are the tools of choice to predict potential distributions of invasive species. Although land-use is a key driver of alien species invasions, it is often assumed that land-use is constant in time. Here we combine historical and present day information, to evaluate whether land-use changes could explain the dynamic of invasion of the American bullfrog Rana catesbeiana ( 5Lithobathes catesbeianus) in Northern Italy, from the 1950s to present-day. We used MAXENT to build habitat suitability models, on the basis of past (1960s, 1980s) and present-day data on land-uses and species distribution. For example, we used models built using the 1960s data to predict distribution in the 1980s, and so on. Furthermore, we used land-use scenarios to project suitability in the future. Habitat suitability models predicted well the spread of bullfrogs in the subsequent temporal step. Models considering land-use changes predicted invasion dynamics better than models assuming constant land-use over the last 50 years. Scenarios of future land-use suggest that suitability will remain similar in the next years. Habitat suitability models can help to understand and predict the dynamics of invasions; however, land-use is not constant in time: land-use modifications can strongly affect invasions; furthermore, both land management and the suitability of a given land-use class may vary in time. An integration of land-use changes in studies of biological invasions can help to improve management strategies.

International audience; Populations of widely distributed species can be subjected to unequal selection pressures, producing differences in rates of local adaptation. We report a laboratory experiment testing tolerance variation to UV-B and polycyclic aromatic hydrocarbons (PAHs) among common frog (Rana temporaria) populations according to their natural exposure level in the field. Studied populations were naturally distributed along two gradients, i.e. UV-B radiation with altitude and level of contamination by PAHs with the distance to emitting sources (road traffic). Tadpoles from eight populations were subjected to (1) no or high level of artificial UV-B; (2) four concentrations of benzo[a]pyrene (BaP) (0, 50, 250, 500 g L-1); (3) simultaneously to UV-B and BaP. Since both stressors are genotoxic, the number of micronucleated erythrocytes (MNE) in circulating red blood cells was used as a bioindicator of tadpole sensitivity. High-altitude populations appear to be locally adapted to better resist UV-B genotoxicity, as they showed the lowest MNE numbers. Conversely, no correlation was observed between levels of PAH contamination in the field and tadpole tolerance to BaP in the laboratory, indicating the absence of local adaptation for BaP tolerance in these populations. Nevertheless, the decrease of MNE formation due to BaP exposure with altitude suggests that high-altitude populations were intrinsically more resistant to BaP genotoxicity. We propose the hypothesis of a co- tolerance between UV-B and BaP in high-altitude common frog populations: local adaptation to prevent and/or repair DNA damage induced by UV-B could also protect these highland populations against DNA damage induced by BaP. The results of this study highlight the role of local adaptation along pollutant gradients leading to tolerance variation, which implies that is it necessary to take into account the history of exposure of each population and the existence of co-tolerance that can hide toxic effects of a new pollutant.

Several experiments have shown that ambient ultraviolet-B radiation (UV-B) has negative effects on the development of amphibians' embryos. We studied the effects of UV-B radiation on development, survival and frequency of deformity during egg development in the Natterjack toad (Bufo calamita) from a semiarid region of Lleida (Catalonia, Spain). Eggs exposed to ambient levels of UV-B and those protected from UV-B with a filter exhibited similar developmental rate, mortality rate and frequency of developmental anomalies. These experiments show that eggs of Bufo calamita of the studied population are able to develop normally during embryonic period when exposed to current high levels of UV-B observed in Catalonia. These results will be used as reference for future studies on geographic variation in UV-B tolerance in this species.

The assessment of species distribution is a first critical phase of biodiversity studies and is necessary to many disciplines such as biogeography, conservation biology and ecology. However, several species are difficult to detect, especially during particular time periods or developmental stages, potentially biasing study outcomes. Here we present a novel approach, based on the limited persistence of DNA in the environment, to detect the presence of a species in fresh water. We used specific primers that amplify short mitochondrial DNA sequences to track the presence of a frog ( Rana catesbeiana ) in controlled environments and natural wetlands. A multi-sampling approach allowed for species detection in all environments where it was present, even at low densities. The reliability of the results was demonstrated by the identification of amplified DNA fragments, using traditional sequencing and parallel pyrosequencing techniques. As the environment can retain the molecular imprint of inhabiting species, our approach allows the reliable detection of secretive organisms in wetlands without direct observation. Combined with massive sequencing and the development of DNA barcodes that enable species identification, this approach opens new perspectives for the assessment of current biodiversity from environmental samples.

Propagule pressure is considered the main determinant of success of biological invasions: when a large number of individuals are introduced into an area, the species is more likely to establish and become invasive. Nevertheless, precise data on propagule pressure exist only for a small sample of invasive species, usually voluntarily introduced. We studied the invasion of the American bullfrog, Rana catesbeiana, into Europe, a species that is considered a major cause of decline for native amphibians. For this major invader with scarce historical data, we used population genetics data (a partial sequence of the mitochondrial cytochrome b gene) to infer the invasion history and to estimate the number of founders of non-native populations. Based on differences between populations, at least six independent introductions from the native range occurred in Europe, followed by secondary translocations. Genetic diversity was strongly reduced in non-native populations, indicating a very strong bottleneck during colonization. We used simulations to estimate the precise number of founders and found that most non-native populations derive from less than six females. This capability of invasion from a very small number of propagules challenges usual management strategies; species with such ability should be identified at an early stage of introduction.

International audience; Despite early reports of its presence, no recent data exist on the distribution of the American bullfrog in Europe, the causes of introduction, or the trends of populations. We monitored the European situation at two spatial scales. In SW France, we performed call surveys over 2,500 wetlands. We found bullfrogs over about 2,000 km(2), apparently the European area in which the strongest expansion of bullfrogs is taking place. In addition, we used questionnaires to investigate the situation at the continental scale. At least 25 independent introductions occurred in Europe; eradication attempts were successful three times, and bullfrog populations are present in five countries. Education programs and monitoring are necessary to reduce the rate of introduction and to start management action as soon as possible.

Polycyclic Aromatic Hydrocarbons (PAHs) are damaging for aquatic organisms such as amphibians. In this study, toxicity of a mixture of three PAHs (naphthalene (2 rings), phenanthrene (3 rings) and pyrene (4 rings)) was tested on Common frog (Rana temporaria) embryos. The protective role of the jelly coat surrounding the eggs was studied by exposing embryos with and without jelly coat to PAHs dissolved in an aqueous solution without organic solvent. Results showed that the mixture of these three PAHs significantly increase embryonic mortality rate after a few hours of exposure. Embryos with jelly coat tend to suffer a lower mortality rate than embryos without jelly. The jelly surrounding eggs is filled by water of the breeding site, which can contain pollutants. Because jelly characteristics vary among species, sensitivity to environmental pollutants and levels of embryonic protection could be different among amphibian species.

International audience; Gregarious behaviour (i.e. living in groups in contrast to a solitary life) is commonly observed in mammals, but rarely documented in amphibians. Environmental features and/or animal mutual attractions can promote the formation of aggregations that may both reduce the risks of dehydration and predation and increase mate access and fitness. Luschan's salamander (Mertensiella luschani) lives in permanently arid Mediterranean environments; individuals shelter in cracks and crevices and leave only during favourable periods. In this study we examined the role of chemical tracks, in self and conspecific recognition (i.e. gregarious/solitary behaviour), on the social structure of this species. Our results show that juveniles and adults of both sexes use chemical scents deposited on substrate to relocate their shelter. In contrast to numerous other salamander species, Luschan's salamanders also use social information, conveyed by conspecific scents, to identify a safe shelter. Furthermore, this scent marking does not play a role in sexual attraction but allows sex discrimination. This species exhibits gregarious behaviour (i.e. conspecific attraction) as a possible adaptation to dry environments. We discuss both ultimate and proximate factors in the evolution from a solitary to a gregarious life.

Times Cited: 24; International audience; Today, with the rapid development of population genomics, the genetic basis of adaptation can be unraveled directly at the genome level, without any prerequisites about the selectively advantageous genes or traits. For nonmodel species, it is now possible to screen many markers randomly scattered across the genome and to distinguish between the neutral genetic background and outlier loci displaying an atypical behavior (e.g., a higher differentiation between populations). This study investigated the genetic frame of adaptation to a gradient of altitude in the common frog (Rana temporaria) by means of a genome scan based on 392 amplified fragment length polymorphism markers. Using two outlier detection methods never applied to dominant data so far, we sought for loci with a genetic differentiation diverging from neutral expectations when comparing populations from different altitudes. All the detected loci were sorted out according to their most probable cause for outlier behavior and classified as false positives, outliers due to local effects, or outliers associated with altitude. Altogether, eight good candidate loci were identified as potentially involved in adaptation to altitude because they were picked out in several independent interaltitude comparisons. This result illustrated the potential of genome-wide surveys to reveal selection signatures along selection gradients, where the association between environmental variables and fitness-related traits may be complex and/or cryptic. In this article, we also underlined the need for confirmation of the selection footprints for the outlier loci. Finally, we provided some preliminary insights into the genetic basis of adaptation along an altitudinal cline in the common frog.

International audience; Organic micropollutants are often damaging for aquatic organisms. Being usually hydrophobic compounds, they are often dissolved in an organic co-solvent which increases their solubility in water. The aim of this study was to study the toxicitv of various solvents on embryos (protected or not by jelly coat) and on tadpoles of the common frog (Rana temporaria). Tested solvents were methanol (MeOH), methylene chloride (CH2Cl2), dimethyl sulfoxyde (DMSO), acetone (Ac) and ethanol (EtOH). Embryos exhibited higher mortality rates than tadpoles. Embryos with jelly were more sensitive to high concentration of solvents than embryos without jelly (except for acetone). According to these results, Ac, DMSO and CH2Cl2 can be used as co-solvents in water to help the dissolution of micropollutants at concentration equal to or lower than 0.001 ml/l for frog embryos, and EtOH, Ac and CH2Cl2 at concentration equal to or lower than 0.01 ml/l for Rana temporaria tadpoles. (c) 2005 Elsevier Ltd. All rights reserved.

Nineteen adult toads equipped with transmitters were followed during and after the breeding period (January to September) in order to estimate their home range area and habitat use in a landscape of cereal agriculture. Median home range area was 0.5 ha (range 0.1-11 ha) during the breeding season (January-April). Home range areas increase during the post-breeding season (April-September) e.g., median minimum concave polygon of 4.1 ha. No relation between home range and toads' body size was observed. Six habitat types were described in the studied area. The proportion of habitats used (i.e. proportion of the pooled positions of 11 toads during the post-breeding season in each habitat) was significantly different from the proportion of available habitats: while crops represented 85% of the available habitat, only 43% of the toads' positions were recorded in this type of habitat. A compositional analysis of habitat preference was performed. At both landscape and individual home range levels, the toads preferred the stone embankments and ditches above all, while the crops were the least preferred habitat. This study highlights the role of habitat linkage and marginal habitats for the persistence of amphibian populations in intensive agricultural and arid landscapes.

International audience; To examine environmental effects on age structure, growth rate and body size, we studied three epigean populations (490-2350 in a.s.l.) and one subterranean (550 in a.s.l.) population of the Pyrenean newt Euproctus asper. The age structures were measured by skeletochronology of phalanges. In the three surface populations, where winter dormancy on land causes an annual growth stop, lines of arrested growth (LAGs) were observed. LAGs in the subterranean population, where individuals stay in the water throughout the year, indicate yearly (at least cyclical) periods of arrested growth even though animals occupy a relatively constant temperature/light environment. The age structures of adults did not differ between surface populations (5-28 yr) and the subterranean population (7-16 yr). Body lengths were highest for the surface population from the lowest altitude. The age, body size and growth traits of the Subterranean population came closer to the values obtained for the surface population located at 490 in a.s.l. than for those living at higher altitudes. We hypothesize that LAGs in subterranean newts result from reduced feeding in winter and that the similarity of age and size structures of subterranean and low-altitude populations argues for a recent colonization of the hypogean environment, where populations can find remaining optimal environmental conditions favorable to these stenothermic and rheophilous animals.

Times Cited: 3; International audience; The pattern of genetic differentiation of the endemic alpine salamander, Salamandra atra, has been studied using amplified fragment length polymorphism (AFLP) from 11 populations throughout the range of the two currently recognized subspecies, atra and aurorae. Five different primer combinations produced 706 bands and were analyzed by constructing a phylogenetic tree using NJ and principal component analysis. Significant genetic variation was revealed by AFLP between and within populations but, our results show a lack of genetic structure. AFLP markers seems to be unsuitable to investigate complex and recent diversification. (C) 2003 Elsevier Inc. All rights reserved.

International audience; River floodplains are disturbance-dominated landscapes where floods are major regulators of both aquatic and nearby terrestrial communities. Amphibians are common inhabitants of floodplains and their life cycle depends on both aquatic and terrestrial habitats. We focused on how different syntopic species of amphibians reacted to the environmental conditions of a large river floodplain. We examined life-history traits such as population age structure and growth in small- and large-bodied species of anurans and urodeles in the lower Danube River floodplain in Romania. Two newt species, Triturus vulgaris (small-bodied) and Triturus dobrogicus (large-bodied), and two anuran taxa, Bombina bombina (small-bodied) and the Rana esculenta complex (large-bodied), were included in the study. The ages of individuals estimated by skeletochronology varied from 3 to 5-6 years for T. vulgaris and from 2-3 to 4-5 years for T. dobrogicus. In the anurans, ages varied from 2 to 5 years in B. bombina and from 4 to 10 years in the R. esculenta complex. The numbers of breeding opportunities (i.e., the number of years the adults reproduce) are similar in both newt species (3), while growth rates and age at maturity differ between the large- and small-bodied species. In anurans, the number of breeding opportunities for the smallest species, B. bombina (4), is associated with a high growth rate and earlier maturation. In the larger R. esculenta complex, the higher number of breeding opportunities (7) is associated with a low growth rate and delayed maturation. The study of age distribution and associated parameters provides useful information on population life history. We discuss how age structure and growth of amphibian populations in large river floodplains can be used as indicators of environmental conditions.

International audience; Solar ultraviolet radiation (UV) is harmful for developing amphibians. As UV increases with altitude and latitude, it is suggested that high altitude and latitude populations have evolved tolerance to high levels of UV. Using laboratory experiments, we tested the hypothesis that Rana temporaria populations from several altitudes (438-2,450 m above sea level) were adapted to UV by assessing the effects of artificial UV on embryos mortality rate, malformations, and body length at hatching. We also tested the protective role of the jelly surrounding the embryos. Without artificial UV exposure, hatching success decreased with altitude of the population. Malformation rates were low for all populations (mean 1.36%), and hatching size increased with altitude. The artificial UV (UV-B, UV-A, and visible) used was similar to the solar spectrum received at high altitude. Exposed embryos had performance similar to that of embryos without exposure: a decreased hatching success with altitude and a low malformation rate (mean 0.85%). However, hatching size did not vary with altitude, and UV-exposed embryos tended to be smaller at hatching than non-exposed embryos. Removal of the protective jelly envelope greatly decreased the performance of UV-exposed embryos: hatching success strongly decreased with altitude and embryos of the highest population (2,450 m asl) did not develop. Malformation reached 4.98%, without population differences, and hatching size of embryos without jelly was smaller than hatching size of non-manipulated embryos with no population effect. This study demonstrates that lowland jellyless embryos were less sensitive (i.e., exhibited a higher survival rate) than highland embryos and, on the other hand, that the jelly envelope was a more efficient protection for embryos in highland than in lowland populations. A trade-off hypothesis is presented to explain this difference in UV tolerance and protection among populations: in a harsh, highland environment (i.e., with a curtailed activity period), embryos have to invest in development and growth and, thus, embryo protection should be a female investment (via the jelly). In a lowland environment, embryonic growth and development are less constrained and embryos are able to invest and use protection or repair mechanisms inherited from their parents.