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Fish introduction into fishless high-altitude lakes has detrimental effects on biodiversity. Removal of alien fish through intensive fishing is cost-intensive and difficult to achieve in productive lakes. Lake Sulzkarsee is the only lake in the National Park Gesäuse, Austria, and was an important breeding site for amphibians until the lake was stocked with fish in the late 1970s. Salmonids were eradicated in 2005, but the lake remained degraded by the introduced minnows (Phoxinus sp.). In 2018, the lake was drained through a siphon pipe and then by pumping out water with dirt water pumps. The deepest part was treated with slaked lime, but several hundred adult minnows survived in sediment crevices and reproduced in the following season. After drainage, the phytoplankton biomass increased. Indicator species, such as Daphnia longispina and amphibians, showed signs of recovery, but they went back to an impacted state when minnows recovered after the failed eradication attempt. Purse seines proved to be the most efficient gear to catch minnows. These results indicate that deep mountain lakes are difficult to drain efficiently. Sediment treatment is required to eliminate all fish.

Terrestrial landscapes surrounding aquatic habitat influence the persistence of amphibian spatially structured populations (SSPs) via their crucial role in providing estivation and overwintering sites, facilitating or hampering dispersal and colonisation, and consequently the maintenance or loss of genetic diversity. To highlight the landscape drivers of genetic variation, we investigated the relationship between the level of genetic variation measured within ponds of the great crested newt (Triturus cristatus), and the composition of the surrounding landscape at various spatial scales. Based on the sampling of 40 ponds in 13 SSPs, the influence of landscape features on several estimators of genetic variation was investigated via linear mixed models, with effects within and between SSPs incorporated. The best models depended on the spatial scale, with more significant associations within radii of 50 and 100 m of core ponds, particularly for allelic richness. Responses within and between SSPs were mostly similar. The availability of aquatic habitat in the landscape had a positive effect, while woodland, arable land and pasture had different effects depending on scale and response variable. Total length of roads within a 250 m radius influenced effective population size negatively. Our results stress the need to investigate the influence of environmental predictors at multiple spatial scales for an adequate understanding of ongoing processes. Generally, the landscape affected genetic variation similarly within and between SSPs. This allowed us to provide general guidelines for the persistence of great crested newt populations, with an emphasis on the importance of the aquatic habitat.

β-N-Methylamino- l -alanine (BMAA), a neurotoxin naturally produced by cyanobacteria, diatoms and dinoflagellates, constitutes a serious environmental and health threat especially during acute blooms, which are becoming more frequent. This neurotoxin is implicated in several neurodegenerative diseases (ND) in humans through contaminated water or food consumption. Even low doses of neurotoxic compounds (NCs) can have lasting effects later in life. In this sense, early stages of development constitute a period of high sensitivity to environmental influence, particularly for the central nervous system. To understand the mechanisms underlying the delayed effects of NCs, newly hatched larvae of the mangrove rivulus fish, Kryptolebias marmoratus, were exposed to two sub-lethal doses of BMAA (20 μg/L and 15 mg/L) for 14 days. This fish naturally produces isogenic lineages due to its self-fertilizing reproduction, which is unique case among vertebrates. It thus provides genetic characteristics that allow scientists to study organisms’ true reaction norm, minimizing genetic variability and focusing exclusively on the effects of the environment. Effect assessment was performed at different levels of biological organization to detect inconspicuous effects of BMAA, since this molecule displays long retention in organisms. BMAA effects on life history traits as well as behavioral traits such as boldness and aggressiveness were assessed more than 100 days after exposure. In addition, the relative expression of 7 potential BMAA target genes was studied, given their involvement in neurotransmission or their association with individual variation in boldness and aggressiveness. Selected genes code for reticulon 4 (RTN4), glutamate vesicular transporter 1 (Slc17a7), glutamine synthetase a (Glula), dopamine receptor D4 (DRD4), monoamine oxidase A (MAOA), calmodulin (CaM) and epedymine (Epd). Despite observing no effects of BMAA on growth, reproduction and behavioral traits, BMAA induced a significant increase of the expression of CaM and MAOA genes at 20 μg/L BMAA compared to the control group. A significant decrease of expression was observed between this lowest BMAA dose and 15 mg/L for DRD4, MAOA and CaM genes. Our results suggest disruption of glutamate turnover, intracellular dopamine depletion and activation of astrocyte protective mechanisms, indicating that BMAA might be excitotoxic. Our study revealed that BMAA can have long-lasting effects on the brain that are suspected to affect phenotypic traits with aging. Furthermore, it highlights the importance of studying delayed effects in ecotoxicological studies.

Anurans have been introduced in many parts of the world and have often become invasive over large geographic areas. Although predation is involved in the declines of invaded amphibian populations, there is a lack of quantitative assessments evaluating the potential risk posed to native species. This is particularly true for Pelophylax water frogs, which have invaded large parts of western Europe, but no studies to date have examined their predation on other amphibians in their invaded range. Predation of native amphibians by marsh frogs (Pelophylax ridibundus) was assessed by stomach flushing once a month over four months in 21 ponds in southern France. Nine percent of stomachs contained amphibians. Seasonality was a major determinant of amphibian consumption. This effect was mediated by body size, with the largest invaders ingesting bigger natives, such as tree frogs. These results show that invasive marsh frogs represent a threat through their ability to forage on natives, particularly at the adult stage. The results also indicate that large numbers of native amphibians are predated. More broadly, the fact that predation was site- and time-specific highlights the need for repeated samplings across habitats and key periods for a clear understanding of the impact of invaders.

Cryptic phylogeographic diversifications provide unique models to examine the role of phylogenetic divergence on the evolution of reproductive isolation, without extrinsic factors such as ecological and behavioural differentiation. Yet, to date very few comparative studies have been attempted within such radiations. Here, we characterize a new speciation continuum in a group of widespread Eurasian amphibians, the Pelobates spadefoot toads, by conducting multilocus (restriction site associated DNA sequencing and mitochondrial DNA) phylogenetic, phylogeographic and hybrid zone analyses. Within the P. syriacus complex, we discovered species‐level cryptic divergences (>5 million years ago [My]) between populations distributed in the Near‐East (hereafter P. syriacus sensu stricto [s.s.]) and southeastern Europe (hereafter P. balcanicus), each featuring deep intraspecific lineages. Altogether, we could scale hybridizability to divergence time along six different stages, spanning from sympatry without gene flow (P. fuscus and P. balcanicus, >10 My), parapatry with highly restricted hybridization (P. balcanicus and P. syriacus s.s., >5 My), narrow hybrid zones (~15 km) consistent with partial reproductive isolation (P. fuscus and P. vespertinus, ~3 My), to extensive admixture between Pleistocene and refugial lineages (≤2 My). This full spectrum empirically supports a gradual build up of reproductive barriers through time, reversible up until a threshold that we estimate at ~3 My. Hence, cryptic phylogeographic lineages may fade away or become reproductively isolated species simply depending on the time they persist in allopatry, and without definite ecomorphological divergence.

Progenesis is considered to have an important role in evolution because it allows the retention of both a larval body size and shape in an adult morphology. However, the cost caused by the adoption of a progenetic process in both males and females remains to be explored to explain the success of progenesis and particularly its biased prevalence across the sexes and environments. Here, through an experimental approach, we used a facultative progenetic species, the palmate newt (Lissotriton helveticus) that can either mature at a small size and retain gills or mature after metamorphosis, to test three hypotheses for sex-specific pay-offs of progenesis in safe versus risky habitats. Goldfish were used because they caused a higher decline in progenetic than metamorphic newts. We determined that progenetic newts have a lower reproductive fitness than metamorphic newts. We also found that, when compared to metamorphs, progenetic males have lower reproductive activity than progenetic females and that predatory risk affects more progenetic than metamorphic newts. By identifying ultimate causes of the female-biased sex ratios found in nature, these results support the male escape hypothesis, that is the higher metamorphosis rate of progenetic males. They also highlight that although progenesis is advantageous in advancing the age at first reproduction, it also brings an immediate fitness cost and this, particularly, in hostile predatory environments. This means that whereas some environmental constraints could favour facultative progenesis, some others, such as predation, can ultimately counter-select progenesis. Altogether, these results improve our understanding of how developmental processes can affect the sexes differently and how species invasions can impair the success of alternative developmental phenotypes.

Observations on the ontogeny and diversity of salamanders provided some of the earliest evidence that shifts in developmental trajectories have made a substantial contribution to the evolution of animal forms. Since the dawn of evo-devo there have been major advances in understanding developmental mechanisms, phylogenetic relationships, evolutionary models, and an appreciation for the impact of ecology on patterns of development (eco-evo-devo). Molecular phylogenetic analyses have converged on strong support for the majority of branches in the Salamander Tree of Life, which includes 764 described species. Ancestral reconstructions reveal repeated transitions between life cycle modes and ecologies. The salamander fossil record is scant, but key Mesozoic species support the antiquity of life cycle transitions in some families. Colonization of diverse habitats has promoted phenotypic diversification and sometimes convergence when similar environments have been independently invaded. However, unrelated lineages may follow different developmental pathways to arrive at convergent phenotypes. This article summarizes ecological and endocrine based causes of life cycle transitions in salamanders, as well as consequences to body size, genome size, and skeletal structure. Salamanders offer a rich source of comparisons for understanding how the evolution of developmental patterns has led to phenotypic diversification following shifts to new adaptive zones. This article is protected by copyright. All rights reserved.

Understanding how long-term changes in environmental conditions influence the way that individuals cope with threats is essential in the context of behavioral adaptation to a rapidly changing world. However, little is known about the behavioral responses to predation risk for individuals that experienced different environmental conditions for extended periods of time, such as food levels and light conditions. In this experimental study, we tested whether previous long-term exposure to different food levels (low versus high) and light conditions (0-h light versus 8-h light) plays a significant role in shaping the antipredator response (i.e., the probability of emerging from the refuge and the distance moved) to stimuli from caged larval dragonflies, in larvae of the fire salamander (Salamandra salamandra). Specifically, we quantified behavioral differences in the response to predation risk in larval salamanders that were reared in the laboratory for 2 months under controlled food and light conditions. The results of this study showed that the interaction between food level and light conditions affected the antipredator behavior of the larvae. Fire salamander larvae maintained at low food levels and in 8-h light conditions emerged from the refuge with a higher probability (i.e., took more risk) than larvae maintained at high food levels and all other combinations of light conditions. Thus, our results highlight the complexity of antipredator responses, pointing attention to the fact that interactions among environmental factors are likely to determine the magnitude of antipredator response. Few studies have investigated the role of multiple environmental factors on the expression of predator-induced behavioral responses. Specifically, because no study has so far investigated the risk-taking behavior in individuals exposed to long-term, contrasting food levels, and light conditions, we investigated this in amphibian larvae. We showed that environmental conditions interactively determined antipredator behavior. This highlights the importance of considering long-term environmental conditions experienced by an organism and their interactions when experimentally studying behavioral variation to adequately understand its expression in natural conditions.

Este artículo contiene 6 figuras, 4 tablas., Historical factors (colonization scenarios, demographic oscillations) and contemporary processes (population connectivity, current population size) largely contribute to shaping species’ present‐day genetic diversity and structure. In this study, we use a combination of mitochondrial and nuclear DNA markers to understand the role of Quaternary climatic oscillations and present‐day gene flow dynamics in determining the genetic diversity and structure of the newt Calotriton asper (Al. Dugès, 1852), endemic to the Pyrenees. Mitochondrial DNA did not show a clear phylogeographic pattern and presented low levels of variation. In contrast, microsatellites revealed five major genetic lineages with admixture patterns at their boundaries. Approximate Bayesian computation analyses and linear models indicated that the five lineages likely underwent separate evolutionary histories and can be tracked back to distinct glacial refugia. Lineage differentiation started around the Last Glacial Maximum at three focal areas (western, central and eastern Pyrenees) and extended through the end of the Last Glacial Period in the central Pyrenees, where it led to the formation of two more lineages. Our data revealed no evidence of recent dispersal between lineages, whereas borders likely represent zones of secondary contact following expansion from multiple refugia. Finally, we did not find genetic evidence of sex‐biased dispersal. This work highlights the importance of integrating past evolutionary processes and present‐day gene flow and dispersal dynamics, together with multilocus approaches, to gain insights into what shaped the current genetic attributes of amphibians living in montane habitats., Economic support was provided by the European Commission LIFE+ project LimnoPirineus (LIFE13 NAT/ES/001210), by the Spanish Government project Funbio (RTI2018-096217-B-I00), by the Interreg POCTEFA ECTOPYR project (EFA031/15) and by the Societas Europaea Herpetologica (SEH, research grant awarded to F.L.). F.L. had a doctoral grant funded by Fundação para a Ciência e Tecnologia (FCT, grant number PD/BD/52598/2014). M.D. is research Director at Fonds de la Recherche Scientifique – FNRS.

Organisms with complex life cycles are characterized by a metamorphosis that allows for a major habitat shift and the exploitation of alternative resources. However, metamorphosis can be bypassed in some species through a process called paedomorphosis, resulting in the retention of larval traits at the adult stage and is considered important at both micro- and macroevolutionary scales. In facultatively paedomorphic populations of newts, some individuals retain gills and a fully aquatic life at the adult stage (paedomorphs), while others undergo complete metamorphosis (metamorphs), allowing for a terrestrial life-stage. Because facultative paedomorphosis affects trophic structures and feeding mechanism of newts, one hypothesis is that it may be maintained as a trophic polymorphism, with the advantage to lessen intraspecific competition during the shared aquatic life-stage. Here, we tested this hypothesis combining stomach content data with stable isotope techniques, using carbon and nitrogen stable isotopes, in facultatively paedomorphic alpine newts Ichthyosaura alpestris. Both stomach content and stable isotope analyses showed that paedomorphs had smaller trophic niches and were more reliant on pelagic resources, while metamorphs relied more on littoral resources, corresponding to a polyphenism along the littoral–pelagic axis and the extension of the population's trophic niche to otherwise ‘underused’ pelagic resources by paedomorphs. Interestingly, stable isotopes revealed that the trophic polyphenism was less marked in males than in females and potentially linked to sexual activity. Although paedomorphosis and metamorphosis are primarily seen as results of tradeoffs between the advantages of using aquatic versus terrestrial habitats, this study provides evidence that additional forces, such as intraspecific trophic niche differences between morphs and trophic niche expansion, may play an important role in the persistence of this dimorphism in heterogeneous environments. Moreover, the different patterns found in males and females show the importance of considering sex to understand the evolutionary ecology of trophic polymorphisms.

Background In species with complex life cycles, size at metamorphosis is a key life-history trait which reflects the complex interactions between costs and benefits of life in the aquatic and terrestrial environments. Whereas the effects of a deteriorating larval habitat (e.g. pond desiccation) on triggering an early metamorphosis have been extensively investigated in amphibians, the consequences of the resulting reduced size at metamorphosis on fitness in the post-metamorphic terrestrial stage remain poorly understood. We tested the hypothesis that a smaller size at metamorphosis negatively affects performance and survival in the ensuing terrestrial stage. Using as model a tropical amphibian (Ceratophrys stolzmanni) showing a large phenotypic plasticity in metamorphosing traits, we evaluated the effects of size at metamorphosis on fitness-related trophic and locomotor performance traits, as well as on growth and survival rates. Results Our results support the hypothesis that a larger size at metamorphosis is correlated with better survival and performance. The survival rate of large metamorphosing individuals was 95%, compared to 60% for those completing metamorphosis at a small size. Locomotor performance and gape size were positively correlated with body size, larger animals being more mobile and capable to ingest larger prey. However, smaller individuals achieved higher growth rates, thus reducing the size gap. Conclusions Overall, size at metamorphosis affected profoundly the chances of survival in the short term, but smaller surviving individuals partly compensated their initial disadvantages by increasing growth rates.

Dispersal is a central process in ecology and evolution. It strongly influences the dynamics of spatially structured populations and affects evolutionary processes by shaping patterns of gene flow. For these reasons, dispersal has received considerable attention from ecologists, evolutionary biologists, and conservationists. Although it has been studied extensively in taxa such as birds and mammals, much less is known about dispersal in vertebrates with complex life cycles such as pond-breeding amphibians. Over the past two decades, researchers have taken an ever-increasing interest in amphibian dispersal and initiated both basic and applied studies, using a broad range of experimental and observational approaches. This body of research reveals complex dispersal patterns, causations, and syndromes, with dramatic consequences for the demography and genetics of amphibian populations. In this review, our goals are to: redefine and clarify the concept of amphibian dispersal; review current knowledge about the effects of individual (i.e., condition-dependent dispersal) and environmental (i.e., context-dependent dispersal) factors during the three stages of dispersal (i.e., emigration, transience, and immigration); identify the demographic and genetic consequences of dispersal in spatially structured amphibian populations; and propose new research avenues to extend our understanding of amphibian dispersal., Hugo Cayuela warmly thanks the Banting Postdoctoral Fellowships program for its financial support. Further-more, Mathieu Denoël is Research Director at Fonds dela Recherche Scientifique—FNRS. During manuscript writing, Andrés Valenzuela-Sánchez was supported bya FONDECYT de postdoctorado No. 3180107. Any useof trade, firm, and product names is for descriptive purposes only and does not imply endorsement by the U.S.Government. Íñigo Martínez-Solano acknowledges funding by FEDER/Ministerio de Ciencia, Innovación y Universidades—Agencia Estatal de Investigación, Spain,grant CGL2017-83131-P.

Divergence in ecological niche offers organisms the opportunity of exploiting different food and habitat resources, scaling down competition and predation both among species, and within different age or size-classes of the same species. In harsh environments, where abiotic factors determine a clustering of resources during short timespans, competition and predation between organisms is likely to be enhanced. This is the case in tropical dry forests, where amphibians have limited opportunities to feed, their activity being restricted to the short rainy season. One way to maximize resource exploitation while avoiding predation risk is by adopting different diel activity patterns. We tested this hypothesis by comparing activity patterns in adults and recently metamorphosed juveniles of Pacific horned frogs (Ceratophrys stolzmanni) during field surveys and in an experimental study. Field surveys showed that the adults are strictly nocturnal, whereas freshly metamorphosed juveniles can be found active above ground at all hours, with a peak activity during daytime. The average body condition index of juveniles found active during the night was higher than that of juveniles found active during the day, suggesting that the weaker individuals may be constrained to being active during the day. On the other hand, in a laboratory experiment, juveniles that were visually exposed to adults moved less than those in the absence of adults. Both field and experimental observations indicate a temporal niche divergence between life stages. The results of the experiment offer support to the hypothesis that the juveniles in this species display an inverse activity pattern compared to adults, which can reduce competitive interactions and predation pressure from the larger conspecifics.

The fossorial life-history emerged as a response to hostile environmental conditions, such as extreme temperatures and dryness. It evolved independently in different lineages of amphibians, which are particularly vulnerable to dehydration and require a continuous level of humidity because of their permeable skin. For the first time, we test the hypothesis that amphibians are able to adapt their fossorial behaviour to substrate humidity, using the Pacific horned frogs (Ceratophrys stolzmanni) from the Ecuadorian dry forest as a model. When exposed to dry substrate, the animals burrowed much deeper than the ones in wet soil. The capacity to excavate was particularly high in this species: frogs from the dry treatment could be found at more than 1-m depth after just a few hours. Our results reveal a conditional strategy that contributes to explain the persistence of amphibians in dry environments.

The radiation of Palearctic green toads (Bufotes) holds great potential to evaluate the role of hybridization in phylogeography at multiple stages along the speciation continuum. With fifteen species representing three ploidy levels, this model system is particularly attractive to examine the causes and consequences of allopolyploidization, a prevalent yet enigmatic pathway towards hybrid speciation. Despite substantial efforts, the evolutionary history of this species complex remains largely blurred by the lack of consistency among the corresponding literature. To get a fresh, comprehensive view on Bufotes phylogeography, here we combined genome-wide multilocus analyses (RAD-seq) with an extensive compilation of mitochondrial, genome size, niche modelling, distribution and phenotypic (bioacoustics, morphometrics, toxin composition) datasets, representing hundreds of populations throughout Eurasia. We provide a fully resolved nuclear phylogeny for Bufotes and highlight exceptional cyto-nuclear discordances characteristic of complete mtDNA replacement (in 20% of species), mitochondrial surfing during post-glacial expansions, and the formation of homoploid hybrid populations. Moreover, we traced the origin of several allopolyploids down to species level, showing that all were exclusively fathered by the West Himalayan B. latastii but mothered by several diploid forms inhabiting Central Asian lowlands, an asymmetry consistent with hypotheses on mate choice and Dobzhansky-Muller incompatibilities. Their intermediate call phenotypes potentially allowed for rapid reproductive isolation, while toxin compositions converged towards the ecologically-closest parent. Across the radiation, we pinpoint a stepwise progression of reproductive isolation through time, with a threshold below which hybridizability is irrespective of divergence (15My). Finally, we clarified the taxonomy of Bufotes (including genetic analyses of type series) and formally described two new species, B. cypriensis sp. nov. (endemic to Cyprus) and B. perrini sp. nov. (endemic to Central Asia). Embracing the genomic age, our framework marks the advent of a new exciting era for evolutionary research in these iconic amphibians. ispartof: MOLECULAR PHYLOGENETICS AND EVOLUTION vol:141 ispartof: location:United States status: published

Differences in environmental conditions such as those between lakes and streams can produce phenotypic variation and ultimately promote evolutionary diversification. Some species of newts and salamanders can occupy these habitats and express alternative phenotypes: metamorphs that lose gills at metamorphosis and paedomorphs that retain them at the adult stage. Whereas this process is facultative in some species, it is obligatory in others, thus suggesting that isolation and environmental pressures may have canalized developmental pathways. In this study, we focused our research on the Pyrenean brook newt, Calotriton asper, which is present in both lakes and streams, but whose fully aquatic paedomorphic individuals are only present in lakes. We aimed to determine the genetic structure and differentiation of two paedomorphic populations, including their surrounding stream and lake metamorphic populations, to test whether populations of paedomorphs can constitute evolutionary significant units. Although gene flow was identified between lakes and nearby stream populations, there was a low percentage of dispersers, and the paedomorphic populations were genetically differentiated from the populations of metamorphs. It is likely that the studied lakes have offered peculiar conditions that have allowed the development of a paedomorphic phenotype. These populations and phenotypes therefore constitute good models to understand local adaptations. As each of these populations of paedomorphs can be considered evolutionary significant units that cannot be replaced by other nearby populations in case of a population crash, conservation actions should be focused directly on them., This work was supported by the Biodiversity Conservation Plan of ENDESA, S.A. (ENEL Group) for D.S.; Fonds de la Recherche Scientifique—FNRS under grant numbers J.008.13 and J.0112.16 and Fonds Spéciaux de la Recherche (University of Liège) for M.D. (Research Director at F.R.S.–FNRS); and the Marie Curie COFUND Fellowship for N.O. while at the University of Liège. The research and capture permits for newts were issued by Departamento de Agricultura, Ganaderia y Medio Ambiente (Gobierno de Aragon, Spain).

Antipredator responses are a key determinant of the successful persistence of prey, and behavioural modifications are a frequent antipredator strategy. However, conspecific populations often inhabit heterogeneous environments. This can determine local adaptations, and might also induce variation in antipredator responses. Nevertheless, there is limited information on whether heterogeneity of predation risk among populations determines variation in antipredator response. Here we studied the fire salamander, Salamandra salamandra, a species that can breed in both surface streams and caves, habitats that are predator-rich and predator-free, respectively, and measured differences in antipredator responses across populations with different predation risk. We combined field surveys and laboratory experiments to understand the role of predation risk on the activity patterns of larvae, while measuring behavioural differences between populations. We reared larvae from different habitats in safe and risky conditions and tested their response to predator cues before and after rearing. In the field, predation risk was much higher in surface streams than in caves; larvae moved more in the absence of predators and when the light intensity was low. During laboratory experiments, larvae were less active if reared in risky conditions, but cave larvae showed a stronger response to risk than stream larvae. Therefore, larvae from sites without predators showed higher antipredator responses than those from risky habitats. This response fits the predictions of the risk allocation model, in which prey from habitats with a high background level of risk need to be active even when predators are present, to satisfy their energetic demands. Our findings show that antipredator behaviour may differ strongly between populations and stress the importance of integrating this variability in studies on predatory responses.

In laboratory fish research, the zebrafish Danio rerio (Cyprinidae) represents the equivalent of the mouse in mammalian research. This species has become a major model for studies in developmental and behavioural genetics, neurophysiology, biomedicine, ecotoxicology, and behavioural and evolutionary ecology. To meet the need for accurate and reproducible data in both fundamental and applied sciences, it is of primary importance to be able to tag and/or recognize individual zebrafish. However, classic methods used in fish ecology and aquaculture are generally difficult to apply to such small fish. Recently, various new tagging methods have been developed. This paper presents a first review of current identification and marking methods applied to zebrafish, from external observation methods (such as skin pattern recognition, fin clipping, scale regeneration, colour and transgenic methods) to the most advanced technological developments in electronic (low- and high- radio-frequencies PIT tags, microchip) and image analysis methods (video tracking). This review aims to help researchers and zebrafish facility managers select the identification method (ID) best adapted to their needs. The main characteristics of each ID method are examined (including detection range, durability, speed and repetitiveness, ID code combination, size dependence and ethical considerations), and their pros and cons are summarized in a decision table to help select the most appropriate option for a research or management program. Finally, contextual applications of these ID methods and future developments are discussed., SCOPUS: re.j, info:eu-repo/semantics/published

International audience; Dispersal (i.e. movement from a natal or breeding site to another breeding site) is a central process in ecology and evolution as it affects the eco-evolutionary dynam- ics of spatially structured populations. Dispersal evolution is regulated by the bal- ance between costs and benefits, which is influenced by the individual phenotype (i.e. phenotype-dependent dispersal) and environmental factors (i.e. condition-dependent dispersal). Even though these processes have been extensively studied in species with simple life cycles, our knowledge about these mechanisms in organisms displaying complex life cycles remains fragmentary. In fact, little is specifically known about how the interplay between individual and environmental factors may lead to alternative dispersal strategies that, in turn, lead to the coexistence of contrasted site fidelity phe- notypes. In this paper, we examined breeding dispersal in a pond-breeding amphibian, the great crested newt Triturus cristatus, within usual walking distances for a newt. We took advantage of recent developments in multi-event capture–recapture models and used capture–recapture data (946 newts marked) collected in a spatially structured population occupying a large pond network (73 ponds). We showed a high rate of breeding site infidelity (i.e. pond use) and the coexistence of two dispersal phenotypes, namely, a highly pond faithful phenotype and a dispersing phenotype. Individuals that were site faithful at time t – 1 were therefore more likely to remain site faithful at time t. Our results also demonstrated that the probability that individuals belong to one or the other dispersal phenotypes depended on environmental and individual factors. In particular, we highlighted the existence of a dispersal syndrome implying a covariation pattern among dispersal behavior, body size, and survival. Our work opens new research prospects in the evolution of dispersal in organisms displaying complex life cycles and raises interesting questions about the evolutionary pathways that contribute to the diversification of movement strategies in the wild.

Evolutionary theory predicts the evolution of metamorphosis over paedomorphosis (the retention of larval traits at the adult stage) in response to life in unfavourable habitats and to the benefits of dispersal. Although many organisms are canalised into obligatory complex or simple life cycles, some species of newts and salamanders can express both processes (facultative paedomorphosis). Previous research highlighted the detrimental effect of fish on both metamorphic and paedomorphic phenotypes, but it remains unknown whether predation risk could induce shifts from paedomorphosis to metamorphosis, whether behavioural avoidance could be an alternative strategy to metamorphosis and whether these responses could be sex-biased. Testing these hypotheses is important because metamorphosed paedomorphs are dispersal individuals which could favour the long-term persistence of the process by breeding subsequently in more favourable waters. Therefore, we quantified the spatial behaviour and timing of the metamorphosis of facultative paedomorphic palmate newts Lissotriton helveticus in response to predation risk. We found that fish induced both male and female paedomorphs to hide more often, but behavioural avoidance was not predictive of metamorphosis. Paedomorphs did not metamorphose more in the presence of fish, yet there was an interaction between sex and predation risk in metamorphosis timing. These results improve our understanding of the lower prevalence of paedomorphs in fish environments and of the female-biased sex ratios in natural populations of paedomorphic newts. Integrating sex-dependent payoffs of polyphenisms and dispersal across habitats is therefore essential to understand the evolution of these processes in response to environmental change.

The ‘smooth newt’, the taxon traditionally referred to as Lissotriton vulgaris, consists of multiple morphologically distinct taxa. Given the uncertainty concerning the validity and rank of these taxa, L. vulgaris sensu lato has often been treated as a single, polytypic species. A recent study, driven by genetic data, proposed to recognize five species, L. graecus, L. kosswigi, L. lantzi, L. schmidtleri and a more restricted L. vulgaris. The Carpathian newt L. montandoni was confirmed to be a closely related sister species. We propose to refer to this collective of six Lissotriton species as the smooth newt or Lissotriton vulgaris species complex. Guided by comprehensive genomic data from throughout the range of the smooth newt species complex we 1) delineate the distribution ranges, 2) provide a distribution database, and 3) produce distribution maps according to the format of the New Atlas of Amphibians and Reptiles of Europe, for the six constituent species. This allows us to 4) highlight regions where more research is needed to determine the position of contact zones.

Ant mill, caterpillar circle, bat doughnut, amphibian vortex, duck swirl, and fish torus are different names or 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 andhave 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 informationtransfer. We highlight gaps in our understandding of these ubiquitous behavioral phenomena and discuss future directions for research in vortex studies.

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.

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.

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 colonisers. However, not all amphibian phenotypes are able to persist 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.

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.

A recent paper has suggested that NA2RE, the New Atlas of Amphibians and Reptiles of Europe, does not provide a reliable basis for ecological niche modelling studies due to errors flagging introductions and missing data for the native range of the pond turtle genus Emys. We point out that the original NA2RE paper already acknowledged that it was not aimed for fine-scale ecological distribution modelling and that it had the objective of stimulating research for improving the maps. New works now complement the Atlas in improving the coverage and providing new distribution maps for species within species complex. Moreover, we stress that the NA2RE web platform at present hosts only the distribution data compiled in 2014 from different sources, using the taxonomy adopted by the authors at the time. As with any large database, it is advisable that these data are carefully evaluated and quality-filtered before their use in scientific studies. We defend the reliability of the NA2RE web platform as the currently most comprehensive resource for the comparative chorological study of amphibians and reptiles in Europe, and encourage publication of updates and additions following the most recent taxonomic changes, to continuously improve this database and the Atlas., The authors thank the Societas Europaea Herpetologica for funding the NA2RE project. NS is supported by an IF contract (IF/01526/2013) from Fundação para a Ciência e a Tecnologia (Portugal).

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.

Paedomorphosis is a major evolutionary process that bypasses metamorphosis and allows reproduction in larvae. In newts and salamanders, it can be facultative with paedomorphs retaining gills and metamorphs dispersing. The evolution of these developmental processes is thought to have been driven by the costs and benefits of inhabiting aquatic versus terrestrial habitats. In this context, we aimed at testing the hypothesis that climatic drivers affect phenotypic transition and the difference across sexes because sex-ratio is biased in natural populations. Through a replicated laboratory experiment, we showed that paedomorphic palmate newts ( Lissotriton helveticus ) metamorphosed at a higher frequency when water availability decreased and metamorphosed earlier when temperature increased in these conditions. All responses were sex-biased, and males were more prone to change phenotype than females. Our work shows how climatic variables can affect facultative paedomorphosis and support theoretical models predicting life on land instead of in water. Moreover, because males metamorphose and leave water more often and earlier than females, these results, for the first time, give an experimental explanation for the rarity of male paedomorphosis (the ‘male escape hypothesis’) and suggest the importance of sex in the evolution of paedomorphosis versus metamorphosis.

Paedomorphosis and metamorphosis are two major developmental processes that characterize the evolution of complex life cycles in many lineages. Whereas these processes were fixed in some taxa, they remained facultative in others, with alternative phenotypes expressed in the same populations. From a genetic perspective, it is still unknown whether such phenotypes form a single population or whether they show some patterns of isolation in syntopy. This has deep implications for understanding the evolution of the phenotypes, i.e. towards their persistence or their fixation and speciation. Newts and salamanders are excellent models to test this hypothesis because they exhibit both developmental processes in their populations: the aquatic paedomorphs retain gills, whereas the metamorphs are able to colonize land. Using microsatellite data of coexisting paedomorphic and metamorphic palmate newts (Lissotriton helveticus), we found that they formed a panmictic population, which evidences sexual compatibility between the two phenotypes. The high gene flow could be understood as an adaptation to unstable habitats in which phenotypic plasticity is favored over the fixation of developmental alternatives. This makes then possible the persistence of a polyphenism: only metamorphosis could be maintained in case of occasional drying whereas paedomorphosis could offer specific advantages in organisms remaining in water.

Understanding the way species with similar niches can coexist is a challenge in ecology. The niche partitioning hypothesis has received much support, positing that species can exploit available resources in different ways. In the case of secretive species, behavioural mechanisms of partitioning are still poorly understood. This is especially true for fossorial frogs because individuals hide underground by day and are active only during the night. We investigated the nocturnal activity and tested the niche partitioning hypothesis in two syntopic fossorial spadefoot toads (Pelobates fuscus and Pelobates syriacus) by examining interspecific variation in emergence from the soil. We employed a night vision recording system combined with video tracking analyses in a replicated laboratory setting to quantify individual movement patterns, a procedure that has not been used until now to observe terrestrial amphibians. Most individuals appeared on the surface every night and returned to their original burrow (about 60% of the times), or dug a new one around morning. There was a large temporal overlap between the two species. However, P. syriacus was significantly more active than P. fuscus in terms of total distance covered and time spent moving, while P. fuscus individuals left their underground burrow more frequently than P. syriacus. Consequently, P. fuscus adopted more of a sit-and-wait behaviour compared to P. syriacus, and this could facilitate their coexistence. The use of night video tracking technologies offered the advantage of individually tracking these secretive organisms during their nocturnal activity period and getting fine-grained data to understand their movement patterns.