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Photographic identification of individual animals is a non-invasive and cost-effective method that can provide demographic information on wild populations. This study aims to compare two photo-matching algorithms (Wild-ID and I3S-Spot) using a reintroduced population of pool frogs (Pelophylax lessonae) in the UK as a case study. We compared the following parameters 1) sex and age, 2) image quality, 3) image collection size and 4) processing time to evaluate successful image match rates. There were no significant differences in successful match rates found between sex and age groups. Wild-ID was more sensitive to image quality than I3S-Spot. There was a significant negative relationship between image collection size and successful match rates for I3S-Spot, however, no such relationship for Wild-ID. The findings of our study can be used by conservation practitioners to reduce workload and improve accuracy during population monitoring activities. [ABSTRACT FROM AUTHOR]

Amphibians are among the most threatened vertebrate taxa due to anthropogenic habitat change and emerging pathogens. The fungus Batrachochytrium dendrobatidis (Bd) may cause trade‐offs between the immune responses and other important functions, such as mobility. The pool frog (Pelophylax lessonae) is red‐listed in Sweden, and an earlier study conducted in our study area did not detect the fungus. In this study, 67 Swedish pool frogs were tested for Bd. Of these, 28 adults were provided with external radio transmitters and tracked during the summer and autumn to compare movement among infected and non‐infected individuals. Additionally, we tested some individuals for Bd twice during the summer to study intra‐seasonal variation in individual infections. Our results suggest that Bd has recently invaded these pool frog populations. During autumn, movement distances of infected pool frogs were shorter compared to uninfected individuals, and summer movements within ponds were reduced by increasing Bd load. We also found that the frogs can clear (or reduce) Bd infection during their active season. The results from this study increase understanding of the implications of Bd infections in an anuran fringe population, as well as in amphibian metapopulations, and can further guide amphibian conservation planning and management. [ABSTRACT FROM AUTHOR]

Demographic and age-structured modelling of local populations in a pool frog (Pelophylax lessonae) metapopulation reveals that the natural emigration from a population is of a magnitude which, if all emigrants are lost from the system, enhances local extinction risk in comparison to if the emigrants become immigrants in other local populations. In the latter case, annual population growth rate averaged λ = 1.2, while in the former λ averaged 0.994. Simulations indicated that single local populations in pristine habitat with emigration and no immigration have an extinction probability of 0.532 in 100 years, with extinction occurring from 11 years after isolation and mean time to extinction of 61 years. Such isolated populations were also highly vulnerable to additive mortality. In comparison, two local populations interconnected by dispersal were resilient to increased and higher local mortality provided that connectivity and the source population of immigrants were unaffected. This provides a demographic explanation of extinction patterns observed in the pool frog and other taxa that likely has general relevance for the conservation and management of subdivided populations in various landscapes. [ABSTRACT FROM AUTHOR]

Small Heat Shock Proteins (sHSP) are molecular chaperones that play an essential role in maintaining protein homeostasis and promoting cell survival. In this work, for the first time, multiple cDNAs encoding for small Hsp27 and Hsp30, designed, respectively, as Pb Hsp27-(1-2) and Pb Hsp30-(1-5), were cloned and characterized in the amphibian Pelophylax bergeri , which is a suitable model for studying biological responses to environmental perturbations. Domain architecture analysis showed that Pb Hsp27 and Pb Hsp30 cDNAs displayed the typical signature motifs of the sHSP family such as the conserved α-crystallin domain flanked by variable N-terminal and C-terminal regions. Phylogenetic analysis revealed that Pb Hsp27 and Pb Hsp30 clustered, respectively, with Hsp27 and Hsp30 members of other vertebrates, but more closely with amphibians. Overall Pb Hsp27 and Pb Hsp30 transcriptional activity, analyzed by qRT-PCR, evidenced that, in ex vivo skin exposed to thermal shock and cadmium treatment, Pb Hsp27 and Pb Hsp30 mRNAs were inducible and regulated differently. This study provides the basis for future research on the potential use of Pb Hsp27 and Pb Hsp30 as biomarkers of proteotoxic stress in amphibians. Unlabelled Image • Multiple members for Hsp27 and Hsp30 were identified in the frog Pelophylax bergeri. • Deduced proteins were characterized by typical motifs of HSP27 and HSP30 families. • Phylogenetically, Pb Hsp27 and Pb Hsp30 clustered with Hsp27 and Hsp30 of vertebrates. • Pb Hsp27 and Pb Hsp30 were regulated differently in skin exposed to abiotic stressors. [ABSTRACT FROM AUTHOR]

Distinguishing between native and introduced species can be difficult, particularly at range borders where patchily distributed populations may occur away from a species' natural core range. The case of native pool frog (Pelophylax lessonae) populations at their northern range limit in Europe is particularly interesting. These are morphologically and genetically distinct populations that are patchily distributed and have been reported from the UK, Sweden and Norway, but up until 2013 were thought to be absent from Finland. When pool frog populations were discovered in south-western Finland they were morphologically classified as belonging to this northern clade. However, the origin of these populations has been unclear and it is possible that the Finnish populations originated through human aided introductions, established themselves recently through natural migration, or are indeed previously undiscovered relic populations. To establish the origin and relationship of these frogs to other populations across Europe we used phylogeographical analysis based on microsatellite and mitochondrial DNA markers. Our results indicate that the Finnish, Norwegian, Swedish, UK, as well as Estonian populations belong to the northern clade. The Finnish frogs are most closely related to Swedish northern pool frogs, but are genetically more diverse. This suggests that the Finnish pool frogs are most likely a relic from postglacial migration, though we could not entirely rule out the possibility of a recent natural or human aided colonisation from Sweden. This has implications for the conservation status of the pool frog in Finland, where it thus far has been considered an invasive alien species. [ABSTRACT FROM AUTHOR]

The use of molecular genetic markers is considered in the context of their application to conservation of amphibians and reptiles in the British Isles. Aspects reviewed include population viability, connectivity and origins together with developments in molecular identification. Genetic diversity measures are not in themselves sufficient to identify risks of inbreeding or genetic erosion in the absence of direct measures of individual fitness. Neutral markers are however useful for defining populations, the extent of migration between them and the identification of permeable habitat corridors. Phylogeography has resolved previously uncertain origins of several populations and species found in the British Isles, including Pelophylax lessonae, Bufo calamita and Triturus cristatus. Molecular studies have clarified the species status of toads Bufo bufo, B. spinosus, and grass snakes Natrix helvetica in the British Isles and provided methods for species and clade identifications where this is difficult using morphology alone. DNA-based techniques have revealed the distributions of viral and fungal pathogens and environmental DNA (eDNA) has proved its worth as a technique for surveying pond-breeding amphibians. [ABSTRACT FROM AUTHOR]

Head-starting tadpoles was trialled to assist the programme for the reintroduction of the northern clade of the pool frog Pelophylax lessonae to England. Ten spawn clumps (estimated 1228 eggs) were removed from the reintroduction site and hatched under captive conditions. Survival rate of the eggs varied greatly between clumps, from 11% to 100%, but overall survival to the free-swimming tadpole stage was approximately 50%. Survival rates thereafter were high; 97% for tadpoles reared indoors and 81% for tadpoles grown for part of the larval period outdoors in artificial ponds. Releasing head-started tadpoles substantially increased metamorph productivity at the reintroduction site. The head-starting methodology described is labour intensive but provides an approach that could be used in secondary reintroductions of this species. It therefore merits further development for its potential contribution to the reintroduction of the northern pool frog to England. [ABSTRACT FROM AUTHOR]

There are risks from disease in undertaking wild animal reintroduction programmes. Methods of disease risk analysis have been advocated to assess and mitigate these risks, and post-release health and disease surveillance can be used to assess the effectiveness of the disease risk analysis, but results for a reintroduction programme have not to date been recorded. We carried out a disease risk analysis for the reintroduction of pool frogs ( Pelophylax lessonae) to England, using information gained from the literature and from diagnostic testing of Swedish pool frogs and native amphibians. Ranavirus and Batrachochytrium dendrobatidis were considered high-risk disease threats for pool frogs at the destination site. Quarantine was used to manage risks from disease due to these two agents at the reintroduction site: the quarantine barrier surrounded the reintroduced pool frogs. Post-release health surveillance was carried out through regular health examinations of amphibians in the field at the reintroduction site and collection and examination of dead amphibians. No significant health or disease problems were detected, but the detection rate of dead amphibians was very low. Methods to detect a higher proportion of dead reintroduced animals and closely related species are required to better assess the effects of reintroduction on health and disease. [ABSTRACT FROM AUTHOR]

This paper examines the pre-industrial historical record of Britain's anuran species. The records examined include especially the writings of naturalists and physicians, most notably Gerald of Wales (1188), John of Gaddesden (c.1314), Edward Wotton (1552), Timothie Bright (1580), Thomas Brown (1646), Robert Lovell (1660), Christopher Merrett (1667), Robert Sibbald (1684) and John Morton (1712). The common frog is attested as present throughout the period. Several reliable historical records are located that describe the presence or absence of a water frog species (Peloyphylax spp.: two records of presence, two of absence) and the tree frog (Hyla arborea: five records of presence, three of absence). The moor frog (Rana arvalis) and agile frog (Rana dalmatina) are not described separately - if present in the time period, they may have been considered varieties of the common frog. The evidence of presence comes exclusively from England. The records taken together confirm the presence of populations of water frogs between (at least) the fifteenth and eighteenth century, and provide new evidence attesting to populations of tree frogs between the sixteenth century (when the species may have been introduced) and the eighteenth century (when the species seems to have become locally extinct/locally distributed). [ABSTRACT FROM AUTHOR]

The water-frog L-E system, widespread in Western Europe, comprises the pool frog Pelophylax lessonae and the hybridogenetic edible frog P. esculentus, which originated from hybridization between pool frogs and marsh frogs ( P. ridibundus). In P. esculentus, the lessonae (L) genome is eliminated during meiosis and has to be gained anew each generation from a P. lessonae partner, while the ridibundus (R′) genome is transmitted clonally. It therefore accumulates deleterious mutations, so that R′R′ offspring from P. esculentus× P. esculentus crosses are normally unviable. This system is now threatened by invasive P. ridibundus (RR) imported from Eastern Europe and the Balkans. We investigated the genetic interactions between invasive marsh frogs and native water frogs in a Swiss wetland area, and used genetic data collected in the field to validate several components of a recently postulated mechanism of species replacement. We identified neo- ridibundus individuals derived from crosses between invasive ridibundus and native esculentus, as well as newly arisen hybridogenetic esculentus lineages stemming from crosses between invasive ridibundus (RR) and native lessonae (LL). As their ridibundus genomes are likely to carry less deleterious mutations, such lineages are expected to produce viable ridibundus offspring, contributing to species replacement. However, such crosses with invasive ridibundus only occurred at a limited scale; moreover, RR×LL crosses did not induce any introgression from the ridibundus to the lessonae genome. We did not find any ridibundus stemming from crosses between ancient esculentus lineages. Despite several decades of presence on the site, introduced ridibundus individuals only represent 15 % of sampled frogs, and their spatial distribution seems shaped by specific ecological requirements rather than history of colonization. We therefore expect the three taxa to coexist stably in this area. [ABSTRACT FROM AUTHOR]

The marsh frog ( Pelophylax ridibundus) has been introduced in many areas in Central and Western Europe as a result of commercial trade with Eastern Europe, and is rapidly replacing the native pool frog ( P. lessonae). A large number of Pelophylax species are distributed in Eastern Europe and the strong phenotypic similarity between these species is rendering their identification hazardous. Consequently, alien populations of Pelophylax might not strictly be composed of P. ridibundus as previously suspected. In the present study, we analysed the cytochrome- b and NADH dehydrogenase subunit 3 genes of introduced and native Pelophylax species from Switzerland (299 individuals) in order to properly identify the source populations of the invaders and the genetic status of the native species. Our study highlighted the occurrence of several genetic lineages of invasive frogs in western Switzerland. Unexpectedly, we also showed that several populations of the native pool frog ( P. lessonae) cluster with the Italian pool frog P. bergeri from central Italy (considered by some authors as a subspecies of P. lessonae). Hence, these populations are probably also the result of introductions, meaning that the number of native P. lessonae populations is fewer than expected in Switzerland. These findings have important implications concerning the conservation of the endemic pool frog populations, as the presence of multiple alien species could strongly affect their long-term subsistence. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 112, 442-449. [ABSTRACT FROM AUTHOR]

There are three taxons of central European water frogs of the Pelophylax esculentus complex: two morphologically distinct species, Pelophylax lessonae (LL) and Pelophylax ridibundus (RR), and hybrids Pelophylax esculentus, which can be either diploid (RL) or triploid (LLR or RRL). The morphology of hybrids is supposed to follow genome dosage effect. We describe colouration of water frogs with genome composition verified by chromosome analysis. Typical colouration features in LL were: spots on the ventral side, brown limbs, "weak" femur spotting pattern, brown dorsal folds and yellow-green colour in "waist". Typical RR had dark-green or olive-green limbs, "full" femur spotting pattern, no hip spot and no yellow colour in "waist". For all hybrids the most typical features were strong spots on the ventral side and a mosaic of green and brown colour on limbs. Typical LLR had brown-greenish dorsal folds underlined by a partial black line, "weak" femur spotting pattern and yellow-greenish colour in "waist" and on femur. Typical RL had greenish hind limbs, green dorsal folds, no yellow colour in "waist", and no hip spot. Typical RRL was similar to RL, but had a continuous black line under dorsal folds. There were, however, numerous exceptions to these trends, with the most prominent being much higher than expected variability of colouration of Pelophylax lessonae. Therefore caution must be advised when trying to estimate genome composition of water frogs solely on the basis of colouration. [ABSTRACT FROM AUTHOR]

The article presents the first data on a study of ultraviolet (UV) B exposure and basking behaviour in wild amphibians, with the use of Pelophylax lessonae as a model species, that found inhabitation of a UV-B microclimate by wild frogs to be defined by physical features of their habitat. It also showed basking behaviour to be bi-phasic, with numbers of basking frogs peaking first between nine o'clock and 10 o'clock in the morning, then between two o'clock and thee o'clock in the afternoon.

The article discusses a study on 20 species of green frog's populations throughout Bavaria, Germany. It informs that the aim of the study was to obtain precise data related to the distribution and population structure of the frog population. It states the study focused on detecting occurrence of allochthonous species of green frogs, the distribution of the pool frog pelophylax lessonae, and finding pure hybrid population of green frogs across Bavaria. It also reveals that in the study, frog species were identified on the basis of morphometric measurements and serum albumin polymerase chain reaction (PCR). It further states that in the study edible Frog, pelophylax esculentus was found to be the most common green frog species at the study sites.

The article offers information on the study which focuses on the patterns of road-kills of various amphibians in the region of Vendée, Western France. It states that most amphibians that suffered road-kills are Bufo bufo toad and Rana dalmatina, an agile frog. It says that Pelophylax lessonae posted 4% of road-kills because of its sedentary lifestyles on ponds. It mentions that road-kills of amphibians could be attributed to its migratory movements and road-kills are found on low traffic roads that is bordered by woodland and wetlands.

Background: While emerging diseases are affecting many populations of amphibians, some populations are resistant. Determining the relative contributions of factors influencing disease resistance is critical for effective conservation management. Innate immune defenses in amphibian skin are vital host factors against a number of emerging pathogens such as ranaviruses and the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd). Adult water frogs from Switzerland (Pelophylax esculentus and P. lessonae) collected in the field with their natural microbiota intact were exposed to Bd after experimental reduction of microbiota, skin peptides, both, or neither to determine the relative contributions of these defenses. Results: Naturally-acquired Bd infections were detected in 10/51 P. lessonae and 4/19 P. esculentus, but no disease outbreaks or population declines have been detected at this site. Thus, this population was immunologically primed, and disease resistant. No mortality occurred during the 64 day experiment. Forty percent of initially uninfected frogs became sub-clinically infected upon experimental exposure to Bd. Reduction of both skin peptide and microbiota immune defenses caused frogs to gain less mass when exposed to Bd than frogs in other treatments. Microbiota-reduced frogs increased peptide production upon Bd infection. Ranavirus was undetectable in all but two frogs that appeared healthy in the field, but died within a week under laboratory conditions. Virus was detectable in both toe-clips and internal organs. Conclusion: Intact skin microbiota reduced immune activation and can minimize subclinical costs of infection. Tolerance of Bd or ranavirus infection may differ with ecological conditions. [ABSTRACT FROM AUTHOR]

Amphibian skin secretion represents a cerain scientific interest as a source of biologically active natural peptides. In the present research skin peptidome of wide-spread European frog Rana lessonae (Camerano, 1882) was studied for the first time ever. Peptide sequencing was accomplished with Fourier transform ion cyclotron resonance mass spectrometer in collision-induced and electron capture dissociation modes. A portion of amphibian peptides contains intramolecular C-terminal disulfide cycle which obstructs mass spectrometric sequencing. Two methods were utilized to overcome this difficulty: reduction with dithiotreithol followed by thiol group alkylation and oxidation into sulfonic acid groups with performic acid. Integrated approach employed in the present study allowed the identification of 49 peptides (of 6 to 37 amino acid residues), including 19 novel species. [ABSTRACT FROM AUTHOR]

The article presents a study investigating if the morphology of Western Palearctic water frogs reflects the genome dosage effect (GDE) and if it can be used to determine genome composition. The study involved observing morphologies of "Pelophylax ridibundus" RR, "Pedophylax lessonae" LL, and their hybrid "Pedophylax esculentus" (RL, LLR, or RRL). Discriminant and canonical analyses were applied and results revealed that the L haplotype had a bigger effect on morphology than the R haplotype. All hybrid genotypes were revealed to be closer to P. lessonae.

We describe a non-invasive, PCR-RFLP-based method that allows reliable determination of the European water frog species Pelophylax lessonae and Pelophylax ridibundus and the hybrid form Pelophylax esculentus. Maximum-likelihood analysis of ITS2 sequences revealed two robust monophyletic clades corresponding to water frogs of the P. lessonae and P. ridibundus groups. Three restriction enzymes ( KpnI, HaeII, and SmaI) were used to digest three conserved ITS2 domains. Taxonomic identification was unambiguous; the three restriction enzymes gave the same results. A French reference sample was identified using allozyme electrophoresis. Our PCR-RFLP method confirmed circa 83% of identification of the allozyme method. We conclude that the difference between identifications was caused by introgression. [ABSTRACT FROM AUTHOR]

In this paper we present the most southern distribution record of Pelophylax lessonae species in Romania, and of the L-R-E (lessonae-ridibundus-esculentus) population system as well. The recorded population is situated near the village Izvoarele, in Mehedinti County, South-Western Romania. We have captured 52 individuals of water frogs during one hour of work in the investigated habitat. In the case of each form of water frogs we have captured both males and females. Most individuals of water frogs were represented by the species P. ridibundus, followed by the hybrid P. esculentus. The fewest captured individuals belonged to the species P. lessonae. [ABSTRACT FROM AUTHOR]

Understanding the factors that affect the process of metamorphosis in species with complex life cycles, and in particular their variation within and among populations, has been rarely explored until recently. We examined the effects of temperature environment on several metamorphic characteristics in three populations of the pool frog (Rana lessonae Camerano, 1882) by rearing individuals at two temperature environments (20 and 25 °C). Higher temperature shortened the metamorphic period and reduced the absolute mass loss, although there was no difference between the temperatures in the percentage of mass lost. No differences among the populations were detected, but there was significant intrapopulation variation both in the mean and in the plasticity for the duration of metamorphosis. These results indicate that several aspects of metamorphosis are plastic in amphibians, these traits may have considerable intrapopulation variation, and that temperature is a strong factor affecting the process of metamorphosis. [ABSTRACT FROM AUTHOR]

In animals with complex life cycles, the environment experienced early during the development may have strong effects on later performance and fitness. We investigated the intraspecific variation in the effects of larval temperature environment on the morphology and locomotory performance of juvenile pool frogs Rana lessonae originating from three closely located populations of the northern fringe metapopulation in central Sweden. Tadpoles were raised individually at two temperatures (20 and 25 °C) until metamorphosis. We measured the morphology of the metamorphs and tested the jumping performance of the froglets after complete tail absorption. We found that early temperature environment affected juvenile morphology, metamorphs from high-temperature environments having relatively longer hindlimbs (tibiofibulas) and longer tails when weight at metamorphosis was accounted for. In absolute terms, froglets from low temperature jumped significantly longer; however, after correcting for size differences the relationship was reversed, individuals raised at high temperature performing better. In both temperatures, relative jumping performance was positively associated with tibiofibula and body length. Populations differed both in metamorphic traits and in jumping capacity, especially at low temperature, suggesting microgeographical variation in temperature sensitivity within the metapopulation. Our results indicate that the temperature environment experienced during the early aquatic stages can influence the morphology and performance of juvenile frogs, and that these effects can be population specific. [ABSTRACT FROM AUTHOR]

Background: We report the expression pattern of 5S rDNA in the eggs of water frogs Rana lessonae, Rana ridibunda and Rana esculenta using the quantitative real-time PCR. This kind of research had never been performed before. Results: 5S rDNA relative expression of the Rana ridibunda oocytes is approximately six times higher in comparison to the Rana lessonae oocytes. The oocytes of the investigated Rana esculenta frogs, in respect of 5S rDNA relative expression ratio, were very similar to the Rana ridibunda oocytes. Conclusion: We suggest the possibility of using 5S rDNA as the internal control gene, in the studies of relative mRNA quantitative assays in water frog oocytes, because of its characteristic specific expression pattern in the Rana lessonae, Rana ridibunda and Rana esculenta oocytes [ABSTRACT FROM AUTHOR]

Aim To infer the evolutionary history of Rana ( Pelophylax) lessonae Camerano within its inferred Quaternary refugial range, and to shed light on the processes that have contributed to shaping the patterns of diversity within the southern European peninsulas. Location The Italian peninsula south of the Alps and Sicily. Methods Sequence analysis of a mitochondrial cytochrome b gene fragment in 149 individuals sampled from 25 localities. Results Three mitochondrial DNA (mtDNA) phylogroups were identified, distributed in northern Italy, the whole Italian peninsula south of the northern Apennines, and Sicily. Syntopy between the northern and peninsular lineages was observed close to the northern Apennines. The northern lineage was the most differentiated, showing a net sequence divergence of 4.8 ± 0.8% with respect to the two others, whereas the net divergence between peninsular and Sicilian lineages was 2.6 ± 0.6%. Analysis of molecular variance (amova) revealed that 93% of the overall variation occurred between these three groups. Historical demographic statistics support a recent expansion for both the northern and peninsular groups, but not for the Sicilian group. In both northern and peninsular Italy, such an expansion was likely to have occurred during the last glaciation. Main conclusions Our results suggest that a number of microevolutionary processes were involved in shaping the present genetic structure of R. lessonae in Italy. These encompass allopatric differentiations in three distinct Pleistocene refugia, recent population expansions and secondary contacts. Our results, together with some previous work, support (1) the existence of a suture zone in the northern Apennines, and (2) the possibility of population expansions during the last glacial phase, when a vast widening of the lowland floodplain habitats followed sea-level fall, particularly in northern Italy. When compared with previous analyses of allozyme data, it appears that the peninsular mtDNA lineage has recently replaced the Sicilian one in southern Calabria, and we suggest that this event occurred due to selective introgression. The implications of such an occurrence for the study of factors underlying the patterns of diversity within this southern European biodiversity hotspot are discussed. Taxonomic implications of the results are also evaluated. [ABSTRACT FROM AUTHOR]

During 2006 and 2007 we encountered in south-western Romania four populations of Rana lessonae. Their determination was made on the basis of both the morphological and chromatic features. All of the pool frog records in Romania are found at the proximity of the species' general range; being practically in connection with it. Thus, aside from the glacial refuge from Italy, the populations from south-western Romania are amongst the most southerly populations of the species at entire Europe level, making up the south-eastern limit of its range. The populations from south-western Romania seem to be isolated from the other populations from Romania both geographically, ecologically (temperature and humidity), and as habitat type (mountain brook). It can therefore be theorized that the species Rana lessonae had in south-western Romania a secondary glacial refuge. [ABSTRACT FROM AUTHOR]

Predator-induced morphological plasticity is a model system for investigating phenotypic plasticity in an ecological context. We investigated the genetic basis of the predator-induced plasticity in Rana lessonae by determining the pattern of genetic covariation of three morphological traits that were found to be induced in a predatory environment. Body size decreased and tail dimensions increased when reared in the presence of preying dragonfly larvae. Genetic variance in body size increased by almost an order of magnitude in the predator environment, and the first genetic principal component was found to be highly significantly different between the two environments. The across environment genetic correlation for body size was significantly below 1 indicating that different genes contributed to this trait in the two environments. Body size may therefore be able to respond to selection independently in the two environments to some extent. [ABSTRACT FROM AUTHOR]

The article focuses on a study which investigated water frog populations in South-Western France to determine their taxonomic diversity and sympatry. A confirmation of the presence of Rana lessonae populations in the region is stated. Results of an assessment of the presence of sympatry between Rana perezi and Rana lessonae are discussed. The existence of two new taxonomic assemblages is revealed.

Hybridization is a widespread phenomenon in many vertebrate groups. Prezygotic isolating mechanisms, probably caused by selection against hybrids with reduced fitness, reduce the likelihood of such events. Although hybrid-reduced fitness relatively to parental species is common, hybridization can also be beneficial, and hybrids sometimes outperform the pure species type. In this study, we examined two potential processes, Hubbs’s principle and male–male competition, which could enhance hybridization in the waterfrog complex and thus explain the proportion of heterospecific pairs collected in a natural pond. Firstly, by collecting 791 frogs in the field to study pair and chorus composition, we showed that in a mixed Rana lessonae– Rana esculenta population, the scarcity of hybrid R. esculenta males did not account for the proportion of heterospecific pairs: indeed, when examining pairing composition in six different choruses, we found that hybrid males were always under-represented and that R. esculenta females were found paired with R. lessonae males. Secondly, we investigated experimentally whether or nor male–male competition mechanism could explain pair formation in waterfrogs. Our mating speed experiment highlights mechanisms that could explain heterospecific pairs in a context of promiscuous mating where scramble competition was intense. To measure the rapidity with which a male grasps a female, we placed males in a grid cage with a female, and the dynamics of pair formation was monitored. R. esculenta males showed a lower pairing success than R. lessonae males as a smaller proportion of them amplexed females, and more time was needed for them to get amplexed. Thus, a less adaptative mechanism than female mate choice may also explain the mating pattern observed in waterfrog species. [ABSTRACT FROM AUTHOR]

Abstract Introduced species often pose serious threats to biodiversity, but occasionally confusion arises as to whether a species really is introduced or is in fact an overlooked native. A recent UK conservation dilemma has centred on the status of the pool frog Rana lessonae. This species has been the subject of documented introductions from central and southern Europe since the early 1800s, the accepted position being that all UK R. lessonae populations are descended from these introductions. However, a closer examination of early UK literature sources, and recent discoveries of isolated, native R. lessonae populations in Sweden and Norway, led some herpetologists to question whether the species was in fact present as a native at some locations prior to the introductions. Research was initiated along four major lines of enquiry: genetic, bioacoustic, archaeozoological and archival. A high degree of convergence among the genetic and bioacoustic investigations demonstrated that the potentially native UK pool frogs were closely related to Scandinavian frogs, thus ruling out introductions from further south as a potential origin. Subfossil evidence of pool frogs was found from ca. 1000 years before present, demonstrating that the species occurred in the UK prior to known introductions. Archival sources produced no historical support for introductions from northern Europe. The postglacial history inferred for these northern populations is consistent with the known climatic and geographical conditions. Taken together, the evidence for the native status of the pool frog is compelling, and furthermore the UK population appears to be part of a distinct northern clade. [ABSTRACT FROM AUTHOR]

The pool frog,Rana lessonae, has historically been considered an introduction into Britain, with Italy the most likely source. Recently, the possibility of native status for a Norfolk pool frog population was raised. We used random amplified DNA (RAPD) analyses to clarify the status issue. Nine arbitrarily designed primers detected 160 polymorphisms in 174 pool frogs from 11 European locations. Polymorphism levels varied widely, being lowest in the northern populations and highest in the south. As with many isolated populations, the peninsular and insular populations of Sweden, Norway and Britain showed relatively little polymorphism. Principal component and cluster analysis showed clear geographical groupings. The Norfolk, Norwegian and Swedish individuals formed a closely related group− a northern clade, substantiating native status for the Norfolk population, which, interestingly, had idiosyncratic features suggestive of a distinctive evolutionary history. Phylograms constructed from RAPD data were consistent with an unexpected postglacial colonization route, in which the northern clade derived from migration out of Italy, via Hungary and Poland, though cryptic glacial refugia in Eastern Europe are an alternative explanation. Our RAPD analyses concur with a parallel microsatellite investigation. Both genetic studies and bioacoustic and archaeozoological findings support native status for Norfolk pool frogs and have prompted a programme for re-establishing the northern clade in England. © 2005 The Linnean Society of London,Biological Journal of the Linnean Society, 2005,85, 41–51. [ABSTRACT FROM AUTHOR]

1. We investigated the morphological responses of larvalRana lessonaeto the presence of two predators with substantially different prey-detection and capture techniques; larval dragonflies (Aeshna cyanea) and the Pumpkinseed Sunfish (Lepomis gibossus).2. We also examined the functional implications of any predator-induced morphological variation on their swimming ability by assessing performance during the initial stages of a startle response.3. We found the morphological responses of larvalR. lessonaewere dependent on the specific predator present. Tadpoles raised in the presence of dragonfly larvae preying upon conspecific tadpoles developed total tail heights 5·4% deeper and tail muscles 4·7% shallower than tadpoles raised in a non-predator environment, while tadpoles raised with sunfish possessed tails 2% shallower and tail muscles 2·5% higher than non-predator-exposed tadpoles.4. Predator-induced morphological variation also significantly influenced swimming performance. Tadpoles raised with sunfish possessed swimming speeds 9·5 and 14·6% higher than non- and dragonfly predator groups, respectively.5. Thus, the expression of these alternative predator-morphs leads to a functional trade-off in performance between the different environments.Functional Ecology(2005)19, 238 –244doi: 10.1111/j.1365-2435.2005.00958.x [ABSTRACT FROM AUTHOR]

The risk allocation hypothesis predicts that temporal variation in predation risk can influence how animals allocate feeding behavior among situations that differ in danger. We tested the risk allocation model with tadpoles of the frog Rana lessonae, which satisfy the main assumptions of this model because they must feed to reach metamorphosis within a single season, their behavioral defense against predators is costly, and they can respond to changes in risk integrated over time. Our experiment switched tadpoles between artificial ponds with different numbers of caged dragonfly larvae and held them at high and low risk for different portions of their lives. Tadpoles responded strongly to predators, but they did not obey the risk allocation hypothesis: as the high-risk environment became more dangerous, there was no tendency for tadpoles to allocate more feeding to the low-risk environment, and as tadpoles spent more time at risk, they did not increase feeding in both environments. Our results suggest that the model might be more applicable when the time spent under high predation risk is large relative to the time required to collect resources. [ABSTRACT FROM AUTHOR]

For several decades, behavioral ecologists have studied the effects of the environment on the behavior of individuals; but only fairly recently they have started to ask the reverse question: how do the behavioral strategies of individuals affect the composition and dynamics of populations and communities? Although intuitively obvious, this feedback from individual to higher levels is difficult to demonstrate, except in systems with exceptionally fast and marked responses of the populations to the behavior of its members. Such a system exists in sperm-dependent species. In European water frogs, for instance, successful reproduction of a hybrid species (R. esculenta, genotype LR) requires mating with one of its parental species (R. lessonae, genotype LL), except in the rare cases where hybrids are triploid. The sexual host LL, however, should avoid matings with the sexual parasite LR, because the resulting LR offspring will eliminate the L genome from their germ line. In this study we investigate how this conflict is solved. Since water frog hybrids come in both sexes, rather than as females only like in other sperm-dependent systems, we performed the tests with both females and males. One individual was given a choice between two individuals of the opposite sex, one an LL and the other an LR. In both species, females showed the predicted preference for LL males, whereas males did not discriminate between LL and LR females. On the individual level, we interpret the sex difference in choosiness by the lower costs from mating with the wrong species (LR) and the higher benefits from mating with large individuals in males than in females. In “normal” species, male preference for large (i.e. more fecund) females is advantageous, but in this system such a choice can result in mating with the larger LR females. With respect to the structure and dynamics of mixed populations, we discuss that the observed female preference is consistent with the higher mating success of LL males found in nature. Hence, mate female choice is a strong candidate for a mechanism promoting coexistence of the sperm-dependent hybrid and its sexual host. This confirms predictions from previous theoretical models. [ABSTRACT FROM AUTHOR]