Native Frogs Research Articles

Novel sounds, native responses: exploring the acoustic consequences of Eleutherodactylus johnstonei’s invasion in urban areas

BackgroundBiological invasions pose a critical threat to biodiversity, affecting ecological balance and native species’ communication. Eleutherodactylus johnstonei, an exotic anuran in São Paulo, vocalizes at intensities that could interfere with native anuran species, potentially causing acoustic masking.MethodsWe evaluated the effects of E. johnstonei's calls on the vocalizations of two native species, Scinax imbegue and Physalaemus cuvieri, both with and without spectral overlap with the invasive species. Field playbacks were conducted using six versions of stimuli, including E. johnstonei's calls, the native Boana bischoffi (as a control), and white noise. We recorded response calls and behavioral changes of S. imbegue and P. cuvieri males.ResultsThe calls of E. johnstonei did not affect the spectral or temporal parameters of the native species’ announcement calls. However, S. imbegue males displayed behavioral responses such as cessation of vocalization or movement away from the noise source. Additionally, B. bischoffi's calls and white noise influenced native species’ call parameters.DiscussionOur findings reveal that exotic species’ vocalizations may disrupt native anurans’ acoustic behavior. This impact varies with species and context, underlining the need for further research on anuran acoustic interactions across different frequencies and acoustic environments to fully understand the effects of exotic acoustic interference.

Physiological and morphological traits affect contemporary range expansion and implications for species distribution modelling in an amphibian species.

Species range shifts due to climate alterations have been increasingly well-documented. Although amphibians are one of the most sensitive groups of animals to environmental perturbations due to climate change, almost no studies have offered evidence of poleward distribution shifts in this taxon in response to climate warming. Range shifts would be facilitated by variation in traits associated with the ability of species to persist and/or shift their range in the face of climate change, but the extent and consequences of intraspecific variation in these traits is unclear. We studied the role of intraspecific variation in the ongoing range shift of green treefrogs (Hyla cinerea) in response to climate change. We explored factors that are often associated with range shifts to test the hypothesis that there are differences in these traits between recently range-expanded and nearby historical populations. We then tested the consequences of intraspecific variation for modelling climate-induced range shifts by comparing species distribution models (SDMs) that used as input either data from the entire species range or separate inputs from 'subpopulations' corresponding to the historical range or the recently expanded range. We expected that building a separate SDM for each population would more accurately characterize the species range if historical and expanded populations differed in traits related to their response to climate. We found that critical thermal minimum decreased and thermal breadth increased with latitude, but the effect of latitude was significantly stronger for expanded populations compared to historical populations. Additionally, we found that individuals from expanded populations had longer leg lengths when compared to their historical counterparts. Finally, we found higher model accuracy for one of the population-level SDMs than the species-level SDM. Our results suggest that thermal tolerance and dispersal morphologies are associated with amphibian distributional shifts as these characteristics appear to facilitate rapid range expansion of a native anuran. Additionally, our modelling results emphasize that SDM accuracy could be improved by dividing a species range to consider potential differences in traits associated with climate responses. Future research should identify the mechanisms underlying intraspecific variation along climate gradients to continue improving SDM prediction of range shifts under climate change.

Predation on eggs and larvae of the Japanese brown frog Rana japonica Boulenger, 1879 by the invasive crayfish Procambarus clarkii (Girard, 1852) (Decapoda: Astacidea: Cambaridae) under laboratory conditions

Abstract We hypothesized that the North American invasive crayfish Procambarus clarkii (Girard, 1852) can negatively affect the populations of native frog species through predation. We conducted three laboratory experiments to examine whether P. clarkii can prey on eggs or larvae of the Japanese native frog Rana japonicaBoulenger, 1879: Experiment I crayfish + frog egg in an aquarium without a substrate or aquatic plants, Experiment II crayfish + frog larva in an aquarium without a substrate or aquatic plants, and Experiment III crayfish + frog larva in an aquarium with a substrate and aquatic plants as shelter for the larva. We used three experimental groups of crayfish individuals (small, intermediate, and large size), each of 10 individuals, and simultaneously placed one crayfish individual and one egg or frog larva in the same aquarium for 24 h and checked for predation by the crayfish. We found that 88.9% and 86.7% of eggs and larvae used in Experiments I and II were preyed upon, respectively. Predation rate of frog larvae was still high (77.8%) in Experiment III, suggesting that crayfish can potentially find and prey on frog larvae in nature. Predation on frog eggs or larvae was high regardless of the crayfish body size. Our results indicate that P. clarkii can potentially have a marked effect on the population of R. japonica by preying on eggs and larvae.

Effect of water stress on locomotor performance in Pleurodema nebulosum (Anura: Leptodactylidae) a native frog from the Argentina Monte desert

Locomotion is a fundamental aspect in the life cycle of any organism, and plays a crucial role in survival, feeding, escaping from predators, territoriality, and reproduction. Locomotion in amphibian anurans includes swimming, walking, jumping, climbing, and gliding. Amphibians living in arid regions face a constant compromise between hydration balance and locomotor performance. We studied the effects of water stress on the locomotion of the frog Pleurodema nebulosum, a specialist from the Monte Desert. Locomotor performance was measured through different physical variables during the jump. The locomotor performance of P. nebulosum showed a significant decrease in the magnitudes associated with a decrease in body hydration. Our study demonstrated how a desert-adapted frog (P. nebulosum) showed changes in locomotion related to the loss of body water. Additionally, we observed an abrupt drop in locomotion with 15% desiccation, followed by a plateau where the evaluated parameters remained stable. Pleuroderma nebulosum showed a clear adaptation to extreme desiccation. The frogs are rarely found in optimal hydration conditions as the environment in which they develop is extremely stressful from a water perspective. The data evaluated here are the beginning of a deeper exploration of the desert adaptations of South American desert frogs.

Feral frogs, native newts, and chemical cues: identifying threats from and management opportunities for invasive African Clawed Frogs in Washington state.

Invasive species threaten biodiversity globally. Amphibians are one of the most threatened vertebrate taxa and are particularly sensitive to invasive species, including other amphibians. African clawed frogs (Xenopus laevis) are native to Southern Africa but have subsequently become invasive on multiple continents-including multiple parts of North America-due to releases from the pet and biomedical trades. Despite their prevalence as a global invader, the impact of X. laevis remains understudied. This includes the Pacific Northwest of the USA, which now hosts multiple expanding X. laevis populations. For many amphibians, chemical cues communicate important information, including the presence of predators. Here, we tested the role chemical cues may play in mediating interactions between feral X. laevis and native amphibians in the Pacific Northwest. We tested whether native red-legged frog (Rana aurora) tadpoles display an antipredator response to non-native frog (X. laevis) or native newt (rough-skinned newts, Taricha granulosa) predator chemical stimuli. We found that R. aurora tadpoles exhibited pronounced anti-predator responses when exposed to chemical cues from T. granulosa but did not display anti-predator response to invasive X. laevis chemical cues. We also began experimentally testing whether T. granulosa-which produce a powerful neurotoxin tetrodotoxin (TTX)-may elicit an anti-predator response in X. laevis, that could serve to deter co-occupation. However, our short-duration experiments found that X. laevis were attracted to newt chemical stimuli rather than deterred. Our findings show that X. laevis likely poses a threat to native amphibians, and that these native species may also be particularly vulnerable to this invasive predator, compared to native predators, because toxic native newts may not limit X. laevis invasions. Our research provides some of the first indications that native Pacific Northwest species may be threatened by feral X. laevis and provides a foundation for future experiments testing potential management techniques for X. laevis.

Defenses of whirligig beetles against native and invasive frogs.

Many native insects have evolved defenses against native predators. However, their defenses may not protect them from non-native predators due to a limited shared history. The American bullfrog, Aquarana catesbeiana (Anura: Ranidae), which has been intentionally introduced to many countries, is believed to impact native aquatic animals through direct predation. Adults of whirligig beetles (Coleoptera: Gyrinidae), known for swimming and foraging on the water surface of ponds and streams, reportedly possess chemical defenses against aquatic predators, such as fish. Although whirligig beetles potentially encounter both bullfrogs and other frogs in ponds and lakes, the effectiveness of their defenses against frogs has been rarely studied. To assess whether whirligig beetles can defend against native and non-native frogs, we observed the behavioral responses of the native pond frog, Pelophylax nigromaculatus (Anura: Ranidae), and the invasive non-native bullfrog, A. catesbeiana, to native whirligig beetles, Gyrinus japonicus and Dineutus orientalis, in Japan. Adults of whirligig beetles were provided to frogs under laboratory conditions. Forty percent of G. japonicus and D.orientalis were rejected by P. nigromaculatus, while all whirligig beetles were easily consumed by A. catesbeiana. Chemical and other secondary defenses of G. japonicus and D. orientalis were effective for some individuals of P. nigromaculatus but not for any individuals of A. catesbeiana. These results suggest that native whirligig beetles suffer predation by invasive non-native bullfrogs in local ponds and lakes in Japan.

Food preference for native and invasive prey in the naive lancehead pitviper

AbstractThe presence of invasive species in the environment can be highly detrimental. The success of these species depends on their interaction with native ones. The prey–predator relationship between invasive and native species can result in biodiversity loss or the introduction of new food items for local predators. Due to its tropical and extensive nature, Brazil is vulnerable to the colonization of invasive species. Snakes are a group of animals that can act as both predators and prey for invasive species. The pitviper Bothrops jararaca is an abundant and widely distributed native species on the Brazilian coast. Based on this, we conducted a study on the feeding preferences of naive B. jararaca juveniles regarding invasive and native prey. We found that this species exhibits a greater preference for native anurans compared to Rana catesbeiana, an invasive amphibian associated with significant environmental impacts. Additionally, the gecko Hemidactylus mabouia, a prey that triggered intense predatory responses from the pitviper, reveals that this species, even with a short period of coexistence with B. jararaca, has established an intense prey–predator relationship. The negative correlation between prey size and feeding interest, guided solely by olfactory cues, adds a layer of complexity to understanding the feeding choices of B. jararaca, providing valuable insights for conservation and environmental management strategies.Abstract in Portuguese is available with online material.

Ranavirus and helminth parasite co-infection in invasive American bullfrogs in the Atlantic forest, Brazil

Emerging infectious diseases threaten amphibian species across the globe. In Brazil, the American bullfrog (Aquarana catesbeiana) is a highly invasive species that can potentially transmit parasites and pathogens to native amphibians. This is the first assessment of co-infection of Ranavirus and helminth macroparasites in invasive populations of bullfrogs in South America. We collected, measured, and euthanized 65 specimens of A. catesbeiana sampled from 9 sites across three states of Brazil in the Atlantic Forest biome. We collected and identified helminth macroparasites and sampled host liver tissue to test for the presence and load of Ranavirus with quantitative PCR. We documented patterns of prevalence, parasite load, and co-infection with generalized linear mixed models, generalized logistic regressions, and randomization tests. Most individual bullfrogs did not exhibit clinical signs of infection, but the overall Ranavirus prevalence was 27% (95% confidence interval, [CI 17–38]). Bullfrogs were infected with helminth macroparasites from 5 taxa. Co-infection of helminth macroparasites and Ranavirus was also common (21% CI [12–31]). Bullfrog size was positively correlated with total macroparasite abundance and richness, and the best-fitting model included a significant interaction between bullfrog size and Ranavirus infection status. We observed a negative correlation between Ranavirus viral load and nematode abundance (slope = −0.22, P = 0.03). Invasive bullfrogs (A. catesbeiana) in Brazil were frequently infected with both Ranavirus and helminth macroparasites, so adult bullfrogs could serve as reservoir hosts for both pathogens and parasites. However, many macroparasites collected were encysted and not developing. Coinfection patterns suggest a potential interaction between Ranavirus and macroparasites because helminth abundance increased with bullfrog size but was lower in Ranavirus infected individuals. Future studies of bullfrogs in the Atlantic Forest should investigate their potential role in pathogen and parasite transmission to native anurans.

High prevalence and concomitant infection of Ranavirus and Eustrongylides sp. in the invasive American Bullfrog in Brazil

American Bullfrogs, Aquarana catesbeiana, are invasive anuran species distributed worldwide. One of the adverse impacts that this species causes in native communities is as a reservoir host for pathogens and parasites. Here, we report the coinfection of two pathogenic organisms in A. catesbeiana: Ranavirus and the nematode Eustrongylides. Bullfrogs were collected in the wild in a pond close to the urban area of São Paulo, Brazil. The prevalence of both pathogens was high: 77% were infected with ranavirus with a mean viral load of 1010.3 viral copies, and 100% of the bullfrogs were infected by Eustrongylides sp. with a mean intensity of infection of 13.4 specimens per host. Four host specimens (31%) presented pathological signs that seemed to be related to the Eustrongylides sp. infection, such as internal organs adhered to each other due to high intensity and large size of the nematodes, ulcers, and raw flesh wounds caused by the nematode. The pathogenic and concomitant infections have potential zoonotic implications and raise concerns about human infection risks for Eustrongylides infection. Moreover, such infections may represent an additional level of threat to native communities through the potential shifts in patterns of parasite and pathogen transmission. Future research involving the native anuran community is essential to ascertain whether invasive bullfrogs are attenuating or exacerbating diseases such as ranavirosis and eustrongylidiosis.

Widespread occurrence of the amphibian chytrid panzootic lineage in Uruguay is constrained by climate.

The amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) causes chytridiomycosis, a disease among the main causes of amphibian declines worldwide. However, Bd studies on Neotropical amphibians from temperate areas are scarce. We present a comprehensive survey of Bd in Uruguay, in temperate central eastern South America, carried out between 2006 and 2014. Skin swabs of 535 specimens of 21 native and exotic frogs were tested by PCR. We used individual-level data to examine the relationship between infection, climatic variables, and their effects on body condition and the number of prey items found in stomach contents. Infection was widespread in free-ranging anurans with an overall prevalence of 41.9%, detected in 15 native species, wild American bullfrogs Aquarana catesbeiana, and captive specimens of Ceratophrys ornata and Xenopus laevis. Three haplotypes of the Bd ITS region were identified in native amphibians, all belonging to the global panzootic lineage (BdGPL), of which only one was present in exotic hosts. Despite high infection frequencies in different anurans, we found no evidence of morbidity or mortality attributable to chytridiomycosis, and we observed no discernible impact on body condition or consumed prey. Climatic conditions at the time of our surveys suggested that the chance of infection is associated with monthly mean temperature, mean humidity, and total precipitation. Temperatures below 21°C combined with moderate humidity and pronounced rainfall may increase the likelihood of infection. Multiple haplotypes of BdGPL combined with high frequencies of infection suggest an enzootic pattern in native species, underscoring the need for continued monitoring.

Parasitic helminths of alien invasive anurans in Butuan City, Northeastern Mindanao, Philippines.

This study aimed to identify the helminth parasites of invasive anuran species in selected barangays in Butuan City, Philippines. In urbanized areas, invasive species dominate anuran diversity, and one of the primary threats they pose to native wildlife is the transmission of diseases and parasites. Out of the 91 collected individuals of invasive anuran species, Rhinella marina was the most abundant (88 %), followed by Hoplobatrachus rugulosus (12 %) and Kaloula pulchra (3 %). The study identified five species of parasites, with Spirometra sp. being the most prevalent (17.58 %), followed by Echinostoma sp. (16.5 %), Rhabdias bufonis (14.3 %), Cosmocerca sp. (6.6 %), and Strongyloides stercoralis (3.30 %), respectively. Spirometra sp. also had the highest intensity (7.67), followed by Cosmocerca sp. (5), Strongyloides stercoralis (3.33), Rhabdias bufonis (3.30), and Echinostoma sp. (2.73). This parasitological survey revealed that H. rugulosus had the highest prevalence and infection of parasites, and residential areas had the highest parasite prevalence among the habitat types. Adult hosts were found to harbor a higher prevalence and intensity, and male hosts had a higher prevalence. The results highlight the high risk of parasite transmission from anurans to other animals and emphasize the need for the community to control the population of invasive anuran species for the safety of native anurans and to prevent zoonotic transmission to other animals and humans.

Functional and temporal facets of predation by marsh frogs across the aquatic–terrestrial ecotone of ponds and implications in the context of biological invasions

Abstract Freshwater vertebrate predators can exert trophic control over aquatic and littoral communities. Among these predators, post‐metamorphic anurans exhibit a biphasic trophic spectrum by foraging in both terrestrial and aquatic habitats. Many studies have described their diet through the classical taxonomic classification of prey. However, these singular diet habits imply a complex, time‐dependent, realised trophic niche in which predation pressure occurs over many consumers that fill diverse functional roles throughout the aquatic and terrestrial interface of ponds. Among anurans, marsh frogs (Pelophylax ridibundus) have been introduced outside their range in many countries and are now invading nationwide areas, particularly in western Europe. Focusing on their foraging specificities will therefore further the understanding of the trophic role of these alien taxa in pond environments that are highly colonised. We collected stomach contents from 761 marsh frogs from introduced populations in 19 ponds in southern France once a month over 4 months of their active period in the spring. The populations of marsh frogs were studied in a geographic area that was devoid of native water frogs and their origin tracks back as far as south‐eastern Europe (i.e., more than 1,000 km from the studied sites, as evidenced previously by genetic analyses). Marsh frogs exhibited generalist and opportunistic feeding strategies. The trophic niche was strongly asymmetrical and broader in the terrestrial environment than in the aquatic environment. However, predation occurred in communities of large freshwater macroinvertebrates and amphibians. Whereas the composition of the terrestrial diet exhibited strong seasonal variations, predation pressure was continuously exerted on the same aquatic organisms over time. Primary consumers and consumers at higher trophic levels frequenting aquatic benthic, vegetated, pelagic, and surface microhabitats were preyed upon, underlying the multidimensional extent of the predation spectrum. The diversified feeding strategies of alien marsh frogs highlight the extent of potential ecological control by predation on pond communities. Because of their wide trophic niche, they exert predation pressure on most pond organisms, triggering possible top‐down control of the overall aquatic communities. Our results show that the integration of the functional traits and microhabitats of consumed prey may aid in a better understanding of how predation by anurans may target specific components of pond communities. More particularly, this study raises concerns about the predatory role of introduced anurans in the context of biological invasions.

New Zealand native frogs: a special tribute to honour Phil Bishop (1957–2021) for his dedication and contribution to frog research and conservation

New Zealand native frogs: a special tribute to honour Phil Bishop (1957–2021) for his dedication and contribution to frog research and conservation

A review of New Zealand native frog translocations: lessons learned and future priorities

A review of New Zealand native frog translocations: lessons learned and future priorities

Screening for Batrachochytrium dendrobatidis in New Zealand native frogs: 20 years on

Screening for Batrachochytrium dendrobatidis in New Zealand native frogs: 20 years on

First evidence of environmental bioaccumulation of pharmaceuticals on adult native anurans (Rhinella arenarum) from Argentina

The presence of pharmaceutically active compounds (PhACs) in surface water is well known, whereas their natural occurrence in biota is much less explored. The aim of this work was to evaluate the bioaccumulation of PhACs in adult toads of the neotropical species Rhinella arenarum. Three sites were selected in Buenos Aires (Argentina): a reference site (Site 1), a site with direct discharge from a secondary wastewater treatment plant (WWTP) (Site 2) and a site 300 m downstream of the WWTP discharge (Site 3). Surface water samples, as well as muscle, liver and fat bodies of toads were collected, extracted and analyzed by LC-MS/MS. Highly significant differences in total PhACs concentration in surface water (p < 0.005) were detected between Site 2 and the other sites. These concentrations ranged from 0.37 to 52.46 ng/L at Site 1, 0.71–6950.37 ng/L at Site 2, and 0.12–75.45 ng/L at Site 3. In general, bioaccumulation of PhACs in toad tissues was similar between sites and tissues of each site. The highest concentrations were detected in the muscle of toads from Site 3 (1.06–87.24 ng/g dw), followed by liver (1.77–38.10 ng/g dw) and fat bodies (0.68–20.59 ng/g dw) from Site 1. Ibuprofen (6950 ng/L), acetaminophen (3277 ng/L) and valsartan (2504 ng/L) were the compounds with the highest concentrations in surface water from Site 2, whereas acetaminophen (87.2 ng/g dw, muscle from Site 3), desloratadine (38.1 ng/g dw, liver from Site 1), and phenazone (25.9 ng/g dw, liver from Site 1) were the ones that showed the highest concentrations in biota. This is the first time a field study has examined the environmental bioaccumulation of PhACs in anurans, demonstrating their potential for monitoring the status of natural ecosystems.

Invasion of a non‐native anuran likely disrupts pond ecosystems

Abstract Freshwater ecosystems worldwide are under increasing pressure from multiple threats, including invasive species and climate change, with ponds being particularly vulnerable because of their shallow depth and dynamic hydrology. Australian brown tree frogs Litoria ewingii, introduced to New Zealand in 1875, have spread across both main islands, breeding in a large range of shallow fishless ponds. Since native frogs do not produce aquatic tadpoles, any tadpole influence will be novel, so these ecosystems may be especially vulnerable to such influences. To determine the functional role of L. ewingii tadpoles and to uncover potential effects on pond community structure and function, we conducted two 3‐week‐long mesocosm experiments. The first crossed tadpole presence with predatory invertebrate presence. Mesocosms containing tadpoles had a lower biomass of periphyton and macrophytes, and lower abundance of two families of small‐sized invertebrates (Culicidae and Chironomidae) compared to mesocosms without tadpoles, possibly as a consequence of grazing, predation or reduced dipteran oviposition. However, predatory invertebrates did not affect tadpoles except at their smallest stage, so L. ewingii probably are not subject to strong top‐down control by invertebrates in fishless ponds. We evaluated the effects of tadpole density on ecosystem processes in the second experiment where half the mesocosms also were shaded to simulate permanent pond hydrological status; shading stabilised the temperature fluctuations typical of temporary ponds. In shaded mesocosms tadpole density did not change phytoplankton, whereas in unshaded mesocosms, phytoplankton biomass increased with tadpole density, possibly because tadpole excretion enhanced algal growth in high light conditions. Higher densities of tadpoles also decreased dissolved oxygen concentration regardless of shading during the day—potentially an indirect effect of grazing on macrophytes and periphyton reducing photosynthesis. Overall, these non‐native tadpoles are likely to be having large influences on ecosystem processes such as nutrient cycling in small ponds, especially when at high densities. In light of these potential effects on pond ecosystems, and the generalist traits of these frogs which could see them spread to even remote alpine ponds, control measures to prevent further range expansion should be considered in New Zealand.

Non‐native fish facilitate non‐native snails and alter food web structure in experimental pond communities

Abstract Contemporary ecosystems commonly support multiple non‐native species, which can alter community structure and directly or indirectly interact with one another. Novel interactions between invasive species can result in the facilitation or suppression of one or both invaders, making it important to understand the underlying mechanisms that affect invasion outcomes. Goldfish Carassius auratus and Chinese mystery snails Cipangopaludina chinensis have been introduced widely through the aquarium trade and co‐occur in their non‐native ranges. We used an outdoor mesocosm experiment to assess separate and combined effects of goldfish and mystery snails on urban pond community structure and to investigate whether goldfish and mystery snails affected one another positively, neutrally or negatively. We predicted that the distinct trophic levels of each species and the anti‐predator traits of mystery snails would lead to positive interactions between invaders and synergistic effects on the aquatic community. Goldfish directly increased turbidity and decreased filamentous algae, zooplankton, juvenile native snails and survival of amphibians via consumptive effects. Goldfish indirectly increased periphyton, phytoplankton and body size of surviving native green frogs Lithobates clamitans through trophic cascades and/or release from competition. Mystery snails had more subtle effects including reducing growth rates of native grey tree frogs Hyla versicolor, likely through competitive interactions. With goldfish present, mystery snails showed increased reproductive success (higher biomass of juveniles), likely due to indirect competitive release from other herbivores. In contrast to their effects on native snails, goldfish did not consume juvenile mystery snails, likely due to their unique traits (e.g. large size and shell thickness). Mystery snails slightly reduced goldfish growth but did not affect their survival. These results suggest unidirectional facilitation between invaders via indirect changes in the food web. Overall, our study found strong direct and indirect effects of invasive aquarium species, particularly goldfish, and provides experimental support for the invasional meltdown hypothesis within urban waterbodies, which are especially prone to invasions. Read the free Plain Language Summary for this article on the Journal blog.

Diversification dynamics in Caribbean rain frogs (Eleutherodactylus) are uncoupled from the anuran community and consistent with adaptive radiation.

Adaptive radiation is proposed to play a key role in generating differences in species richness among lineages and geographical regions. Due to the importance of ecological divergence in adaptive radiation, species richness is predicted to be influenced by equilibrium diversity dynamics, although the concept continues to generate much debate. An additional important question is whether radiating clades have intrinsic biological characteristics that make them particularly prone to diversify. We tackle these questions by analysing (i) the temporal patterns of diversification of Caribbean Eleutherodactylus frogs, and (ii) assembly of the complete native anuran community of the Caribbean archipelago (197 species), testing for the presence of equilibrium dynamics and whether diversification patterns of Eleutherodactylus differ from those of the rest of the Caribbean anurans. Diversification rates follow the predicted pattern of rapid diversification early in the radiation which gradually decreases towards the present. Eleutherodactylus diversification is significantly faster than that of the Caribbean anuran community, and although equilibrium dynamics influence richness of all Caribbean anurans, Eleutherodactylus shows higher carrying capacity. Our results indicate that ecological opportunity per se is not sufficient for adaptive radiation and that diverse lineages present intrinsic characteristics that enable them to make the most of available opportunity.

American bullfrog (Lithobates catesbeianus) distribution, impact on native amphibians and management priorities in San Carlos, Uruguay

Biological invasions are a major cause of biodiversity and ecosystem services loss. However, information on distribution and impacts is limited for many alien species, restricting the development of local management measures. The aim of this study is: to identify the current situation of the American bullfrog (Lithobates catesbeianus) invasion focus in San Carlos (Maldonado, Uruguay); to evaluate its impacts on native anurans; and to provide management tools. Between 2017 and 2019, 75 permanent ponds were sampled, finding an expanding bullfrog population (occupying 32 ponds, in 16.5 km2). Results show that native anuran richness was lower in the invaded ponds. Observed impacts were greater for the aquatic frogPseudis minuta, probably due to greater encounter rates with the invader. The abundance of tadpoles was also lower in the invaded ponds. The local pond network was explored using graph theory, evaluating its topological role and centrality. In this network, a list of priority ponds was generated to prevent local bullfrog expansion. Given the relatively small size of this population, eradication seems feasible. Focusing on the key nodes could prevent further expansion, by using spatial prioritization to organize the recommended management of the pond network.