Treefrog Species Research Articles

The introduction of three cryptic tree frog species in the Dutch coastal dunes challenges conservation paradigms

Abstract Invasive species are considered one of the main drivers of the sixth mass extinction. Conservation solutions depend on whether a species is also indigenous to the country it invades (i.e., beyond its native range). In the case of invasive cryptic species, genetic tools are required to establish their identity. We illustrate these issues with the human-mediated colonization of the Dutch coastal dunes by Hyla tree frogs. Although previously assumed to concern the indigenous common tree frog H. arborea, European tree frogs comprise a complex of allopatric cryptic species, meaning the taxonomic identity of introduced Dutch populations warrants investigation. We sequence mtDNA for 173 individuals from native and introduced populations across the Netherlands and compare our dataset with hundreds of Hyla haplotypes previously barcoded in the Western Palearctic. Two of the dune populations carry an mtDNA haplotype of the native species H. arborea that occurs naturally elsewhere in the Netherlands. In contrast, mtDNA assigned to the eastern tree frog H. orientalis was detected in all three other dune populations. In one of these populations mtDNA of the Italian tree frog H. intermedia was also found. Not one, but three species of tree frogs have thus been introduced to the Dutch coastal dunes, only one of them being native to the Netherlands. This situation causes a conservation conundrum as some introduced populations are lawfully protected but could pose a threat to local biodiversity. Regarding the ‘true’ exotic tree frog species, all conservation options should be considered.

A new species of insular treefrog in the Litoria thesaurensis species group from the Nakanai Mountains, New Britain, Papua New Guinea

The Islands of East Melanesia have a unique and highly endemic frog fauna derived entirely from overseas colonisation events. Within East Melanesia New Britain is a notable centre of frog diversity and endemism, with at least 15 endemic species, mostly in the ceratobatrachid genus Cornufer. Here we describe the first endemic pelodryadid treefrog from New Britain. The new species is a member of the Litoria thesaurensis species group but can be distinguished from near relatives by aspects of body size, webbing extent, bone pigmentation and male advertisement call. The two known specimens of the new species were collected in Hill Forest on karst basement in the Nakanai Mountains in East New Britain. The new species provides new evidence of diversification of insular PelodrydidaePelodrydidae, and reinforces New Britain, and especially the predominantly karst Nakanai mountains, as a hotspot of frog diversity in East Melanesia. In light of high rates of forest loss and conversion New Britain is also a region of significant conservation concern.

STAGES OF DEVELOPMENT AND METAMORPHOSIS OF TREE FROG POLYPEDATES LEUCOMYSTAX (AMPHIBIA, Rhacophoridae)

Most anurans have complex life cycles involving egg fertilization, embryo and larval development in aquatic habitats. Detailed descriptions of the ontogeny of embryonic, larval metamorphic and post metamorphic frogs are important for understanding the general patterns of development of representative taxa and, by comparisons of different patterns for resolving questions about systematic relationships. For anurans, staging tables are a condensed way of describing ontogenetic changes. Appropriate staging of the larval period, is therefore, fundamental to various life history studies of amphibians suggested that complete tables of development are necessary for accurate comparison of developmental stages in different organisms. Hence, tables of normal stages of development have been worked out for a number of species by several workers. Findings of the present study indicate that under natural environment as well as in the laboratory condition, the development and metamorphosis of Polypedates leucomystax was completed in about 60 – 61 days. This tree frog was observed to be dependent on the ephemeral pools at the breeding sites to complete their life cycle. The duration of development and metamorphosis of this tree frog seems to be similar to the other species of tree frog.

Influence of landscape and connectivity on anuran conservation: population viability analyses to designate protected areas

AbstractThreatened species with restricted ranges are at risk from habitat fragmentation and loss, which amplifies genetic bottleneck and impacts of small changes to their environments. Ecological models including population viability analyses (PVAs) can predict the trajectory of populations in a way that is not invasive or detrimental to the study species. They can therefore be a vital tool in modeling populations for conservation purposes. Although habitat suitability models have been used in studies to suggest areas for protected area designation, PVAs are generally not used in this regard.Dryophytes suweonensisandDryophytes flaviventrisare two threatened treefrog species endemic to the Korean Peninsula. The two species face threats of habitat loss and degradation and predation by invasive species among others. We used an integrated modeling approach combining ecological niche, connectivity, and PVAs in Vortex to determine the likelihood of extinction of each species under baseline and protected area designation scenarios. Designation scenarios were simulated in Vortex through halting future reduction in carrying capacity (halting future degradation to sites through protected area status), reducing effects of catastrophes (mitigating the effects of drought), and reducing mortality rates (controlling invasive predator populations and ex situ raising of tadpoles to maturity). We classified the combination of these management efforts as “active management” as opposed to “no management,” which is currently being practiced. We additionally used a stepwise approach to determine designation priority of individual patches. Under current conditions (no management), the resulting effective metapopulations after 100 years were 167 ± 325 individuals with an 86.5% extinction probability forD. suweonensisand 165 ± 200 individuals with a 90.3% extinction probability forD. flaviventris. Under active management of all sites (93 sites covering 426.9 km2), the extinction probability was 0% for both species with significantly increased metapopulation sizes, 15 910 ± 2855 forD. suweonensis, and 4400 ± 874 forD. flaviventris. Determining designation priority can inform the regulatory bodies on which habitat to designate and whether active or passive management should be applied. Without intervention, these species will be likely to face imminent extinction. In addition to being useful for government‐imposed conservation management, our study can be followed by future studies as a methodology for prioritizing sites for protected area designation.

Diversity and Sexual Dichromatism in Treefrog Throat Coloration: Potential Signal Function?

Sexual dichromatism, where males and females of the same species differ in coloration, is best studied in diurnal animals. Nocturnal animals such as frogs do not seem good candidates for widespread sexual dichromatism, or for the use of visual signals in social communication in general. Yet, up to 25% of treefrog species (Anura: Hylidae) show some degree of sexual difference in their dorsal coloration. The ventral side of frogs is hidden during rest, but the throat region becomes visible in active individuals, especially in calling males. We compiled a database of 249 treefrog species that include members of all seven subfamilies of the Family Hylidae. We document that the throat region of male frogs is frequently colorful and of a different color than the abdomen (ventral dichromatism), that there is interspecific variation in throat coloration, and that males and females differ in throat coloration (sexual dichromatism). We also examined intraspecific variation in throat coloration, using Eastern Gray Treefrogs, Dryophytes versicolor (Hyla versicolor) as the focal species. Here, we document throat color is sexually dimorphic, that it varies among males, is associated with better body condition, and on average is darker in mated compared to unmated males. Our study finds that throat color dichromatism is the most prevalent type of sexual dichromatism in treefrogs, and that throat coloration may have sexual signal function.

Noise affects mate choice based on visual information via cross-sensory interference

Animal communication is often hampered by noise interference. Noise masking has primarily been studied in terms of its unimodal effect on sound information provision and use, while little is known about its cross-modal effect and how animals weigh unimodal and multimodal courtship cues in noisy environments. Here, we examined the cross-modal effects of background noise on female visual perception of mate choice and female preference for multimodal displays (sound + vocal sac) in a species of treefrog. We tested female mate choices using audio/video playbacks in the presence and absence of noise (white noise band-filtered to match or mismatch female sensitive hearing range, heterospecific chorus). Surprisingly, multimodal displays do not improve receiver performance in noise. The heterospecific chorus and white noise band-filtered to match female sensitive hearing ranges, significantly reduced female responses to the attractive visual stimuli in addition to directly impairing auditory information use. Meanwhile, the cross-modal impacts of background noise are influenced to some extent by whether the noise band matches female sensitive hearing range and the difficulty of distinguishing tasks. Our results add to the evidence for cross-modal effects of noise and are the first to demonstrate that background noise can disrupt female responses to visual information related to mate choice, which may reduce the communication efficiency of audiovisual signals in noisy environments and impose fitness consequences. This study has key ecological and evolutionary implications because it illustrates how noise influences mate choice in wildlife via cross-sensory interference, which is crucial in revealing the function and evolution of multimodal signals in noisy environments as well as informing evidence-based conservation strategies for forecasting and mitigating the multimodal impacts of noise interference on wildlife.

On the occurrence of Scinax kennedyi (Pyburn, 1973) (Anura, Hylidae) in the state of Roraima, northern Brazil

Scinax comprises 129 species of treefrogs divided between the S. ruber and the S. catharinae clades. The S. rostratus group belongs to the S. ruber clade, and comprises ten species characterized by having a dark interorbital triangular mark, tubercle on the heel and by vocalizing in a head-down position. Within this group, S. kennedyi and S. rostratus are similar in that they are the only species that do not possess a row of tubercles on the lower jaw. In spite of their morphological similarity, they can be distinguished from each other by male size and advertisement call traits. Scinax kennedyi was described from eastern Colombia, and occurs from central Colombia to western Venezuela, whereas S. rostratus was described from northern Venezuela, and is thought to occur from Panama to eastern Venezuela, and in the Brazilian state of Pará. A recent study reported a population identified as S. rostratus from the state of Roraima, in northern Brazil. However, this population presented substantial differences in male size and advertisement call in comparison to the described for this species, and apparently it best fits the diagnosis of S. kennedyi instead. In view of this, the present study aimed to clarify the identity of this Brazilian population through a reassessment of its specimens and call recordings, together with the examination of data of S. kennedyi from its type locality, and of S. rostratus from northern Venezuela. Acoustic and morphological analyses revealed that specimens from northern Brazil were indeed misidentified as S. rostratus, and hence they were herein reassigned to S. kennedyi. The study therefore demonstrates the occurrence of S. kennedyi in Brazil, extending its distribution ca. 1,120 km east by south from its type locality, and ca. 844 km east-southeast from its easternmost previous record. With this reassessment, a clearer acoustic diagnosis between S. kennedyi and S. rostratus was provided, as well as further data on fine-scale temporal traits of their calls.

Phylogenetic analysis of adaptation in comparative physiology and biomechanics: overview and a case study of thermal physiology in treefrogs.

Comparative phylogenetic studies of adaptation are uncommon in biomechanics and physiology. Such studies require data collection from many species, a challenge when this is experimentally intensive. Moreover, researchers struggle to employ the most biologically appropriate phylogenetic tools for identifying adaptive evolution. Here, we detail an established but greatly underutilized phylogenetic comparative framework - the Ornstein-Uhlenbeck process - that explicitly models long-term adaptation. We discuss challenges in implementing and interpreting the model, and we outline potential solutions. We demonstrate use of the model through studying the evolution of thermal physiology in treefrogs. Frogs of the family Hylidae have twice colonized the temperate zone from the tropics, and such colonization likely involved a fundamental change in physiology due to colder and more seasonal temperatures. However, which traits changed to allow colonization is unclear. We measured cold tolerance and characterized thermal performance curves in jumping for 12 species of treefrogs distributed from the Neotropics to temperate North America. We then conducted phylogenetic comparative analyses to examine how tolerances and performance curves evolved and to test whether that evolution was adaptive. We found that tolerance to low temperatures increased with the transition to the temperate zone. In contrast, jumping well at colder temperatures was unrelated to biogeography and thus did not adapt during dispersal. Overall, our study shows how comparative phylogenetic methods can be leveraged in biomechanics and physiology to test the evolutionary drivers of variation among species.

Positive-to-negative behavioural responses suggest hedonic evaluation in treefrog mate choice.

Sexual competition hinges on the ability to impress other conspecifics, to drive them away or attract them. In such cases, the selective environment may be hedonic or affective in nature, as it consists of the evaluations of the individuals making the decisions. This may contribute to the power of sexual selection because evaluations may range from positive to negative rather than simply from positive to neutral. Selection due to mate choice may therefore be stronger than currently appreciated. Further, change in preferred mate types can occur simply by changes (flips) in the evaluation of similar display features, adding to the dynamism of sexual selection as well as its strength. We tested the hypothesis of positive-to-negative behavioural responses in mate choice with a playback experiment using two treefrog species with 'mirror image' structures in their advertisement and aggressive calls. Female treefrog responses ranged from approach to evasion, and the presence of an aversive stimulus tainted evaluation of an attractive stimulus. Further, females in the two species showed flips in approach/evasion of stimuli with comparable signal structure. These results suggest that hedonic evaluation may have an important role in mate choice and showcase how mechanistic analysis can help understand evolutionary processes.

Morphometry of two cryptic tree frog species at their hybrid zone reveals neither intermediate nor transgressive morphotypes.

Under incomplete reproductive isolation, secondary contact of diverged allopatric lineages may lead to the formation of hybrid zones that allow to study recombinants over several generations as excellent systems of genomic interactions resulting from the evolutionary forces acting on certain genes and phenotypes. Hybrid phenotypes may either exhibit intermediacy or, alternatively, transgressive traits, which exceed the extremes of their parents due to epistasis and segregation of complementary alleles. While transgressive morphotypes have been examined in fish, reptiles, birds, and mammals, studies in amphibians are rare. Here, we associate microsatellite‐based genotypes with morphometrics‐based morphotypes of two tree frog species of the Hyla arborea group, sampled across a hybrid zone in Poland, to understand whether the genetically differentiated parental species also differ in morphology between each other and their hybrids and whether secondary contact leads to the evolution of intermediate or transgressive morphotypes. Using univariate approaches, explorative multivariate methods (principal component analyses) as well as techniques with prior grouping (discriminant function analyses), we find that morphotypes of both parental species and hybrids differ from each other. Importantly, hybrid morphotypes are neither intermediate nor transgressive but found to be more similar to H. orientalis than to H. arborea.

Neural basis of acoustic species recognition in a cryptic species complex.

Sexual traits that promote species recognition are important drivers of reproductive isolation, especially among closely related species. Identifying neural processes that shape species differences in recognition is crucial for understanding the causal mechanisms of reproductive isolation. Temporal patterns are salient features of sexual signals that are widely used in species recognition by several taxa, including anurans. Recent advances in our understanding of temporal processing by the anuran auditory system provide an opportunity to investigate the neural basis of species-specific recognition. The anuran inferior colliculus consists of neurons that are selective for temporal features of calls. Of potential relevance are auditory neurons known as interval-counting neurons (ICNs) that are often selective for the pulse rate of conspecific advertisement calls. Here, we tested the hypothesis that ICNs mediate acoustic species recognition by exploiting the known differences in temporal selectivity in two cryptic species of gray treefrog (Hyla chrysoscelis and Hyla versicolor). We examined the extent to which the threshold number of pulses required to elicit behavioral responses from females and neural responses from ICNs was similar within each species but potentially different between the two species. In support of our hypothesis, we found that a species difference in behavioral pulse number thresholds closely matched the species difference in neural pulse number thresholds. However, this relationship held only for ICNs that exhibited band-pass tuning for conspecific pulse rates. Together, these findings suggest that differences in temporal processing of a subset of ICNs provide a mechanistic explanation for reproductive isolation between two cryptic treefrog species.

Assessing Suitable Habitats for Treefrog Species after Previous Declines in Costa Rica

Treefrogs represent 22% of amphibian species in Costa Rica, but gaps in the knowledge about this group of amphibians can impede conservation efforts. In this study, we first updated the status of Costa Rican treefrogs and found that a total of 38% of treefrog species are threatened according to the most recent IUCN assessment in 2019. Additionally, 21% of Costa Rican treefrog species have a high vulnerability to extinction according to environmental vulnerability scores. Then, we predicted the historical climatic suitability of eight target species that we expected to have exhibited changes in their ranges in the last 20 years. We assessed the location of new occurrence records since 2000 to identify recovery, range expansion, or previously underestimated ranges due to methodological limitations. We also estimated the area of each species’ suitable habitat with two metrics: extent of suitable habitat (ESH) and area of minimum convex polygon (AMCP). Six declined species exhibited recovery (i.e., new occurrences across historical range after 2000), with the widest recovery found in Agalychnis annae. We also found that Isthmohyla pseudopuma appears to have spread after the decline of sympatric species and that the range of I. sukia was originally underestimated due to inadequate detection. We found that the ESH was 32–49% smaller than the AMCP for species that are slowly recovering; however, the ESH is similar or greater than the AMCP for species that are recovering in most of their ranges, as well as rare species with widespread ranges. Results of this work can be used to evaluate the risk of environmental threats and prioritize regions for conservation purposes.

Treefrogs near the top of a tropical rainforest

In May 2019, during a routine canopy survey near the National Forest Ecosystem Research Station at Xishuangbanna, in southwest China, an Asian black-webbed treefrog (Rhacophorus kio) was observed resting on a canopy leaf of a flowering Parashorea chinensis tree (right). The same species was observed again in October 2019, only this time the treefrog was perched on an epiphyte (Microsorum punctatum) at the crown of an adult P chinensis tree (left). The heights of these particular dipterocarp trees were approximately 62 m, and these two frogs were observed at 57.0 m and 34.6 m, respectively, as measured via canopy cranes – far exceeding the maximum vertical height previously recorded (20.5 m for Hyla versicolor) (Ecology 2017; https://doi.org/10.1002/ecy.1843). To the best of our knowledge, these images likely document the highest arboreal frogs that have ever been photographed. It is uncommon to observe frog species in the emergent (top) layer of a tropical rainforest, for a few reasons. For starters, P chinensis is considered one of the tallest tree species in China, capable of growing up to 80 m, which is too high for an amphibian to climb. The relatively hot and dry conditions of the typical canopy habitat also seem unsuitable for amphibians. Furthermore, members of this treefrog species likely rely on foliage to protect themselves from predators and physical exposure, which also effectively conceals them from human observers. Thanks to the development of forest canopy science, biodiversity within the canopy layer, which has been largely overlooked in previous decades, can now be studied more effectively. We suspect that R kio may be attracted to food resources (mainly insects) during the flowering season in the emergent layer. If this is so, how many other amphibian species may be found in the canopy layer? And how are worldwide declines in large trees due to deforestation, habitat fragmentation, and climate change influencing the populations of frog species?

Giant Tree Frog diversification in West and Central Africa: Isolation by physical barriers, climate, and reproductive traits.

Secondary sympatry amongst sister lineages is strongly associated with genetic and ecological divergence. This pattern suggests that for closely related species to coexist in secondary sympatry, they must accumulate differences in traits that mediate ecological and/or reproductive isolation. Here, we characterized inter- and intraspecific divergence in three giant tree frog species whose distributions stretch across West and Central Africa. Using genome-wide single-nucleotide polymorphism data, we demonstrated that species-level divergence coincides temporally and geographically with a period of large-scale forest fragmentation during the late Pliocene. Our environmental niche models further supported a dynamic history of climatic suitability and stability, and indicated that all three species occupy distinct environmental niches. We found modest morphological differentiation amongst the species with significant divergence in tympanum diameter and male advertisement call. In addition, we confirmed that two species occur in secondary sympatry in Central Africa but found no evidence of hybridization. These patterns support the hypothesis that cycles of genetic exchange and isolation across West and Central Africa have contributed to globally significant biodiversity. Furthermore, divergence in both ecology and reproductive traits appear to have played important roles in maintaining distinct lineages. At the intraspecific level, we found that climatic refugia, precipitation gradients, marine incursions, and potentially riverine barriers generated phylogeographic structure throughout the Pleistocene and into the Holocene. Further studies examining phenotypic divergence and secondary contact amongst these geographically structured populations may demonstrate how smaller scale and more recent biogeographic barriers contribute to regional diversification.

Multi‐Species Occupancy Modeling Provides Novel Insights into Amphibian Metacommunity Structure and Wetland Restoration

A fundamental goal of community ecology is to understand species-habitat relationships and how they shape metacommunity structure. Recent advances in occupancy modeling enable habitat relationships to be assessed for both common and rare species within metacommunities using multi-species occupancy models (MSOM). These models account for imperfect species detection and offer considerable advantages over other analytical tools commonly used for community analyses under the elements of metacommunity structure (EMS) framework. Here, we demonstrate that MSOM can be used to infer habitat relationships and test metacommunity theory, using amphibians. Repeated frog surveys were undertaken at 55 wetland sites in southeastern Australia. We detected 11 frog species from three families (Limnodynastidae, Myobatrachidae, and Pelodryadidae). The rarest species was detected at only one site whereas the most common species was detected at 42 sites (naive occupancy rate 0.02-0.76). Two models were assessed representing two competing hypotheses; the best-supported model included the covariates distance to the nearest site (connectivity), wetland area, presence of the non-native eastern mosquitofish (Gambusia holbrooki), proportion cover of emergent vegetation, an interaction term between Gambusia and emergent vegetation cover, and the proportion canopy cover over a site. Hydroperiod played no detectable role in metacommunity structure. We found species-habitat relationships that fit with current metacommunity theory: occupancy increased with wetland area and connectivity. There was a strong negative relationship between occupancy and the presence of predatory Gambusia, and a positive interaction between Gambusia and emergent vegetation. The presence of canopy cover strongly increased occupancy for several tree frog species, highlighting the importance of terrestrial habitat for amphibian community structure. We demonstrated how responses by amphibians to environmental covariates at the species level can be linked to occupancy patterns at the metacommunity scale. Our results have clear management implications: wetland restoration projects for amphibians and likely other taxa should maximize wetland area and connectivity, establish partial canopy cover, and eradicate Gambusia or provide aquatic vegetation to mitigate the impact of this non-native fish. We strongly advocate the use of MSOM to elucidate the habitat drivers behind animal occupancy patterns and to derive unbiased occupancy estimates for monitoring programs.

Gynogenetic diploids, tetraploids, or octoploids, and a path to polyploidy in anuran amphibians.

Unreduced gametes have been implicated in the evolution of polyploid species of plants and animals and are normally produced by female anuran amphibians. Such eggs may initiate the evolution of polyploid species that have arisen independently in several anuran families. Polyploid females could also produce unreduced eggs that might lead to species with higher ploidy levels, or their eggs may develop gynogenetically to reduce the ploidy level. Diploid Hyla chrysoscelis (2n = 24) and tetraploid H. versicolor (4n = 48) are sibling cryptic species of North American grey treefrogs. Artificial crosses using H. versicolor females and genetically distant diploid males were performed to produce haploid H. versicolor and to assess the production of unreduced eggs in this tetraploid species. Gynogenetic diploid (haploid H. versicolor), allotriploid, gynogenetic tetraploid, allopentaploid, autohexaploid, and gynogenetic octoploid tadpoles were confirmed using chromosome counts from tadpole tail tip squashes. The transformation and survival of different ploidies varied. Gynogenetic diploids transformed but expressed aspects of haploid syndrome and died before or shortly after transformation.

Seasonal Habitat Preferences and Response to Water Quality Parameters of Tree Frog Species in a Neotropical Wetland

Seasonal Habitat Preferences and Response to Water Quality Parameters of Tree Frog Species in a Neotropical Wetland

Advertisement call of two Liuixalus species (Anura: Rhacophoridae) endemic to Hainan Island, China

Advertisement calls potentially represent honest signals for delimiting species and sexual selection. Quantitative statistics of individual variation in advertisement call properties can be used to predict female preferences for particular signal properties. In this study, advertisement call properties and their individual variation was analyzed in two endemic treefrog species, Liuixalus hainanus and L. ocellatus. Together with the description of the advertisement calls, our goals included determining whether call properties can be used to distinguish between the two species on the field, which acoustic properties are likely play a role in species or individual recognition, and whether they could predict the signaler’s body size. We found that the dominant frequency, call duration, inter-call interval, and note number of monosyllabic calls in L. hainanus were significantly higher or longer than those in L. ocellatus. The dominant frequency was classified as a static property; the call duration, inter-call interval, inter-note interval, and note number were classified as dynamic properties in both species. The inter-note interval of multisyllabic calls was correlated with body mass, and the pulse number of monosyllabic calls was correlated with snout-vent length in L. ocellatus. These results indicate that the dominant frequency strongly contributed to species recognition of L. hainanus and L. ocellatus males. Acoustic properties reflected the signaler’s body size in L. ocellatus but did not in L. hainanus. The difference in advertisement call characteristics between the two species may be due to the different reproductive strategies associated with different selection pressures and may promote the sharing of similar habitats by the two species.

The importance of determining species sensitivity to environmental change: a tree frog example

AbstractConservation schemes typically place species into categories, ranging roughly from rare to common or from vulnerable to least concern. Although a species may not be categorized as rare or vulnerable, it still may be sensitive to environmental change and, therefore, at risk of decline. To illustrate the importance of determining species sensitivity, we documented the relative sensitivities of four species of tree frogs, none of which have been designated particularly rare or vulnerable, to environmental change. Our research was conducted in central Florida, where prior research had suggested that Dryophytes femoralis and Dryophytes gratiosus were more sensitive to environmental change than Dryophytes cinereus and Dryophytes squirellus. A comparison of species characteristics and a field study of local abundances supported the dichotomy. Particularly, important environmental factors affecting the two more‐sensitive species adversely appear to be habitat selectivity, at a smaller scale, and nearness to the species’ southern range limits, at a larger scale. We suspected that one of the more‐sensitive species, D. gratiosus, is particularly sensitive to environmental change and that the cause is related to reproduction and/or growth. A series of laboratory analyses suggested strongly that the realized production of adults was less for D. gratiosus than for D. femoralis. Despite their identical placement in categorization schemes, the four species exhibited substantial differences in sensitivity to environmental change. A strong case can be made that the degree of sensitivity of D. gratiosus warrants increased conservation attention for the species. Our results indicate the potential value of field work and the generation of species‐specific information in improving categorization schemes, of broadening the categorization criteria typically employed, to accommodate sensitivity to environmental change, and of considering geographical scale in categorization schemes more than is done at present.

Diet of a bromeligenous species of treefrog in the Brazilian semiarid.

Phyllodytes tuberculosus is a bromeligenous anuran species whose geographic distribution is restricted to areas of the Caatinga and to transition zones between Caatinga and Atlantic Forest in the central-south of the state of Bahia. Its existence in close relationship with bromeliads and its occurrence in dry and highly seasonal environments drove us to the supposition that species is opportunistic/generalist regard to diet. We collected the items present in the stomach of 43 P. tuberculosus individuals with stomach-flushing method. Of these, 18 stomach contents were obtained during the dry period (April-October), and 25 during the rainy period (November-March). We recorded nine classes of prey, finding the greatest relative importance for the categories Formicidae and Coleoptera in dry season and Blattodea (Termites), Formicidae and Coleoptera in the rainy season. Phyllodytes tuberculosus presented a varied, possibly opportunistic diet in semiarid environments. Additionally, we report an apparent temporal differentiation related to the typical Caatinga seasonality. This study adds to the data on the natural history of an anuran species adapted to a semiarid environment with a narrow geographic distribution.