Torrent Frog Research Articles

Snake-like bird hisses induce anti-predator responses in a frog

Some snakes emit hissing calls which are imitated by birds to deter potential predators. However, the effect of these snake and bird hisses on anuran risk recognition is not yet explored. Here we hypothesize that these hisses may advertise dangers to frogs and evoke their anti-predator responses. We used little torrent frogs (Amolops torrentis) as subjects and conducted sound playbacks to test their anti-predator behaviors. We found that little torrent frogs changed their calling behaviors during sympatric snake hiss playbacks, but showed no response to white noise and allopatric snake hiss playbacks. They did not respond to sympatric avian hiss that has low acoustic similarity with snake sounds. However, they decreased calling activity in response to sympatric avian hiss that has high acoustic similarity with snakes. As compared to other treatments, more individuals ceased calling during the playbacks of the highly similar bird hiss. These results suggest that frogs may recognize risks from snake and snake-like hissing calls and perform anti-predator responses.

Goal-directed bodily signals in birds and frogs.

Researchers have recently described the wing-fluttering signal of Japanese tits and eyeblink signal of concave-eared torrent frogs as bodily communication that elicits specific responses. I assess the evidence that these may be intentional, goal-directed signals using established criteria for gestural communication.

A new species of the genus Amolops (Amphibia: Ranidae) and the first national record of Amolops vitreus from China

Abstract The torrent frogs of the genus Amolops represent a great anuran diversification in southern China and Southeast Asia. Previous studies have shown that, the diversity of this genus still remains underestimated. During herpetological surveys from 2021 to 2022, several Amolops specimens were collected from the international border regions of southwestern Yunnan Province, China. Herein, we utilized molecular phylogenetic and morphological data to identify these specimens. Our findings indicate the presence of a separate and previously unknown lineage in the A. viridimaculatus group, which we formally describe as a new species. Furthermore, the specimen from Xishuangbanna National Nature Reserve clustered with A. vitreus from the paratype, supporting the morphological diagnosis. Therefore, we describe a new species and a new species record for China. Our study contributes to the species richness of the genus Amolops as well as the diversity of amphibians in China. Notably, our discovery brings the total number of Amolops species to 85 and the total number of torrent frog species known to occur in China to 53. In addition, our study further confirmed that Yunnan and Indochina Peninsula have similar faunal composition, implying that more studies are needed to achieve a complete understanding of the species diversity and distribution pattern.

Female frogs communicate with males through blinking

Blinking is a behavior unique to animal taxa with motile eyelids, such as most amphibians and reptiles as well as all birds and mammals1. Eyelid movement has physiological functions, such as lubricating the cornea and washing away dust, but its potential signaling functions are not well understood1,2. The use of eyeblinks as a social signal is currently thought to be restricted to some primates, especially humans and their companion animals, but has not been verified in other taxa1,3,4. Here, through field observation and experiments, we demonstrate that female concave-eared torrent frogs (Odorrana tormota), which inhabit noisy streams, use eyeblinks to communicate with males to urge them to initiate amplexus for mating. Our findings reveal that eyeblinks may serve as a social signal in non-primate species.

A new species of Amolops (Amphibia, Anura, Ranidae) from Guizhou Province, China.

The Torrent frogs of the genus Amolops are widely distributed in Nepal and northern India eastwards to southern China and southwards to Malaysia. The genus currently contains 84 species. Previous studies indicated underestimated species diversity in the genus. In the context, a new species occurring from the mountains in the northwestern Guizhou Province, China is found and described based on morphological comparisons and molecular phylogenetic analyses, Amolopsdafangensissp. nov. Phylogenetic analyses based on DNA sequences of the mitochondrial 16S rRNA and COI genes supported the new species as an independent lineage. The uncorrected genetic distances between the 16S rRNA and COI genes in the new species and its closest congener were 0.7% and 2.6%, respectively, which are higher than or at the same level as those among many pairs of congeners. Morphologically, the new species can be distinguished from its congeners by a combination of the following characters: body size moderate (SVL 43.2-46.8 mm in males); head length larger than head width slightly; tympanum distinct, oval; vocal sacs absent; vomerine teeth present; dorsolateral folds weak formed by series of glands; nuptial pads present on the base of finger I; heels overlapping when thighs are positioned at right angles to the body; tibiotarsal articulation reaching the level far beyond the tip of the snout when leg stretched forward.

Movement or plasticity: acoustic responses of a torrent frog to stream geophony

Abstract Vocalization is the main form of communication in many animals, including frogs, which commonly emit advertisement calls to attract females and maintain spacing. In noisy environments such as streams, mechanisms to maximize signaling efficiency may include vocal plasticity and/or movement of individuals to quieter sections, but which strategy is used is still uncertain. We investigated the influence of stream geophony on the advertisement call of the torrent frog Hylodes perere in the Atlantic Rainforest, in southeastern Brazil. In a mark-recapture study, we tested if males remain in their territories and thus adjust their advertisement calls to maximize their communication. We ran linear mixed models to verify the relationship of call parameters and stream geophony, body size, and environmental temperature. We found that males remained in the same location across time, increased call intensity in noisier environments, but did not reduce call effort. Males also increased the dominant frequency in these situations, suggesting a modulation in this parameter. Our results indicate that territoriality is an important factor for males to increase call intensity to surpass stream noise instead of repositioning along the stream. However, because call effort was maintained, we suggest that sexual selection is crucial in this system, favoring males that better detect others and adjust their call efficiency. This is the first study to evaluate simultaneously frog movements and adaptations to geophony, which contributes to the investigation of the concomitant environmental and sexual selective pressures in species that communicate in noisy environments.

Progressive Design of a Ranatuerin-2 Peptide from Amolops wuyiensis: Enhancement of Bioactivity and In Vivo Efficacy.

Antimicrobial peptides (AMPs) that exert multiple functions are considered promising candidates to combat the bacterial drug resistance crisis. Nowadays, targeted peptide modification has been widely recognised to improve biological activity and make up for deficiencies in clinical applications such as toxicity. In this study, a helix-loop peptide was isolated and identified from the skin secretion of the Wuyi torrent frog Amolops wuyiensis, namely, ranatuerin-2-AW (R2AW) (GFMDTAKNVAKNVAATLLDKLKCKITGGC). Target modifications were made to R2AW to study the structure-activity relationships and to optimise its bioactivities. Five analogues were progressively designed via residue substitution and truncation and the antibacterial and anticancer activities were evaluated. We found that the serine-substitution and cyclic-domain-deletion products showed similar antibacterial activity to the natural peptide R2AW, implying that the disulphide bridge and Rana box were dispensable for the antibacterial activity of ranatuerin-2 peptides. Notably, the cationicity- and hydrophobicity-enhanced variant, [Lys4,19, Leu20]R2AW(1-22)-NH2, exhibited significantly optimised antibacterial and anticancer activities. Additionally, it killed bacteria by membrane disruption at a highly efficient rate. Moreover, [Lys4,19, Leu20]R2AW(1-22)-NH2 exerted potential in vivo efficacy in a methicillin-resistant Staphylococcus aureus (MRSA)-infected waxworm model. Overall, this study demonstrated some rational design ideas for optimising the dual antibacterial and anticancer activities of ranatuerin-2 peptides and it proposes [Lys4,19, Leu20]R2AW(1-22)-NH2 as an appealing candidate for therapeutic development.

Comment on 'Parasite defensive limb movements enhance acoustic signal attraction in male little torrent frogs'.

Zhao et al. recently reported results which, they claim, suggest that sexual selection produces the multimodal displays seen in little torrent frogs (Amolops torrentis) by co-opting limb movements that originally evolved to support parasite defense (Zhao et al., 2022). Here, we explain why we believe this conclusion to be premature.

Response to comment on 'Parasite defensive limb movements enhance acoustic signal attraction in male little torrent frogs'.

Recently we showed that limb movements associated with anti-parasite defenses can enhance acoustic signal attraction in male little torrent frogs (Amolops torrentis), which suggests a potential pathway for physical movements to become co-opted into mating displays (Zhao et al., 2022). Anderson et al. argue for alternative explanations of our results and provide a reanalysis of part of our data (Anderson et al., 2023). We acknowledge some of the points raised and provide an additional analysis in support of our hypothesis.

Systematics of the Lao torrent frog, Amolops cremnobatus Inger & Kottelat, 1998 (Anura: Ranidae), with descriptions of four new species

Abstract The Lao torrent frog Amolops cremnobatus Inger & Kottelat, 1998 was recently hypothesized, based on mitochondrial DNA, to consist of more than a single species across its range in Laos and flanking regions of Vietnam and Thailand. We tested this hypothesis using mitochondrial DNA, nuclear DNA, and quantitative and qualitative morphological data from adults and larvae. We found corroborating lines of evidence for five distinct evolutionary lineages that we hypothesize to be species. Amolops cremnobatus sensu stricto is restricted to the southeastern portion of its previous range, and remaining populations are described as four new species. Some of the new species are easier to diagnose with morphology as larvae than as adults. Further sampling in northern Thailand may reveal an additional species of this torrent frog complex.

Large X-effects are absent in torrent frogs with nascent sex chromosomes.

Sex chromosomes are popularized as a special role in driving speciation. However, the empirical evidence from natural population processes has been limited to organisms with degenerated sex chromosomes, where hemizygosity is mainly considered to act as the driver of reproductive isolation. Here, we examined several hybrid zones of torrent frog Amolops mantzorum species complex, using an approach by mapping species-diagnostic loci onto the reference genome to compare sex-linked versus autosomal patterns of introgression. We find little support in sex-linked incompatibilities for large X-effects for these populations in hybrid zones with homomorphic sex chromosomes, due to the absence of the hemizygous effects. As expected, the large X-effects were not found in those with heteromorphic but newly evolved sex chromosomes, owing to the absence of strong genetic differences between X and Y chromosomes. The available data so far on amphibians suggest little role for sex-linked genes in speciation. The large X-effects in those with nascent sex chromosomes may not be as ubiquitous as presumed across the animal kingdom.

The risks of standing out to mate: Predation of Hylodes cardosoi by Bothrops jararaca

AbstractVocalization, visual and chemical signals are courtship behaviours of anurans that may expose them to the risk of predation. Here, we described a predation event in which a population of the torrent frog Hylodes cardosoi was in intense courtship behaviour and one individual was caught by a specimen of the pitviper Bothrops jararaca. The predation event was recorded in a region of Atlantic Forest, Paraná, Brazil. We hypothesized that the pitviper was ambush hunting and captured a female frog that was attracted by the vocalization of a nearby male. Predatory interactions are important ecological factors driving the evolution and population size of both prey and predator. This report increases the prey richness described for B. jararaca and also extends the known geographic distribution of H. cardosoi. Our observation contributes to knowledge of the natural history of the species involved.

New record and dietary ecology of a poorly known frog, Amolopsshihaitaoi Wang, Li, Du, Hou & Yu, 2022 (Amphibia, Anura, Ranidae), from Ha Giang Province, Vietnam.

The Hekou Torrent Frog (Amolopsshihaitaoi) was recently discovered from southern China and northern Vietnam in 2022. The knowledge about natural history and feeding ecology of this species is virtually lacking. Based on our recent fieldwork in northern Vietnam, we report a new population of A.shihaitaoi from Ha Giang Province. In this study, we provide novel data on the diet of A.shihaitaoi, based on stomach content analyses of 36 individuals (17 males and 19 females). A total of 36 prey categories with 529 items, comprising 515 items of invertebrates and 14 unidentified items, were found in the stomachs of A.shihaitaoi. The dominant prey items of the species were Hymenoptera (Formicidae), Orthoptera (Acrididae), Lepidoptera (Lepidoptera other), Mantodea (Mantidae) and Araneae. The importance index (Ix) of prey categories ranged from 7.1% to 11.5%. Hymenoptera (Formicidae) had the highest frequency of prey items, found in 36 stomachs.

The succession of gut microbiota in the concave-eared torrent frog (Odorrana tormota) throughout developmental history.

The gut microbiota of amphibians plays a crucial role in maintaining health and adapting to various developmental stages. The composition of gut microbial community is influenced by the phylogeny, habitat, diet, and developmental stage of the host. The present study analyzed the microbiota in the intestine of O. tormota at 11 developmental stages (from the tadpole at Gosner stage 24 to the 3-year-old adult) using high-throughput 16S rRNA sequencing. Alpha diversity index analysis of the microbiota revealed that the index decreased from tadpole at Gosner stage 24 to adult frog stage, remained stable during the adult frog stages, but increased significantly at the early metamorphosis and hibernation preparation stages. The gut microbiota structure is similar in adult frogs but differs significantly in other developmental stages. Furthermore, the dominant phyla of gut microbiota in tadpoles were Proteobacteria, Firmicutes, Actinobacteria, and Bacteroidetes, whereas those in adult frogs were Proteobacteria, Firmicutes, Bacteroidetes, and Verrucomicrobia. Host and environmental factors jointly affected the gut microbial diversity and community composition of O. tormota, but developmental stage, feeding habit, and habitat type had a more significant influence. The microbial community in the gut varies with the developmental stage of the host and constantly adapts to the survival requirements of the host. These findings advance our understanding of the evolutionary mechanism of amphibian gut microbiota in maintaining health homeostasis and adaptation.

Discovery and analysis of a novel antimicrobial peptide B1AW from the skin secretion of Amolops wuyiensis and improving the membrane-binding affinity through the construction of the lysine-introduced analogue

In the development and study of antimicrobial peptides (AMPs), researchers have kept a watchful eye on peptides from the brevinin family because of their extensive antimicrobial activities and anticancer potency. In this study, a novel brevinin peptide was isolated from the skin secretions of the Wuyi torrent frog, Amolops wuyiensis (A. wuyiensisi), named B1AW (FLPLLAGLAANFLPQIICKIARKC). B1AW displayed anti-bacterial activity against Gram-positive bacteria Staphylococcus aureus (S. aureus), methicillin-resistant Staphylococcus aureus (MRSA), and Enterococcus faecalis (E. faecalis). B1AW-K was designed to broaden the antimicrobial spectrum of B1AW. The introduction of a lysine residue generated an AMP with enhanced broad-spectrum antibacterial activity. It also displayed the ability to inhibit the growth of human prostatic cancer PC-3, non-small lung cancer H838, and glioblastoma cancer U251MG cell lines. In molecular dynamic (MD) simulations, B1AW-K had a faster approach and adsorption to the anionic membrane than B1AW. Therefore, B1AW-K was considered a drug prototype with a dual effect, which deserves further clinical investigation and validation.

Changes in vocal characteristics of male concave-eared torrent frogs (<i>Odorrana tormota</i>) in different chorus tides

Changes in vocal characteristics of male concave-eared torrent frogs (<i>Odorrana tormota</i>) in different chorus tides

An update of the geographical distribution of Hylodes pipilans (Canedo & Pombal, 2007), an endemic Torrent frog of the Brazilian Atlantic Forest, with comments on its conservation

ABSTRACT The Brazilian Atlantic Forest (BAF) is hotspot for conservation priorities due to the high concentration and maintenance of biodiversity, comprising more than 600 species of amphibians, of which 88% are endemic to this biome. Many of these species are under some level of threat, especially those with restricted distributions to mountainous regions. Hylodes is the most speciose genus within Hylodidae, housing 26 recognized species of the diurnal frogs related to streams of forest massifs in the BAF. Hylodes pipilans is endemic to the state of Rio de Janeiro, considered restricted to the Serra do Órgãos mountains. Here, we updated its records based on fieldwork, bioacoustics analysis, and museum data, enhancing the species distribution comprehension. Additionally, we evaluate its occurrence inside of protected areas, updating information to subsidize conservation actions for this poorly known Torrent frog. We recorded individuals of H. pipilans in Parque Nacional da Serra dos Órgãos and Reserva Biológica do Tinguá. The vocalizations analyzed were compatible with the bioacoustics traits of H. pipilans. Its distribution covers part of six municipalities in the Serra dos Órgãos Mountain range, northern portion of Serra do Mar, between 245 and 814 meters above sea level. The new record to the Reserva Biológica do Tinguá is the species southernmost record. Despite the previous assessment on the conservation status of H. pipilans suggest as a least concern species, little is known about its occurrence extension, occupancy area, population trends, and ecological information. Thus, the present study is particularly important to enhance the understanding of altitudinal and geographic distribution range for H. pipilans. These will assist in the species conservation status reassessment.

Avian Alarm Calls Do Not Induce Anti-Predator Response in Three Anuran Species.

Many species produce alarm calls in response to predators, and the anti-predator signals are often used by other species. Eavesdropping on heterospecific alarm calls has been widely found in bird and mammal species. Other taxa, such as reptiles and amphibians, however, receive limited attention at present. Here, we selected three types of alarm calls of Japanese Tits (Parus minor) that were evoked by the Siberian Chipmunk (Eutamias sibiricus), Eurasian Sparrow Hawk (Accipiter nisus), and model snake (Elaphe spp.), respectively, and then carried out playback experiments to test whether three frog species changed their behaviors in response to the three treatments of Japanese Tit calls while the tit's territory song was used as a control. The results showed that Little Torrent Frogs (Amolops torrentis), Ornamented Pygmy Frogs (Microhyla fissipes) and Spot-legged Treefrogs (Polypedates megacephalus) did not jump off their positions in response to the same four acoustic signals. They also did not change their calling behaviors in response to the alarm calls of Japanese Tits. This study found no evidence that these anuran species can eavesdrop on heterospecific tits' alarm signals.

Amolops putaoensis Gan, Qin, Lwin, Li, Quan, Liu & Yu, 2020, a newly recorded torrent frog for China

Amolops putaoensis is a recently described torrent frog species from A. monticola group that is known only from its type locality, northern Myanmar. We compared morphology and mitochondrial DNA sequence data from ten recently collected adult male specimens from the upper Dulong River System in Gongshan County, Yunnan Province, China, to the original description of A. putaoensis. Both datasets strongly supported referring the Chinese specimens to A. putaoensis, extending the known range of this species by approximately 133.7 km distance into China. Molecular phylogenetic analyses recovered A. putaoensis to be closely related to A. aniqiaoensis, A. kohimaensis, A. monticola, and A. adicola. We use the newly collected Chinese specimens to expand the morphological description of the species.

Population size and survival of the Brazilian Torrent Frog Hylodes heyeri (Anura, Hylodidae)

AbstractPopulation dynamics are influenced by environmental variability and understanding the abundance and persistence of individuals and populations is a fundamental goal of population ecology. Thus, estimating demographic parameters to identify the factors important for population variability is required to understand temporal and spatial dynamics. The stream‐living diurnal frog Hylodes heyeri is endemic to the Atlantic Forest of Brazil in the states of Paraná, São Paulo and Santa Catarina. Here we use capture‐mark‐recapture methods to estimate survival rates and population size of this Brazilian Torrent Frog in Pico do Marumbi State Park, Paraná. We used CJS models for an open population to estimate apparent survival, capturability and population size in two streams. The number of captures during each session was positively correlated with the minimum weekly temperature. Despite that correlation, the most parsimonious model of survival and capturability was the constant model for both parameters, resulting in a monthly survival rate of 0.38 (95% CI = 0.30–0.46). Thus, only the abundance of the frog differed in the two streams (79 vs. 36), with the population size estimate of 187 individuals. Reproduction is seasonal in the Brazilian Torrent Frog and so the low monthly survival rate suggests that animals move over time rather than die, because 38% month−1 survival should result in <1% of the population remaining after 5 months. Thus, researchers must recognize that populations are labile and individuals often move or are washed downstream during heavy rainfall, generating apparently rapid local turnover that is unlikely to reflect true mortality.