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This article provides a detailed description of the tadpole of the Hyloxalus nexipus frog species, focusing on its geographic variation and morphological characteristics. The researchers collected specimens from Ecuador and Peru and examined their coloration and measurements. The document emphasizes the importance of studying tadpoles in understanding anuran species. It also discusses the morphology and characteristics of tadpoles belonging to the Hyloxalus genus of poison dart frogs, noting specific differences in the upper jaw sheath and the position of the upper fin in Hyloxalus nexipus tadpoles. The information is based on detailed observations of single specimens in different developmental stages and references other relevant studies on tadpole morphology and taxonomy. [Extracted from the article]

Aim: Aposematic animals, i.e., those that are defended and warn potential predators through signals, are suggested to have resource‐gathering advantages against non‐aposematic ones. We here explore this in a biogeographic framework expecting that aposematic species are better dispersers, which translates into larger geographic range size. Location: South America. Taxon: Poison frogs (Amphibia; Aromobatidae and Dendrobatidae). Methods: We use 43 toxic and 26 non‐toxic poison frog species from the lowlands only as representatives of aposematic and non‐aposematic study organisms, respectively. Realised and potential geographic ranges are calculated using minimum convex polygon and species distribution modelling methods, respectively. Accounting for species body size and phylogeny, we test if both range and aposematism are correlated using linear mixed‐effects models. Results: Aposematic and non‐aposematic species neither differ in realised nor in potential geographic range size. There was no effect on body size. Main Conclusions: The role of aposematism is not yet as clear as suggested and determinants of poison frog range sizes are multifaceted. A more integrative approach is needed using the information on behaviour, predation risk, and reproductive biology to assess the role of aposematism on observed species distributions. Such data are not yet available for most species, neither poison frogs nor other aposematic animals. [ABSTRACT FROM AUTHOR]

Neotropical poison frogs (Aromobatidae, Dendrobatidae) are known for their complex behavior including site fidelity and home range maintenance. It has been shown in a few poison frog species that these amphibians are able to return to their home ranges after experimental translocation. In this study we asked if Ameerega trivittata can be allocated to the species performing homing behavior. In this taxon, males and females show home range behavior, while sexes were not distinguished in our study. Fieldwork was carried out in a wild population at Panguana (Peru), using replacement distances of 150 m, 600 m and 900 m. In total, 79 frogs were translocated. Most rapidly returned to their home ranges from all translocation distances, with a decrease of the homing success with longer distance. Among the poison frogs studied so far, it is remarkable that A. trivittata is the only one known to be able to return from 900 m (which perhaps is a remarkable homing distance for anurans in general), while maximum return distances in other species are less than 50% of this. Ameerega trivittata is one of the largest poison frogs (maximum snout-vent length 55 mm). However, long distance homing was not explained by the species' body size. We rather expect that 'good knowledge' of the general area (in terms of integration of learned landmarks) that frogs live in is the reason for the ability of long distance homing in our focal taxon. [ABSTRACT FROM AUTHOR]

We reconstructed nearly complete mitogenomes for three species of poison frogs, Dendrobates auratus, D. leucomelas, and D. tinctorius, from RNAseq data. We recovered the 13 protein-coding genes, 22 tRNA genes (except tRNA-Val for D. leucomelas), and two rRNA genes for all three species, plus partial sequences of the control region. The order of genes agrees with that known from a previously sequenced D. auratus, being the most commonly found for neobatrachian frogs. Based on full-sibling comparisons we estimate the probable error rate of Illumina-RNAseq reconstructed mitogenomes of up to 0.15%. [ABSTRACT FROM AUTHOR]

The protection of offspring against predators and competitors is especially important in organisms using spatially separated breeding resources, impeding the offspring's chances to escape. One example of such isolated reproductive resources are phytotelmata (small water bodies in plant axils), exploited by the Neotropical poison frog Ranitomeya variabilis (Dendrobatidae) for both clutch and tadpole deposition. Because poison frog tadpoles are often cannibalistic, parents tend to avoid deposition with conspecifics. Previous studies have shown that this avoidance is based on chemical cues produced by conspecific tadpoles. Further, cues produced by phylogenetically less-related tadpoles (Bufonidae) were avoided for clutch but not tadpole depositions. We analyzed how the different responses to tadpole cues are triggered. We tested the reactions of parental R. variabilis to tadpole cues of species differing in two aspects: whether or not they are dendrobatids, and whether or not they reproduce in phytotelmata. We found that for clutch deposition, tadpole cues were always avoided, i.e., all tadpoles were treated by the frogs as if they pose a danger to the eggs. However, responses varied for tadpole depositions: while dendrobatid larvae living in phytotelmata were avoided, those breeding in streams were not. Non-poison frog tadpoles were ignored when associated with habitat other than phytotelmata, but they were preferred when living in phytotelmata. This suggests that both phylogeny and tadpole habitat are important triggers for the decisions made by R. variabilis. Only tadpoles using the same breeding resources are considered as relevant for the frog's own larvae (i.e., as a potential danger or food resource), while further decisions are related to evolutionary relationship. [ABSTRACT FROM AUTHOR]

The quality of breeding sites is of great importance for the reproductive success and accordingly the fitness of many animal species. Hence, individuals should decide carefully where to rear their offspring. Often parents have to account for multiple characteristics of habitat quality at once, which in turn might change over time. Specimens confronted with such variability may evolve the ability to display context-dependant decision plasticity. Anuran amphibians breeding in ephemeral pools largely face two risks for their offspring: desiccation and predation. The Neotropical poison frog Ranitomeya variabilis deposits both eggs and tadpoles in phytotelmata. These small tadpole nurseries lower the risk of offspring predation. However, because most poison frog tadpoles are cannibalistic, even these pools need to be surveyed for predators, and parents tend to avoid deposition with conspecifics. We tested if this avoidance behaviour does change in parental R. variabilis depending on seasonal circumstances. Over several months we provided the frogs the option to deposit their eggs or tadpoles in pools that did and did not contain chemical cues of cannibalistic conspecifics, respectively. During the rainy season, frogs strongly avoided conspecific cues for both eggs and tadpoles. Anyway, with the change to the dry season, parental preferences changed such that parent frogs were more likely to deposit tadpoles (but not eggs) in pools containing cues of conspecific tadpoles. We suggest that R. variabilis, a species that typically isolates its cannibalistic offspring, has evolved a plastic feeding behaviour with regard to the risk of phytotelmata desiccation. We interpret that parents provide older tadpoles with younger 'trophic' tadpoles in order to accelerate their development and save them from impending desiccation. [ABSTRACT FROM AUTHOR]

The poison frog Ranitomeya reticulata was studied for 3 months while mark-recapture surveys were performed. Ranitomeya species deposit terrestrial clutches and carry tadpoles to phytotelmata with few taxa performing biparental brood care including larval feeding. Home range size and spatial affinity to phytotelmata in the genus are linked to mating systems. In R. reticulata, individual home range size and overlap were similar in both sexes, indicating equal levels of site fidelity. Although territory defence was never observed, strong intrasexual intolerance within individuals' core areas was found. The large intersexual home range overlap for breeding pairs indicated that mate fidelity occurs. Individuals' home ranges were not overlapping, suggesting that R. reticulata lacks pair-bonding or strongly cooperative behaviour in parental duties. The number of ground bromeliads containing phytotelmata and home range size of males were positively correlated. Our findings suggest that females do not perform egg-feeding and male-only parental care is likely. [ABSTRACT FROM AUTHOR]

A phylogenetic approach was performed to infer whether variation in conspicuous colour-patterns of a poison frog (Dendrobatidae: Dendrobates tinctorius) has evolved neutrally or under selection. Colour and pattern were split into components that were separately analysed and subsequently re-grouped via principal component analysis. This revealed four different ‘displayed’ factors on the dorsal and lateral views versus one ‘concealed’ factor on the ventral view. Based on the assumption that current patterns of trait variation contain information about the evolutionary history of the phenotype, we correlated these trait components to a neutrally evolving gene fragment (cytochrome b). The concealed factor was significantly correlated with the marker fragment, which identified it as having evolved under genetic drift. Noncorrelation of all displayed factors with the marker may indicate the evolution of colour patterns on dorsum and flanks under selection. In our example, colour pattern should therefore be regarded as a multicomponent signal system. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 93, 433–444. [ABSTRACT FROM AUTHOR]

A new dendrobatid frog of the genus Colostethus is described from the Cordillera El Sira, an isolated mountain ridge in the upper Amazon basin of central Peru. It has bright yellowish dorsolateral stripes thus resembling Colostethus exasperatus, Colostethus sp. (cf. exasperatus), and Colostethus nexipus, all from the upper Amazon basin of Ecuador and Peru. In morphology, the new species is most similar to Colostethus mcdiarmidi from the eastern Andean slopes of Bolivia and Colostethus alessandroi from the eastern Andean slopes of Peru. The new species can be distinguished from all these taxa on the basis of coloration including the color of the ring around pupil in life, adult male size, length of Finger I relative to Finger II, and toe webbing extension. The advertisement call and aspects of the skeleton of the new species are described. [ABSTRACT FROM AUTHOR]

Abstract: Poison frogs of the family Dendrobatidae contain cryptic as well as brightly colored, presumably aposematic species. The prevailing phylogenetic hypothesis assumes that the aposematic taxa form a monophyletic group while the cryptic species (Colostethus sensu lato) are basal and paraphyletic. Analysis of 86 dendrobatid sequences of a fragment of the 16S rRNA gene resulted in a much more complex scenario, with several clades that contained aposematic as well as cryptic taxa. Monophyly of the aposematic taxa was significantly rejected by SH-tests in an analysis with additional 12S and 16S rDNA fragments and reduced taxon sampling. The brightly colored Allobates femoralis and A. zaparo (Silverstone) comb. nov. (previously Epipedobates) belong in a clade with cryptic species of Colostethus. Additionally, Colostethus pratti was grouped with Epipedobates, and Colostethus bocagei with Cryptophyllobates. In several cases, the aposematic species have general distributions similar to those of their non-aposematic sister groups, indicating multiple instances of regional radiations in which some taxa independently acquired bright color. From a classificatory point of view, it is relevant that the type species of Minyobates, M. steyermarki, resulted as the sister group of the genus Dendrobates, and that species of Mannophryne and Nephelobates formed monophyletic clades, corroborating the validity of these genera. Leptodactylids of the genera Hylodes and Crossodactylus were not unambiguously identified as the sister group of the Dendrobatidae; these were monophyletic in all analyses and probably originated early in the radiation of Neotropical hyloid frogs. [Copyright &y& Elsevier]

In the anuran family Dendrobatidae, aposematic species obtain their toxic or unpalatable alkaloids from dietary sources, a process known as sequestering. To understand how toxicity evolved in this family, it is paramount to elucidate the pathways of alkaloid processing (absorption, metabolism, and sequestering). Here, we used an exploratory skin gene expression experiment in which captive-bred dendrobatids were fed alkaloids. Most of these experiments were performed with Dendrobates tinctorius, but some trials were performed with D. auratus, D. leucomelas and Allobates femoralis to explore whether other dendrobatids would show similar patterns of gene expression. We found a consistent pattern of up-regulation of genes related to muscle and mitochondrial processes, probably due to the lack of mutations related to alkaloid resistance in these species. Considering conserved pathways of drug metabolism in vertebrates, we hypothesize alkaloid degradation is a physiological mechanism of resistance, which was evidenced by a strong upregulation of the immune system in D. tinctorius, and of complement C2 across the four species sampled. Probably related to this strong immune response, we found several skin keratins downregulated, which might be linked to a reduction of the cornified layer of the epidermis. Although not conclusive, our results offer candidate genes and testable hypotheses to elucidate alkaloid processing in poison frogs. [ABSTRACT FROM AUTHOR]

Anuran amphibians have intensively been studied to understand Amazonian biodiversity. Improved methods and sampling has revealed that many widespread nominal species in fact are complexes of species with smaller allopatric ranges. Pan-Amazonian anuran species are rather an exception. In a case study using the three-striped poison frog (Anura: Dendrobatidae: Ameerega trivittata), we ask how the pan-Amazonian distribution of this taxon can be explained and hypothesize that dispersal has played a major role. Species delimitation and intraspecific relationships of the study species were examined from novel and existing (GenBank) sequences of the mitochondrial 16S rRNA gene from 108 specimens of 38 localities using maximum likelihood and Bayesian methods. We performed BioGeoBEARS models using a time-calibrated population tree to reconstruct the biogeographic history. Our results support that A. trivittata is a pan-Amazonian species scattered over its geographic range. Being of Late Miocene origin, the species rapidly spread into newly available space and repeatedly dispersed for-and backward, while vicariance played a major role only in the Early Pliocene. We suggest that intrinsic morphological and life history characteristics (adult size, relative reproductive success) make A. trivittata a more successful disperser than other species, so that riverine barriers are more permeable and hamper allopatric speciation. We conclude that there is no universal causality explaining Amazonia biodiversity, because species-specific biological characteristics are key determents of biogeographical histories. Comparatively better dispersal advantages foster larger geographic ranges and can explain pan-Amazonian distributions. [ABSTRACT FROM AUTHOR]

We studied territorial interactions with respect to inter- and intraspecific communication of Ranitomeya imitator with the syntopic species Ranitomeya variabilis. These poison frogs (Dendrobatidae) are phenotypically very similar and are considered to be Müllerian mimics. Males of both species use calls for intraspecific communication, but only R. imitator males use calls to advertise and defend their territories. We hypothesized that, to avoid the risk of ‘wasting’ energy for territorial defence, R. imitator males should be able to discriminate between conspecifics and its model species R. variabilis by the structure of its call. We conducted phonotaxis field experiments attracting wild R. imitator males towards (1) an R. imitator advertisement call, (2) an R. variabilis call, (3) four modified calls with the temporal call parameters note length and internote interval substituted between the two species, and (4) two R. imitator calls at different dominant frequencies beyond the call's known natural range. Male R. imitator did not show responses towards any R. variabilis call (original or modified to match the R. imitator call), but did approach the sound source during playbacks of R. imitator calls with properties of R. variabilis. They also approached their own advertisement call when the dominant frequency was modified. This shows that modified call parameters did not have significant effects on R. imitator males' ability to discriminate their own call from that of R. variabilis. We conclude that the call parameters note length, internote interval or dominant frequency are not essential for call discrimination in R. imitator, perhaps suggesting that among Müllerian mimic anurans, discrimination of conspecifics and heterospecifics acts at a more complex level. [ABSTRACT FROM AUTHOR]

Parental care is a common strategy among vertebrates to ensure successful reproduction. Anuran amphibians have evolved a remarkable diversity of reproductive methods including advanced levels of parental care. Among the most derived strategies are those of the Neotropical poison frogs (Dendrobatidae). These amphibians exhibit a wide array of behavioural traits such as egg guarding, larval transport by parental frogs and larval feeding with trophic (unfertilized) eggs. Ranitomeya variabilis from the upper Amazon basin in Peru deposits both eggs and tadpoles in phytotelmata. The exploitation of these small pools is advantageous as it lowers the risk of predation, but it is more costly because of limited resource availability. Additionally, poison frog larvae are often cannibalistic, so the identification and avoidance of conspecifics represents an adaptive behaviour for these amphibians. While studies have shown that poison frogs actively avoid depositing with conspecifics, the mechanism for assessing pool quality remains unknown. In field experiments, we found that parental R. variabilis frogs used chemical cues to recognize the presence of tadpoles in phytotelmata. Furthermore, they distinguished between cannibalistic and noncannibalistic tadpoles, a behaviour that supports the survival of their own offspring. [Copyright &y& Elsevier]

The article presents a study on the neotropical poison frogs Ranitomeya (R.) imitator and R. fantastica, to determine whether there more than one mode of breeding resource between the two species. It states that R. imitator and R. variabilis coexist through functional resource partitioning and niche segregation and avoid competition against each other through specialization. The study, which was conducted at a forest in San Martin, Peru from July 22 to November 17, 2008, involves the use of 125 artificial phytotelmata with 500 milliliters (ml) of water that were attached to 25 trees in the study site. The result shows that niche partitioning, such as the size of breeding pools, could be a sufficient niche differentiation to avoid competition between the R. imitator and R. fantastica.

• We present the first comprehensive phylogeny for the poison frog Ameerega from genome-scale data. • There is evidence for at least six undescribed species of Ameerega. • Our phylogenetic reconstruction of Ameerega differs strongly from previously published ones. • Ameerega almost certainly has its origins in the Andes Mountains. • Ameerega most likely diverged from its sister taxon ~20 million years ago. The Amazonian poison frog genus Ameerega is one of the largest yet most understudied of the brightly colored genera in the anuran family Dendrobatidae, with 30 described species ranging throughout tropical South America. Phylogenetic analyses of Ameerega are highly discordant, lacking consistency due to variation in data types and methods, and often with limited coverage of species diversity in the genus. Here, we present a comprehensive phylogenomic reconstruction of Ameerega , utilizing state-of-the-art sequence capture techniques and phylogenetic methods. We sequenced thousands of ultraconserved elements from over 100 tissue samples, representing almost every described Ameerega species, as well as undescribed cryptic diversity. We generated topologies using maximum likelihood and coalescent methods and compared the use of maximum likelihood and Bayesian methods for estimating divergence times. Our phylogenetic inference diverged strongly from those of previous studies, and we recommend steps to bring Ameerega taxonomy in line with the new phylogeny. We place several species in a phylogeny for the first time, as well as provide evidence for six potential candidate species. We estimate that Ameerega experienced a rapid radiation approximately 7–11 million years ago and that the ancestor of all Ameerega was likely an aposematic, montane species. This study underscores the utility of phylogenomic data in improving our understanding of the phylogeny of understudied clades and making novel inferences about their evolution. [ABSTRACT FROM AUTHOR]