Explore the vast range of titles available.

Rapid spread of disease is a hazard in our interconnected world. The chytrid fungus Batrachochytrium dendrobatidis was identified in amphibian populations about 20 years ago and has caused death and species extinction at a global scale. Scheele et al. found that the fungus has caused declines in amphibian populations everywhere except at its origin in Asia (see the Perspective by Greenberg and Palen). A majority of species and populations are still experiencing decline, but there is evidence of limited recovery in some species. The analysis also suggests some conditions that predict resilience

Theory predicts that sexually dimorphic traits under strong sexual selection, particularly those involved with intersexual signaling, can accelerate speciation and produce bursts of diversification. Sexual dichromatism (sexual dimorphism in color) is widely used as a proxy for sexual selection and is associated with rapid diversification in several animal groups, yet studies using phylogenetic comparative methods to explicitly test for an association between sexual dichromatism and diversification have produced conflicting results. Sexual dichromatism is rare in frogs, but it is both striking and prevalent in African reed frogs, a major component of the diverse frog radiation termed Afrobatrachia. In contrast to most other vertebrates, reed frogs display female-biased dichromatism in which females undergo color transformation, often resulting in more ornate coloration in females than in males. We produce a robust phylogeny of Afrobatrachia to investigate the evolutionary origins of sexual dichromatism in this radiation and examine whether the presence of dichromatism is associated with increased rates of net diversification. We find that sexual dichromatism evolved once within hyperoliids and was followed by numerous independent reversals to monochromatism. We detect significant diversification rate heterogeneity in Afrobatrachia and find that sexually dichromatic lineages have double the average net diversification rate of monochromatic lineages. By conducting trait simulations on our empirical phylogeny, we demonstrate that our inference of trait-dependent diversification is robust. Although sexual dichromatism in hyperoliid frogs is linked to their rapid diversification and supports macroevolutionary predictions of speciation by sexual selection, the function of dichromatism in reed frogs remains unclear. We propose that reed frogs are a compelling system for studying the roles of natural and sexual selection on the evolution of sexual dichromatism across micro- and macroevolutionary timescales

One of the greatest challenges for biodiversity conservation is the poor understanding of species diversity. Molecular methods have dramatically improved our ability to uncover cryptic species, but the magnitude of cryptic diversity remains unknown, particularly in diverse tropical regions such as the Amazon Basin. Uncovering cryptic diversity in amphibians is particularly pressing because amphibians are going extinct globally at an alarming rate. Here, we use an integrative analysis of two independent Amazonian frog clades, Engystomops toadlets and Hypsiboas treefrogs, to test whether species richness is underestimated and, if so, by how much. We sampled intensively in six countries with a focus in Ecuador (Engystomops: 252 individuals from 36 localities; Hypsiboas: 208 individuals from 65 localities) and combined mitochondrial DNA, nuclear DNA, morphological, and bioacoustic data to detect cryptic species. We found that in both clades, species richness was severely underestimated, with more undescribed species than described species. In Engystomops, the two currently recognized species are actually five to seven species (a 150–250% increase in species richness); in Hypsiboas, two recognized species represent six to nine species (a 200–350% increase). Our results suggest that Amazonian frog biodiversity is much more severely underestimated than previously thought.

Poison dart frogs ( Dendrobatidae ) are known for their aposematic coloration and toxic skin, making them a frequent subject of interest and research. However, descriptions of new species of Ranitomeya were interrupted for more than a decade. The implementation of a RAPELD (Rapid Assessment surveys of Long-Term Ecological Research) module in the Juruá River basin, a highly biodiverse and underexplored region, led to the record of a Ranitomeya species with blue dorsal stripes and coppery limbs. Herein we use morphological, morphometric, advertisement call, natural history, tadpole data and genetic data to describe the new species. Our phylogenetic analysis places the species within the Ranitomeya vanzolinii clade, and all delimitation methods confirmed its status as a new species. The species is characterized by its (i) small size (snout-vent length: males 15.2–17.0 mm, females 14.4–16.9 mm), (ii) dorsum with light sky-blue stripes on a reddish-brown ground, and metallic copper limbs with reddish-brown spots, (iii) ring-shaped granular region on the belly, (iv) toes with poorly developed lateral fringes, (v) later tadpole stages with tooth rows P1 = P2 > P3, P3 of 83–87% of P1, and conspicuous light sky-blue dorsal stripes, and (vi) cricket-like advertisement call consisting of 16–35 notes, call duration of 490–1,005 ms, note duration of 8.2–16.9 ms and dominant frequency of 5,168–6,029 Hz. The discovery of the new species emphasizes the significance of researching under-sampled regions like the Juruá River basin, and the usefulness of using a multidisciplinary approach to reveal new dendrobatid species.

Many vertebrates have distinctive blue-green bones and other tissues due to unusually high biliverdin concentrations—a phenomenon called chlorosis. Despite its prevalence, the biochemical basis, biology, and evolution of chlorosis are poorly understood. In this study, we show that the occurrence of high biliverdin in anurans (frogs and toads) has evolved multiple times during their evolutionary history, and relies on the same mechanism—the presence of a class of serpin family proteins that bind biliverdin. Using a diverse combination of techniques, we purified these serpins from several species of nonmodel treefrogs and developed a pipeline that allowed us to assemble their complete amino acid and nucleotide sequences. The described proteins, hereafter named biliverdinbinding serpins (BBS), have absorption spectra that mimic those of phytochromes and bacteriophytochromes. Our models showed that physiological concentration of BBSs fine-tune the color of the animals, providing the physiological basis for crypsis in green foliage even under near-infrared light. Additionally, we found that these BBSs are most similar to human glycoprotein alpha-1-antitrypsin, but with a remarkable functional diversification. Our results present molecular and functional evidence of recurrent evolution of chlorosis, describe a biliverdin-binding protein in vertebrates, and introduce a function for a member of the serpin superfamily, the largest and most ubiquitous group of protease inhibitors.

Climate change is widely recognized as one of the main threats to biodiversity 1 and predicting its consequences is critical to conservation efforts. A wide range of studies have evaluated the effects of future climate using taxon-based metrics 3,4 , but few studies to date have applied a phylogenetic approach to forecast these impacts. Here, we show that future climate change is expected to significantly modify not only species richness, but also phylogenetic diversity and phylogenetic endemism of Neotropical frogs. Our results show that by 2050, the ranges of 42.20% ( n  = 213) of species are projected to shrink and the range of 1.71% of species ( n  = 9) are projected to disappear. Furthermore, we find that areas of high SR and PD are not always congruent with areas of high PE. Our study highlights the projected impacts of climate change on Neotropical frog diversity and identifies target areas for conservation efforts that consider not just species numbers, but also distinct evolutionary histories. Climate change is a major threat to biodiversity. This study predicts that climate change will reshape Neotropical frog diversity, causing losses in phylogenetic diversity and phylogenetic endemism, with many species facing severe range contractions by 2050.

Brachycephalus are miniaturized diurnal frogs inhabiting the leaf litter of the Brazilian Atlantic Forest, mainly in montane areas. The genus includes 42 currently recognized species, 35 of which being described since 2000. This study describes a new species of Brachycephalus from the B. pernix species group discovered at Serra do Quiriri, Santa Catarina, Brazil. Morphological and acoustic comparisons were made with other species in the species group, and high-resolution computed tomography was used for osteological examination. The phylogenetic position was based on partitioned Bayesian analysis of mitochondrial (16S rRNA) and nuclear DNA sequences (β-fibrinogen, ribosomal Protein L3, and tyrosinase exon 1). We collected 32 individuals and recorded 13 calls of the new species. It is distinguished by 18 characters including snout-vent length 8.9-11.3 mm for males and 11.7-13.4 mm for females, general bright orange coloration of the body with small green and brown irregular points, and advertisement call including note groups (two notes per group, with 1-4 pulses per note). Phylogenetic data indicate that the new species is closely related to B. auroguttatus and B. quiririensis, which also occur at Serra do Quiriri. A review of diagnoses among species of the B. pernix group is provided. We propose classifying the new species as Least Concern. Serra do Quiriri experienced semi-arid periods in the Quaternary, with forests likely occurring at lower altitudes. As the climate became wetter, these forests expanded upward as cloud forests, forming patches amidst grasslands, leading to speciation by allopatry (microrefugia) of B. quiririensis, B. auroguttatus, and the new species. This process continues, with recent observations of Brachycephalus colonizing newly formed cloud forests at high altitudes. We propose the creation of the Refúgio de Vida Silvestre (RVS) Serra do Quiriri to protect this and other endemic species, without requiring government acquisition of private land.

Anura (frogs and toads) constitute over 88% of living amphibian diversity but many important questions about their phylogeny and evolution remain unresolved. For this study, we developed an efficient method for sequencing anuran mitochondrial DNAs (mtDNAs) by amplifying the mitochondrial genome in 12 overlapping fragments using frog-specific universal primer sets. Based on this method, we generated 47 nearly complete, new anuran mitochondrial genomes and discovered nine novel gene arrangements. By combining the new data and published anuran mitochondrial genomes, we assembled a large mitogenomic data set (11,007 nt) including 90 frog species, representing 39 of 53 recognized anuran families, to investigate their phylogenetic relationships and evolutionary history. The resulting tree strongly supported a paraphyletic arrangement of archaeobatrachian (=nonneobatrachian) frogs, with Leiopelmatoidea branching first, followed by Discoglossoidea, Pipoidea, and Pelobatoidea. Within Neobatrachia, the South African Heleophrynidae is the sister-taxon to all other neobatrachian frogs and the Seychelles-endemic Sooglossidae is recovered as the sister-taxon to Ranoidea. These phylogenetic relationships agree with many nuclear gene studies. The chronogram derived from two Bayesian relaxed clock methods (MultiDivTime and BEAST) suggests that modern frogs (Anura) originated in the early Triassic about 244 Ma and the appearance of Neobatrachia took place in the late Jurassic about 163 Ma. The initial diversifications of two species-rich superfamilies Hyloidea and Ranoidea commenced 110 and 133 Ma, respectively. These times are older than some other estimates by approximately 30–40 My. Compared with nuclear data, mtDNA produces compatible time estimates for deep nodes (>150 Ma), but apparently older estimates for more shallow nodes. Our study shows that, although it evolves relatively rapidly and behaves much as a single locus, mtDNA performs well for both phylogenetic and divergence time inferences and will provide important reference hypotheses for the phylogeny and evolution of frogs.

Antipredator defenses and warning signals typically evolve in concert. However, the extensive variation across taxa in both these components of predator deterrence and the relationship between them are poorly understood. Here we test whether there is a predictive relationship between visual conspicuousness and toxicity levels across 10 populations of the color-polymorphic strawberry poison frog,Dendrobates pumilio. Using a mouse-based toxicity assay, we find extreme variation in toxicity between frog populations. This variation is significantly positively correlated with frog coloration brightness, a viewer-independent measure of visual conspicuousness (i.e., total reflectance flux). We also examine conspicuousness from the view of three potential predator taxa, as well as conspecific frogs, using taxon-specific visual detection models and three natural background substrates. We find very strong positive relationships between frog toxicity and conspicuousness for bird-specific perceptual models. Weaker but still positive correlations are found for crab andD. pumilioconspecific visual perception, while frog coloration as viewed by snakes is not related to toxicity. These results suggest that poison frog colors can be honest signals of prey unpalatability to predators and that birds in particular may exert selection on aposematic signal design.

The reproductive modes of anurans (frogs and toads) are the most diverse of terrestrial vertebrates, and a major challenge is identifying selective factors that promote the evolution or retention of reproductive modes across clades. Terrestrialized anuran breeding strategies have evolved repeatedly from the plesiomorphic fully aquatic reproductive mode, a process thought to occur through intermediate reproductive stages. Several selective forces have been proposed for the evolution of terrestrialized reproductive traits, but factors such as water systems and co-evolution with ecomorphologies have not been investigated. We examined these topics in a comparative phylogenetic framework using Afrobatrachian frogs, an ecologically and reproductively diverse clade representing more than half of the total frog diversity found in Africa (~400 species). We infer direct development has evolved twice independently from terrestrialized reproductive modes involving subterranean or terrestrial oviposition, supporting evolution through intermediate stages. We also detect associations between specific ecomorphologies and oviposition sites, and demonstrate arboreal species exhibit an overall shift toward using lentic water systems for breeding. These results indicate that changes in microhabitat use associated with ecomorphology, which allow access to novel sites for reproductive behavior, oviposition, or larval development, may also promote reproductive mode diversity in anurans.