Multilocus phylogeny of Paratelmatobiinae (Anura: Leptodactylidae) reveals strong spatial structure and previously unknown diversity in the Atlantic Forest hotspot

Effects of Amazonian flying rivers on frog biodiversity and populations in the Atlantic rainforest

Given the speed at which humans are changing the climate, species with high degrees of endemism may not have time to avoid extinction through adaptation. We investigated through teleconnection analysis the origin of rainfall that determines the phylogenetic diversity of rainforest frogs and the effects of microclimate differences in shaping the morphological traits of isolated populations (which contribute to greater phylogenetic diversity and speciation). We also investigated through teleconnection analysis how deforestation in Amazonia can affect ecosystem services that are fundamental to maintaining the climate of the Atlantic rainforest biodiversity hotspot. Seasonal winds known as flying rivers carry water vapor from Amazonia to the Atlantic Forest, and the breaking of this ecosystem service could lead Atlantic Forest species to population decline and extinction in the short term. Our results suggest that the selection of morphological traits that shape Atlantic Forest frog diversity and their population dynamics are influenced by the Amazonian flying rivers. Our results also suggest that the increases of temperature anomalies in the Atlantic Ocean due to global warming and in the Amazon forest due to deforestation are already breaking this cycle and threaten the biodiversity of the Atlantic Forest hotspot.

Rapid karyotypic evolution with high diploid number variation in a rare genus of bromeligenous frogs

Bromeligenous Crossodactylodes is a leptodactylid genus closely related to Paratelmatobius and Scythrophrys. The diploid number in all karyotyped species of these two latter genera is 24, which diverges from the modal diploid number (2n = 22) in the family. Here, we analyzed three species of Crossodactylodes and found karyotypes with 2n = 30, 2n = 32, and 2n = 36, diploid numbers that have not been reported in any other diploid leptodactylid species to date. Reconstruction of the ancestral chromosome number indicated that the diploid number changed from 22 to 24 in the common ancestor of Crossodactylodes, Paratelmatobius, and Scythrophrys, and that progressive increases in diploid number have occurred in Crossodactylodes. The large number of telocentric/subtelocentric chromosomes in karyotypes with higher diploid numbers raises the possibility that centric fissions may have occurred during the evolution of Paratelmatobiinae. Three metacentric chromosomes, probably involved in fission events, were inferred to be present in the common ancestor of all species of Crossodactylodes, but in C. bokermanni. Chromosome mapping of the satellite DNA PcP190 suggests homology between one arm of metacentric chromosome 1 of Crossodactylodes sp. 3 and telocentric chromosome 2 of C. itambe, supporting one of the presumed centric fission events.

Evolution of macroglands and defensive mechanisms in Leiuperinae (Anura: Leptodactylidae)

Anurans show a wide variety of anti-predator mechanisms, and the species of the Neotropical clade Leiuperinae display several of them. Most species of Edalorhina, Physalaemus and Pleurodema show eyespots, hidden bright colours, macroglands in a inguinal/lumbar position, defensive behaviours and/or chemical defence. We conducted a histological analysis of dorsal and lumbar skin and revised the colour patterns, defensive behaviours and glandular secretions to study the diversity and evolution of anti-predator mechanisms associated with macroglands. We describe 17 characters and optimize these in a phylogenetic hypothesis of Leiuperinae. In the most recent common ancestor of Edalorhina + Engystomops + Physalaemus + Pleurodema, a particular type of serous gland (the main component of macroglands) evolved in the lumbar skin, along with the absence of the Eberth–Katschenko layer. A defensive behaviour observed in leiuperines with macroglands includes four displays (‘crouching down’ behaviour, rear elevation, body inflation and eye protection), all present in the same ancestor. The two elements associated with aposematism (hidden bright colours and eyespots) evolved independently in several species. Our results provide phylogenetic evidence for the startle-first hypothesis, which suggests that behavioural displays arise as sudden movements in camouflaged individuals to avoid predatory attacks, before the origin of bright coloration.

A brief history of research in campo rupestre: identifying research priorities and revisiting the geographical distribution of an ancient, widespread Neotropical biome

Few ecologists and evolutionary biologists are familiar with the ecology and evolution of the campo rupestre, an ancient azonal peinobiome characterized by a fire-prone, nutrient-impoverished, montane vegetation mosaic, home to thousands of endemics and climate refugia. With the goal of providing a synthetic view of the campo rupestre, we provide a brief historical account of the biological research, revisit its geographical distribution and identify knowledge gaps. The azonal campo rupestre is distributed as isolated and naturally fragmented sky islands, mostly in Central and Eastern Brazil and in the Guyana Shield, with significant areas across the Amazon, Cerrado, Atlantic Forest, Caatinga and Pantanal. Our proposal to elevate campo rupestre to the level of biome is expected to improve communication among scientists and consolidate the use of the term campo rupestre in the ecological and evolutionary literature, as is the case for analogous ecosystems, such as kwongan, fynbos, páramos and tepuis. Based on the identification of knowledge gaps, we propose a research programme comprising ten key topics that can foster our understanding of the ecology and evolution of campo rupestre and, potentially, support conservation strategies.

Evidence of introgression in endemic frogs from the campo rupestre contradicts the reduced hybridization hypothesis

The campo rupestre ecosystem is considered an old, climatically buffered, infertile landscape. As a consequence, long-term isolation is thought to have played an important role in the diversification of its biota. Here, we tested for hybridization between two endemic leaf frogs from the campo rupestre. We used sequence markers and coalescent models to verify haplotype sharing between the species, to test the existence and direction of gene flow, and to reconstruct the spatiotemporal dynamics of gene flow. Additionally, ecological niche modelling (ENM) was used to assess for potential co-occurrence by overlapping the climatic niche of these species since the middle Pleistocene. We found haplotype sharing and/or lack of differentiation in four nuclear fragments, one of them associated with introgression. The coalescent models support introgressive hybridization unidirectionally from Pithecopus megacephalus to P. ayeaye, occurring ~300 kya. ENM corroborates this scenario, revealing areas of potential environmental niche overlap for the species at about 787 kya. These results contradict the expectation of reduced hybridization, while ENM suggests climatic fluctuation rather than stability for the two species. The reduced hybridization hypothesis needs to be further investigated because our results suggest that it may have unrealistic premises at least for animals.