Paula Cabral Eterovick

In many ecosystems, anthropogenic warming is reshaping thermal regimes, leading to resource quality declines and imposing a dual constraint for ectotherms: elevated metabolic demand coupled with reduced assimilable energy. We tested whether plasticity in gut morphology and gut microbiome can buffer amphibian larvae against these concurrent stressors. Common frog ( Rana temporaria ) tadpoles were reared at two temperatures (18 vs. 24.5°C) crossed with three food-quality treatments (low, medium, high). We quantified growth and developmental rates, critical thermal limits (CT _max , CT _min ), gut morphology (mass, relative length), and gut bacterial diversity and composition, together with predicted functional pathways. Warming accelerated growth and development and increased CT _max . Food quality increased growth and development, with temperature-dependent effects on developmental rate and CT _max . Gut mass declined at higher temperature and low-quality diets, but relative gut length showed only modest diet effects and no temperature dependence. Bacterial community composition and structure shifted with temperature and food quality. Predicted pathways suggest functional reconfiguration under warming and low food quality, consistent with sustaining energy acquisition and mitigating metabolic and oxidative stress. Together, these results implicate microbiome plasticity, rather than gut morphological plasticity, as a candidate mechanism supporting larval performance and heat-tolerance acclimation under warming and low food quality.

Diet influences animal health and their microbiomes, potentially affecting how they cope with environmental stressors such as rising temperatures and altered food quality associated with climate change. Using a multifactorial experiment, larvae of the frog Rana temporaria were reared on three diets differing in protein, fat, and animal‐derived components (low‐, intermediate‐, and high‐quality), at two temperatures (18°C and 24.5°C), and either exposed or not to a simulated heatwave (28°C for 48 h). We examined how these treatments and associated shifts in gut bacterial indicators and predicted microbial metabolic pathways related to nutrient assimilation, host health (body condition and developmental rate), and escape behaviour. Larvae maintained body condition and developed faster at 24.5°C, with higher diet quality further accelerating development. An intermediate‐quality diet reduced responsiveness to an aversive stimulus at 24.5°C, although this effect disappeared following heatwave exposure. Heatwave conditions were associated with increased abundance of Klebsiella and a predicted increase in the myo‐inositol degradation pathway, which may influence membrane dynamics and signalling and may increase attention levels. Despite microbial shifts, host performance remained similar across most treatments, suggesting substantial microbiome plasticity and the presence of functionally redundant enterotypes that help buffer environmental stress.

Data on species distribution is fundamental for conservation planning. However, acquisition of high‐quality data demands great sampling effort and time, especially in biodiverse regions. Furthermore, species detectability is frequently not considered during species inventories based on conventional methods, and this could potentially compromise biodiversity assessments when detectability is low. In this context, environmental DNA (eDNA) metabarcoding is a new promising method to study species distribution and community composition through the detection of DNA left by animals in environmental samples (e.g., water). We aimed to compare the detectability of eDNA metabarcoding in comparison to conventional field inventory methods in tropical, species‐rich frog communities with previously documented field‐inventory‐based low detectability for most species (Serra do Cipó, Southeastern Brazil). Field inventories recorded 23 species, whereas eDNA sequences were successfully assigned to 18 taxa (14 to species level), this number being limited by the incomplete reference library (only 19 out of 40 species in the study site were represented). Among 11 species detected by both methods, eDNA metabarcoding provided higher detectability for four species and similar performance for the remaining ones. eDNA metabarcoding also detected three species not observed in field surveys. Despite the incomplete sequence database, in seven out of ten streams eDNA metabarcoding detected more species than field inventories assessing either adult individuals or all life stages. We strongly recommend that eDNA surveys are performed in combination with sequencing efforts to include missing species into reference libraries. It is also important to further investigate variables likely to influence detectability (e.g., inhibitors, DNA transport and degradation, effects of life history and behavior on DNA release) to improve the efficacy of this promising method and speed acquisition of species distribution data in the conservation race against the pace of human impacts on the planet.

Mountains are hotspots of biodiversity and endemism, but biogeography and diversification in tropical montane grasslands remain poorly understood. We reviewed hypotheses explaining the origin of vertebrate fauna ranging from phylogeography to community-scale patterns, while also considering historical biogeography and macroevolutionary dynamics in campo rupestre in the Espinhaço Range. We conducted a systematic review of papers published in 1945–2023 on vertebrate ecology, biogeography, and diversification in campo rupestre. The vertebrate fauna of campo rupestre is characterized by high levels of biodiversity and endemism relative to area extent across most taxa. Unfortunately, such diversity is increasingly threatened, with ~20% of endemic species listed on the IUCN Red List. Hummingbirds are key pollinators, whereas seed dispersal is performed primarily by generalist birds, small mammals, and lizards. A combination of isolation, range shifts, and species persistence played key roles in shaping diversification dynamics in these ancient mountains. High levels of diversity, endemism, and the occurrence of threatened species underscore the pressing need for funding conservation of the outstanding biodiversity in the Espinhaço Range. We propose a research agenda to fill knowledge gaps and promote research needed to provide a more complete understanding of the biogeographical scenario and accelerate protection strategies.

Motivation: Here, we make available a second version of the BioTIME database, which compiles records of abundance estimates for species in sample events of ecological assemblages through time. The updated version expands version 1.0 of the database by doubling the number of studies and includes substantial additional curation to the taxonomic accuracy of the records, as well as the metadata. Moreover, we now provide an R package (BioTIMEr) to facilitate use of the database.Main Types of Variables Included: The database is composed of one main data table containing the abundance records and 11 metadata tables. The data are organised in a hierarchy of scales where 11,989,233 records are nested in 1,603,067 sample events, from 553,253 sampling locations, which are nested in 708 studies. A study is defined as a sampling methodology applied to an assemblage for a minimum of 2 years.Spatial Location and Grain: Sampling locations in BioTIME are distributed across the planet, including marine, terrestrial and freshwater realms. Spatial grain size and extent vary across studies depending on sampling methodology. We recommend gridding of sampling locations into areas of consistent size.Time Period and Grain: The earliest time series in BioTIME start in 1874, and the most recent records are from 2023. Temporal grain and duration vary across studies. We recommend doing sample‐level rarefaction to ensure consistent sampling effort through time before calculating any diversity metric.Major Taxa and Level of Measurement: The database includes any eukaryotic taxa, with a combined total of 56,400 taxa.Software Format: csv and. SQL.

The interaction of widespread stressors such as nitrate pollution and increasing temperatures associated with climate change is likely to affect aquatic ectotherms such as amphibians. The metamorphic and physiological traits of amphibian larvae during the critical onset of metamorphosis are particularly susceptible to these stressors. We used a crossed experimental design subjecting Rana temporaria larvae to four constant rearing temperatures (18, 22, 26, 28°C) crossed with three environmentally relevant nitrate concentrations (0, 50, 100 mg l−1) to investigate the interactive and individual effects of these stressors on metamorphic (i.e. growth and development) and physiological traits (i.e. metabolism and heat tolerance) at the onset of metamorphosis. Larvae exposed to elevated nitrate concentrations and thermal stress displayed increased metabolic rates but decreased developmental rate, highlighting interactive effects of these stressors. However, nitrate pollution alone had no effect on either metamorphic or physiological traits, suggesting that detoxification processes were sufficient to maintain homeostasis but not in combination with increased rearing temperatures. Furthermore, larvae exposed to nitrate displayed diminished abilities to exhibit temperature-induced plasticity in metamorphosis timing and heat tolerance, as well as reduced acclimation capacity in heat tolerance and an increased thermal sensitivity of metabolic rate to higher temperatures. These results highlight the importance of considering the exposure to multiple stressors when investigating how natural populations respond to global change.

Nitrate pollution and global warming are ubiquitous stressors likely to interact and affect the health and survival of wildlife, particularly aquatic ectotherms. Animal health is largely influenced by its microbiome (commensal/symbiotic microorganisms), which responds to such stressors. We used a crossed experimental design including three nitrate levels and five temperature regimes to investigate their interactive and individual effects on an aquatic ectotherm, the European common frog. We associated health biomarkers in larvae with changes in gut bacteria diversity and composition. Larvae experienced higher stress levels and lower body condition under high temperatures and nitrate exposure. Developmental rate increased with temperature but decreased with nitrate pollution. Alterations in bacteria composition but not diversity are likely to correlate with the observed outcomes in larvae health. Leucine degradation decreased at higher temperatures corroborating accelerated development, nitrate degradation increased with nitrate level corroborating reduced body condition and an increase in lysine biosynthesis may have helped larvae deal with the combined effects of both stressors. These results reinforce the importance of associating traditional health biomarkers with underlying microbiome changes. Therefore, we urge studies to investigate the effects of environmental stressors on microbiome composition and consequences for host health in a world threatened by biodiversity loss.

Amphibians and fishes play a central role in shaping the structure and function of freshwater environments. These organisms have a limited capacity to disperse across different habitats and the thermal buffer offered by freshwater systems is small. Understanding determinants and patterns of their physiological sensitivity across life history is, therefore, imperative to predicting the impacts of climate change in freshwater systems. Based on a systematic literature review including 345 experiments with 998 estimates on 96 amphibian (Anura/Caudata) and 93 freshwater fish species (Teleostei), we conducted a quantitative synthesis to explore phylogenetic, ontogenetic, and biogeographic (thermal adaptation) patterns in upper thermal tolerance (CT_max) and thermal acclimation capacity (acclimation response ratio, ARR) as well as the influence of the methodology used to assess these thermal traits using a conditional inference tree analysis. We found globally consistent patterns in CT_max and ARR, with phylogeny (taxa/order), experimental methodology, climatic origin, and life stage as significant determinants of thermal traits. The analysis demonstrated that CT_max does not primarily depend on the climatic origin but on experimental acclimation temperature and duration, and life stage. Higher acclimation temperatures and longer acclimation times led to higher CT_max values, whereby Anuran larvae revealed a higher CT_max than older life stages. The ARR of freshwater fishes was more than twice that of amphibians. Differences in ARR between life stages were not significant. In addition to phylogenetic differences, we found that ARR also depended on acclimation duration, ramping rate, and adaptation to local temperature variability. However, the amount of data on early life stages is too small, methodologically inconsistent, and phylogenetically unbalanced to identify potential life cycle bottlenecks in thermal traits. We, therefore, propose methods to improve the robustness and comparability of CT_max/ARR data across species and life stages, which is crucial for the conservation of freshwater biodiversity under climate change.

The interaction of widespread stressors such as nitrate pollution and increasing temperatures associated with climate change are likely to affect aquatic ectotherms such as amphibians. The metamorphic and physiological traits of amphibian larvae during the critical onset of metamorphosis are particularly susceptible to these stressors. We conducted a common-garden experiment using Rana temporaria larvae subjected to four constant acclimation temperatures (18, 22, 26, 28 °C) crossed with three environmentally relevant nitrate concentrations (0, 50, 100 mg × L ^-1 ) to investigate the interactive and individual effects of these stressors on metamorphic (i.e., growth and development) and physiological traits (i.e., metabolism and heat tolerance) at the onset of metamorphosis. Larvae exposed to elevated nitrate concentrations and thermal stress displayed increased metabolic rates but decreased developmental rate, highlighting interactive effects of these stressors. However, nitrate pollution alone had no effect on either metamorphic or physiological traits, suggesting that detoxification processes were sufficient to maintain homeostasis but not in combination with increased acclimation temperatures. Furthermore, larvae exposed to nitrate displayed diminished abilities to exhibit temperature-induced plasticity in metamorphosis timing and heat tolerance, as well as reduced acclimation capacity in metabolic rate and heat tolerance to higher temperatures. These results highlight the importance of considering the exposure to multiple stressors when investigating how natural populations respond to global change.

The structure of many aquatic food webs is influenced by tadpole survivorship and duration of seasonal occupancy, which depend on tadpole diet. Pollen has been occasionally reported to occur in tadpole diets, and the available studies show that tadpoles have a strong preference for this supposedly nutritive resource. Thus, we aimed to test whether a diet composed of pollen from varied plant species would boost tadpole growth, development, and agility/mobility, compared to a regular artificial balanced and nutritive diet. Tadpoles in initial developmental stages 25 and 30 grew more when fed with pollen, compared to artificial food and a mixture of both diets. Those initially in stage 30 advanced more developmental stages during one month when fed exclusively with pollen. Tadpoles fed with pollen moved longer distances in response to an aversive stimulus simulating a predatory attack than tadpoles fed with artificial food or a mixed diet. Our results corroborate the hypotheses of pollen being a very important food source to aquatic consumers such as tadpoles, being likely to influence the structure of aquatic food webs through tadpole nutrition and modulation of growth/development speed, as well as tadpole ability to escape predators.