Nor climate nor human impact factors: Chytrid infection shapes the skin bacterial communities of an endemic amphibian in a biodiversity hotspot.

The bacterial communities of the amphibian skin (i.e., the bacteriome) are critical to the host's innate immune system.

Interpopulation differences in male reproductive effort drive the population dynamics of a host exposed to an emerging fungal pathogen.

Compensatory recruitment is a key demographic mechanism that has allowed the coexistence of populations of susceptible amphibians with Batrachochytrium dendrobatidis (Bd), a fungus causing one of the most devastating emerging infectious disease ever recorded among vertebrates. However, the underlying processes (e.g.

Bioclimatic and anthropogenic variables shape the occurrence of Batrachochytrium dendrobatidis over a large latitudinal gradient.

Amphibian chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd), has caused the greatest known loss of biodiversity due to an infectious disease. We used Bd infection data from quantitative real-time PCR (qPCR) assays of amphibian skin swabs collected across Chile during 2008-2018 to model Bd occurrence with the aim to determine bioclimatic and anthropogenic variables associated with Bd infection. Also, we used Bd presence/absence records to identify geographical Bd high-risk areas and compare Bd prevalence and infection loads between amphibian families, ecoregions, and host ecology.

Could plasticity mediate highlands lizards' resilience to climate change? A case study of the leopard iguana (Diplolaemus leopardinus) in Central Andes of Argentina.

The predicted rise of global temperatures is of major concern for ectotherms because of its direct impact on their behavior and physiology. As physiological performance mediates a species' resilience to warming exposure, physiological plasticity could greatly reduce the susceptibility to climate change. We studied the degree to which Diplolaemus leopardinus lizards are able to adjust behavioral and physiological traits in response to short periods of temperature change.

Why disease ecology needs life-history theory: a host perspective.

When facing an emerging infectious disease of conservation concern, we often have little information on the nature of the host-parasite interaction to inform management decisions. However, it is becoming increasingly clear that the life-history strategies of host species can be predictive of individual- and population-level responses to infectious disease, even without detailed knowledge on the specifics of the host-parasite interaction. Here, we argue that a deeper integration of life-history theory into disease ecology is timely and necessary to improve our capacity to understand, predict and mitigate the impact of endemic and emerging infectious diseases in wild populations.

Shrinking dinosaurs and the evolution of endothermy in birds.

The evolution of endothermy represents a major transition in vertebrate history, yet how and why endothermy evolved in birds and mammals remains controversial. Here, we combine a heat transfer model with theropod body size data to reconstruct the evolution of metabolic rates along the bird stem lineage. Results suggest that a reduction in size constitutes the path of least resistance for endothermy to evolve, maximizing thermal niche expansion while obviating the costs of elevated energy requirements.

Testing the metabolic homeostasis hypothesis in amphibians.

A number of hypotheses about compensatory mechanisms that allow ectothermic animals to cope with the latitudinal decrease in ambient temperature ( T) have been proposed during the last century. One of these hypotheses, the 'metabolic homeostasis' hypothesis (MHH), states that species should show the highest thermal sensitivity of the metabolic rate ( Q) at the colder end of the range of Ts they usually experience in nature. This way, species should be able to minimize maintenance costs during the colder hours of the day, but quickly take advantage of increases in T during the warmer parts of the day.

Natural selection on plasticity of thermal traits in a highly seasonal environment.

For ectothermic species with broad geographical distributions, latitudinal/altitudinal variation in environmental temperatures (averages and extremes) is expected to shape the evolution of physiological tolerances and the acclimation capacity (i.e., degree of phenotypic plasticity) of natural populations.

Thermal physiological traits and plasticity of metabolism are sensitive to biogeographic breaks in a rock-pool marine shrimp.

Populations of broadly distributed species commonly exhibit latitudinal variation in thermal tolerance and physiological plasticity. This variation can be interrupted when biogeographic breaks occur across the range of a species, which are known to affect patterns of community structure, abundance and recruitment dynamics. Coastal biogeographic breaks often impose abrupt changes in environmental characteristics driven by oceanographic processes and can affect the physiological responses of populations inhabiting these areas.

Quantitative Genetic Modeling of the Parental Care Hypothesis for the Evolution of Endothermy.

There are two heuristic explanations proposed for the evolution of endothermy in vertebrates: a correlated response to selection for stable body temperatures, or as a correlated response to increased activity. Parental care has been suggested as a major driving force in this context given its impact on the parents' activity levels and energy budgets, and in the offspring's growth rates due to food provisioning and controlled incubation temperature. This results in a complex scenario involving multiple traits and transgenerational fitness benefits that can be hard to disentangle, quantify and ultimately test.

Thermal performance curves under daily thermal fluctuation: A study in helmeted water toad tadpoles.

Most research in physiological ecology has focused on the effects of mean changes in temperature under the classic "hot vs cold" acclimation treatment; however, current evidence suggests that an increment in both the mean and variance of temperature could act synergistically to amplify the negative effects of global temperature increase and how it would affect fitness and performance-related traits in ectothermic organisms. We assessed the effects of acclimation to daily variance of temperature on thermal performance curves of swimming speed in helmeted water toad tadpoles (Calyptocephalella gayi). Acclimation treatments were 20°C ± 0.

Intraspecific geographic variation in thermal limits and acclimatory capacity in a wide distributed endemic frog.

Intraspecific variation in physiological traits and the standard metabolic rate (SMR) is common in widely distributed ectotherms since populations at contrasting latitudes experiences different thermal conditions. The climatic variability hypothesis (CVH) states that populations at higher latitudes presents higher acclimation capacity than those at lower latitudes, given the wider range of climatic variability they experience. The endemic four-eyed frog, Pleurodema thaul is widely distributed in Chile.

The multigenerational effects of water contamination and endocrine disrupting chemicals on the fitness of .

Water pollution due to human activities produces sedimentation, excessive nutrients, and toxic chemicals, and this, in turn, has an effect on the normal endocrine functioning of living beings. Overall, water pollution may affect some components of the fitness of organisms (e.g.

Exploring physiological plasticity and local thermal adaptation in an intertidal crab along a latitudinal cline.

Intertidal organisms have evolved physiological mechanisms that enable them to maintain performance and survive during periods of severe environmental stress with temperatures close to their tolerance limits. The level of these adaptive responses in thermal physiology can vary among populations of broadly distributed species depending on their particular environmental context and genetic backgrounds. Here we examined thermal performances and reaction norms for metabolic rate (MR) and heart rate (HR) of seven populations of the porcelanid crab Petrolisthes violaceus from markedly different thermal environments across the latitudinal gradient of ~3000km.

Spatio-temporal environmental variation mediates geographical differences in phenotypic responses to ocean acidification.

Phenotypic plasticity is expected to play a major adaptive role in the response of species to ocean acidification (OA), by providing broader tolerances to changes in CO conditions. However, tolerances and sensitivities to future OA may differ among populations within a species because of their particular environmental context and genetic backgrounds. Here, using the climatic variability hypothesis (CVH), we explored this conceptual framework in populations of the sea urchin across natural fluctuating CO/pH environments.

Geographical gradients in selection can reveal genetic constraints for evolutionary responses to ocean acidification.

Geographical gradients in selection can shape different genetic architectures in natural populations, reflecting potential genetic constraints for adaptive evolution under climate change. Investigation of natural pH/pCO variation in upwelling regions reveals different spatio-temporal patterns of natural selection, generating genetic and phenotypic clines in populations, and potentially leading to local adaptation, relevant to understanding effects of ocean acidification (OA). Strong directional selection, associated with intense and continuous upwellings, may have depleted genetic variation in populations within these upwelling regions, favouring increased tolerances to low pH but with an associated cost in other traits.

Effects of amphibian phylogeny, climate and human impact on the occurrence of the amphibian-killing chytrid fungus.

Chytridiomycosis, due to the fungus Batrachochytrium dendrobatidis (Bd), has been associated with the alarming decline and extinction crisis of amphibians worldwide. Because conservation programs are implemented locally, it is essential to understand how the complex interactions among host species, climate and human activities contribute to Bd occurrence at regional scales. Using weighted phylogenetic regressions and model selection, we investigated geographic patterns of Bd occurrence along a latitudinal gradient of 1500 km within a biodiversity hot spot in Chile (1845 individuals sampled from 253 sites and representing 24 species), and its association with climatic, socio-demographic and economic variables.

Anticipatory gene regulation driven by maternal effects in an insect-host system.

Adaptive mechanisms involved in the prediction of future environments are common in organisms experiencing temporally variable environments. One of these is AGR (anticipatory gene regulation); in which differential gene expression occur in an individual, triggered by the experience of an ancestor. In this study, we explored the existence of AGR driven by a maternal effect, in an insect-host system.

Mitochondrial phenotype of marsupial torpor: Fuel metabolic switch in the Chilean mouse-opossum Thylamys elegans.

Torpor is a phenotype characterized by a controlled decline of metabolic rate and body temperature. During arousal from torpor, organs undergo rapid metabolic reactivation and rewarming to near normal levels. As torpor progress, animals show a preference for fatty acids over glucose as primary source of energy.

Thermoregulation in endotherms: physiological principles and ecological consequences.

In a seminal study published nearly 70 years ago, Scholander et al. (Biol Bull 99:259-271, 1950) employed Newton's law of cooling to describe how metabolic rates (MR) in birds and mammals vary predictably with ambient temperature (T a). Here, we explore the theoretical consequences of Newton's law of cooling and show that a thermoregulatory polygon provides an intuitively simple and yet useful description of thermoregulatory responses in endothermic organisms.

Impact of global warming at the range margins: phenotypic plasticity and behavioral thermoregulation will buffer an endemic amphibian.

When dispersal is not an option to evade warming temperatures, compensation through behavior, plasticity, or evolutionary adaptation is essential to prevent extinction. In this work, we evaluated whether there is physiological plasticity in the thermal performance curve (TPC) of maximum jumping speed in individuals acclimated to current and projected temperatures and whether there is an opportunity for behavioral thermoregulation in the desert landscape where inhabits the northernmost population of the endemic frog Pleurodema thaul. Our results indicate that individuals acclimated to 20°C and 25°C increased the breath of their TPCs by shifting their upper limits with respect to when they were acclimated at 10°C.

Geographic variation in thermal physiological performance of the intertidal crab Petrolisthes violaceus along a latitudinal gradient.

Environmental temperature has profound effects on the biological performance and biogeographical distribution of ectothermic species. Variation of this abiotic factor across geographic gradients is expected to produce physiological differentiation and local adaptation of natural populations depending on their thermal tolerances and physiological sensitivities. Here, we studied geographic variation in whole-organism thermal physiology of seven populations of the porcelain crab Petrolisthes violaceus across a latitudinal gradient of 3000 km, characterized by a cline of thermal conditions.