Miguel Tejedo

Estación Biológica de Doñana · Evolutionary Ecology

Global studies of organismal distribution and climatic vulnerability rely on the mostly untested assumption that heat tolerance restricts the maximum temperatures estimated at the warm edges of their geographic distribution (Tmax). Herein we test this assumption across the animal kingdom and examine whether the strength of restrictions depends on h...

Critical thermal limits (CTmax and CTmin) decrease with elevation, with greater change in CTmin, and the risk to suffer heat and cold stress increasing at the gradient ends. A central prediction is that populations will adapt to the prevailing climatic conditions. Yet, reliable support for such expectation is scant because of the complexity of inte...

Current climate change is generating accelerated increase in extreme heat events and organismal plastic adjustments in upper thermal tolerances, (critical thermal maximum -CTmax ) are recognized as the quicker mitigating mechanisms. However, current research casts doubt on the actual mitigating role of thermal acclimation to face heat impacts, due...

Global warming is predicted to increase both average temperatures and the frequency and duration of heat waves. Tropical ectotherms, particularly those living in warm environments are more prone to receive heat impacts. Then, it is crucial to identify those populations already exposed to high temperatures that may be at risk of decimation by ongoin...

The climate variability hypothesis posits that increased environmental thermal variation should select for thermal generalists, while stable environments should favor thermal specialists. This hypothesis has been tested on large spatial scales, such as latitude and elevation, but less so on smaller scales reflective of the experienced microclimate....

Phenotypic plasticity of the upper critical thermal limits (CTmax) may be crucial for ectotherms when it enables them to respond rapidly to extreme and novel thermal conditions. Although current studies have widely reported on the effect of increasing temperature on the magnitude of the plastic response of ectotherms, little is known about timing o...

To understand species′ climatic vulnerability, our measures of species’ thermal tolerance should predict their geographic thermal limits. Yet, this assumption is ungranted. We tested if animals′ heat tolerance restrict the warmest temperatures they can live at (Tmax), distinguishing among species differently challenged by their thermal environment....

Critical thermal limits (CTmax and CTmin) are predicted to decrease with elevation, with greater change in CTmin, and the risk to suffer heat and cold stress increasing at the gradient ends. A central prediction is that populations will adapt to the prevailing climatic conditions. Yet, reliable support for such expectation is scant because of the c...

Determining both the age structure and growth pattern allows to establish the causal factors, environmental and/or genetic, that eventually may be responsible for the observed pattern of divergence. We examined the variation in age structure and growth pattern across populations of two toad species, Pelobates cultripes and Epidalea calamita that ex...

Climate change may have dramatic consequences for communities through both direct effects of peak temperatures upon individual species and through interspecific mismatches in thermal sensitivities of interacting organisms which mediate changes in interspecific interactions (i.e. predation). Despite this, there is a paucity of information on the pat...

Communities usually possess a multitude of interconnected trophic interactions within food webs. Their regulation generally depends on a balance between bottom-up and top-down effects. However, if sensitivity to temperature varies among species, rising temperatures may change trophic interactions via direct and indirect effects. We examined the cri...

Current assessments of organismal vulnerability to global warming are focusing on physiological trait-based indices that may allow biologically sounding estimates of heating risk at the local scale. However, intraspecific variability in both exposure and physiological performance may determine large heterogeneity in the distribution of heating risk...

Variation and population structure play key roles in the speciation process, but adaptive intraspecific genetic variation is commonly ignored when forecasting species niches. Amphibians serve as excellent models for testing how climate and local adaptations shape species distributions due to physiological and dispersal constraints and long generati...

1. The vulnerability of species to climate change is jointly influenced by geographic phenotypic variation, acclimation, and behavioral thermoregulation. The importance of interactions between these factors, however, remains poorly understood. 2. We demonstrate how advances in mechanistic niche modelling can be used to integrate and assess the inf...

Captive-bred organisms are widely used in ecology, evolution and conservation research, especially in scenarios where natural populations are scarce or at risk of extinction. Yet, it is still unclear whether captivity may alter thermal tolerances, crucial traits to predict species resilience to global warming. Here, we study whether captive-bred ta...

Here, we describe the extreme plasticity in colour variation in the tadpole of the executioner clownfrog, Dendropsophus carnifex (Anura: Hylidae), found across nearby ponds in Mindo (Ecuador). Tadpole coloration was compared between individuals from four distinct ponds revealing two explicit colour schemes, a pale phenotype which is commonly descri...

Aim: We analysed elevational and microclimatic drivers of thermal tolerance diversity in a tropical mountain frog clade to test three macrophysiological predictions: less spatial variation in upper than lower thermal limits (Bretts' heat-invariant hypothesis); narrower thermal tolerance ranges in habitats with less variation in temperature (Janzen'...

Climate change and infectious disease by the chytrid fungus Batrachochytrium dendrobati-dis (Bd) are major drivers of amphibian extinctions, but the potential interactions of these two factors are not fully understood. Temperature is known to influence (1) the infectivity, pathogenicity and virulence of Bd; (2) host-parasite dynamics, especially wh...

From experimental trials examining CTmax of both tadpoles and toadlets from the two studied localities. (XLS)

Complex life-histories may promote the evolution of different strategies to allow optimal matching to the environmental conditions that organisms can encounter in contrasting environments. For ectothermic animals, we need to disentangle the role of stage-specific thermal tolerances and developmental acclimation to predict the effects of climate cha...

Several amphibian lineages epitomize the faunal biodiversity crises, with numerous reports of population declines and extinctions worldwide. Predicting how such lineages will cope with environmental changes is an urgent challenge for biologists. A promising framework for this involves mechanistic modeling, which integrates organismal ecophysiologic...

The current global warming scenario has led to a renewed interest in determining which species are more vulnerable to climate change. Hence, it is important to understand which factors can affect estimates of species vulnerability. We determined the critical thermal maxima (CTmax) for six species of North American anuran larvae and measured the env...

Parsley frogs (Pelodytes) comprise the only genus in the family Pelodytidae, an ancient anuran lineage that split from their closest relatives over 140 million years ago. Pelodytes is a Palearctic group restricted to Western Eurasia including three extant species: the eastern species P. caucasicus, endemic to the Caucasus area, and two closely rela...

The climate variability hypothesis (CVH) states that a positive relationship may exist between the breadth of thermal tolerance range and the level of climatic variability experienced by taxa with increasing latitude, especially in terrestrial ectotherms. Under CVH, we expected to find a correspondence between both thermal tolerance limits (CTmax a...

While temperature variation is known to cause large-scale adaptive divergence, its potential role as a selective factor over microgeographic scales is less well understood. Here, we investigated how variation in breeding pond temperature affects divergence in multiple physiological (thermal performance curve (TPC) and critical thermal maximum (CTma...

Habitat fragmentation may involve a loss of genetic diversity and increments the vulnerability to species persistence. It could be a particular issue when coupled with other negative factors as the predicted climatic changes and the emergence of infectious diseases. In Southern Iberian Peninsula several endemic amphibian species have confined and f...

Painted frogs (Discoglossus) contain five to six species of Western Palearctic anurans that are mainly distributed in allopatry. We here provide the first comprehensive assessment of the phylogeography of the Moroccan species D. scovazzi and geographically characterize its contact zone with D. pictus in Eastern Morocco. Discoglossus scovazzi shows,...

To forecast biological responses to changing environments, we need to understand how a species's physiology varies through space and time and assess how changes in physiological function due to environmental changes may interact with phenotypic changes caused by other types of environmental variation. Amphibian larvae are well known for expressing...

Painted frogs (Discoglossus) contain 5-6 species of Western Palearctic anurans that are mainly distributed in allopatry. We here provide the first comprehensive assessment of the phylogeography of the Moroccan D. scovazzi and geographically characterize its contact zone with D. pictus in Eastern Morocco. Discoglossus scovazzi shows, in general, a w...

Aim Under the Hutchinsonian concept of the realized niche, biotic interactions and dispersal limitation may prevent species from fully occupying areas that they could tolerate physiologically. This can hamper the translation of physiological limits into climatically defined range limits and distorts inferences of evolutionary changes of the adaptiv...

In Southern Iberian Peninsula, the endemic Betic Midwife Toad, Alytes dickhilleni is confined exhibiting fragmented distributions. This species is considered vulnerable by the Internationa Union for Conservation of Nature (IUCN) because of its very fragmented distribution and declining populations in recent decades. This species is also included in...

Many studies have assessed the impact of different pollutants on amphibians across a variety of experimental venues (laboratory, mesocosm, and enclosure conditions). Past reviews, using vote-counting methods, have described pollution as one of the major threats faced by amphibians. However, vote-counting methods lack strong statistical power, do no...

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The morphological differentiation among Pelodytes species is analysed based on a sample of disarticulated bones from the main osteological regions of the male adult skeleton. A set of 35 interspecifically diagnostic characters, analysed under different outgroup hypotheses, clearly shows that P. ibericus and P. punctatus are a sister-group with resp...

Predicting the biodiversity impacts of global warming implies that we know where and with what magnitude these impacts will be encountered. Amphibians are currently the most threatened vertebrates, mainly due to habitat loss and to emerging infectious diseases. Global warming may further exacerbate their decline in the near future, although the imp...

Anurans breed in a variety of aquatic habitats with contrasting levels of desiccation risk, which may result in selection for faster development during larval stages. Previous studies suggest that species in ephemeral ponds reduce their developmental times to minimize desiccation risks, although it is not clear how variation in desiccation risk aff...

This article documents the addition of 238 microsatellite marker loci to the Molecular Ecology Resources Database. Loci were developed for the following species: Alytes dickhilleni, Arapaima gigas, Austropotamobius italicus, Blumeria graminis f. sp. tritici, Cobitis lutheri, Dendroctonus ponderosae, Glossina morsitans morsitans, Haplophilus subterr...

Several studies have assessed the effects of nitrogenous compounds on amphibian behavior. However, few have focused on the effects of their combination with other stressors or on the variation of the response to pollutants among populations. We analyzed the effect of nitrogenous compounds (NH(4)(+); NO(2)(-); NO(3)(-), both alone and in combination...

1. Current studies indicate that estimates of thermal tolerance limits in ectotherms depend on the experimental protocol used, with slower and presumably more ecologically relevant rates of warming negatively affecting the upper thermal limits (CTmax). Recent empirical evidence also gives credence to earlier speculations suggesting that estimates o...

The evolution of environmentally-induced changes in phenotype or reaction norm implies both the existence at some time of genetic variation within a population for that plasticity measured by the presence of genotype x environment interaction (G x E), and that phenotypic variation affects fitness. Otherwise, the genetic structure of polygenic trait...

Nonlethal tail injury resulting from unsuccessful predation attempts is common in anuran larvae and can potentially induce significant fitness costs in terms of survival and growth. We tested the hypotheses that the alien red swamp crayfish, Procambarus clarkii, is an important inducer of tail injury in tadpoles of the Iberian spadefoot toad, Pelob...

We report the occurrence of facultative paedomorphosis in the three species of newts (Pleurodeles waltl, Lissotriton boscai and Triturus pygmaeus) from dry and seasonal Mediterranean areas from southern Spain. These are the first records of paedomorphosis for P. waltl and L. boscai, and the second for T. pygmaeus. Other than the previous T. pygmaeu...

In organisms with complex life cycles, environmentally induced plasticity across sequential stages can have important consequences on morphology and life history traits such as developmental and growth rates. However, previous research in amphibians and other ectothermic vertebrates suggests that some morphological traits are generally insensitive...

In the toad Bufo calamita, among-population variation of size follows roughly a converse Bergmann cline, but populations exist that do not fit this pattern. We propose that latitudinal body size variation is a byproduct of adaptive covariation among the life-history traits juvenile growth rate, longevity and lifetime fecundity. We choose five popul...