Ecophysiology of Amphibians: Information for Best Mechanistic Models

Abstract

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 ecophysiological features and ecological models as a means to establish causal and consequential relationships of species with their physical environment. Solid frameworks built for other tetrapods (e.g., lizards) have proved successful in this context, but its extension to amphibians requires care. First, the natural history of amphibians is distinct within tetrapods, for it includes a biphasic life cycle that undergoes major habitat transitions and changes in sensitivity to environmental factors. Second, the accumulated data on amphibian ecophysiology is not nearly as expressive, is heavily biased towards adult lifeforms of few non-tropical lineages, and overlook the importance of hydrothermal relationships. Thus, we argue that critical usage and improvement in the available data is essential for enhancing the power of mechanistic modeling from the physiological ecology of amphibians. We highlight the complexity of ecophysiological variables and the need for understanding the natural history of the group under study and indicate directions deemed crucial to attaining steady progress in this field.

Peptides for Skin Protection and Healing in Amphibians

“…In any case, it is clear that some species are able to tolerate human-mediated environmental changes observed both at the local (e.g., land-use transformation, pollutants) and at the global level (e.g., climate change) better than others. These species might acquire tolerance to unpredictable environmental alterations by possessing a more complex array of innate behavioral, ecophysiological, or immunological features that are still poorly understood [64,65].…”

How likely are adaptive responses to mitigate the threats of climate change for amphibians globally?

“…A second important aspect to consider is whether the purely genetic adaptive model (MSER) is realistic? It is expected that ecological traits such as temperature tolerance can show some degree of plasticity and indeed other factors are known to compensate for thermal tolerance, including morphological, ontogenetic and behavioral adjustments (Bovo et al 2018). Although we do not know exactly the proportion of variation allowed by phenotypic plasticity, even low levels of b (up to 15% in equation 3) in Chevin et al's (2010) model will result in much less alarming patterns (see Urban et al 2014).…”

“…However, the ecological significance of these results depends on several assumptions about the way Haldanes and MSER are calculated, in terms of likelihood of extinction and failure to adapt to the predicted climate change for the vast majority of species (see below). Anyway, it is important to consider that, given our current knowledge of adaptive potential and physiological responses to temperature changes in amphibians (i.e., Ficetola and Maiorano 2016;Bovo et al 2018), our approach may be only a first approximation toward a macroecological evaluation of global patterns of potential evolutionary rescue in relation to the threats posed by climate change. More refined experimental approaches to better define demographic and genetic parameters, as well as their phylogenetic patterns, may help in improving the first results shown here and help clarify the conservation status of many species (see Nori et al 2018).…”

“…In general, these studies predict high rates of species losses due to climate change and interaction with other factors, mainly habitat loss (although the effects of the pathogenic fungal disease chytridiomycosis is, in principle, independent of these two other threats; see Hof et al 2011). However, as already pointed out, it is possible that evolutionary rescue may buffer extinctions and geographic range loss, so understanding potential adaptations to increasing temperatures is one of the frontlines in amphibian ecophysiological research (Angilletta 2009, Urban et al 2014, Ficetola and Maiorano 2016, Bovo et al 2018.…”

Adult—Juvenile interactions and temporal niche partitioning between life-stages in a tropical amphibian

“…Because of their permeable wet skin used for respiration, amphibians are prone to desiccation, and, since the ratio between surface and volume is higher in smaller animals, juveniles are theoretically more susceptible to dehydration compared to adults [ 32 – 34 ]. As a result, it is expected that juveniles would be more likely to be active during nighttime [ 35 , 36 ]. Nevertheless, in a small number of species, empirical observations show that the opposite phenomenon takes place, with adults being predominantly nocturnal and juveniles exhibiting diurnal activity [ 35 , 37 ].…”