Many species are classified as Data Deficient, because there is a knowledge gap about distribution range and population size and trends. This situation may be a problem in conservation, because the extinction risk of these species is unknown. In the present study, we analyzed all Brazilian anuran species classified as Data Deficient in the IUCN Red List to propose a method to know the conservation status of Data Deficient species. We used the time since species description coupled with the known current species distribution size to indicate the potential conservation status of Data Deficient species. We considered 231 Data Deficient anuran species in Brazil, in which most species (n = 166 spp.) are newly described and restricted geographically (Group D). Group A (n = 9 spp.) and C (n = 18 spp.) were composed by species widely distributed and Group B (n = 37 spp.) was composed by species described more than 50 years ago and geographically restricted. Data Deficient is not a threatened category, however it indicates a need to obtain more information about the species listed, but unfortunately financial resource is limited. We suggested that the species allocated in the group B in our analyses must be priorities in future studies, because it is possible that these are threatened. Our analysis used the amphibian anuran from Brazil as model to propose some action that may be useful to known the conservation status of Data Deficient species.
We investigated the phylogeny and biogeography of the Rhinella marina group, using molecular, morphological, and skin-secretion data, contributing to an understanding of Neotropical faunal diversification. The maximum-parsimony and Bayesian analyzes of the combined data recovered a monophyletic R. marina group. Molecular dating based on Bayesian inferences and fossil calibration placed the earliest phylogenetic split within the R. marina group at ∼ 10.47 MYA, in the late Miocene. Two rapid major diversifications occurred from Central Brazil, first northward (∼ 8.08 MYA) in late Miocene and later southward (∼ 5.17 MYA) in early Pliocene. These results suggest that barriers and dispersal routes created by the uplift of Brazilian Central Shield and climatic changes explain the diversification and current species distributions of the R. marina group. Dispersal-vicariance analyzes (DIVA) indicated that the two major diversifications of the R. marina group were due to vicariance, although eleven dispersals subsequently occurred.
Despite the widespread use of ecological niche models (ENMs) for predicting the responses of species to climate change, these models do not explicitly incorporate any population‐level mechanism. On the other hand, mechanistic models adding population processes (e.g. biotic interactions, dispersal and adaptive potential to abiotic conditions) are much more complex and difficult to parameterize, especially if the goal is to predict range shifts for many species simultaneously. In particular, the adaptive potential (based on genetic adaptations, phenotypic plasticity and behavioral adjustments for physiological responses) of local populations has been a less studied mechanism affecting species’ responses to climatic change so far. Here, we discuss and apply an alternative macroecological framework to evaluate the potential role of evolutionary rescue under climate change based on ENMs. We begin by reviewing eco‐evolutionary models that evaluate the maximum sustainable evolutionary rate under a scenario of environmental change, showing how they can be used to understand the impact of temperature change on a Neotropical anuran species, the Schneider's toad Rhinella diptycha. Then we show how to evaluate spatial patterns of species’ geographic range shift using such models, by estimating evolutionary rates at the trailing edge of species distribution estimated by ENMs and by recalculating the relative amount of total range loss under climate change. We show how different models can reduce the expected range loss predicted for the studied species by potential ecophysiological adaptations in some regions of the trailing edge predicted by ENMs. For general applications, we believe that parameters for large numbers of species and populations can be obtained from macroecological generalizations (e.g. allometric equations and ecogeographical rules), so our framework coupling ENMs with eco‐evolutionary models can be applied to achieve a more accurate picture of potential impacts from climate change and other threats to biodiversity.
Geographical gradients of body size express climate-driven constraints on animals, but whether they exist and what causes them in ectotherms remains contentious. For amphibians, the water conservation hypothesis posits that larger bodies reduce evaporative water loss (EWL) along dehydrating gradients. To address this hypothesis mechanistically, we build on well-established biophysical equations of water exchange in anurans to propose a state-transition model that predicts an increase of either body size or resistance to EWL as alternative specialization along dehydrating gradients. The model predicts that species whose water economy is more sensitive to variation in body size than to variation in resistance to EWL should increase in size in response to increasing potential evapotranspiration (PET). To evaluate the model predictions, we combine physiological measurements of resistance to EWL with geographic data of body size for four different anuran species. Only one species, Dendropsophus minutus, was predicted to exhibit a positive body size-PET relationship. Results were as predicted for all cases, with one species-Boana faber-showing a negative relationship. Based on an empirically verified mathematical model, we show that clines of body size among anurans depend on the current values of those traits and emerge as an advantage for water conservation. Our model offers a mechanistic and compelling explanation for the cause and variation of gradients of body size in anurans.
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