Implications of dehydration and temperature in the physiology and behavior during the estivation of the Iberian spadefoot toads (Pelobates cultripes)

• Grant number: 22/15975-6
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• Start date: April 26, 2023
• End date: April 25, 2024
• Field of knowledge: Biological Sciences - Physiology - Compared Physiology
• Principal Investigator: Fernando Ribeiro Gomes
• Grantee: Estefany Caroline Guevara Molina
• Supervisor: Ivan Gomez-Mestre
• Host Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Institution abroad: Estación Biológica de Doñana, Spain
• Associated to the scholarship: 22/00330-0 - Integrative effects of thermal tolerance and dehydration in the early life stages of Neotropical treefrogs, BP.DR

Abstract

One of the most frequent environmental consequences of current climate change are high temperatures and droughts in several regions of the world. Europe and specifically the Iberian Peninsula is one of the regions that are being severely affected by these extreme climatic events. In this context, anurans are the group of vertebrates that have been most affected, because, in order to reproduce and survive, they strongly depend on environmental temperature and humid conditions. In addition, anurans go through different life stages, colonizing aquatic and terrestrial environments. Several studies have explored the effects of heat and dehydration on the physiology and behavior of these organisms at different life stages, such as tadpoles and adults. Important times such as the reproductive season have also been considered to reveal the physiological and behavioral responses of these organisms during reproduction under stressful climatic conditions. However, integrative studies between temperature and dehydration to understand the physiological consequences of other crucial times for many temperate anuran species, such as estivation, are relatively scarce. During the dry season in Europe, mostly anuran species estivate to survive the heat and drought prior to the breeding season. This has been a relatively successful response for many species. However, we do not know the integrated effects of dehydration and high temperatures during estivation on both the physiology and behavior of anurans. During April 2023-April 2024 we want to carry out an integrative ecophysiology project by assess the effects of dehydration and temperature during the estivation of Pelobates cultripes, a species distributed over the Iberian Peninsula. We intend to explore at the physiological level by measuring corticosterone and aldosterone concentrations in the urine of individuals that will be experimentally subjected to estivation in wet and dry substrates. Corticosterone and aldosterone levels will give us information on both stress and osmoregulation of the individuals during the experiments. In addition, we will estimate the basal metabolic rate of the individuals. Since we know that dehydration can reduce the thermal tolerance of anurans, we will explore whether estivation combined with dehydration will alter the thermal tolerance of individuals. To do this, we will measure the voluntary thermal maximum of individuals after estivation experiments. We expect to find that individuals that estivate on dry substrates have a higher thermal sensitivity and tolerate lower temperatures in their environments. With all, this project aims to understand the physiological and behavioral implications of heat and dehydration during and after estivation. This project could be replicated in other species in both temperate and tropical regions, which are facing the constant challenges of climate change and for which more information is needed on their physiological and behavioral response mechanisms to these scenarios. (AU)