Effect of dehydration on water balance and behavior of Anuran Amphibians: A study on the genus Rhinella (Family: Bufonidae)

• Grant number: 24/09640-7
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: March 01, 2025
• End date: February 28, 2027
• Field of knowledge: Biological Sciences - Zoology - Physiology of Recent Groups
• Principal Investigator: Denis Otavio Vieira de Andrade
• Grantee: Luis Fernando Montes Benitez
• Host Institution: Instituto de Biociências (IB). Universidade Estadual Paulista (UNESP). Campus de Rio Claro. Rio Claro , SP, Brazil
• Associated research grant: 21/10910-0 - Physiological capacities and resilience facing climate change: exploring the functional dimension in ectothermic vertebrates, AP.TEM

Abstract

Dehydration is considered a potent stressor in anuran amphibians, affecting the physiology and behavior of individuals. In this context, the ability to detect, absorb, and conserve water is central to maintaining the osmotic balance of amphibians. This ability can vary considerably among different species of anurans. Therefore, in the present study, we aim to investigate how behavioral and physiological responses involved in locating, rehydrating, and conserving water can contribute to maintaining water homeostasis in terrestrial anurans. For this, we will use different species of the genus Rhinella, which differ not only in organismal attributes but also occupy environments with varying water availability. We propose to test the general hypothesis that "Rhinella species found in drier habitats have a greater ability to detect, absorb, and conserve water compared to species from humid environments." This proposal involves collecting data under controlled laboratory conditions on the animals' ability to find water sources when challenged by dehydration. In addition to this main objective, we also intend to evaluate how plasma osmolarity (Osm), hematocrit (Hct), blood hemoglobin content ([Hb]), and plasma concentrations of sodium, chloride, potassium, and urea, as well as rates of evaporative water loss and water rehydration, are affected by dehydration and whether there are differences among the studied species. Our working hypothesis for this second part of the study is that Rhinella species from drier regions will exhibit greater increases in body fluid concentrations when exposed to different levels of dehydration, have lower rates of evaporative water loss, and reabsorb water more efficiently than Rhinella species from mesic environments.