Interaction of dehydration and thermal tolerance in egg masses of the red-eyed treefrog Agalychnis callidryas (Anura: Hylidae)

• Grant number: 18/04534-3
• Support Opportunities: Scholarships abroad - Research Internship - Master's degree
• Start date: June 01, 2018
• End date: August 31, 2018
• Field of knowledge: Biological Sciences - Physiology - Compared Physiology
• Principal Investigator: Fernando Ribeiro Gomes
• Grantee: Estefany Caroline Guevara Molina
• Supervisor: Karen Warkentin
• Host Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Institution abroad: Smithsonian Institution, Panamá, Panama
• Associated to the scholarship: 17/14382-3 - Interaction of behavior and physiology of anurans in response to thermal and water stress: an approach to understand the vulnerability of anurans to climate change, BP.MS

Abstract

The increase in global temperature is associated with changes in water availability (e.g. low frequency rainfall), which is causing droughts in some regions of the world. Anurans are a group particularly sensitive to these environmental changes, due to their ectothermic condition and the requirement of bodies of water for their reproduction. There are several factors that affect the biology of these organisms, which makes it one of the groups of vertebrates most threatened with extinction. Considering the above, and that the anurans in general deposit their eggs on terrestrial substrates, or directly in the water, some studies shows of the terrestrial eggs masses can also be affected by the external environment. However, there is no evidence of the effects that dehydration can have on temperatures that can tolerate the terrestrial eggs masses in their environment. Some indices of thermal tolerance, such as Voluntary Temperature Maximum (VTM), have been used to estimate vulnerability of several ectotherms (e.g. lizards and adult's anurans) to stressful thermal and hydric conditions. Nevertheless, there is no evidence of the effects that dehydration can have on temperatures that can tolerate the terrestrial eggs masses in their environment, and there is no evidence is known to integrate dehydration with indexes of thermal tolerance such as VTM, in egg masses. For this, to test our objectives, we will use as a study model clutches and embryos of the treefrog Agalychnis callidryas, present in a biological station of the Smithsonian Tropical Research Institute in Gamboa, Panamá, during the months of June-August of this year. These objectives are: To evaluate if the embryos of A. callidryas have a Voluntary Temperature Maximum (VTM) that causes its early hatching and to evaluate the effects of the dehydration of clutches and their embryos in the response to your VTM. This study is important to establish a method to measure thermal tolerance in egg masses, to know the interaction of dehydration with the VTM in this stage of life, which may indicate vulnerability of terrestrial eggs masses to hydric and thermal stressful conditions. These objectives can be evaluated in other species and, consequently, conservation strategies can be established for those areas where temperatures may be too high for the optimal development and prevalence of many anuran populations.