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Latitude-Induced and Behaviorally Thermoregulated Variations in Upper Thermal Tolerance of Two Anuran Species

SIMPLE SUMMARY: Thermal tolerance can help understand species’ response to climate change, but regional scale data is missing. We filled this gap by investigating intraspecific variations in the critical thermal maximum (CTmax) of Rana uenoi tadpoles collected from rice paddies and Bufo sachalinensi...

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Autores principales: Kim, Ye Inn, Chuang, Ming-Feng, Borzée, Amaël, Kwon, Sera, Jang, Yikweon
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9598288/
https://www.ncbi.nlm.nih.gov/pubmed/36290410
http://dx.doi.org/10.3390/biology11101506
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author Kim, Ye Inn
Chuang, Ming-Feng
Borzée, Amaël
Kwon, Sera
Jang, Yikweon
author_facet Kim, Ye Inn
Chuang, Ming-Feng
Borzée, Amaël
Kwon, Sera
Jang, Yikweon
author_sort Kim, Ye Inn
collection PubMed
description SIMPLE SUMMARY: Thermal tolerance can help understand species’ response to climate change, but regional scale data is missing. We filled this gap by investigating intraspecific variations in the critical thermal maximum (CTmax) of Rana uenoi tadpoles collected from rice paddies and Bufo sachalinensis tadpoles collected from lakes, over a five-degree latitudinal gradient. We found a positive relationship between latitude and CTmax in R. uenoi tadpoles, although they did not display specific thermoregulatory behaviors. In contrast, none of the abiotic factors were related to CTmax in B. sachalinensis, but the tadpoles swam closer to the water surface when water temperature increased. Thus, R. uenoi displays a physiological adaptive response while B. sachalinensis behaviorally thermoregulate. This is important as species specific responses to climate change have to be understood for their conservation. ABSTRACT: Although thermal tolerance along geographical gradients gives an insight into species’ response to climate change, current studies on thermal tolerance are strongly skewed towards global-scale patterns. As a result, intraspecific variations are often assumed to be constant, despite a lack of evidence. To understand population-specific responses to thermal stress, we investigated the presence of intraspecific variations in the critical thermal maximum (CTmax) of tadpoles in two anuran species, Rana uenoi and Bufo sachalinensis. The study was conducted across a five-degree latitudinal gradient in the Republic of Korea. We exposed the tadpoles to increasing temperatures and recorded the CTmax for 270 R. uenoi individuals from 11 sites, collected in rice paddies, and for 240 B. sachalinensis individuals from ten sites, collected in reservoirs. We also recorded the swimming performance and behavior of the tadpoles when placed in an experimental apparatus during CTmax measurements. We then used linear regressions to determine the relationship between abiotic factors and CTmax. In R. uenoi, we found a positive relationship between latitude and CTmax, but the tadpoles did not display specific thermoregulatory behaviors. In B. sachalinensis, none of the abiotic factors such as climate and geographic coordinates were related to CTmax, but we detected a tendency to swim close to the water surface when water temperature was increasing. For R. uenoi, we tentatively relate the CTmax variability across the latitudinal gradient to a physiological adaptive response associated with habitat characteristics that are assumed to be fluctuating, as the species inhabits small water bodies prone to drying out. In the case of B. sachalinensis, the behavior observed may be linked to oxygen depletion and thermoregulation, as it may buffer temperature changes in the absence of physiological adjustment. These findings suggest that intra-specific variations in CTmax are greater than generally accounted for, and thermal conditions of natural environments are important for understanding thermal tolerance in ectothermic species. Our results highlight that species’ specific responses to climate warmings need to be studied to better protect species against climate change.
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spelling pubmed-95982882022-10-27 Latitude-Induced and Behaviorally Thermoregulated Variations in Upper Thermal Tolerance of Two Anuran Species Kim, Ye Inn Chuang, Ming-Feng Borzée, Amaël Kwon, Sera Jang, Yikweon Biology (Basel) Article SIMPLE SUMMARY: Thermal tolerance can help understand species’ response to climate change, but regional scale data is missing. We filled this gap by investigating intraspecific variations in the critical thermal maximum (CTmax) of Rana uenoi tadpoles collected from rice paddies and Bufo sachalinensis tadpoles collected from lakes, over a five-degree latitudinal gradient. We found a positive relationship between latitude and CTmax in R. uenoi tadpoles, although they did not display specific thermoregulatory behaviors. In contrast, none of the abiotic factors were related to CTmax in B. sachalinensis, but the tadpoles swam closer to the water surface when water temperature increased. Thus, R. uenoi displays a physiological adaptive response while B. sachalinensis behaviorally thermoregulate. This is important as species specific responses to climate change have to be understood for their conservation. ABSTRACT: Although thermal tolerance along geographical gradients gives an insight into species’ response to climate change, current studies on thermal tolerance are strongly skewed towards global-scale patterns. As a result, intraspecific variations are often assumed to be constant, despite a lack of evidence. To understand population-specific responses to thermal stress, we investigated the presence of intraspecific variations in the critical thermal maximum (CTmax) of tadpoles in two anuran species, Rana uenoi and Bufo sachalinensis. The study was conducted across a five-degree latitudinal gradient in the Republic of Korea. We exposed the tadpoles to increasing temperatures and recorded the CTmax for 270 R. uenoi individuals from 11 sites, collected in rice paddies, and for 240 B. sachalinensis individuals from ten sites, collected in reservoirs. We also recorded the swimming performance and behavior of the tadpoles when placed in an experimental apparatus during CTmax measurements. We then used linear regressions to determine the relationship between abiotic factors and CTmax. In R. uenoi, we found a positive relationship between latitude and CTmax, but the tadpoles did not display specific thermoregulatory behaviors. In B. sachalinensis, none of the abiotic factors such as climate and geographic coordinates were related to CTmax, but we detected a tendency to swim close to the water surface when water temperature was increasing. For R. uenoi, we tentatively relate the CTmax variability across the latitudinal gradient to a physiological adaptive response associated with habitat characteristics that are assumed to be fluctuating, as the species inhabits small water bodies prone to drying out. In the case of B. sachalinensis, the behavior observed may be linked to oxygen depletion and thermoregulation, as it may buffer temperature changes in the absence of physiological adjustment. These findings suggest that intra-specific variations in CTmax are greater than generally accounted for, and thermal conditions of natural environments are important for understanding thermal tolerance in ectothermic species. Our results highlight that species’ specific responses to climate warmings need to be studied to better protect species against climate change. MDPI 2022-10-14 /pmc/articles/PMC9598288/ /pubmed/36290410 http://dx.doi.org/10.3390/biology11101506 Text en © 2022 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Kim, Ye Inn
Chuang, Ming-Feng
Borzée, Amaël
Kwon, Sera
Jang, Yikweon
Latitude-Induced and Behaviorally Thermoregulated Variations in Upper Thermal Tolerance of Two Anuran Species
title Latitude-Induced and Behaviorally Thermoregulated Variations in Upper Thermal Tolerance of Two Anuran Species
title_full Latitude-Induced and Behaviorally Thermoregulated Variations in Upper Thermal Tolerance of Two Anuran Species
title_fullStr Latitude-Induced and Behaviorally Thermoregulated Variations in Upper Thermal Tolerance of Two Anuran Species
title_full_unstemmed Latitude-Induced and Behaviorally Thermoregulated Variations in Upper Thermal Tolerance of Two Anuran Species
title_short Latitude-Induced and Behaviorally Thermoregulated Variations in Upper Thermal Tolerance of Two Anuran Species
title_sort latitude-induced and behaviorally thermoregulated variations in upper thermal tolerance of two anuran species
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9598288/
https://www.ncbi.nlm.nih.gov/pubmed/36290410
http://dx.doi.org/10.3390/biology11101506
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