Heat-Induced Hatching: Clarifying Effects of Hydration and Heating Rate on Behavioral Thermal Tolerance of Red-Eyed Treefrog Embryos.

IF 2.2 4区 生物学 Q2 BIOLOGY
Integrative Organismal Biology Pub Date : 2025-06-05 eCollection Date: 2025-01-01 DOI:10.1093/iob/obaf023
Estefany Caroline Guevara-Molina, Fernando Ribeiro Gomes, Karen M Warkentin
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Abstract

Anurans are one of the most diverse groups of vertebrates but also most threatened by current climate change effects such as increasing environmental temperatures and more frequent and prolonged periods without rain. Many tropical anurans lay terrestrial eggs that are particularly vulnerable to drying and warming. In some such species, embryos hatch prematurely to escape from drying eggs. In red-eyed treefrogs, Agalychnis callidryas, embryos hatch early to escape both drying and excessive warming, expressing a behavioral thermal tolerance (i.e., VTMax). Prior research suggested that drying reduces the VTMax of embryos. However, because hydrated clutches warmed more slowly, the effect of drying on VTMax was confounded with that of faster warming. To disentangle these dynamics, we designed a novel apparatus to warm terrestrial frog egg-clutches at controlled rates and minimize evaporative cooling. We independently manipulated clutch hydration and heat input to assess their individual and combined effects on embryo VTMax. Proportional egg-volume loss was similar across hydration × heat input categories. High heat input resulted in higher clutch warming rates and shorter trial durations, across hydration levels. Within clutches, warming rates differed between back and surface thermocouple positions, generating thermal gradients as warming progressed. Clutch dehydration reduced embryo VTMax, with no main or interacting effect of heat input. This evidence that egg drying reduces thermal tolerance across testing conditions supports a direct role for hydration in the behavioral decisions of warming embryos, rather than an indirect effect mediated by changes in evaporative cooling. It suggests that embryos assessing risk integrate information about hydration, and perhaps changes in hydration, with information about current and changing temperature. These findings highlight the value of methods to independently manipulate hydration and heating rate, showing the complexity of thermal ecology in embryonic ectotherms. We encourage further research on temperature and hydration effects on embryo hatching to better understand tropical anurans' adaptive strategies under climate change.

热诱导孵化:澄清水化和加热速率对红眼树蛙胚胎行为耐热性的影响。
无尾动物是最多样化的脊椎动物群体之一,但也最受当前气候变化影响的威胁,如环境温度升高和更频繁和更长时间的无雨期。许多热带无尾猿在陆地上产下的蛋特别容易受到干燥和变暖的影响。在一些这样的物种中,胚胎过早孵化以逃离干燥的卵。在红眼树蛙(Agalychnis callidryas)中,胚胎早期孵化以逃避干燥和过度温暖,表现出行为上的热耐受性(即VTMax)。先前的研究表明,干燥会降低胚胎的VTMax。然而,由于水合离合器变暖更慢,干燥对VTMax的影响与变暖更快的影响相混淆。为了解开这些动力学,我们设计了一种新的装置,以控制速率加热陆地蛙卵,并最大限度地减少蒸发冷却。我们分别控制离合器的水分和热量输入,以评估它们对胚胎VTMax的单独和联合影响。不同水合×热输入类别的蛋体积损失比例相似。高热量输入导致更高的离合器升温率和更短的试验持续时间,跨越水合水平。在离合器内部,背面和表面热电偶位置之间的升温速率不同,随着升温的进行产生热梯度。离合脱水降低了胚胎VTMax,热输入无主要影响或交互影响。卵子干燥降低了测试条件下的热耐受性,这一证据支持水合作用在变暖胚胎的行为决定中起直接作用,而不是由蒸发冷却变化介导的间接影响。这表明,评估风险的胚胎将水合作用的信息,以及水合作用的变化,与当前和变化的温度信息结合起来。这些发现突出了独立控制水化和加热速率的方法的价值,显示了胚胎变温动物热生态的复杂性。我们鼓励进一步研究温度和水分对胚胎孵化的影响,以更好地了解热带无尾猿在气候变化下的适应策略。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
CiteScore
3.70
自引率
6.70%
发文量
48
审稿时长
20 weeks
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