Bedard Robin E, Weaver Savannah J, Moniz Haley A, Boback Scott M, Taylor Emily N
Biological Sciences Department, California Polytechnic State University San Luis Obispo, 1 Grand Avenue, San Luis Obispo, CA 93407, USA.
Biology Department, Dickinson College, 28 North College Street, Carlisle, PA 17013, USA.
J Exp Biol. 2025 Jan 15;228(2). doi: 10.1242/jeb.247964. Epub 2025 Jan 30.
Viviparous snakes may be particularly vulnerable to predicted increases in drought because of the high hydric costs associated with embryonic development and gestation, and their reliance on limited free-standing bodies of water or rain events for hydration. Drought will have negative implications for viper populations if females become increasingly water stressed and resorb developing embryos to conserve bodily water. We conducted a study to investigate the importance of drinking water in late-term pregnancy and its effect on cutaneous evaporative water loss (CEWL). We measured hydration and water loss in response to supplemental hydration during the final stages of embryonic development and gestation in arid-adapted prairie rattlesnakes (Crotalus viridis). Our goal was to assess how supplemental water affects hydration status and water loss (via CEWL) of females during and after pregnancy, and of their neonates before and after their first ecdysis. Supplemental hydration of pregnant C. viridis improved their hydration state and their neonates were also born more hydrated than those from control mothers, showing that they transfer water to neonates via the placenta even over a very short period in the late stages of pregnancy. The supplementally hydrated maternal C. viridis experienced slightly higher rates of CEWL compared with control snakes, but CEWL was primarily driven by ambient temperature and vapor pressure deficit at the time of measurement. At birth, neonate plasma osmolality and CEWL were both directly associated with their mothers' plasma osmolality and CEWL. Additionally, we found that neonate CEWL increased after the first ecdysis, suggesting that natal skin may help neonates avoid desiccation. Investigating and quantifying physiological implications of water shortage and dehydration can help us better understand the effects of drought and predict how wild populations of arid-adapted reptiles may respond to the predicted increase in frequency and severity of droughts.
由于胚胎发育和妊娠相关的高水分成本，以及它们对有限的独立水体或降雨事件进行补水的依赖，胎生蛇类可能特别容易受到预测的干旱增加的影响。如果雌性蛇类的水分压力越来越大，并吸收发育中的胚胎以保存身体水分，干旱将对蝰蛇种群产生负面影响。我们进行了一项研究，以调查妊娠后期饮水的重要性及其对皮肤蒸发失水（CEWL）的影响。我们测量了适应干旱的草原响尾蛇（Crotalus viridis）在胚胎发育和妊娠的最后阶段，补充水分后的水合作用和水分流失情况。我们的目标是评估补充水分如何影响怀孕雌性及其后代在怀孕期间和之后、以及新生幼蛇在第一次蜕皮前后的水合状态和水分流失（通过CEWL）。对怀孕的草原响尾蛇补充水分改善了它们的水合状态，它们的新生幼蛇出生时的水合程度也比对照母蛇的幼蛇更高，这表明即使在怀孕后期的很短时间内，它们也会通过胎盘将水分传递给新生幼蛇。与对照蛇相比，补充水分的孕蛇草原响尾蛇的CEWL率略高，但CEWL主要受测量时的环境温度和蒸汽压亏缺驱动。出生时，新生幼蛇的血浆渗透压和CEWL都与它们母亲的血浆渗透压和CEWL直接相关。此外，我们发现新生幼蛇在第一次蜕皮后CEWL增加，这表明出生时的皮肤可能有助于新生幼蛇避免脱水。研究和量化缺水和脱水的生理影响，有助于我们更好地理解干旱的影响，并预测适应干旱的爬行动物野生种群对预测的干旱频率和严重程度增加的反应。
