Department of Biology, Functional Morphology Group, University of Antwerp, Wilrijk, Belgium.
Department of Biology, Faculty of Natural Sciences, University of Sarajevo, Sarajevo, Bosnia-Hercegovina.
Integr Zool. 2021 May;16(3):336-353. doi: 10.1111/1749-4877.12492. Epub 2020 Oct 13.
Amphibians produce defensive chemicals which provide protection against both predators and infections. Within species, populations can differ considerably in the composition and amount of these chemical defenses. Studying intraspecific variation in toxins and linking it to environmental variables may help us to identify the selective drivers of toxin evolution, such as predation pressure and infection risk. Recently, there has been a renewed interest in the unique toxins produced by salamanders from the genus Salamandra: the samandarines. Despite this attention, intraspecific variation has largely been ignored within Salamandra-species. The aim of this study was to investigate whether geographic variation in profiles of samandarines exists, by sampling 4 populations of Salamandra atra over its range in the Dinaric Alps. In addition, we preliminary explored whether potential variation could be explained by predation (counting the number of snake species) and infection risk (cultivation and genomic analyses of collected soil samples). Salamanders from the 4 populations differed in toxin composition and in the size of their poison glands, although not in overall toxin quantity. Nor predation nor infection risk could explain this variation, as populations barely differed in these variables. Sampling over a much broader geographic range, using better estimators for predation and infection risk, will contribute to an improved understanding of how environment may shape variation in chemical defenses. Nevertheless, as the 4 populations of S. atra did differ in their toxin profiles, we propose that this species provides an interesting opportunity for further ecological and evolutionary studies on amphibian toxins.
两栖动物会产生防御性化学物质，这些物质可以抵御捕食者和感染。在同一物种内，种群之间这些化学防御物质的组成和含量可能存在显著差异。研究毒素的种内变异，并将其与环境变量联系起来，可以帮助我们确定毒素进化的选择驱动因素，如捕食压力和感染风险。最近，人们对蝾螈属（Salamandra）的独特毒素重新产生了兴趣： samandarines。尽管如此，Salamandra 物种内部的种内变异在很大程度上仍被忽视。本研究的目的是通过在迪纳里克阿尔卑斯山脉范围内采样 4 个 Salamandra atra 种群，来调查 samandarines 图谱是否存在地理变异。此外，我们初步探索了潜在的变异是否可以通过捕食（计算蛇类的数量）和感染风险（收集土壤样本的培养和基因组分析）来解释。来自 4 个种群的蝾螈在毒素组成和毒腺大小上存在差异，尽管毒素总量没有差异。捕食和感染风险都无法解释这种变异，因为这些变量在种群中几乎没有差异。在更广泛的地理范围内进行采样，并使用更好的捕食和感染风险估计值，将有助于更好地了解环境如何塑造化学防御的变异。然而，由于 S. atra 的 4 个种群在其毒素图谱上存在差异，我们提出该物种为进一步研究两栖动物毒素的生态和进化提供了一个有趣的机会。
