Sinsch Ulrich
Department of Biology, Zoology Group, University of Koblenz, 56070 Koblenz, Germany.
Animals (Basel). 2024 Oct 5;14(19):2869. doi: 10.3390/ani14192869.
Conspecific amphibian populations may vary widely in local demography and average body size throughout their geographical range. The environmental drivers of variation may reflect geographical gradients or local habitat quality. Among fire salamander populations (), local demography shows a limited range of variation because high concentrations of skin toxins reduce mortality from predation to a minimum, whereas average adult body size varies significantly over a wide range. This study on four neighboring populations inhabiting the catchments of low-order streams in the upper middle Rhine Valley (Koblenz, Germany) focuses on the identification of local environmental drivers of variation in age and body size. I collected 192 individuals at two localities per stream, measured snout-vent length, clipped a toe for posterior skeletochronological age determination, and released salamanders in situ again. Populations were similar in age distribution. Local habitat quality accounted for a significant proportion of demographic variability, mediated by the impact of landscape-induced mortality risk, including roads and agriculture. Still, the main effect of variation in habitat quality was on adult body size, the result of growth rates of aquatic larvae and terrestrial juveniles. Larvae exposed to non-lethal heavy metal contamination in streams developed into smaller juveniles and adults than clean-water larvae, providing evidence for carry-over effects from one stage to another. The generally small average adult size in the Rhine Valley populations compared to those in other parts of the distribution range indicates the action of a still unidentified environmental driver.
同物种的两栖动物种群在其地理分布范围内，当地人口统计学特征和平均体型可能会有很大差异。这种差异的环境驱动因素可能反映地理梯度或当地栖息地质量。在火蝾螈种群中，当地人口统计学特征的变化范围有限，因为高浓度的皮肤毒素将捕食死亡率降至最低，而成年蝾螈的平均体型在很大范围内有显著差异。这项针对莱茵河中上游流域（德国科布伦茨）低阶溪流集水区的四个相邻种群的研究，重点是确定年龄和体型变化的当地环境驱动因素。我在每条溪流的两个地点收集了192只个体，测量了吻肛长度，剪下一个脚趾用于后续骨骼年代学年龄测定，然后将蝾螈再次放归原地。各种群的年龄分布相似。当地栖息地质量在人口统计学变异中占很大比例，这是由景观导致的死亡风险（包括道路和农业）的影响介导的。尽管如此，栖息地质量变化的主要影响还是在成年蝾螈的体型上，这是水生幼虫和陆生幼体生长速度的结果。与清洁水体中的幼虫相比，暴露于溪流中低致死剂量重金属污染的幼虫发育成的幼体和成体体型更小，这为从一个阶段到另一个阶段的遗留效应提供了证据。与分布范围其他地区的种群相比，莱茵河流域种群成年蝾螈的平均体型普遍较小，这表明存在一个尚未确定的环境驱动因素在起作用。
