Bartolini Fabrizio, Giomi Folco
NEMO Nature and Environment Management Operators S.R.L., Viale Mazzini 26, 50132 Florence, Italy.
Via Maniciati 6, 35129 Padua, Italy.
Conserv Physiol. 2021 Apr 12;9(1):coab006. doi: 10.1093/conphys/coab006. eCollection 2021.
Endemic and relict species are often confined to ecological refugia or over fragmented distributions, representing priority conservation subjects. Within these sites, the individual population may realize distinct niches to a varying degree of specialization. An emblematic example is provided by freshwater species segregated in thermal-mineral springs, where individuals may face highly diverse microclimates in limited geographic areas. Downscaling the characterization of physiological traits to microclimatic niches becomes pivotal to adopt effective conservation measures in these heterogeneous habitats. (Brot, 1862) is an endangered relict snail endemic to a small number of thermal-mineral streams in central Italy. Here we describe the thermal tolerance of two populations of inhabiting streams with distinctly different thermal regimes, investigating the extent of physiological and behavioural specialization to such diverse microclimatic niches. The comparison of oxygen consumption rates of a population dwelling in temperate streams, characterized by seasonal temperature fluctuations (12-27°C), with a population experiencing constantly hot water (35-38°C) revealed the absence of any seasonal or geographic effect on metabolic compensation. Conversely, mobility performances were maximized in the population inhabiting the hot stream. Interestingly, here, the snails exhibited emersion behaviour outside the water, triggered by temperatures above 37°C. In the field, individuals of this population are observed inactive on stream banks, conceivably to minimize the metabolic cost that otherwise would be induced by remaining in the hot water. Only a few individuals from the temperate stream exhibited the same behaviour when exposed to elevated temperatures, suggesting the exaptation of a pre-existing trait during the evolutionary process of adaptation to hot waters. The present results provide elements for the best practice in future programmes aimed at reintroducing stocks of threatened species across heterogeneous habitats. Our study further underlines the relevance of downscaling data collection for endangered species conservation in order to recognize microclimatic specializations.
特有物种和残遗物种往往局限于生态避难所或分布过度破碎化的区域，是优先保护对象。在这些区域内，各个种群可能会在不同程度的专业化过程中实现独特的生态位。一个典型的例子是栖息在温泉中的淡水物种，在有限的地理区域内，个体可能面临高度多样的小气候。将生理特征的描述细化到小气候生态位对于在这些异质栖息地采取有效的保护措施至关重要。（Brot，1862）是一种濒危的残遗蜗牛，原产于意大利中部少数温泉溪流。在这里，我们描述了栖息在热状况明显不同的溪流中的两个种群的耐热性，研究了它们对如此多样的小气候生态位的生理和行为专业化程度。将栖息在温带溪流（特征为季节性温度波动，12 - 27°C）中的种群与处于持续热水环境（35 - 38°C）中的种群的耗氧率进行比较，结果显示代谢补偿不存在任何季节性或地理效应。相反，栖息在热溪流中的种群的移动能力表现最佳。有趣的是，在这里，蜗牛在水温高于37°C时会表现出出水行为。在野外，可以观察到这个种群的个体在溪岸不活动，推测这是为了将否则会因留在热水中而产生的代谢成本降至最低。只有少数来自温带溪流的个体在暴露于高温时表现出相同行为，这表明在适应热水的进化过程中一个预先存在的特征发生了适应性改变。目前的结果为未来旨在将受威胁物种种群重新引入异质栖息地的计划中的最佳实践提供了依据。我们的研究进一步强调了为濒危物种保护而细化数据收集的相关性，以便识别小气候专业化情况。
