1. Interspecific competition may be particularly exacerbated when occurring between native and invasive alien species, with environmental conditions affecting drivers of natural selection and shaping spatio-temporal dynamics of animal communities. The effects of invaders are particularly evident in aquatic ecosystems with delicate and complex balances, such as Mediterranean coastal wetlands, characterized by unpredictable water flows and variable reserves. Understanding how native species respond to human-induced biological invasions is of paramount importance for planning management measures aiming at conservation purposes.
2. This study investigated whether the occurrence of a competing invader species resulted in changes in the ecological adaptations of a native species by comparing two coastal wetland fish species: the invasive eastern mosquitofish Gambusia holbrooki and the native Mediterranean killifish Aphanius fasciatus of conservation concern. The hypothesis was tested by sampling fishes at a coastal Ramsar site in central Italy, over 2 years.
3. Generalized linear mixed models were used to examine the occurrence of killifish in relation to water parameters and the presence of its putative competitor. The aim was to determine whether salinity, temperature, and water depth influenced the presence and abundance of killifish when in sympatry with mosquitofish.
4. Both the probability of presence and abundance of killifish increased with water salinity, but this increase was stronger when mosquitofish was present. Increasing water temperature and water depth were associated with a higher probability of presence and abundance of killifish respectively, although the effect of water depth was small. Both salinity and the presence of the invader acted synergistically in characterizing and shaping the population structure of the native species.
5. Living in the most extreme and stressed environments, the killifish is potentially at higher risk of extinction. These results highlight the importance of considering the interplay between multiple abiotic stressors combined with comparative data between invasive and native species as increasingly critical to aid in conservation efforts.

中文翻译：

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推到边缘：当与入侵的 Gambusia holbrooki 一致时，环境因素驱动 Aphanius fasciatus 的生态反应

1. 当本地物种和外来入侵物种之间发生时，种间竞争可能会特别加剧，环境条件会影响自然选择的驱动因素并塑造动物群落的时空动态。入侵者的影响在具有微妙和复杂平衡的水生生态系统中尤为明显，例如地中海沿海湿地，其特点是不可预测的水流和可变的储量。了解本地物种如何应对人类引起的生物入侵对于规划旨在保护目的的管理措施至关重要。
2. 本研究通过比较两种沿海湿地鱼类：入侵性东部蚊鱼Gambusia holbrooki和保护关注的本土地中海鳉鱼Aphanius fasciatus，调查了竞争入侵物种的出现是否会导致本地物种的生态适应发生变化。通过在意大利中部的一个沿海拉姆萨尔遗址对鱼类进行采样超过 2 年，对该假设进行了检验。
3. 广义线性混合模型用于检查与水参数及其假定竞争对手的存在相关的鳉鱼的发生。目的是确定盐度、温度和水深是否影响与蚊鱼共存的鳉鱼的存在和丰度。
4. 鳉鱼存在的概率和丰度都随着水的盐度而增加，但当存在蚊鱼时，这种增加的幅度更大。尽管水深的影响很小，但水温和水深的增加分别与鳉鱼的存在概率和数量增加有关。盐度和入侵者的存在在表征和塑造本地物种的种群结构方面具有协同作用。
5. 生活在最极端和压力最大的环境中，鳉鱼可能面临更高的灭绝风险。这些结果强调了考虑多种非生物压力因素之间的相互作用以及入侵物种和本地物种之间的比较数据的重要性，这对于帮助保护工作越来越重要。