Pirroni Sara, de Pennafort Dezen Laura, Santi Francesco, Riesch Rüdiger
Department of Biological Sciences Centre for Ecology, Evolution and Behaviour Royal Holloway University of London Egham UK.
Ecol Evol. 2021 Mar 15;11(9):4379-4398. doi: 10.1002/ece3.7334. eCollection 2021 May.
Eastern mosquitofish () are among the most widely introduced freshwater species globally. To gain a better understanding of feeding patterns in non-native populations, and which local factors may influence them at the population level, we carried out gut content analysis on 163 specimens from nine invasive populations in Italy and Spain. Based on previous studies, we predicted that (a) mosquitofish are omnivores with a preference for detritus and cladocerans; (b) they display size- and population-specific differences in gut morphologies and diet, with larger fish feeding more intensively over a wider range of prey items; and (c) some of the variation would be associated with differences in local environmental and climatic factors. Our results confirmed our first prediction, because mosquitofish fed on a variety of diet items, among which detritus and Cladocera dominated. However, not a single diet item was shared among all populations. Congruent with our second prediction, we further identified size- and population-specific differences in the occurrence of some diet items and gut morphologies. However, observed patterns in dietary habits did not seem to be driven by the environmental and climatic variables we had quantified. The fairly variable diet likely aids invasion success and helps explain the ubiquity of invasive mosquitofish across Italy and Spain, as mosquitofish seem to be able to rely on whatever a local habitat provides. We further propose that size-specific differences likely capture the substantial sexual size dimorphism (males are smaller than females), while population-specific differences are likely the result of differences in local prey abundance. The lack of an influence of temperature on dietary habits suggests that mosquitofish feeding ecology may be less impacted by rising temperatures than other freshwater fish species. If true, then this suggests climate change-induced effects may further exacerbate the competitive superiority of mosquitofish over native species in the future.
东部食蚊鱼（）是全球引入范围最广的淡水物种之一。为了更好地了解非本地种群的摄食模式，以及哪些当地因素可能在种群水平上影响它们，我们对来自意大利和西班牙九个入侵种群的163个样本进行了肠道内容物分析。基于之前的研究，我们预测：（a）食蚊鱼是杂食动物，偏好碎屑和枝角类动物；（b）它们在肠道形态和饮食上表现出大小和种群特异性差异，较大的鱼在更广泛的猎物种类上摄食更密集；（c）一些变化将与当地环境和气候因素的差异有关。我们的结果证实了我们的第一个预测，因为食蚊鱼以各种食物为食，其中碎屑和枝角类动物占主导。然而，所有种群之间没有一种食物是相同的。与我们的第二个预测一致，我们进一步确定了一些食物种类的出现和肠道形态在大小和种群上的特异性差异。然而，观察到的饮食习惯模式似乎不是由我们量化的环境和气候变量驱动的。相当多样的饮食可能有助于入侵成功，并有助于解释入侵食蚊鱼在意大利和西班牙无处不在的现象，因为食蚊鱼似乎能够依赖当地栖息地提供的任何食物。我们进一步提出，大小特异性差异可能反映了显著的两性异形（雄性比雌性小），而种群特异性差异可能是当地猎物丰度差异的结果。温度对饮食习惯缺乏影响表明，食蚊鱼的摄食生态可能比其他淡水鱼物种受温度上升的影响更小。如果是这样，那么这表明气候变化引起的影响可能会在未来进一步加剧食蚊鱼相对于本地物种的竞争优势。
