Scharnweber Kristin
Department of Ecology and Genetics - Limnology Uppsala University Uppsala Sweden.
Ecol Evol. 2020 Jul 7;10(15):8358-8367. doi: 10.1002/ece3.6543. eCollection 2020 Aug.
Phenotypic divergence in response to divergent natural selection between environments is a common phenomenon in species of freshwater fishes. Intraspecific differentiation is often pronounced between individuals inhabiting lakes versus stream habitats. The different hydrodynamic regimes in the contrasting habitats may promote a variation of body shape, but this could be intertwined with morphological adaptations to a specific foraging mode. Herein, I studied the divergence pattern of the European minnow (), a common freshwater fish that has received little attention despite its large distribution. In many Scandinavian mountain lakes, European minnows are considered as being invasive and were found to pose threats to the native fish populations due to resource competition. Minnows were recently found to show phenotypic adaptations in lake versus stream habitats, but the question remained if this divergence pattern is related to differences in resource use. I therefore studied the patterns of minnow divergence in morphology (i.e., using geometric morphometrics) and trophic niches (i.e., using stomach content analyses) in the lake Ånnsjön and its tributaries to link the changes in body morphology to the feeding on specific resources. Lake minnows showed a strong reliance on benthic Cladocera and a more streamlined body shape with a more upward facing snout, whereas stream minnows fed on macroinvertebrates (larvae and adults) to a higher degree and had a deeper body with a snout that was pointed down. Correlations showed a significant relationship of the proportion of macroinvertebrates in the gut and morphological features present in the stream minnows. The results of this study highlight the habitat-specific divergence pattern in morphology and resource use in this ubiquitous freshwater fish. Consequently, interspecific interactions of invasive minnows and the native fish population could differ in the respective food webs and resource competition could target different native fish species in the contrasting habitats.
在不同环境中，因自然选择的差异而导致的表型分化是淡水鱼类物种中的常见现象。在栖息于湖泊和溪流栖息地的个体之间，种内分化往往很明显。不同栖息地的水动力状况不同，这可能促使体型发生变化，但这可能与特定觅食方式的形态适应相互交织。在此，我研究了欧洲 minnows（此处原文未给出具体中文名）的分化模式，这是一种常见的淡水鱼，尽管分布广泛，但很少受到关注。在许多斯堪的纳维亚山区湖泊中，欧洲 minnows 被视为入侵物种，由于资源竞争，它们被发现对本地鱼类种群构成威胁。最近发现，minnows 在湖泊和溪流栖息地表现出表型适应，但这种分化模式是否与资源利用的差异有关仍不清楚。因此，我研究了 Ånnsjön 湖及其支流中 minnows 在形态（即使用几何形态测量学）和营养生态位（即使用胃内容物分析）方面的分化模式，以将身体形态的变化与特定资源的摄食联系起来。湖泊中的 minnows 强烈依赖底栖枝角类动物，身体形状更流线型，吻部更向上；而溪流中的 minnows 则更多地以大型无脊椎动物（幼虫和成虫）为食，身体更深，吻部向下。相关性分析表明，溪流中的 minnows 肠道中大型无脊椎动物的比例与形态特征之间存在显著关系。这项研究的结果突出了这种常见淡水鱼在形态和资源利用方面的栖息地特异性分化模式。因此，入侵的 minnows 与本地鱼类种群之间的种间相互作用在各自的食物网中可能不同，并且在不同的栖息地中，资源竞争可能针对不同的本地鱼类物种。
