Invasive species can be powerful models for studying contemporary evolution in natural environments. As invading organisms often encounter new habitats during colonization, they will experience novel selection pressures. Threespine stickleback (Gasterosteus aculeatus complex) have recently colonized large parts of Switzerland and are invasive in Lake Constance. Introduced to several watersheds roughly 150 years ago, they spread across the Swiss Plateau (400–800 m a.s.l.), bringing three divergent hitherto allopatric lineages into secondary contact. As stickleback have colonized a variety of different habitat types during this recent range expansion, the Swiss system is a useful model for studying contemporary evolution with and without secondary contact. For example, in the Lake Constance region there has been rapid phenotypic and genetic divergence between a lake population and some stream populations. There is considerable phenotypic variation within the lake population, with individuals foraging in and occupying littoral, offshore pelagic, and profundal waters, the latter of which is a very unusual habitat for stickleback. Furthermore, adults from the lake population can reach up to three times the size of adults from the surrounding stream populations, and are large by comparison to populations globally. Here, we review the historical origins of the threespine stickleback in Switzerland, and the ecomorphological variation and genomic basis of its invasion in Lake Constance. We also outline the potential ecological impacts of this invasion, and highlight the interest for contemporary evolution studies.

中文翻译：

---

康斯坦茨湖的三刺棘鱼：近期入侵的生态和基因组基质

入侵物种可以成为研究自然环境中当代进化的强大模型。由于入侵生物在殖民过程中经常遇到新的栖息地，它们将经历新的选择压力。三刺棘鱼（Gasterosteus aculeatus complex）最近在瑞士的大部分地区定居，并在康斯坦茨湖入侵。大约 150 年前，它们被引入到几个流域，遍布瑞士高原（海拔 400-800 米），将三个迄今为止不同的异域谱系带入二次接触。由于棘鱼在最近的范围扩大期间定居了各种不同的栖息地类型，因此瑞士系统是研究有和没有二次接触的当代进化的有用模型。例如，在康斯坦茨湖地区，湖泊种群和一些河流种群之间出现了快速的表型和遗传差异。湖泊种群中存在相当大的表型变异，个体在沿海、近海中上层和深水水域觅食和占据，后者是刺鱼非常不寻常的栖息地。此外，来自湖泊种群的成虫的体型可达周围河流种群成虫的三倍，与全球种群相比，它们的体型很大。在这里，我们回顾了瑞士三刺棘鱼的历史起源，及其入侵康斯坦茨湖的生态形态变异和基因组基础。我们还概述了这次入侵的潜在生态影响，并强调了对当代进化研究的兴趣。