Ecol Evol. 2012 Jun;2(6):1083-98. doi: 10.1002/ece3.234.
An increasing number of exotic animals are causing ecological problems. Therefore, for better ecosystem management, it is important to understand how exotic species colonize and adapt to novel environments. The threespine sticklebacks (Gasterosteus aculeatus) can be a good vertebrate model system to explore the ecological and genetic mechanisms of adaptation not only in natural populations, but also in non-native populations. Although morphological changes have been documented in several introduced populations of stickleback, little is known about the dietary changes during colonization into novel environments. Here, we investigated the morphological and dietary changes of exotic threespine stickleback populations introduced into three Japanese crater lakes (Lake Towada, Lake Kussharo, and Lake Shikotsu). Sticklebacks were introduced into the crater lakes likely along with salmonids transplanted for aquaculture. The stickleback population in Lake Kussharo had multiple mitochondrial haplotypes and had larger phenotypic variances than other crater lake stickleback populations that had only one mitochondrial haplotype. Compilation of historical data on the morphology and stomach contents of the Lake Towada stickleback population showed that substantial shifts in body size and stomach contents occurred after colonization. Some of these changes may be related to an outbreak of the Schistocephalus parasite. These results suggest that sticklebacks can change their morphology and trophic ecology when they colonize novel environments. Therefore, extreme care should be taken when salmonids are transported between watersheds for aquaculture and that long-term monitoring of exotic species is essential for ecosystem management. In addition, further genetic studies on phenotypic changes in crater lake sticklebacks would help elucidate the genetic mechanisms underlying the adaptation of exotic fishes to novel environments.
越来越多的外来动物正在造成生态问题。因此，为了更好地进行生态系统管理，了解外来物种如何在新环境中定殖和适应是很重要的。三刺鱼（Gasterosteus aculeatus）可以作为一个很好的脊椎动物模式系统，不仅可以在自然种群中，也可以在非本地种群中探索适应的生态和遗传机制。尽管在几个引入的三刺鱼种群中已经记录到形态变化，但对于在进入新环境时的饮食变化却知之甚少。在这里，我们研究了引入日本三个火山口湖（十和田湖、屈斜路湖和钏路湖）的外来三刺鱼种群的形态和饮食变化。这些三刺鱼可能是随着用于水产养殖的鲑鱼一起被引入火山口湖的。屈斜路湖的三刺鱼种群具有多种线粒体单倍型，与其他只有一种线粒体单倍型的火山口湖三刺鱼种群相比，表现出更大的表型方差。对十和田湖三刺鱼种群的形态和胃内容物的历史数据进行汇编表明，在定殖后，其体型和胃内容物发生了实质性的变化。这些变化中的一些可能与 Schistocephalus 寄生虫的爆发有关。这些结果表明，三刺鱼在定殖新环境时可以改变其形态和营养生态。因此，在鲑鱼为水产养殖而在流域之间运输时应格外小心，并且对外来物种进行长期监测对于生态系统管理是必不可少的。此外，对火山口湖三刺鱼的表型变化进行进一步的遗传研究将有助于阐明外来鱼类适应新环境的遗传机制。
