Korsu Kai, Huusko Ari, Muotka Timo
Department of Biology, University of Oulu, PO Box 3000, 90014, Oulu, Finland.
Proc Natl Acad Sci U S A. 2007 Jun 5;104(23):9725-9. doi: 10.1073/pnas.0610719104. Epub 2007 May 21.
An ability to understand and predict invasions is elemental for controlling the detrimental effects of introduced organisms on native biota. In eastern North America, European brown trout generally dominates over, and eventually replaces, the native brook trout. We show here that in northern Europe the pattern of replacement between these two species is reversed: when transferred to North European streams, brook trout spread extensively and partially replaced the native brown trout. The effect of brook trout on brown trout was habitat-specific: brook trout excluded the native species only in small tributary streams where the reproduction of brown trout was severely reduced, whereas in larger streams brown trout was largely unaffected. Thus, the pattern of coexistence among the two salmonids in our study area is approaching that typically observed in North American streams. In both areas, brook trout ultimately settles in small headwater streams, but the process of replacement differs profoundly: in North Europe, brook trout replaces brown trout in headwater streams, whereas in North America these same streams are the ultimate refuge area for brook trout under the invasion pressure by brown trout. Our results underline the importance of knowing species' niche characteristics to explain and predict biological invasions.
理解和预测物种入侵的能力是控制外来生物对本地生物群有害影响的关键要素。在北美东部，欧洲褐鳟通常占据主导地位，并最终取代本地的溪鳟。我们在此表明，在北欧这两个物种的取代模式却相反：当被转移到北欧溪流中时，溪鳟广泛扩散并部分取代了本地的褐鳟。溪鳟对褐鳟的影响因栖息地而异：溪鳟仅在小型支流中排除了本地物种，在这些地方褐鳟的繁殖严重减少，而在较大的溪流中褐鳟基本未受影响。因此，我们研究区域内这两种鲑科鱼类的共存模式正趋近于北美溪流中通常观察到的模式。在这两个地区，溪鳟最终都栖息在小型源头溪流中，但取代过程却大不相同：在北欧，溪鳟在源头溪流中取代了褐鳟，而在北美，这些相同的溪流是溪鳟在褐鳟入侵压力下的最终避难区域。我们的结果强调了了解物种生态位特征对于解释和预测生物入侵的重要性。
