Jäger Ilonka, Schjørring Solveig
Department of Evolutionary Ecology, Max-Planck-Institute of Limnology, Plön, Germany.
Evolution. 2006 Mar;60(3):616-22. doi: 10.1554/05-450.1.
We studied experimental double infections of the cestode Schistocephalus solidus in its stickleback host. In particular, we were interested in how two important components of the cestode's transmission success-establishment and growth within the fish host-were affected by the relatedness of the two parasites in a double exposure and by the timing of the two exposures, that is, whether they occurred simultaneously or sequentially. We found that male sticklebacks more often became infected (singly or doubly) if the two cestodes in the exposures were related, whereas female sticklebacks were more easily infected (singly or doubly) when exposed to two unrelated cestodes. Irrespective of the fish's gender, successful infections more often contained both cestodes when they were related. In sequential exposures with related as well as unrelated cestodes, the cestode in the later exposure survived better and also grew larger than the cestode from the first exposure, despite being one week younger. Our results emphasize that within-host dynamics and factors acting at this level can play an important role in determining a parasite's transmission success.
我们研究了绦虫实尾裂头绦虫在其棘背鱼宿主中的实验性双重感染。具体而言，我们感兴趣的是，绦虫传播成功的两个重要组成部分——在鱼类宿主体内的定殖和生长——如何受到双重暴露中两种寄生虫的亲缘关系以及两次暴露时间的影响，即它们是同时发生还是相继发生。我们发现，如果暴露中的两种绦虫具有亲缘关系，雄性棘背鱼更常被感染（单次或双重感染），而雌性棘背鱼在暴露于两种无亲缘关系的绦虫时更容易被感染（单次或双重感染）。无论鱼的性别如何，当两种绦虫具有亲缘关系时，成功感染中更常同时含有这两种绦虫。在对有亲缘关系和无亲缘关系的绦虫进行相继暴露时，尽管后一次暴露的绦虫比第一次暴露的绦虫小一周，但后一次暴露的绦虫存活得更好，生长得也更大。我们的结果强调，宿主体内动态以及在此层面起作用的因素在决定寄生虫的传播成功方面可以发挥重要作用。
