Parasitism may enhance rather than reduce the predatory impact of an invader
Parasitism may enhance rather than reduce the predatory impact of an invader
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DOI：
10.1098/rsbl.2010.0171
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发表时间：
2010-10-23
期刊：
影响因子：
3.3
通讯作者：
Dunn, Alison M.
中科院分区：
文献类型：
--
作者：
Dick, Jaimie T. A.;Armstrong, Michael;Dunn, Alison M.
入侵物种可对群落产生深远影响，人们日益认识到，这种影响可能是由寄生作用引起的。“敌人释放”假说假定入侵者可能是成功的，并由于逃离寄生而产生很大影响。或者，我们假设，寄生虫可能会增加宿主的摄食率，因此寄生入侵者可能会增加社区的影响。在这里，我们调查的影响，寄生对入侵淡水端足类钩虾捕食的影响。高达70%的人感染了棘头虫寄生虫Echinorhynchus truttae，但寄生的个体在身体状况上与未寄生的个体没有什么不同。被寄生的个体消耗了显着更多的猎物（Asellus aquaticus;等足目）比unparasitized个人。被寄生和未被寄生的个人显示II型功能反应（FR），与FR的寄生的个人上升更陡峭，具有更高的渐近线，与未被寄生的个人相比。虽然寄生虫减少了个别女性的健身，我们预测人口招聘的影响不大，因为寄生虫的患病率低，在生殖高峰期。因此，寄生虫的捕食率，但低人口健身效果的人均效果，因此可能会增加，而不是减少这种入侵者的影响。
Invasive species can have profound impacts on communities and it is increasingly recognized that such effects may be mediated by parasitism. The 'enemy release' hypothesis posits that invaders may be successful and have high impacts owing to escape from parasitism. Alternatively, we hypothesize that parasites may increase host feeding rates and hence parasitized invaders may have increased community impacts. Here, we investigate the influence of parasitism on the predatory impact of the invasive freshwater amphipod Gammarus pulex. Up to 70 per cent of individuals are infected with the acanthocephalan parasite Echinorhynchus truttae, but parasitized individuals were no different in body condition to those unparasitized. Parasitized individuals consumed significantly more prey (Asellus aquaticus; Isopoda) than did unparasitized individuals. Both parasitized and unparasitized individuals displayed Type-II functional responses (FRs), with the FR for parasitized individuals rising more steeply, with a higher asymptote, compared with unparasitized individuals. While the parasite reduced the fitness of individual females, we predict a minor effect on population recruitment because of low parasite prevalence in the peak reproductive period. The parasite thus has a large per capita effect on predatory rate but a low population fitness effect, and thus may enhance rather than reduce the impact of this invader.