Cheney Karen L, Côté Isabelle M
School of Biological Sciences, Centre for Ecology, Evolution and Conservation, University of East Anglia, Norwich, UK.
Biol Lett. 2005 Jun 22;1(2):162-5. doi: 10.1098/rsbl.2004.0288.
The exact nature of many interspecific interactions remains unclear, with some evidence suggesting mutualism and other evidence pointing to parasitism for the same pair of interacting species. Here, we show spatial variation in the outcome of the cleaning relationship between Caribbean cleaning gobies (Elacatinus evelynae) and longfin damselfish (Stegastes diencaeus) over the distribution range of these species, and link this variation to the availability of ectoparasites. Cleaning interactions at sites with more ectoparasites were characterized by greater reductions in ectoparasite loads on damselfish clients and lower rates of removal of scales and mucus (i.e. cheating) by cleaning gobies, whereas the opposite was observed at sites where ectoparasite abundance was lower. For damselfish clients, cleaning was therefore clearly mutualistic in some locations, but sometimes neutral or even parasitic in others. Seasonal variability in ectoparasite abundance may ensure that locally low parasite availability, which promotes cleanerfish cheating, may be a transient condition at any given site. Conflicting conclusions about the nature of cleaning symbioses may, therefore, be explained by variation in ectoparasite abundance.
许多种间相互作用的确切性质仍不清楚，一些证据表明是互利共生，而另一些证据则表明同一对相互作用的物种之间是寄生关系。在这里，我们展示了在加勒比清洁虾虎鱼（Elacatinus evelynae）和长鳍雀鲷（Stegastes diencaeus）的分布范围内，清洁关系结果的空间变化，并将这种变化与体外寄生虫的可获得性联系起来。在体外寄生虫较多的地点，清洁相互作用的特征是雀鲷宿主身上的体外寄生虫负荷减少得更多，而清洁虾虎鱼去除鳞片和黏液（即欺骗行为）的比率较低；而在体外寄生虫丰度较低的地点，观察到的情况则相反。因此，对于雀鲷宿主来说，清洁在某些地点显然是互利共生的，但在其他地点有时是中性的，甚至是寄生性的。体外寄生虫丰度的季节性变化可能确保局部寄生虫可获得性低（这会促使清洁鱼出现欺骗行为）在任何给定地点可能是一种短暂的状况。因此，关于清洁共生性质的相互矛盾的结论可能可以用体外寄生虫丰度的变化来解释。
