Andersson Jens, Johansson Frank, Söderlund Tony
Department of Ecology and Environmental Science, Umeå University, 90187 Umeå, Sweden.
Proc Biol Sci. 2006 Feb 22;273(1585):431-7. doi: 10.1098/rspb.2005.3343.
Predator cues and diet, when studied separately, have been shown to affect body shape of organisms. Previous studies show that the morphological responses to predator absence/presence and diet may be similar, and hence could confound the interpretation of the causes of morphological differences found between groups of individuals. In this study, we simultaneously examined the effect of these two factors on body shape and performance in crucian carp in a laboratory experiment. Crucian carp (Carassius carassius) developed a shallow body shape when feeding on zooplankton prey and a deep body shape when feeding on benthic chironomids. In addition, the presence of chemical cues from a pike predator affected body shape, where a shallow body shape was developed in the absence of pike and a deep body shape was developed in the presence of pike. Foraging activity was low in the presence of pike cues and when chironomids were given as prey. Our results thereby suggest that the change in body shape could be indirectly mediated through differences in foraging activity. Finally, the induced body shape changes affected the foraging efficiency, where crucians raised on a zooplankton diet or in the absence of pike cues had a higher foraging success on zooplankton compared to crucian raised on a chironomid diet or in the presence of pike. These results suggest that body changes in response to predators can be associated with a cost, in terms of competition for resources.
单独研究时，捕食者线索和饮食已被证明会影响生物体的体型。先前的研究表明，对捕食者存在与否和饮食的形态学反应可能相似，因此可能会混淆对不同个体组之间形态差异原因的解释。在本研究中，我们在实验室实验中同时研究了这两个因素对鲫鱼体型和性能的影响。鲫鱼以浮游动物为食时会发育出浅体型，以底栖摇蚊为食时会发育出深体型。此外，来自梭子鱼捕食者的化学线索的存在会影响体型，在没有梭子鱼的情况下会发育出浅体型，在有梭子鱼的情况下会发育出深体型。在有梭子鱼线索存在且以摇蚊为猎物时，觅食活动较低。我们的结果因此表明，体型的变化可能通过觅食活动的差异间接介导。最后，诱导的体型变化影响了觅食效率，与以摇蚊为食或在有梭子鱼线索存在的情况下饲养的鲫鱼相比，以浮游动物为食或在没有梭子鱼线索的情况下饲养的鲫鱼在浮游动物上的觅食成功率更高。这些结果表明，捕食者引起的体型变化在资源竞争方面可能与成本相关。
