Department of Theoretical Ecology, Institute of Entomology, Biology Centre ASCR, and Institute of Mathematics and Biomathematics, Faculty of Science, University of South Bohemia, Branisovská 31, 37005 Ceské Budejovice, Czech Republic.
J Theor Biol. 2010 Sep 21;266(2):211-8. doi: 10.1016/j.jtbi.2010.06.034. Epub 2010 Jun 30.
Recent modeling studies exploring the effect of consumers' adaptivity in diet composition on food web complexity invariably suggest that adaptivity in foraging decisions of consumers makes food webs more complex. That is, it allows for survival of a higher number of species when compared with non-adaptive food webs. Population-dynamical models in these studies share two features: parameters are chosen uniformly for all species, i.e. they are species-independent, and adaptive foraging is described by the search image model. In this article, we relax both these assumptions. Specifically, we allow parameters to vary among the species and consider the diet choice model as an alternative model of adaptive foraging. Our analysis leads to three important predictions. First, for species-independent parameter values for which the search image model demonstrates a significant effect of adaptive foraging on food web complexity, the diet choice model produces no such effect. Second, the effect of adaptive foraging through the search image model attenuates when parameter values cease to be species-independent. Finally, for the diet choice model we observe no (significant) effect of adaptive foraging on food web complexity. All these observations suggest that adaptive foraging does not always lead to more complex food webs. As a corollary, future studies of food web dynamics should pay careful attention to the choice of type of adaptive foraging model as well as of parameter values.
最近的建模研究探索了消费者在饮食组成方面的适应性对食物网复杂性的影响，这些研究无一例外地表明，消费者在觅食决策方面的适应性使食物网更加复杂。也就是说，与非适应性食物网相比，它允许更多物种的生存。这些研究中的种群动态模型有两个共同特征：所有物种的参数都是均匀选择的，即它们是与物种无关的，适应性觅食由搜索图像模型来描述。在本文中，我们放宽了这两个假设。具体来说，我们允许参数在物种之间变化，并考虑饮食选择模型作为适应性觅食的替代模型。我们的分析得出了三个重要的预测。首先，对于搜索图像模型显示适应性觅食对食物网复杂性有显著影响的与物种无关的参数值，饮食选择模型则没有这种影响。其次，当参数值不再是与物种无关时，搜索图像模型中适应性觅食的影响会减弱。最后，对于饮食选择模型，我们观察到适应性觅食对食物网复杂性没有（显著）影响。所有这些观察结果表明，适应性觅食并不总是导致更复杂的食物网。因此，未来关于食物网动态的研究应该仔细注意选择适应性觅食模型的类型以及参数值。
