Vázquez Diego P, Simberloff Daniel
Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, Tennessee 37996-1610, USA.
Am Nat. 2002 Jun;159(6):606-23. doi: 10.1086/339991.
Niche breadth of species has been hypothesized to be associated with species' responses to disturbance. Disturbance is usually believed to affect specialists negatively, while generalists are believed to benefit from disturbance; we call this the "specialization-disturbance" hypothesis. We also propose an associated hypothesis (the "specialization-asymmetry-disturbance" hypothesis) under which both specialization and asymmetry of interactions would explain species' responses to disturbance. We test these hypotheses using data from a plant-pollinator system that has been grazed by cattle (i.e., a biological disturbance) in southern Argentina. We quantified specialization in species interactions, specialization of interaction partners, and species' responses to disturbance. We found no relationship between degree of specialization and a species' response to disturbance. We also found that plant-pollinator interactions tend to be asymmetric in this system; there was no relationship between the degree of specialization of a given species and the degree of specialization of its interaction partners. However, asymmetry of interactions did not explain the variability in species' responses to disturbance. Thus, both hypotheses are rejected by our data. Possible reasons include failure to assess crucial resources, substantial direct effects of disturbance, inaccurate measures of specialization, difficulty detecting highly nonlinear relationships, and limitations of a nonexperimental approach. Or, in fact, there may be no relationship between specialization and response to disturbance.
物种的生态位宽度被假设与物种对干扰的反应有关。通常认为干扰对 specialists 有负面影响，而 generalists 则被认为从干扰中受益；我们将此称为“专业化 - 干扰”假说。我们还提出了一个相关假说（“专业化 - 不对称性 - 干扰”假说），根据该假说，相互作用的专业化和不对称性都将解释物种对干扰的反应。我们使用来自阿根廷南部一个植物 - 传粉者系统的数据来检验这些假说，该系统受到牛的放牧（即生物干扰）。我们量化了物种相互作用中的专业化、相互作用伙伴的专业化以及物种对干扰的反应。我们发现专业化程度与物种对干扰的反应之间没有关系。我们还发现，在这个系统中植物 - 传粉者相互作用往往是不对称的；给定物种的专业化程度与其相互作用伙伴的专业化程度之间没有关系。然而，相互作用的不对称性并不能解释物种对干扰反应的变异性。因此，我们的数据否定了这两个假说。可能的原因包括未能评估关键资源、干扰的实质性直接影响、专业化的不准确测量、难以检测高度非线性关系以及非实验方法的局限性。或者，实际上，专业化与对干扰的反应之间可能没有关系。
