Pfister Catherine A
Department of Zoology, NJ-15, University of Washington, Seattle, WA 98195, USA, , , , , , US.
Oecologia. 1998 Mar;114(1):118-126. doi: 10.1007/s004420050427.
Despite the increasing sophistication of ecological models with respect to the size and spatial arrangement of habitat, there is relatively little empirical documentation of how species dynamics change as a function of habitat size and the fraction of habitat occupied. In an assemblage of tidepool fishes, I used maximum-likelihood estimation to test whether models which included habitat size provided a better fit to empirical data on extinction and colonization probabilities than models that assumed constant probabilities over all habitats. I found species differences in how extinction and colonization probabilities scaled with habitat size (and hence local population size). However, there was little evidence for a relationship between extinction and colonization probabilities and the fraction of occupied tidepools, as assumed in simple metapopulation models. Instead, colonization and extinction were independent of the fraction of occupied tidepools, favoring a MacArthur-Wilson island-mainland model. When I incorporated declines in extinction probability with tidepool volume in a simple simulation model, I found that predicted occupancy could change greatly, especially when colonization was low. However, the predicted fraction of occupied patches in the simulation model changed little when I incorporated the range of values reported here for extinction and colonization and the rate at which they scale with habitat size. Quantifying extinction and colonization patterns of natural populations is fundamental to understanding how species are distributed spatially and whether metapopulation models of species occupancy provide explanatory power for field populations.
尽管生态模型在栖息地大小和空间布局方面日益复杂，但关于物种动态如何随栖息地大小和被占据的栖息地比例而变化的实证记录相对较少。在一组潮池鱼类中，我使用最大似然估计来检验包含栖息地大小的模型是否比假设所有栖息地概率恒定的模型更能拟合灭绝和定殖概率的实证数据。我发现灭绝和定殖概率随栖息地大小（进而随当地种群大小）变化的方式存在物种差异。然而，几乎没有证据表明灭绝和定殖概率与被占据潮池的比例之间存在关系，而简单的集合种群模型中假定存在这种关系。相反，定殖和灭绝与被占据潮池的比例无关，这支持了麦克阿瑟 - 威尔逊岛 - 大陆模型。当我在一个简单的模拟模型中纳入灭绝概率随潮池体积的下降时，我发现预测的占有率可能会发生很大变化，尤其是在定殖率较低时。然而，当我纳入这里报告的灭绝和定殖值范围以及它们随栖息地大小变化的速率时，模拟模型中被占据斑块的预测比例变化很小。量化自然种群的灭绝和定殖模式对于理解物种如何在空间上分布以及物种占有率的集合种群模型是否能为野外种群提供解释力至关重要。
