Community and Conservation Ecology Group, University of Groningen, PO Box 14, 9750 AA Haren, The Netherlands.
Ecol Lett. 2005 May;8(5):493-504. doi: 10.1111/j.1461-0248.2005.00745.x.
Species abundances are undoubtedly the most widely available macroecological data, but can we use them to distinguish among several models of community structure? Here we present a Bayesian analysis of species-abundance data that yields a full joint probability distribution of each model's parameters plus a relatively parameter-independent criterion, the posterior Bayes factor, to compare these models. We illustrate our approach by comparing three classical distributions: the zero-sum multinomial (ZSM) distribution, based on Hubbell's neutral model, the multivariate Poisson lognormal distribution (MPLN), based on niche arguments, and the discrete broken stick (DBS) distribution, based on MacArthur's broken stick model. We give explicit formulas for the probability of observing a particular species-abundance data set in each model, and argue that conditioning on both sample size and species count is needed to allow comparisons between the two distributions. We apply our approach to two neotropical communities (trees, fish). We find that DBS is largely inferior to ZSM and MPLN for both communities. The tree data do not allow discrimination between ZSM and MPLN, but for the fish data ZSM (neutral model) overwhelmingly outperforms MPLN (niche model), suggesting that dispersal plays a previously underestimated role in structuring tropical freshwater fish communities. We advocate this approach for identifying the relative importance of dispersal and niche-partitioning in determining diversity of different ecological groups of species under different environmental conditions.
物种丰度无疑是最广泛可用的宏观生态学数据，但我们能否利用它们来区分几种群落结构模型？在这里，我们提出了一种对物种丰度数据进行贝叶斯分析的方法，该方法可得出每个模型参数的完整联合概率分布，以及一个相对独立于参数的标准，即后验贝叶斯因子，以比较这些模型。我们通过比较三种经典分布来说明我们的方法：基于 Hubbell 中性模型的零和多项分布（ZSM）、基于生态位论点的多元泊松对数正态分布（MPLN）和基于 MacArthur 断棍模型的离散断棍分布（DBS）。我们给出了在每个模型中观察到特定物种丰度数据集的概率的显式公式，并认为需要对样本大小和物种数量进行条件化，以便在两种分布之间进行比较。我们将我们的方法应用于两个新热带群落（树木、鱼类）。我们发现，对于这两个群落，DBS 在很大程度上不如 ZSM 和 MPLN。树木数据不允许在 ZSM 和 MPLN 之间进行区分，但对于鱼类数据，ZSM（中性模型）大大优于 MPLN（生态位模型），这表明扩散在构建热带淡水鱼类群落结构方面发挥了以前被低估的作用。我们提倡这种方法，以确定在不同环境条件下，扩散和生态位分割在确定不同生态类群物种多样性方面的相对重要性。
