Presley Steven J, Higgins Christopher L, López-González Celia, Stevens Richard D
Department of Ecology and Evolutionary Biology, Center for Environmental Sciences and Engineering, University of Connecticut, Storrs, CT 06269-4210, USA.
Oecologia. 2009 Jul;160(4):781-93. doi: 10.1007/s00442-009-1341-x. Epub 2009 Apr 18.
Techniques to evaluate elements of metacommunity structure (EMS; coherence, species turnover and range boundary clumping) have been available for several years. Such approaches are capable of determining which idealized pattern of species distribution best describes distributions in a metacommunity. Nonetheless, this approach rarely is employed and such aspects of metacommunity structure remain poorly understood. We expanded an extant method to better investigate metacommunity structure for systems that respond to multiple environmental gradients. We used data obtained from 26 sites throughout Paraguay as a model system to demonstrate application of this methodology. Using presence-absence data for bats, we evaluated coherence, species turnover and boundary clumping to distinguish among six idealized patterns of species distribution. Analyses were conducted for all bats as well as for each of three feeding ensembles (aerial insectivores, frugivores and molossid insectivores). For each group of bats, analyses were conducted separately for primary and secondary axes of ordination as defined by reciprocal averaging. The Paraguayan bat metacommunity evinced Clementsian distributions for primary and secondary ordination axes. Patterns of species distribution for aerial insectivores were dependent on ordination axis, showing Gleasonian distributions when ordinated according to the primary axis and Clementsian distributions when ordinated according to the secondary axis. Distribution patterns for frugivores and molossid insectivores were best described as random. Analysis of metacommunities using multiple ordination axes can provide a more complete picture of environmental variables that mold patterns of species distribution. Moreover, analysis of EMS along defined gradients (e.g., latitude, elevation and depth) or based on alternative ordination techniques may complement insights based on reciprocal averaging because the fundamental questions addressed in analyses are contingent on the ordination technique that is employed.
评估元群落结构要素（EMS；连贯性、物种周转率和范围边界聚集）的技术已经存在数年了。这些方法能够确定哪种理想化的物种分布模式最能描述元群落中的分布情况。然而，这种方法很少被采用，元群落结构的这些方面仍然知之甚少。我们扩展了一种现有方法，以便更好地研究响应多种环境梯度的系统的元群落结构。我们使用从巴拉圭各地26个地点获得的数据作为模型系统，来演示这种方法的应用。利用蝙蝠的存在-缺失数据，我们评估了连贯性、物种周转率和边界聚集情况，以区分六种理想化的物种分布模式。对所有蝙蝠以及三个食性组合（食虫空中捕食者、食果动物和犬吻蝠科食虫动物）中的每一个进行了分析。对于每组蝙蝠，分别针对由对应平均法定义的排序的主轴和次轴进行了分析。巴拉圭蝙蝠元群落的主轴和次轴表现出克莱门茨分布。食虫空中捕食者的物种分布模式取决于排序轴，根据主轴排序时呈现格利森分布，根据次轴排序时呈现克莱门茨分布。食果动物和犬吻蝠科食虫动物的分布模式最好描述为随机分布。使用多个排序轴对元群落进行分析，可以更全面地了解塑造物种分布模式的环境变量。此外，沿着定义的梯度（如纬度、海拔和深度）或基于替代排序技术对EMS进行分析，可能会补充基于对应平均法的见解，因为分析中涉及的基本问题取决于所采用的排序技术。
