Rabosky Daniel L, Reid Julian, Cowan Mark A, Foulkes Jeff
Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853, USA.
Oecologia. 2007 Dec;154(3):561-70. doi: 10.1007/s00442-007-0849-1. Epub 2007 Sep 14.
Both local and regional processes may contribute to community diversity and structure at local scales. Although many studies have investigated patterns of local or regional community structure, few have addressed the extent to which local community structure influences patterns within regional species pools. Here we investigate the role of body size in community assembly at local and regional scales in Ctenotus lizards from arid Australia. Ctenotus has long been noted for its exceptional species diversity in the Australian arid-zone, and previous studies have attempted to elucidate the processes underlying species coexistence within communities of these lizards. However, no consensus has emerged on the role of interspecific competition in the assembly and maintenance of Ctenotus communities. We studied Ctenotus communities at several hundred sites in the arid interior of Australia to test the hypothesis that body sizes within local and regional Ctenotus assemblages should be overdispersed relative to null models of community assembly, and we explored the relationship between body size dispersion at local and regional scales. Results indicate a striking pattern of community-wide overdispersion of body size at local scales, as measured by the variance in size ratios among co-occurring species. However, we find no evidence for body size overdispersion within regional species pools, suggesting a lack of correspondence between processes influencing the distribution of species phenotypes at local and regional scales. We suggest that size ratio constancy in Ctenotus communities may have resulted from contemporary ecological interactions among species or ecological character displacement, and we discuss alternative explanations for the observed patterns.
局部和区域过程都可能在局部尺度上影响群落的多样性和结构。尽管许多研究调查了局部或区域群落结构的模式，但很少有研究探讨局部群落结构对区域物种库内模式的影响程度。在这里，我们研究了来自澳大利亚干旱地区的栉趾虎蜥蜴在局部和区域尺度上群落组装过程中体型的作用。栉趾虎长期以来因其在澳大利亚干旱地区的特殊物种多样性而受到关注，之前的研究试图阐明这些蜥蜴群落中物种共存的潜在过程。然而，关于种间竞争在栉趾虎群落组装和维持中的作用尚未达成共识。我们在澳大利亚干旱内陆的数百个地点研究了栉趾虎群落，以检验以下假设：相对于群落组装的零模型，局部和区域栉趾虎组合中的体型应该过度分散，并且我们探讨了局部和区域尺度上体型分散之间的关系。结果表明，通过同时出现的物种之间的体型比差异来衡量，在局部尺度上存在群落范围内体型过度分散的显著模式。然而，我们没有发现区域物种库内体型过度分散的证据，这表明在影响局部和区域尺度上物种表型分布的过程之间缺乏对应关系。我们认为栉趾虎群落中体型比的恒定可能是由于物种之间当代的生态相互作用或生态特征替代导致的，并且我们讨论了对观察到的模式的其他解释。
