Cavender-Bares Jeannine, Keen Adrienne, Miles Brianna
Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, Minnesota 55108, USA.
Ecology. 2006 Jul;87(7 Suppl):S109-22. doi: 10.1890/0012-9658(2006)87[109:psofpc]2.0.co;2.
Consideration of the scale at which communities are defined both taxonomically and spatially can reconcile apparently contradictory results on the extent to which plants show phylogenetic niche conservatism. In plant communities in north central Florida, we collected species abundances in 55 0.1-ha plots in several state parks. When communities were defined narrowly to include a single phylogenetic lineage, such as Quercus, Pinus, or Ilex, neighbors tended to be less related than expected (phylogenetic overdispersion) or there was no pattern. If the same communities were defined more broadly, such as when all seed plants were included, neighbors tended to be more related than expected (phylogenetic clustering). These results provide evidence that species interactions among close relatives influence community structure, but they also show that niche conservatism is increasingly evident as communities are defined to include greater phylogenetic diversity. We also found that, as the spatial scale is increased to encompass greater environmental heterogeneity, niche conservatism emerges as the dominant pattern. We then examined patterns of trait evolution in relation to trait similarity within communities for 11 functional traits for a single phylogenetic lineage (Quercus) and for all woody plants. Among the oaks, convergent evolution of traits important for environmental filtering contributes to the observed pattern of phylogenetic overdispersion. At the broader taxonomic scale, traits tend to be conserved, giving rise to phylogenetic clustering. The shift from overdispersion to clustering can be explained by the increasing conservatism of traits at broader phylogenetic scales.
从分类学和空间角度考虑群落的定义尺度，能够调和关于植物在多大程度上表现出系统发育生态位保守性这一问题上看似矛盾的结果。在佛罗里达州中北部的植物群落中，我们在几个州立公园的55个0.1公顷的样地中收集了物种丰度数据。当群落被狭义定义为仅包含单一系统发育谱系时，比如栎属、松属或冬青属，其相邻物种的亲缘关系往往比预期的要低（系统发育过分散），或者没有特定模式。如果将同样的群落定义得更宽泛，比如当所有种子植物都被纳入时，相邻物种的亲缘关系往往比预期的更紧密（系统发育聚类）。这些结果表明近亲之间的物种相互作用会影响群落结构，但同时也表明，随着群落被定义为包含更广泛的系统发育多样性，生态位保守性愈发明显。我们还发现，随着空间尺度扩大以涵盖更大的环境异质性，生态位保守性成为主导模式。然后，我们针对单一系统发育谱系（栎属）和所有木本植物的11个功能性状，研究了群落内性状进化与性状相似性的关系。在栎属植物中，对环境过滤起重要作用的性状的趋同进化，导致了观察到的系统发育过分散模式。在更宽泛的分类学尺度上，性状往往是保守的，从而产生系统发育聚类。从过分散到聚类的转变，可以用更宽泛的系统发育尺度上性状越来越保守来解释。
