Committee on Evolutionary Biology, University of Chicago, Chicago, IL 60637, USA.
Proc Biol Sci. 2010 Nov 22;277(1699):3427-35. doi: 10.1098/rspb.2010.0628. Epub 2010 Jun 9.
Species are unevenly distributed among genera within clades and regions, with most genera species-poor and few species-rich. At regional scales, this structure to taxonomic diversity is generated via speciation, extinction and geographical range dynamics. Here, we use a global database of extant marine bivalves to characterize the taxonomic structure of climate zones and provinces. Our analyses reveal a general, Zipf-Mandelbrot form to the distribution of species among genera, with faunas from similar climate zones exhibiting similar taxonomic structure. Provinces that contain older taxa and/or encompass larger areas are expected to be more species-rich. Although both median genus age and provincial area correlate with measures of taxonomic structure, these relationships are interdependent, nonlinear and driven primarily by contrasts between tropical and extra-tropical faunas. Provincial area and taxonomic structure are largely decoupled within climate zones. Counter to the expectation that genus age and species richness should positively covary, diverse and highly structured provincial faunas are dominated by young genera. The marked differences between tropical and temperate faunas suggest strong spatial variation in evolutionary rates and invasion frequencies. Such variation contradicts biogeographic models that scale taxonomic diversity to geographical area.
物种在进化枝和区域内的属中分布不均匀，大多数属物种较少，少数属物种较多。在区域尺度上，这种分类多样性的结构是通过物种形成、灭绝和地理范围动态产生的。在这里，我们使用一个全球现存海洋双壳类数据库来描述气候带和省的分类结构。我们的分析揭示了物种在属间分布的一般齐普夫-曼德布洛特形式，具有相似气候带的动物群表现出相似的分类结构。包含较老分类群和/或包含较大面积的省份预计会有更多的物种。虽然中值属年龄和省级区域都与分类结构的度量相关，但这些关系是相互依赖的、非线性的，主要由热带和亚热带动物群之间的对比驱动。在气候带内，省级区域和分类结构在很大程度上是脱钩的。与属年龄和物种丰富度应该正相关的预期相反，多样化和高度结构化的省级动物群主要由年轻的属主导。热带和温带动物群之间的显著差异表明进化率和入侵频率存在强烈的空间变化。这种变化与将分类多样性按地理区域进行划分的生物地理模型相矛盾。
