Huang Shan, Roy Kaustuv, Valentine James W, Jablonski David
Department of Geophysical Sciences, University of Chicago, Chicago, IL 60637;
Section of Ecology, Behavior and Evolution, University of California, San Diego, La Jolla, CA 92093; and.
Proc Natl Acad Sci U S A. 2015 Apr 21;112(16):4903-8. doi: 10.1073/pnas.1412219112.
Paleontological data provide essential insights into the processes shaping the spatial distribution of present-day biodiversity. Here, we combine biogeographic data with the fossil record to investigate the roles of parallelism (similar diversities reached via changes from similar starting points), convergence (similar diversities reached from different starting points), and divergence in shaping the present-day latitudinal diversity gradients of marine bivalves along the two North American coasts. Although both faunas show the expected overall poleward decline in species richness, the trends differ between the coasts, and the discrepancies are not explained simply by present-day temperature differences. Instead, the fossil record indicates that both coasts have declined in overall diversity over the past 3 My, but the western Atlantic fauna suffered more severe Pliocene-Pleistocene extinction than did the eastern Pacific. Tropical western Atlantic diversity remains lower than the eastern Pacific, but warm temperate western Atlantic diversity recovered to exceed that of the temperate eastern Pacific, either through immigration or in situ origination. At the clade level, bivalve families shared by the two coasts followed a variety of paths toward today's diversities. The drivers of these lineage-level differences remain unclear, but species with broad geographic ranges during the Pliocene were more likely than geographically restricted species to persist in the temperate zone, suggesting that past differences in geographic range sizes among clades may underlie between-coast contrasts. More detailed comparative work on regional extinction intensities and selectivities, and subsequent recoveries (by in situ speciation or immigration), is needed to better understand present-day diversity patterns and model future changes.
古生物学数据为了解塑造当今生物多样性空间分布的过程提供了重要见解。在这里，我们将生物地理学数据与化石记录相结合，以研究平行性（从相似起点通过变化达到相似多样性）、趋同性（从不同起点达到相似多样性）和分歧性在塑造沿北美两海岸的海洋双壳类动物当今纬度多样性梯度中的作用。尽管两个动物区系都呈现出物种丰富度随纬度升高而下降的预期总体趋势，但两海岸的趋势有所不同，而且这些差异不能简单地用当今的温度差异来解释。相反，化石记录表明，在过去300万年里，两海岸的总体多样性都有所下降，但西大西洋动物区系在上新世 - 更新世遭受的灭绝比东太平洋更严重。热带西大西洋的多样性仍然低于东太平洋，但暖温带西大西洋的多样性通过迁入或原地起源得以恢复并超过了温带东太平洋。在分类群层面，两海岸共有的双壳类科朝着当今的多样性发展遵循了多种路径。这些谱系层面差异的驱动因素尚不清楚，但在上新世地理分布范围广的物种比地理分布受限的物种更有可能在温带地区存续，这表明过去各分类群地理分布范围大小的差异可能是两海岸差异的基础。需要对区域灭绝强度和选择性以及随后的恢复情况（通过原地物种形成或迁入）进行更详细的比较研究，以更好地理解当今的多样性模式并模拟未来的变化。
