Vermeij Geerat J
University of California at Davis Department of Geology One Shields Avenue, Davis, CA 95616, USA.
Proc Biol Sci. 2005 Dec 7;272(1580):2545-50. doi: 10.1098/rspb.2005.3177.
Data on the geographical distribution, phylogeny and fossil record of cool-temperate North Atlantic shell-bearing molluscs that live in waters shallower than 100 m depth belong to two biogeographic provinces, one in eastern North America north of Cape Cod, the other in northern Europe. Amphi-Atlantic species, which are found in both provinces, comprise 30.8% of the 402 species in the northeastern Atlantic and 47.3% of the 262 species in the northwestern Atlantic. Some 54.8% of these amphi-Atlantic species have phylogenetic origins in the North Pacific. Comparisons among fossil Atlantic faunas show that amphi-Atlantic distributions became established in the Middle Pliocene (about 3.5 million years ago), and that all represent westward expansions of European taxa to North America. No American taxa spread eastward to Europe without human assistance. These results are in accord with previous phylogeographic studies among populations within several amphi-Atlantic species. Explanations for the unidirectional expansion of species across the Atlantic remain uncertain, but may include smaller size and greater prior extinction of the North American as compared to the European fauna and biased transport mechanisms. Destruction of the European source fauna may jeopardize faunas on both sides of the Atlantic.
生活在深度小于100米水域的北大西洋温带带壳软体动物的地理分布、系统发育和化石记录数据属于两个生物地理省份，一个在科德角以北的北美东部，另一个在北欧。在两个省份都能发现的跨大西洋物种，占东北大西洋402个物种的30.8%，占西北大西洋262个物种的47.3%。这些跨大西洋物种中约54.8%的系统发育起源于北太平洋。对化石大西洋动物群的比较表明，跨大西洋分布在晚上新世（约350万年前）就已确立，并且所有这些分布都代表欧洲分类群向西扩展到北美。没有人类的帮助，没有美国分类群向东扩散到欧洲。这些结果与之前对几种跨大西洋物种内种群的系统地理学研究一致。物种跨大西洋单向扩张的原因仍不确定，但可能包括与欧洲动物群相比，北美动物群体型较小、先前灭绝率较高以及有偏向性的传播机制。欧洲源动物群的破坏可能危及大西洋两岸的动物群。
