de Vargas C, Norris R, Zaninetti L, Gibb S W, Pawlowski J
Département de Zoologie et Biologie Animale, Université de Genève, 1224 Chêne-Bougeries, Switzerland.
Proc Natl Acad Sci U S A. 1999 Mar 16;96(6):2864-8. doi: 10.1073/pnas.96.6.2864.
The fossil record of planktonic foraminifers is a key source of data on the biodiversity and evolution of marine plankton. One of the most distinctive foraminiferal taxa, Orbulina universa, widely used as a stratigraphic and paleoclimatic index, has always been regarded as a single species. Here we present a phylogenetic analysis of Orbulina small subunit rDNA sequences from 25 pelagic stations covering 100 degrees latitude in the Atlantic Ocean. The genetic data reveal the presence of three cryptic species, whose distribution is clearly correlated to hydrographic provinces, and particularly to sea-surface total chlorophyll a concentration. Our results, together with previous studies, suggest that a considerable part of the diversity among planktonic foraminifers has been overlooked in morphological taxonomies. Our data also support the idea that planktonic foraminifers, even if adapted to particular hydrographic conditions, are high-dispersal organisms whose speciation may be similar to that of other high-dispersal taxa in which reproductive mechanisms and behavior, rather than just geographic barriers to dispersal, play key roles in species formation and maintenance.
浮游有孔虫的化石记录是有关海洋浮游生物的生物多样性和进化的关键数据来源。最具特色的有孔虫类群之一——环球圆幅虫，被广泛用作地层和古气候指标，一直被视为单一物种。在此，我们对来自大西洋25个远洋站点、覆盖100度纬度范围的环球圆幅虫小亚基核糖体DNA序列进行了系统发育分析。遗传数据揭示存在三个隐存种，它们的分布与水文区域显著相关，特别是与海面总叶绿素a浓度相关。我们的研究结果与之前的研究共同表明，浮游有孔虫的相当一部分多样性在形态分类学中被忽视了。我们的数据还支持这样一种观点，即浮游有孔虫即使适应特定的水文条件，也是高扩散性生物，其物种形成可能与其他高扩散类群相似，在这些类群中，生殖机制和行为而非仅仅是扩散地理障碍，在物种形成和维持中起关键作用。
