热带西太平洋浮游有孔虫Globigerinoides ruber(白色)的基因型研究及其古海洋学意义

GENOTYPES OF THE PLANKTONIC FORAMINIFERA GLOBIGERINOIDES RUBER (WHITE) IN THE TROPICAL WESTERN PACIFIC OCEAN AND THEIR IMPLICATION ON THE PALAEOCEANOGRAPHIC RECONSTRUCTIONS

Globigerinoides ruber是最常见的热带-亚热带浮游有孔虫种类,被广泛地应用于古环境重建。本实验通过浮游生物垂直拖网采集热带西太平洋海区目标站位表层200 m以浅水体中的浮游有孔虫,在体视显微镜下挑选出单个活体G.ruber(白色)个体,采用DOC法提取虫体的总DNA,利用有孔虫特异性引物扩增SSU rDNA目的片段。我们通过构建系统发育树研究了G.ruber(白色)基因型多样性,并比较了不同基因型G.ruber(白色)的形态差异和分布特点。ML/BI树显示:在热带西太平洋海区获得的G.ruber(白色)样本中,有两大基因型Type I和Type II,Type I又包括Type Ia、Type Ib2两种类型。Type I和Type II个体的形态特征和栖息环境存在明显差异:Type I个体的三个房室呈显著的球状,主要分布在表层30 m以浅的水体中;Type II个体的三个房室呈扁平的近似球状,主要分布在水深30 m以下的水体中。本工作是对热带西太平洋浮游有孔虫DNA分子数据的重要补充,旨在为古海洋学重建提供更加精确的替代性指标。

Globigerinoides ruber is the most common tropical-subtropical planktonic foraminiferal species,which is widely used in paleoenvironmental reconstructions.In this study,we collected living planktonic foraminifera with plankton nets(76μm mesh size)at depths from surface waters to 200 m in the target stations from the tropical western Pacific Ocean.Living Globigerinoides ruber(white)individuals were picked out under stereo-microscope.The total DNA in a single specimen was extracted by DOC method,and the SSU rDNA target fragment was amplified by using foraminiferal specific primers.We studied the genetic diversity of G.ruber(white)by constructing phylogenetic tree,and compared the morphological dissimilarities and distribution characteristics of G.ruber(white)with different genotypes.ML/BI tree showed that there were mainly two genotypes,viz.,Type I and Type II in the specimens,and the Type I cluster included 2 subclusters(Type Ia and Type Ib2).The morphological characteristics and habitats of Type I and Type II individuals were significantly different:G.ruber(white)[Type I]had three spherical chambers,mainly living in the surface water(0~30 m);G.ruber(white)[Type II]had three compressed subspherical chambers,mainly living at depths below 30 m.Our work aims to provide more accurate alternative indicators for paleoceanographic reconstructions.Our results are the important supplements for the DNA data of planktonic foramini-fera in the tropical western Pacific Ocean.