Phylogeny and rates of molecular evolution of planktonic foraminifera: SSU rDNA sequences compared to the fossil record
Phylogeny and rates of molecular evolution of planktonic foraminifera: SSU rDNA sequences compared to the fossil record
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DOI：
10.1007/pl00006232
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发表时间：
1997-09-01
影响因子：
3.9
通讯作者：
Pawlowski, J
中科院分区：
文献类型：
--
作者：
deVargas, C;Zaninetti, L;Pawlowski, J
浮游有孔虫是海洋原生生物，其钙质外壳形成海洋沉积物，广泛用于地层和古环境分析。在这里比较了浮游有孔虫的化石记录和从核糖体DNA序列推断的分子生物学。18个部分SSU rDNA序列的物种代表所有的现代浮游生物的家庭（Globigerinidae，Hastigerinidae，Globorotaliidae，Candeinidae），并比较了7个序列代表的底栖有孔虫的主要群体。系统发育分析表明，多系起源的浮游有孔虫。Candeinidae、Globorotaliidae和Globigerinidae + Hastigerinidae分支似乎独立起源于有孔虫演化的不同时期。然而，它们之间关系的推断受到异质性替代率的限制。SSU rDNA的进化速率从Globigerinidae的4.0 x 10（-9）置换/位点/年到Globorotaliidae的小于1.0 x 10（-9）置换/位点/年不等。这些变化可能与对生活方式的不同适应水平有关。在Globigerinidae中观察到时钟样的进化，分子和古生物学数据是一致的。在系统发育的Globorotaliidae是明显的偏见，在两个物种（G。truncatulinoides和Menardii）。我们的研究揭示了不同的绝对进化速率在所有的分类水平在南极有孔虫，并证明了它们的系统发育重建的影响。
Planktonic foraminifera are marine protists, whose calcareous shells form oceanic sediments and are widely used for stratigraphic and paleoenvironmental analyses. The fossil record of planktonic foraminifera is compared here to their molecular phylogeny inferred from ribosomal DNA sequences. Eighteen partial SSU rDNA sequences from species representing all modern planktonic families (Globigerinidae, Hastigerinidae, Globorotaliidae, Candeinidae) were obtained and compared to seven sequences representing the major groups of benthic foraminifera. The phylogenetic analyses indicate a polyphyletic origin for the planktonic foraminifera. The Candeinidae, the Globorotaliidae, and the clade Globigerinidae + Hastigerinidae seem to have originated independently, at different epochs in the evolution of foraminifera. Inference of their relationships, however, is limited by substitution rates of heterogeneity. Rates of SSU rDNA evolution vary from 4.0 x 10(-9) substitutions/site/year in the Globigerinidae to less than 1.0 x 10(-9) substitutions/site/year in the Globorotaliidae. These variations may be related to different levels of adaptation to the planktonic mode of life. A clock-like evolution is observed among the Globigerinidae, for which molecular and paleontological data are congruent. Phylogeny of the Globorotaliidae is clearly biased by rapid rates of substitution in two species (G. truncatulinoides and G, menardii). Our study reveals differences in absolute rates of evolution at all taxonomic levels in planktonic foraminifera and demonstrates their effect on phylogenetic reconstructions.