Evaluation of the meaning of foraminiferal test morphology based on DNA sequences

为了评价底栖有孔虫测试形态的意义，对选定的几个属进行了分子系统发育分析。由于这些属在形态上已经有了很好的记载，所以我们选择了GLabratella和玻利瓦属及其近缘属进行分析。DNA提取和聚合酶链式反应技术大多采用Pawlowski等人。(1995年)。我们从路易斯安那州立大学的核糖体DNA中分析了约650个核苷酸碱基对，每一步都使用了针对有孔虫的特异引物。将扩增出的DNA片段克隆到质粒载体上，然后用自动测序仪进行测序。GLabratella本地种群内的遗传变异低于玻利维亚种群和氨种群。这可能反映了有孔虫属之间繁殖方式的差异。根据核苷酸测序数据计算的分子系统发育与基于形态数据的系统发育具有不同的聚类群。用简约法和邻接法计算了分子系统发育树。然而，分子数据的聚类组与基于功能形态的形态聚类组有很好的相关性。例如，孔径区周围的放射状沟槽可能与生殖行为有关，在按分子聚类分类的分类群中是相似的。其中一个种群内的变异大于我们所研究的其他整个物种内的变异。然而，这种种群的形态变异是有孔虫种群的典型变化，不可能根据形态特征对种群进行细分。这些结果表明，从功能形态的角度对有孔虫测试形态进行重新评估，可能会建立基于形态的与分子系统发育相一致的系统发育。

To evaluate the meaning of benthic foraminiferal test morphology, molecular phylogenetic analyzes have carried out for several selected genera. Glabratella and Bolivina and related genera were selected for analysis, because these genera have been well documented morphologically. Both DNA extractions and PCR techniques were mostly adopted from Pawlowski et al. (1995). We analyzed about 650 nucleotic acid base pairs from LSU ribosomal DNA.Specific primers for foraminifera were used for each PCR step. Amplified DNA fragments were cloned at plasmid vectors, then sequenced with an automatic sequencer.DNA sequences of forminifera show several interesting results. Genetic variation within local populations of Glabratella is lower than in Bolivina and Ammonia. This may reflect differences in mode of reproduction among foraminiferal genera. Molecular phylogenies calculated from nucleotide sequencing data had different cluster groups than a phylogeny based on morphological data. Calculations of the molecular phylogenetic trees were made with both parsimony and neighbor joining methods. Cluster groups of molecular data were, however, well related to morphological cluster groups that are based on functional morphology. For instance, radial grooves around the aperture area, which may be related to reproductive behavior, is similar among taxa grouped by molecular clustering. In Glabratella opercularis the variation within one of the populations was greater than that fpund within other entire species that we have studied. Whithin this population morphological variation is typical for foraminiferal populations and it is not possible to subdivide the population based on morphological characters. These results suggest that reevaluation of foraminiferal test morphology from the view point of functional morphology may enable creation of phylogenies based on morphology that are cnoformable with molecular phylogenies.