论文部分内容阅读
介形类 (Ostracoda)因其丰富的化石记录和广布的海陆现生代表类群 ,而被认为是进化生物学中研究生物多样性产生机制和演变历程的颇具潜力的重要模式生物。介形类在甲壳亚门中的谱系发生位置、起源及其内部各类群间的系统关系还存在诸多争议。基于其体制构造的形态学特征 ,介形类被归入甲壳亚门下的颚足纲(Maxillopoda) ,但来自 18S r DNA序列数据分析却显示 Maxillopoda不是单系群。基于化石记录和壳体形态特征 ,高肌虫 (Bradoriida)长期以来被认为是介形类的一个祖先类群 ,但保存有软躯体的早寒武世化石的研究表明 ,Bradoriida不是介形类甚至可能也不属于甲壳类。不同的研究者所强调的壳体和肢体形态特征各异 ,导致介形类最大的现生类群速足目 (Podocopida)的四个超科之间的关系也存在诸多推测。壳体和肢体特征在系统演化意义上的不兼容 ,需要分子生物学等证据的介入。分子、形态和化石证据的积累及各种信息整合是系统演化研究的必然趋势。
Ostracoda is regarded as a potential and important model organism for studying the mechanism and evolution of biodiversity in evolutionary biology because of its rich fossil records and widespread representative groups of marine and land living creatures. There are still many controversies about the location and origin of the genealogies and the systematic relationship among the various species within the genera. Based on the morphological features of their institutional architecture, the orthomorphic class is classified as Maxillopoda under the crustacean subphylum, but analysis of 18S r DNA sequence data shows that Maxillopoda is not a monophyletic group. Based on fossil record and shell morphological features, Bradoriida has long been considered an ancestral group of ostracods, but studies of prewar Cambrian fossils that hold soft soles have shown that Bradoriida is not even an orthodox class Nor belong to crustaceans. There are also many speculations about the relationship between the four superfamilies of the genus Podocopida, which is the largest one of the most widely observed species, which is emphasized by different researchers. The incompatibility of the shell and limb features in the evolutionary sense of the system requires the involvement of molecular biology and other evidence. The accumulation of molecular, morphological and fossil evidence and the integration of various information are the inevitable trends in the study of systematic evolution.