Sogin M L, Morrison H G, Hinkle G, Silberman J D
Center for Molecular Evolution, Marine Biological Laboratory, Woods Hole, Massachusetts 02543, USA.
Microbiologia. 1996 Mar;12(1):17-28.
Molecular systematics has revolutionized our understanding of microbial evolution. Phylogenetic frameworks relating all organisms in this biosphere can be inferred from comparisons of slowly evolving molecules such as the small and large subunit ribosomal RNAs. Unlike today's text book standard, the "Five Kingdoms" (plants, animals, fungi, protists and bacteria), molecular studies define three primary lines of descent (Eukaryotes, Eubacteria, and Archaebacteria). Within the Eukaryotes, the "higher" kingdoms (Fungi, Plantae, and Animalia) are joined by at least two novel complex evolutionary assemblages, the "Alveolates" (ciliates, dinoflagellates and apicomplexans) and the "Stramenopiles" (diatoms, oomycetes, labyrinthulids, brown algae and chrysophytes). The separation of these eukaryotic groups (described as the eukaryotic "crown") occurred approximately 10(9) years ago and was preceded by a succession of earlier diverging protist lineages, some as ancient as the separation of the prokaryotic domains. The molecular phylogenies suggest that multiple endosymbiotic events introduced plastids into discrete eukaryotic lineages.
分子系统学彻底改变了我们对微生物进化的理解。通过比较缓慢进化的分子，如小亚基和大亚基核糖体RNA，可以推断出这个生物圈中所有生物之间的系统发育框架。与当今教科书标准的“五界”（植物、动物、真菌、原生生物和细菌）不同，分子研究定义了三条主要的进化谱系（真核生物、真细菌和古细菌）。在真核生物中，“高等”界（真菌、植物界和动物界）至少与两个新的复杂进化组合相连，即“囊泡虫类”（纤毛虫、甲藻和顶复门原虫）和“不等鞭毛类”（硅藻、卵菌、网粘菌、褐藻和金藻）。这些真核生物类群（被称为真核生物的“冠群”）的分离大约发生在10亿年前，在此之前有一系列更早分化的原生生物谱系，其中一些与原核生物域的分离一样古老。分子系统发育表明，多次内共生事件将质体引入了不同的真核生物谱系。
