Molecular phylogeny of the volvocine flagellates.
Molecular phylogeny of the volvocine flagellates.
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DOI：
10.1093/oxfordjournals.molbev.a040710
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发表时间：
1992
影响因子：
10.7
通讯作者：
A. Larson;M. Kirk;D. Kirk
中科院分区：
文献类型：
--
作者：
A. Larson;M. Kirk;D. Kirk
系统发育研究的大约2,000个碱基的序列从大的和小的核编码的核糖体RNA被用来调查团藻属的起源。目前归入团藻科的群体和多细胞属形成了一个单系群，该群在系统发育上与莱茵衣藻的关系比与其他测试的单细胞绿色鞭毛虫（包括真配子衣藻、蛋白核小球藻和湖泊红球藻）的关系更密切。对251个遗传信息核苷酸位置的统计分析拒绝了“volvocine谱系”假说，该假说假定从单细胞生物（如衣原体）到群体生物（例如，生殖器属（Gonium）、盘虫属（Pandorina）、真多虫属（Eudorina）和多多虫属（Pleodorina）的多细胞生物体，表现出体积、细胞数量和细胞分化的趋势，而多细胞生物体具有完全分化的体细胞和生殖细胞（团藻属（Volvox））。团藻属似乎不是单系的。好望角团藻（Volvox capensis）福尔斯不属于团藻属（Volvox aureus、V. carteri和V. obversus）的一个谱系，这两个团藻谱系与某些群体属的关系比它们之间的关系更密切。这意味着团藻的二系起源来自不同的群体团藻类祖先，一些群体属的系统发育起源来自多细胞（即，团藻）的祖先，或两者。考虑到与以前发表的意见，这些结果表明，在团藻科中发现的不同层次的组织和发育的复杂性代表替代稳定状态，其中进化的转变发生了几次在这个组的系统发育史。
Phylogenetic studies of approximately 2,000 bases of sequence from the large and small nuclear-encoded ribosomal RNAs are used to investigate the origins of the genus Volvox. The colonial and multicellular genera currently placed in the family Volvocaceae form a monophyletic group that is significantly closer phylogenetically to Chlamydomonas reinhardtii than it is to the other unicellular green flagellates that were tested, including Chlamydomonas eugametos, Chlorella pyrenoidosa, and Haematococcus lacustris. Statistical analysis of 251 phylogenetically informative nucleotide positions rejects the "volvocine lineage" hypothesis, which postulates a monophyletic evolutionary progression from unicellular organisms (such as Chlamydomonas), through colonial organisms (e.g., Gonium, Pandorina, Eudorina, and Pleodorina) demonstrating increasing size, cell number, and tendency toward cellular differentiation, to multicellular organisms having fully differentiated somatic and reproductive cells (in the genus Volvox). The genus Volvox appears not to be monophyletic. Volvox capensis falls outside a lineage containing other representatives of Volvox (V. aureus, V. carteri, and V. obversus), and both of these Volvox lineages are more closely related to certain colonial genera than they are to each other. This implies either a diphyletic origin of Volvox from different colonial volvocacean ancestors, a phylogenetic derivation of some of the colonial genera from a multicellular (i.e., Volvox) ancestor, or both. Considered together with previously published observations, these results suggest that the different levels of organizational and developmental complexity found in the Volvocaceae represent alternative stable states, among which evolutionary transitions have occurred several times during the phylogenetic history of this group.