Normark Benjamin B
Section of Ecology and Systematics, Cornell University, Ithaca, New York, 14853.
Evolution. 1996 Apr;50(2):734-745. doi: 10.1111/j.1558-5646.1996.tb03883.x.
Molecular-phylogenetic studies of parthenogenetic animals have been a valuable recent addition to the literature on the evolutionary biology of sex. By illuminating the origins and ages of parthenogenetic lineages, such studies can help to define the temporal scale at which selection acts against parthenogenetic lineages, as well as provide an essential framework for further study. Although parthenogenetic weevils have played an important role in cytogenetic and protein-electrophoretic studies of parthenogenesis, they have not previously been subjects of DNA-based molecular-phylogenetic study. A mitochondrial DNA study of Aramigus tessellatus, a species complex of weevils native to South America, indentified 12 distinct (1-9% divergent) maternal lineages, of which 2 represent sexual populations, while at least 9 represent parthenogenetic lineages. These lineages partially correspond to lineages previously recognized by morphological differences. Phylogenetic analysis found 14 most parsimonious trees, according to which parthenogenesis appears to have arisen 3-7 times. There is a monophyletic group of lineages (the "brown clade"), having up to 4.5% sequence divergence within it, which may be primitively parthenogenetic and over 2 million years old.
孤雌生殖动物的分子系统发育研究是近期性进化生物学文献中的一项重要内容。通过揭示孤雌生殖谱系的起源和年代，此类研究有助于确定选择作用于孤雌生殖谱系的时间尺度，并为进一步研究提供重要框架。尽管孤雌生殖象鼻虫在孤雌生殖的细胞遗传学和蛋白质电泳研究中发挥了重要作用，但此前它们尚未成为基于DNA的分子系统发育研究的对象。对南美本土象鼻虫物种复合体阿拉米古斯镶嵌象鼻虫进行的线粒体DNA研究，识别出了12个不同的（差异为1%-9%）母系谱系，其中2个代表有性繁殖种群，而至少9个代表孤雌生殖谱系。这些谱系部分对应于此前根据形态差异识别出的谱系。系统发育分析发现了14棵最简约树，据此孤雌生殖似乎出现了3至7次。有一个单系谱系群（“棕色分支”），其内部序列差异高达4.5%，可能是原始孤雌生殖的，且有200多万年的历史。
