Trewick Steve A, Morgan-Richards Mary, Collins Lesley J
Allan Wilson Centre for Molecular Ecology & Evolution, Ecology Group PN 624, Institute of Natural Resources, Massey University, Private Bag 11-222, Palmerston North, New Zealand.
Mol Phylogenet Evol. 2008 Sep;48(3):799-808. doi: 10.1016/j.ympev.2008.05.025. Epub 2008 May 27.
The hybrid stick insect genus Acanthoxyla Uvarov 1944 is unusual for an obligate parthenogen, in the extreme morphological diversity it exhibits that has led to eight species being recognised. The New Zealand sexual species Clitarchus hookeri [White, A. 1846. The zoology of the Voyage of H.M.S. Erebus and Terror. In: 1 Insects of New Zealand. E.W. Janson, London.] is the putative parental species in the hybridization that gave rise to the hybrid lineage Acanthoxyla. In an effort to identify the maternal ancestor of Acanthoxyla we sequenced nuclear 28S rDNA and/or mtDNA COI & COII of all nine endemic New Zealand stick insect genera, representing 17 of the 22 described species. We also sequenced 28S from eight non-New Zealand stick insects to supplement published 28S sequence data that provided a taxonomically and geographically broad sampling of the phasmids. We applied a novel search algorithm (SeqSSi=Sequence Similarity Sieve) to assist in selection of outgroup taxa for phylogenetic analysis prior to alignment. Phylogenetic reconstructions resolved an exclusively New Zealand clade to which the maternal lineage of Acanthoxyla belonged, but did not support existing higher level taxonomy of stick insects. We did not find a sexual maternal species for Acanthoxyla but phylogenetic relationships indicate that this species lived in New Zealand and could be classified among the New Zealand Phasmatinae. Among the available taxa, the nearest evolutionary neighbours to the New Zealand phasmid fauna as a whole were predominantly from the New Zealand region (Fiji, Australia, New Guinea, New Caledonia and South America). As it appears to be an orphan, it is interesting to speculate that a combination of parthenogenetic reproduction and/or hybrid vigour in Acanthoxyla may have contributed to the extinction of its mother.
1944年乌瓦罗夫提出的杂交竹节虫属Acanthoxyla，对于专性孤雌生殖昆虫来说很不寻常，它展现出了极端的形态多样性，这使得该属已识别出八个物种。新西兰有性生殖物种克氏竹节虫（Clitarchus hookeri [怀特，A. 1846年。皇家海军舰艇“幽冥号”和“恐怖号”航行中的动物学。载于：1. 新西兰昆虫。E.W. 詹森，伦敦。]）被认为是杂交产生Acanthoxyla杂交谱系的亲本物种。为了确定Acanthoxyla的母系祖先，我们对新西兰所有九个特有竹节虫属的核28S核糖体DNA和/或线粒体DNA细胞色素氧化酶亚基I及细胞色素氧化酶亚基II进行了测序，这些属代表了已描述的22个物种中的17个。我们还对八种非新西兰竹节虫的28S进行了测序，以补充已发表的28S序列数据，这些数据提供了竹节虫在分类学和地理上的广泛样本。在比对之前，我们应用了一种新颖的搜索算法（SeqSSi = 序列相似性筛选）来协助选择用于系统发育分析的外类群分类单元。系统发育重建解析出一个仅包含新西兰类群的分支，Acanthoxyla的母系谱系属于该分支，但并不支持现有的竹节虫高级分类法。我们没有找到Acanthoxyla的有性生殖母系物种，但系统发育关系表明该物种生活在新西兰，并且可以归类到新西兰竹节虫亚科中。在现有的分类单元中，作为一个整体，与新西兰竹节虫动物群最近的进化邻居主要来自新西兰地区（斐济、澳大利亚、新几内亚、新喀里多尼亚和南美洲）。由于它似乎是一个孤立物种，推测Acanthoxyla的孤雌生殖和/或杂种优势的结合可能导致了其母体的灭绝，这是很有意思的。
