Evidence for widespread cryptic sexual generations in apparently purely asexual Andricus gallwasps
Evidence for widespread cryptic sexual generations in apparently purely asexual Andricus gallwasps
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DOI：
10.1111/j.1365-294x.2007.03573.x
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发表时间：
2008-01-01
影响因子：
4.9
通讯作者：
McVean, Gilean A. T.
中科院分区：
文献类型：
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作者：
Stone, Graham N.;Atkinson, Rachel J.;McVean, Gilean A. T.
栎瘿蜂（Hypltera，Cynipidae，Cynipini）是常见的以周期性孤雌生殖（CP）方式繁殖的7个主要动物类群之一。CP分类群研究中的一个主要问题是谱系失去有性世代的频率，并作为纯粹的无性辐射而多样化。大多数橡树瘿蜂物种只知道从无性世代，和继发性损失的性别已被确凿地证明在几个物种，特别是泛北极属Andricus的成员。这增加了在Cynipini中广泛的二次性丧失的可能性，以及纯粹单性生殖谱系内的多样化。我们使用两种方法的等位基因频率数据的分析的基础上，测试通过一个主要的西部古北系的gallwasp属Andricus分布在8个明显的无性繁殖的欧洲物种的隐有性世代。所有表现出足够水平的多态性（7/8）的物种表现出与周期性单性生殖的性别兼容的签名。我们还使用DNA序列数据来检验这一假设，即对这些性世代的无知（尽管对这一群体进行了广泛的研究）是由于未能区分已知但形态上无法区分的性世代。这一假设得到以下支持：35个序列被主要的cynipid分类学家归因于一个单一的有性成年形态种，Andricus burgundus，被发现代表至少六个Andricus物种的有性世代。我们确认在总共11个Andricus物种的隐性有性世代，这表明在Andricus中二次性丧失是罕见的。
Oak gallwasps (Hymenoptera, Cynipidae, Cynipini) are one of seven major animal taxa that commonly reproduce by cyclical parthenogenesis (CP). A major question in research on CP taxa is the frequency with which lineages lose their sexual generations, and diversify as purely asexual radiations. Most oak gallwasp species are only known from an asexual generation, and secondary loss of sex has been conclusively demonstrated in several species, particularly members of the holarctic genus Andricus. This raises the possibility of widespread secondary loss of sex in the Cynipini, and of diversification within purely parthenogenetic lineages. We use two approaches based on analyses of allele frequency data to test for cryptic sexual generations in eight apparently asexual European species distributed through a major western palaearctic lineage of the gallwasp genus Andricus. All species showing adequate levels of polymorphism (7/8) showed signatures of sex compatible with cyclical parthenogenesis. We also use DNA sequence data to test the hypothesis that ignorance of these sexual generations (despite extensive study on this group) results from failure to discriminate among known but morphologically indistinguishable sexual generations. This hypothesis is supported: 35 sequences attributed by leading cynipid taxonomists to a single sexual adult morphospecies, Andricus burgundus, were found to represent the sexual generations of at least six Andricus species. We confirm cryptic sexual generations in a total of 11 Andricus species, suggesting that secondary loss of sex is rare in Andricus.