Werren J H, Jaenike J
Department of Biology, University of Rochester, New York 14627, USA.
Heredity (Edinb). 1995 Sep;75 ( Pt 3):320-6. doi: 10.1038/hdy.1995.140.
Bacterial symbionts belonging to the genus Wolbachia are associated with postzygotic reproductive incompatibility in a number of insect species. Using polymerase chain reaction (PCR) amplification of bacterial gene sequences, strains from 10 species belonging to the closely related quinaria, testacea and tripunctata groups of Drosophila were screened for the presence of Wolbachia in their reproductive tissues. Those screened included the mycophagous species D. falleni, D. recens, D. phalerata, D. testacea, D. neotestacea, D. orientacea, D. putrida and D. tripunctata, and the nonmycophagous species D. palustris and D. quinaria. Two species, D. recens and D. orientacea, were found to be infected with Wolbachia. Subsequent tests of four additional strains of D. recens found all to be infected with the bacteria. It was established that these bacteria cause partial cytoplasmic incompatibility in D. recens by antibiotic curing followed by crosses between cured and uncured strains. Curing was confirmed by a PCR assay. Although most species of insects shown to be infected with Wolbachia are cosmopolitan and/or have undergone recent range expansion in association with human activity, D. recens and D. orientacea are endemic species with specialized ecological habits. Preliminary molecular phylogenetic analysis indicates that, among the species we examined, D. quinaria is most closely related to D. recens. To determine whether the bacteria are involved in reproductive isolation between these two species, reciprocal crosses were carried out between D. quinaria and both infected and uninfected (cured) strains of D. recens. Although these species did mate with each other, all interspecific crosses failed to yield hybrid progeny, indicating that the bacteria are not responsible for reproductive incompatibility between these species.
属于沃尔巴克氏体属的细菌共生体与许多昆虫物种的合子后生殖不相容性有关。利用细菌基因序列的聚合酶链反应（PCR）扩增，对果蝇中密切相关的quinaria、testacea和tripunctata组的10个物种的菌株进行了生殖组织中沃尔巴克氏体存在情况的筛选。筛选的物种包括食菌物种法氏果蝇、 recens果蝇、具斑果蝇、testacea果蝇、新testacea果蝇、东方果蝇、腐臭果蝇和三斑果蝇，以及非食菌物种沼地果蝇和quinaria果蝇。发现recens果蝇和东方果蝇两个物种感染了沃尔巴克氏体。随后对recens果蝇的另外四个菌株进行测试，发现所有菌株都感染了这种细菌。通过抗生素清除细菌，然后对清除和未清除的菌株进行杂交，确定这些细菌在recens果蝇中导致部分细胞质不相容。通过PCR检测确认了细菌的清除。虽然大多数被证明感染沃尔巴克氏体的昆虫物种是世界性的，和/或与人类活动相关联经历了最近的范围扩张，但recens果蝇和东方果蝇是具有特殊生态习性的特有物种。初步的分子系统发育分析表明，在我们研究的物种中，quinaria果蝇与recens果蝇关系最为密切。为了确定这些细菌是否参与这两个物种之间的生殖隔离，在quinaria果蝇与感染和未感染（清除）的recens果蝇菌株之间进行了正反交。虽然这些物种确实相互交配，但所有种间杂交都未能产生杂交后代，这表明这些细菌不是这些物种之间生殖不相容的原因。
