Section Animal Ecology, Institute of Biology Leiden, Leiden University, P.O. Box 9505, 2300, RA, Leiden, The Netherlands.
Mol Ecol. 2013 Sep;22(17):4433-44. doi: 10.1111/mec.12397. Epub 2013 Jul 23.
Wolbachia are endosymbiotic bacteria known to manipulate the reproduction of their hosts. These manipulations are expected to have consequences on the population genetics of the host, such as heterozygosity levels, genetic diversity and gene flow. The parasitoid wasp Tetrastichus coeruleus has populations that are infected with parthenogenesis-inducing Wolbachia and populations that are not infected. We studied the population genetics of T. coeruleus between and within Wolbachia-infected and uninfected populations, using nuclear microsatellites and mitochondrial DNA. We expected reduced genetic diversity in both DNA types in infected populations. However, migration and gene flow could introduce new DNA variants into populations. We therefore paid special attention to individuals with unexpected (genetic) characteristics. Based on nuclear and mitochondrial DNA, two genetic clusters were evident: a thelytokous cluster containing all Wolbachia-infected, parthenogenetic populations and an arrhenotokous cluster containing all uninfected, sexual populations. Nuclear and mitochondrial DNA did not exhibit concordant patterns of variation, although there was reduced genetic diversity in infected populations for both DNA types. Within the thelytokous cluster, there was nuclear DNA variation, but no mitochondrial DNA variation. This nuclear DNA variation may be explained by occasional sex between infected females and males, by horizontal transmission of Wolbachia, and/or by novel mutations. Several females from thelytokous populations were uninfected and/or heterozygous for microsatellite loci. These unexpected characteristics may be explained by migration, by inefficient transmission of Wolbachia, by horizontal transmission of Wolbachia, and/or by novel mutations. However, migration has not prevented the build-up of considerable genetic differentiation between thelytokous and arrhenotokous populations.
沃尔巴克氏体是一种内共生菌，已知其可以操纵宿主的繁殖。这些操纵预计会对宿主的种群遗传学产生影响，例如杂合度水平、遗传多样性和基因流。寄生蜂 Tetrastichus coeruleus 有感染孤雌生殖诱导型沃尔巴克氏体的种群和未感染的种群。我们使用核微卫星和线粒体 DNA 研究了 T. coeruleus 在感染和未感染沃尔巴克氏体的种群之间和种群内部的种群遗传学。我们预计感染种群的两种 DNA 类型的遗传多样性都会降低。然而，迁移和基因流可能会将新的 DNA 变体引入种群。因此，我们特别关注具有意外（遗传）特征的个体。基于核和线粒体 DNA，有两个遗传聚类是明显的：一个是包含所有感染的孤雌生殖种群的孤雌生殖聚类，另一个是包含所有未感染的有性生殖种群的雄蜂生殖聚类。核和线粒体 DNA 并没有表现出一致的变异模式，尽管两种 DNA 类型的感染种群的遗传多样性都降低了。在孤雌生殖聚类中，存在核 DNA 变异，但线粒体 DNA 没有变异。这种核 DNA 变异可能是由感染的雌性和雄性之间偶尔发生的性行为、沃尔巴克氏体的水平传播和/或新突变引起的。来自孤雌生殖种群的一些雌性未被感染和/或在微卫星基因座上为杂合。这些意外特征可能是由迁移、沃尔巴克氏体的低效传播、沃尔巴克氏体的水平传播和/或新突变引起的。然而，迁移并没有阻止孤雌生殖和雄蜂生殖种群之间建立可观的遗传分化。
