Gazla I N, Carracedo M C
Departamento de Biología Funcional, Area de Genética, Facultad de Medicina, Universidad de Oviedo, Oviedo, Spain.
Genet Mol Res. 2009 Jul 28;8(3):861-9. doi: 10.4238/vol8-3gmr595.
Wolbachia are bacteria that live inside the cells of a large number of invertebrate hosts and are transmitted from infected females to their offspring. Their presence is associated with cytoplasmic incompatibility in several species of Drosophila. Cytoplasmic incompatibility results when the sperm of infected males fertilize eggs of uninfected females, causing more or less intense embryonic mortality (unidirectional incompatibility). This phenomenon also appears in crosses between populations infected with different Wolbachia strains (bidirectional incompatibility). The influence of Wolbachia infection on host populations has attracted attention as a potentially rapid mechanism for development of reproductive isolation and subsequent speciation. We examined the influence of this bacterium on reproductive isolation in interspecific crosses between Drosophila melanogaster and D. simulans. We found that Wolbachia infection negatively affected these two species in homospecific crosses. However, in interspecific crosses, it only influenced sexual isolation, as infected females more frequently hybridized than females free of infection; postzygotic reduction of fitness (bidirectional cytoplasmic incompatibility) was not detected. This would be explained by the existence of several modes of rescue systems in these two species, reducing cytoplasmic incompatibility between them. Wolbachia does not appear to cause reproductive isolation between these two species.
沃尔巴克氏体是一种存在于大量无脊椎动物宿主细胞内的细菌，可由受感染的雌性宿主传播给其后代。在几种果蝇中，它们的存在与细胞质不亲和性有关。当受感染雄性的精子使未受感染雌性的卵子受精时，就会导致细胞质不亲和，或多或少会造成严重的胚胎死亡（单向不亲和）。这种现象也出现在感染了不同沃尔巴克氏体菌株的种群之间的杂交中（双向不亲和）。沃尔巴克氏体感染对宿主种群的影响，作为一种潜在的快速产生生殖隔离及随后物种形成的机制，已引起了人们的关注。我们研究了这种细菌对黑腹果蝇和拟暗果蝇种间杂交中生殖隔离的影响。我们发现，在同种杂交中，沃尔巴克氏体感染对这两个物种有负面影响。然而，在种间杂交中，它只影响性隔离，因为受感染的雌性比未受感染的雌性更频繁地杂交；未检测到合子后适应性降低（双向细胞质不亲和）。这可以通过这两个物种中存在几种拯救系统模式来解释，这些模式减少了它们之间的细胞质不亲和性。沃尔巴克氏体似乎不会导致这两个物种之间的生殖隔离。
