Institut de Recherche en Sciences de la Santé, Bobo-Dioulasso, Burkina Faso.
Centre for Applied Entomology and Parasitology, School of Life Sciences, Keele University, Staffordshire, United Kingdom.
PLoS One. 2020 Oct 29;15(10):e0240625. doi: 10.1371/journal.pone.0240625. eCollection 2020.
Within the Anopheles gambiae complex, the sibling species An. coluzzii and An. gambiae are undergoing sympatric speciation. These species are characterized by rare hybrids in most of their geographical distribution. A strong assortative mating mediated by spatial swarm segregation has been shown whereas no intrinsic post-zygotic barriers have been found in laboratory conditions. To test the role of the hybridisation in reproductive isolation in natural populations transplant experiment are therefore needed to establish the significance of post-zygotic barriers. Previous studies indicated that predation is one of the major forces driving ecological divergence between An. gambiae and An. coluzzii. Here we extended these studies to their hybrids. Parental species and their F1 hybrids from reciprocal crosses were generated by the forced-mating technique as follows: female An. coluzzii × male An. coluzzii; female An. coluzzii × male An. gambiae; female An. gambiae × male An. coluzzii and female An. gambiae × Male An. gambiae. First instar larvae of each group from the crossing (here after An. coluzzii, Hybrid COL/GAM, Hybrid GAM/COL and An. gambiae, respectively) were transplanted in a field experiment with predation effect. Emergence success, development time of larvae and body size of the newly emerging adults were estimated as fitness components and then compared between parental species and F1 hybrids in absence and in presence of predators. Our findings confirm that An. coluzzii had higher fitness than An. gambiae in presence of predators versus in absence of predators. Moreover, the fitness of the F1 hybrid COL/GAM whose female parent was An. coluzzii matched that of An. coluzzii while that of the F1 reciprocal hybrid GAM/COL was similar to An. gambiae.
在冈比亚按蚊复合体中，亲缘种冈比亚按蚊和塞内加尔按蚊正在经历同域物种形成。这些物种在其大部分地理分布区都有罕见的杂种。已经表明，存在由空间群分离介导的强交配选择性，而在实验室条件下没有发现内在的合子后障碍。因此，需要进行移植实验来测试杂种在自然种群中的生殖隔离中的作用，以确定合子后障碍的重要性。以前的研究表明，捕食是驱动冈比亚按蚊和塞内加尔按蚊之间生态分歧的主要力量之一。在这里，我们将这些研究扩展到它们的杂种。通过强制交配技术产生了来自相互交叉的亲代物种及其 F1 杂种：雌性冈比亚按蚊×雄性冈比亚按蚊；雌性冈比亚按蚊×雄性塞内加尔按蚊；雌性塞内加尔按蚊×雄性冈比亚按蚊和雌性塞内加尔按蚊×雄性冈比亚按蚊。从杂交中产生的每个组的第一龄幼虫（以下分别为冈比亚按蚊、杂交 COL/GAM、杂交 GAM/COL 和冈比亚按蚊）在具有捕食效应的田间实验中进行了移植。作为适合度成分，分别在有无捕食者的情况下，比较了亲代物种和 F1 杂种的成虫出现成功率、幼虫发育时间和新出现成虫的体型。我们的研究结果证实，在有捕食者的情况下，冈比亚按蚊的适合度高于冈比亚按蚊，而在没有捕食者的情况下则相反。此外，雌性亲本为冈比亚按蚊的 F1 杂种 COL/GAM 的适合度与冈比亚按蚊相匹配，而 F1 回交杂种 GAM/COL 的适合度则与冈比亚按蚊相似。
