Bezault Etienne, Rognon Xavier, Clota Frederic, Gharbi Karim, Baroiller Jean-Francois, Chevassus Bernard
UMR110 Cirad-Ifremer INTREPID, 34398 Montpellier, France.
Int J Evol Biol. 2012;2012:817562. doi: 10.1155/2012/817562. Epub 2012 Jun 18.
Tilapia species exhibit a large ecological diversity and an important propensity to interspecific hybridisation. This has been shown in the wild and used in aquaculture. However, despite its important evolutionary implications, few studies have focused on the analysis of hybrid genomes and their meiotic segregation. Intergeneric hybrids between Oreochromis niloticus and Sarotherodon melanotheron, two species highly differentiated genetically, ecologically, and behaviourally, were produced experimentally. The meiotic segregation of these hybrids was analysed in reciprocal second generation hybrid (F2) and backcross families and compared to the meiosis of both parental species, using a panel of 30 microsatellite markers. Hybrid meioses showed segregation in accordance to Mendelian expectations, independent from sex and the direction of crosses. In addition, we observed a conservation of linkage associations between markers, which suggests a relatively similar genome structure between the two parental species and the apparent lack of postzygotic incompatibility, despite their important divergence. These results provide genomics insights into the relative ease of hybridisation within cichlid species when prezygotic barriers are disrupted. Overall our results support the hypothesis that hybridisation may have played an important role in the evolution and diversification of cichlids.
罗非鱼种类呈现出巨大的生态多样性以及种间杂交的重要倾向。这在野外已得到证实，并应用于水产养殖。然而，尽管其具有重要的进化意义，但很少有研究聚焦于杂交基因组及其减数分裂分离的分析。尼罗罗非鱼和黑边罗非鱼这两个在遗传、生态和行为上高度分化的物种之间的属间杂种是通过实验产生的。利用一组30个微卫星标记，在正反交第二代杂种（F2）和回交家系中分析了这些杂种的减数分裂分离情况，并与两个亲本物种的减数分裂进行了比较。杂种减数分裂显示出符合孟德尔预期的分离，与性别和杂交方向无关。此外，我们观察到标记之间的连锁关联具有保守性，这表明尽管两个亲本物种存在重要差异，但它们的基因组结构相对相似，且明显不存在合子后不相容性。这些结果为丽鱼科物种在合子前屏障被破坏时杂交相对容易的情况提供了基因组学见解。总体而言，我们的结果支持杂交可能在丽鱼科的进化和多样化中发挥了重要作用这一假说。
