Department of Biology, Emory University Atlanta, Georgia, 30322 ; Howard Hughes Medical Institute, Janelia Farm Research Campus 19700 Helix Drive, Ashburn, Virginia, 20147.
Ecol Evol. 2013 Jul;3(7):2061-74. doi: 10.1002/ece3.619. Epub 2013 Jun 3.
Sexual isolation, the reduced tendency to mate, is one of the reproductive barriers that prevent gene flow between different species. Various species-specific signals during courtship contribute to sexual isolation between species. Drosophila albomicans and D. nasuta are closely related species of the nasuta subgroup within the Drosophila immigrans group and are distributed in allopatry. We analyzed mating behavior and courtship as well as cuticular hydrocarbon profiles within and between species. Here, we report that these two species randomly mated with each other. We did not observe any sexual isolation between species or between strains within species by multiple-choice tests. Significant difference in the courtship index was detected between these two species, but males and females of both species showed no discrimination against heterospecific partners. Significant quantitative variations in cuticular hydrocarbons between these two species were also found, but the cuticular hydrocarbons appear to play a negligible role in both courtship and sexual isolation between these two species. In contrast to the evident postzygotic isolation, the lack of sexual isolation between these two species suggests that the evolution of premating isolation may lag behind that of the intergenomic incompatibility, which might be driven by intragenomic conflicts.
性隔离，即交配倾向降低，是阻止不同物种基因流动的生殖隔离之一。求偶过程中的各种种特异性信号有助于物种间的性隔离。白背果蝇和 D. nasuta 是果蝇移民群中 nasuta 亚群的近缘种，分布于异地。我们分析了种内和种间的交配行为和求偶行为以及表皮碳氢化合物图谱。在这里，我们报告说这两个物种可以随机交配。通过多项选择测试，我们没有观察到种间或种内品系之间存在任何性隔离。这两个物种的求偶指数存在显著差异，但两个物种的雄性和雌性对异性伴侣没有歧视。这两个物种之间还发现了表皮碳氢化合物的显著定量变化，但表皮碳氢化合物在这两个物种的求偶和性隔离中似乎作用不大。与明显的合子后隔离相反，这两个物种之间不存在性隔离表明，交配前隔离的进化可能滞后于基因组间不兼容性的进化，这可能是由基因组内冲突驱动的。
