Etges William J, de Oliveira Cássia Cardoso, Gragg Erin, Ortíz-Barrientos Daniel, Noor Mohamed A F, Ritchie Michael G
Program in Ecology and Evolutionary Biology, Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas 72701, USA.
Evolution. 2007 May;61(5):1106-19. doi: 10.1111/j.1558-5646.2007.00104.x.
Few studies have examined genotype by environment (GxE) effects on premating reproductive isolation and associated behaviors, even though such effects may be common when speciation is driven by adaptation to different environments. In this study, mating success and courtship song differences among diverging populations of Drosophila mojavensis were investigated in a two-environment quantitative trait locus (QTL) analysis. Baja California and mainland Mexico populations of D. mojavensis feed and breed on different host cacti, so these host plants were used to culture F2 males to examine host-specific QTL effects and GxE interactions influencing mating success and courtship songs. Linear selection gradient analysis showed that mainland females mated with males that produced songs with significantly shorter L(long)-IPIs, burst durations, and interburst intervals. Twenty-one microsatellite loci distributed across all five major chromosomes were used to localize effects of mating success, time to copulation, and courtship song components. Male courtship success was influenced by a single detected QTL, the main effect of cactus, and four GxE interactions, whereas time to copulation was influenced by three different QTLs on the fourth chromosome. Multiple-locus restricted maximum likelihood (REML) analysis of courtship song revealed consistent effects linked with the same fourth chromosome markers that influenced time to copulation, a number of GxE interactions, and few possible cases of epistasis. GxE interactions for mate choice and song can maintain genetic variation in populations, but alter outcomes of sexual selection and isolation, so signal evolution and reproductive isolation may be slowed in diverging populations. Understanding the genetics of incipient speciation in D. mojavensis clearly depends on cactus-specific expression of traits associated with courtship behavior and sexual isolation.
很少有研究考察基因型与环境互作（GxE）对交配前生殖隔离及相关行为的影响，尽管在物种形成由适应不同环境驱动时，这种影响可能很常见。在本研究中，通过双环境数量性状基因座（QTL）分析，研究了分化的莫哈韦果蝇种群之间的交配成功率和求偶歌差异。莫哈韦果蝇的下加利福尼亚半岛种群和墨西哥大陆种群在不同的寄主仙人掌上取食和繁殖，因此利用这些寄主植物培养F2雄性果蝇，以检验寄主特异性QTL效应以及影响交配成功率和求偶歌的GxE互作。线性选择梯度分析表明，大陆雌性果蝇与那些发出的歌曲具有显著更短的L（长）-IPI、爆发持续时间和爆发间隔的雄性果蝇交配。分布于所有五条主要染色体上的21个微卫星基因座被用于定位交配成功率、交配时间和求偶歌成分的影响。雄性求偶成功率受一个检测到的QTL、仙人掌的主要效应以及四个GxE互作的影响，而交配时间受第四条染色体上三个不同QTL的影响。对求偶歌的多位点限制最大似然（REML）分析揭示了与影响交配时间的相同第四条染色体标记相关的一致效应、一些GxE互作以及少数可能的上位性情况。配偶选择和求偶歌的GxE互作可以维持种群中的遗传变异，但会改变性选择和隔离的结果，因此在分化种群中信号进化和生殖隔离可能会减缓。显然，了解莫哈韦果蝇初始物种形成的遗传学依赖于与求偶行为和性隔离相关性状的仙人掌特异性表达。
