Data from: Genetics of incipient speciation in Drosophila mojavensis. III. Life history divergence in allopatry and reproductive isolation

We carried out a three-tiered genetic analysis of egg-to-adult development time and viability in ancestral and derived populations of cactophilic D. mojavensis to test the hypothesis that evolution of these life history characters has shaped premating reproductive isolation in this species. First, a common garden experiment with 11 populations from Baja California and mainland Mexico and Arizona reared on two host cacti revealed significant host plant X region and population interactions for viability and development time. Second, replicated line crosses with cactus-reared flies revealed autosomal, X chromosome, cytoplasmic, and autosome X cactus influences on development time. Third, a QTL analysis of development time differences on 1688 Baja X mainland F2 males revealed eight QTL. Eight GxE interactions were also detected, caused by longer development times associated with mainland alleles reared a mainland host with smaller differences among Baja genotypes on a Baja host plant. Four QTL influenced both development time and cuticular hydrocarbon differences associated with courtship success, and there was a significant QTL-based correlation between development time and cuticular hydrocarbon variation. Thus, the regional shifts in life histories that evolved once D. mojavensis invaded mainland Mexico from Baja California by shifting host plants were genetically correlated with variation in cuticular hydrocarbon-based mate preferences.

本研究针对嗜仙人掌性莫哈韦果蝇（Drosophila mojavensis）的祖先种群与衍生种群的卵至成虫发育时长及生活力开展三层遗传分析，以检验“该物种生活史性状的演化塑造了其交配前生殖隔离”这一假说。首先，针对下加利福尼亚、墨西哥本土以及亚利桑那州的11个种群开展同质园实验，将其饲养于两种寄主仙人掌上，结果显示在生活力与发育时长两个性状上，寄主植物×区域以及种群间均存在显著交互作用。其次，针对以仙人掌饲养的果蝇开展重复品系杂交实验，结果表明常染色体、X染色体、细胞质遗传效应以及常染色体-寄主植物交互作用均对发育时长存在影响。第三，针对1688份下加利福尼亚×墨西哥本土的F2代雄蝇开展发育时长差异的数量性状基因座（Quantitative Trait Locus，简称QTL）分析，共鉴定出8个QTL；同时还检测到8个基因型-环境互作（Genotype-Environment Interaction，简称GxE），其产生机制为：在大陆寄主植物上饲养时，携带大陆等位基因的个体发育时长更长，而在下加利福尼亚寄主植物上饲养时，巴哈基因型间的发育时长差异更小。另有4个QTL同时影响发育时长以及与求偶成功率相关的表皮碳氢化合物（cuticular hydrocarbon）差异，且发育时长与表皮碳氢化合物变异之间存在基于QTL的显著相关性。综上，当莫哈韦果蝇通过转换寄主植物从下加利福尼亚入侵至墨西哥本土后，其所演化出的生活史区域分化，与基于表皮碳氢化合物的配偶偏好变异存在遗传相关性。