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维果蝇（Drosophila mojavensis）的祖先种群与衍生种群开展了三级遗传分析，旨在检验该物种的生活史性状演化可塑造交配前生殖隔离这一假说。首先，针对采自下加利福尼亚、墨西哥本土以及亚利桑那州的11个种群开展同质园实验，以两种宿主仙人掌饲养果蝇，结果显示宿主植物×区域及种群的交互效应对卵至成虫存活率与发育时长均存在显著影响；其次，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、细胞质遗传以及常染色体-X染色体联合对发育时长均存在宿主仙人掌相关的调控效应；第三，对1688头由下加利福尼亚种群与本土种群杂交获得的F2代雄蝇开展发育时长差异的数量性状基因座（QTL）分析，共鉴定出8个QTL，同时检测到8个基因-环境互作（G×E, Genotype-Environment Interaction），其具体表现为在本土宿主上饲养时，携带本土等位基因的个体发育时长更长，而在下加利福尼亚宿主上饲养时，下加利福尼亚种群各基因型间的发育时长差异相对更小；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差异，且发育时长与表皮碳氢化合物变异间存在基于QTL的显著相关关系。综上，当莫哈维果蝇通过转换宿主植物从下加利福尼亚入侵墨西哥本土后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。