Program in Ecology and Evolutionary Biology, Department of Biological Sciences, University of Arkansas, Fayetteville, Arizona 72701, USA.
Evolution. 2010 Dec;64(12):3549-69. doi: 10.1111/j.1558-5646.2010.01096.x.
We carried out a three-tiered genetic analysis of egg-to-adult development time and viability in ancestral and derived populations of cactophilic Drosophila 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 species revealed significant host plant X region and population interactions for viability and development time, evidence for host plant adaptation. Second, replicated line crosses with flies reared on both hosts revealed autosomal, X chromosome, cytoplasmic, and autosome X cactus influences on development time. Viability differences were influenced by host plants, autosomal dominance, and X chromosomal effects. Many of the F(1) , F(2) , and backcross generations showed evidence of heterosis for viability. Third, a QTL analysis of male courtship song and epicuticular hydrocarbon variation based on 1688 Baja × mainland F(2) males also revealed eight QTL influencing development time differences. Mainland alleles at six of these loci were associated with longer development times, consistent with population-level differences. Eight G × E interactions were also detected caused by longer development times of mainland alleles expressed on a mainland host with smaller differences among Baja genotypes reared on the Baja host plant. Four QTL influenced both development time and epicuticular 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.
我们对祖先生殖隔离和衍生种群的卵至成虫发育时间和活力进行了三层遗传分析，以检验以下假设：这些生活史特征的进化塑造了该物种的交配前生殖隔离。首先，在巴哈加利福尼亚和墨西哥大陆以及亚利桑那州的 11 个种群进行了一个共同花园实验，这些种群在两种宿主植物上饲养，结果显示出活力和发育时间的显著宿主植物 X 区域和种群相互作用，这证明了宿主植物的适应性。其次，用两种宿主饲养的复制线杂交揭示了常染色体、X 染色体、细胞质和常染色体 X 仙人掌对发育时间的影响。活力差异受宿主植物、常染色体显性、X 染色体效应的影响。许多 F(1)、F(2)和回交代显示出对活力杂种优势的证据。第三，基于 1688 个巴哈×大陆 F(2)雄蝇的求偶歌曲和表皮碳氢化合物变异的 QTL 分析也揭示了 8 个影响发育时间差异的 QTL。这些位点中的 6 个大陆等位基因与较长的发育时间相关，这与种群水平的差异一致。还检测到 8 个 G × E 相互作用，这是由于大陆等位基因在大陆宿主上的表达导致较长的发育时间与在巴哈宿主植物上饲养的巴哈基因型之间的差异较小。四个 QTL 影响发育时间和与求偶成功相关的表皮碳氢化合物差异，并且发育时间与表皮碳氢化合物变异之间存在显著的基于 QTL 的相关性。因此，一旦 D. mojavensis 从巴哈加利福尼亚侵入墨西哥大陆并改变了宿主植物，这种生活史的区域变化与基于表皮碳氢化合物的交配偏好的变异在遗传上是相关的。
