Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, Bellaterra (Barcelona), Spain.
J Hered. 2019 Jan 7;110(1):102-117. doi: 10.1093/jhered/esy057.
We investigated rates of chromosomal evolution in Drosophila mojavensis using whole-genome sequence information from D. mojavensis, Drosophila buzzatii, and Drosophila virilis. Drosophila mojavensis is a cactophilic species of the repleta group living under extreme ecological conditions in the deserts of the Southwestern United States and Northwestern México. The genome of D. buzzatii, another member of the repleta group, was recently sequenced and the largest scaffolds anchored to all chromosomes using diverse procedures. Chromosome organization between D. mojavensis and D. buzzatii was compared using MUMmer and GRIMM software. Our results corroborate previous cytological analyses that indicated chromosome 2 differed between these 2 species by 10 inversions, chromosomes X and 5 differed by one inversion each, and chromosome 4 was homosequential. In contrast, we found that chromosome 3 differed by 5 inversions instead of the expected 2 that were previously inferred by cytological analyses. Thirteen of these inversions occurred in the D. mojavensis lineage: 12 are fixed and one of them is a polymorphic inversion previously described in populations from Sonora and Baja California, México. We previously investigated the breakpoints of chromosome 2 inversions fixed in D. mojavensis. Here we characterized the breakpoint regions of the 5 inversions found in chromosome 3 in order to infer the molecular mechanism that generated each inversion and its putative functional consequences. Overall, our results reveal a number of gene alterations at the inversion breakpoints with putative adaptive consequences that point to natural selection as the cause for fast chromosomal evolution in D. mojavensis.
我们使用来自荒漠果蝇（Drosophila mojavensis）、荒漠棒眼果蝇（Drosophila buzzatii）和沙漠拟暗果蝇（Drosophila virilis）的全基因组序列信息，研究了荒漠果蝇的染色体进化速率。荒漠果蝇是一种嗜仙人掌的物种，属于 repleta 组，生活在美国西南部和墨西哥西北部沙漠的极端生态条件下。repleta 组的另一个成员荒漠棒眼果蝇的基因组最近被测序，并且使用各种程序将最大的支架锚定到所有染色体上。我们使用 MUMmer 和 GRIMM 软件比较了荒漠果蝇和荒漠棒眼果蝇之间的染色体组织。我们的结果证实了先前的细胞学分析，表明这两个物种的第 2 号染色体有 10 个倒位不同，X 和 5 号染色体各有一个倒位不同，而 4 号染色体是同源的。相比之下，我们发现 3 号染色体的倒位数量不是之前细胞学分析推断的 2 个，而是 5 个。其中 13 个倒位发生在荒漠果蝇的谱系中：12 个是固定的，其中一个是之前在墨西哥索诺拉州和下加利福尼亚州的种群中描述的多态性倒位。我们之前研究了固定在荒漠果蝇中的第 2 号染色体倒位的断点。在这里，我们对在 3 号染色体上发现的 5 个倒位的断点区域进行了特征描述，以推断产生每个倒位的分子机制及其潜在的功能后果。总的来说，我们的结果揭示了在倒位断点处的许多基因改变，具有潜在的适应性后果，表明自然选择是荒漠果蝇快速染色体进化的原因。
