Genetic Basis of Species Differences in Drosophila

描述(申请人提供)：我们实验室的长期目标是通过遗传分析了解导致新物种和物种在行为和形态特征上差异的进化力量，识别与这些差异有关的基因，并最终确定物种形成的遗传学是否存在一般模式。我们建议在果蝇亚群中最近出现分歧的两对姐妹物种中研究这些问题。我们的具体问题如下： 1.杂交种雄性不育的遗传基础是什么？它们之间的形态和行为差异是什么？这些物种表现出强烈的性隔离和杂交雄性不育，以及在腹部色素沉着和雄性求爱歌曲方面的强烈差异。我们建议使用精细结构分子作图来获得影响色素沉着和杂交不育的一小组候选基因，以及初步的全基因组范围的QTL作图研究，以研究雄性交配歌曲中可能在性隔离中起作用的种间差异。 2.哪些基因是导致拟南岛盘藻和毛盘盘藻之间的性隔离的基因？我们对这两个物种之间性别隔离的QTL图谱揭示了基因组中影响配偶歧视的几个小区域。我们建议使用精细结构的遗传图谱在两性中更准确地定位“性隔离”基因。 3.物种间允许多大程度的渗入？我们建议通过在一对密切相关的物种之间构建实验室‘杂交群’，并跟踪几年来分子标记的染色体片段、诊断形态特征和性别隔离的演变，来确定单独进化的物种的基因组之间允许多少混合。 4.如何解释“杂交区”和野生杂交种的遗传组成的异常？在圣多美岛发现的自然产生的杂交种很特别：它们都是雄性，都是F1杂交种，母亲是圣多美斑潜蝇，而且几乎所有的杂交种都出现在高海拔地区，超出了亲本物种的范围。我们将进行耐受性和偏好的实验室研究，以了解这些异常现象。我们的结果可能与理解包括人类在内的其他动物群体中物种的起源有关。

DESCRIPTION (provided by applicant): The long-term goals of our laboratory are to understand though genetic analysis the evolutionary forces producing new species and species differences in behavioral and morphological traits, to identify the genes involved in such differences and, ultimately, to determine if there are general patterns in the genetics of speciation. We propose to study these questions in two pairs of recently-diverged sister species in the Drosophila melanogaster subgroup. Our specific questions are the following: 1. What are genetic bases of hybrid male sterility and morphological and behavioral differences between D. santomea and D. yakuba? These species show strong sexual isolation and hybrid male sterility, as well as strong differences in abdominal pigmentation and male courtship song. We propose to use fine-structure molecular mapping to derive a small set of candidate genes affecting pigmentation and hybrid sterility, as well as an initial genome-wide QTL mapping study of an interspecific difference in male mating song that may play a role in sexual isolation. 2. What are the genes responsible for sexual isolation between D. simulans and D. mauritiana? Our QTL mapping of sexual isolation between these two species has revealed several small regions of the genome affecting mate discrimination. We propose to localize "sexual isolation" genes more accurately in both sexes using fine-structure genetic mapping. 3. How much introgression is permissible among species? We propose to determine how much mixing between separately-evolved species' genomes is permissible by constructing laboratory 'hybrid swarms' between pairs of closely-related species, and following the evolution of molecularly marked chromosome segments, diagnostic morphological traits, and sexual isolation over several years. 4. What explains anomalies in the "hybrid zone" and genetic composition of hybrids in the wild? Naturally- occurring hybrids found on Sao Tome Island are peculiar: they are all male, all F1 hybrids having a D. santomea mother, and nearly all of them occur at high altitude outside the range of either parental species. We will perform laboratory studies of tolerance and preference to understand these anomalies. Our results may be relevant to understanding the origin of species in other animal groups, including humans.