GENETICS AND EVOLUTION OF MORPHOLOGY IN DROSOPHILA

动物生殖器和相关结构的形态学， 精子移植的功能通常非常复杂和多样化 尤其是昆虫。 为 例如，果蝇有7个兄弟物种，其中 唯一可靠的鉴定形态特征是 男性生殖器 因为这些第二性征 似乎是进化过程中最先改变的角色之一 新物种，他们提供了一些优势， 研究种间遗传和分子基础 形态上的差异。 该项目有3个具体 目标。 (1)一个目的是确定遗传结构的 D. mauritiana和D. simulans，属于blanogaster亚组， 物种 该方法是标记大约70段的 一个物种的基因组中含有含眼的P元件插入片段 颜色标记。 每个片段将单独渗入到 其他物种的基因组通过重复回交26 世代，然后进行纯合。 变异分析 这些行中的生殖器字符将提供 影响这些性状的基因数量和相对的 这些影响的程度。 在某些情况下， 还将研究显性和上位性。 (2)D. 与雄性的发育有关 生殖器将通过增强子检测器筛选和P- 元素诱变 增强子检测器插入显示 在雄性和雌性生殖盘中的不同表达模式 有可能识别出参与产生性行为的基因， 两性生殖器 这一潜力将由 通过不精确的切除， P元素。 (3)当生殖器功能丧失时， 发现，它们在引起种间差异中的可能作用 将通过杂交试验进行研究。 的任何基因 似乎对这些差异有很大的贡献， 克隆并鉴定其分子结构。 分子 这些差异的基础可以通过以下方式进行研究： 利用P元件转化进行种间基因转移。 与 这些信息，人们可以开始回答长期存在的问题， 结构和调控基因的相对重要性 形态进化的变化。

The morphology of animal genitalia and associated structures that function in sperm transfer is often very complex and divergent among closely related species, particularly in insects. For example, Drosophila melanogaster has 7 sibling species, among which the only reliable morphological characters for identification are the male genitalia. Because these secondary sexual characteristics appear to be among the first characters to change in the evolution of new species, they provide a number of advantages for investigating the genetic and molecular basis of interspecific differences in morphology. The proposed project has 3 specific aims. (1) One aim is to determine the genetic architecture of the differences in male genitalia between D. mauritiana and D. simulans, which belong to the melanogaster subgroup of sibling species. The approach is to mark approximately 70 segments of the genome of one species with P-element insertions containing eye color marker. Each segment will be introgressed individually into the genome of the other species by repeated backcrossing for 26 generations and then made homozygous. Analysis of variation in genitalic characters among these lines will provide an estimate of the number of genes that affect these traits and the relative magnitude of those effects. In some cases, the importance of dominance and epistasis will also be investigated. (2) Genes of D. melanogaster that are involved in the development of the male genitalia will be identified by enhancer detector screening and P- element mutagenesis. Enhancer detector insertions that show a different pattern of expression in male and female genital discs potentially identify genes involved in producing the sexually dimorphic genitalia. This potential will be investigated by inducing mutations in nearby genes through imprecise excisions of the P-element. (3) When loss of function genitalic mutants are found, their possible role in causing interspecific differences will be investigated through a hybridization test. Any gene that appears to contribute substantially to these differences will be cloned and its molecular structure characterized. The molecular basis of these differences can then be investigated by interspecific gene transfer using P-element transformation. With this information, one can begin to answer long standing questions about the relative importance of structural and regulatory genetic changes in morphological evolution.