近緣種是研究種化形成機制的絕佳材料。不同種間的雜交不相容現象，代表物種之間的分化程度與生殖隔離現象。在分子機制上種間的不相容是需要兩個以上的基因交互作用而成，然而，即使基因交互作用的理論已經成為探討雜交後不相容的主要觀點，目前仍未找出能和種化基因相互作用的基因。根據之前的近緣種雜交實驗，我們得知當一段來自模里西斯果蠅性染色體的小片段被置換到擬黃果蠅上會造成雄性子代的不孕，而在置換區域發現造成此不孕現象的主要Homeobox 基因，OdsH，需要其他鄰近基因的共同作用才能造成完整的雄性子代的不孕，其中位於OdsH上游500 ~700 kb區域中已被證實存在可以幫助OdsH 造成完整不孕的輔助因子。為了更深入了解OdsH和它的輔助因子的位置及功能表現，我們設計了兩個品種雜交實驗，第一個試驗，在擬黃果蠅把OdsH和其下游650 kb的區域換成來自於模里西斯果蠅的染色體，結果發現OdsH除了上游之外，下游也有輔助因子的存在，且OdsH的Homeobox在雄性雜交不孕中扮演重要的角色。第二個實驗，我們把OdsHsim 換成OdsHmau，並建造其上游擁有來自於模里西斯果蠅染色體不同長短片段的品系，經由觀察比較各品系雄性子代的精子數量，發現當OdsHmau 缺乏來自於模里西斯果蠅的輔助因子時，會有少量精子產生，而且此現象出現的頻率受模里西斯果蠅染色體涵蓋區域的大小及溫度所影響，證實OdsHmau所產生的完整雄性不孕是經由多個基因作用才能完成。

The genetic dissection of closely related species is requisite for understanding the process of speciation. Inter-specific hybrid incompatibility represents species divergence and acts as a reproductive isolation barrier between species. Epistatic interactions have been a hallmark of hybrid incompatibility. However, no gene has been heretofore identified as interacting factor of any speciation genes. Nevertheless, previous studies showed that OdsH, a hybrid male sterility gene, requires other nearby interacting element(s) in the upstream of OdsH to confer full hybrid sterility effect. In order to identify the interacting elements of OdsH, two recombinant mappings were designed. The first recombinant mapping generated the sterile recombinant lines with introgression at OdsH downstream region (16D-17C) and demonstrated that there should be other interacting genes existed at downstream region to contribute complete hybrid male sterility. This result also indicates that the homeodomain across exons 2 and 3 of OdsH is essential in hybrid male sterility. In the second recombinant mapping, the fertility associated with mini-introgression segments showed that the interaction of multiple genes cause hybrid male sterility. I also found that the environmental factor, temperatures, is important in hybrid fitness when the fertility situations of hybrid males are identified as sub-fertile. It suggested that the genetic architecture of the hybrid male sterility contributed by OdsH is very complicated.

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