| 摘要: | 在自然界中，常常觀察到兩個或兩個以上的性狀功能環環相扣，從天擇或性擇方面來看，這些性狀組成了一個複雜而完整的選汰單位，基因調控的改變已經成為影響單一性狀發育與演化的準則，但是對基因調控網絡(GRNs)之間的交互影響和連接，如何影響功能性相關聯的性狀之演化，到目前為止尚嫌不足。本研究意旨利用包含模式物種黃果蠅在內的東方區黃果蠅種群，其雄蟲特有的翅斑和展翅行為在求偶中所扮演的功能性聯結，來探討哪些基因與GRNs的改變，以及其改變的特性，如何去影響這些性狀功能形成聯結與演化。首先，我們將會先在一對可以雜交產下後代的姊妹物種中，尋找影響翅斑發育和決定展翅行為的遺傳因子，在這對姊妹種中，牽牛花果蠅 (D. elegans) 雄蟲具有翅斑與展翅行為兩性狀，但是高山果蠅 (D. gunungcola) 雄蟲則皆不具有兩種性狀，利用種內性別差異與種間性狀差異的特性，進行比較基因體分析與蛹期翅膀與成蟲腦部的比較轉錄體分析，鑑識出可能影響兩性狀發育的基因後，我們會利用RT-qPCR、RNA in situ 和轉殖基因等實驗發法去驗證這些基因的功能與特性。接下來，我們將會使用比較轉錄體分析的方法，比較黃果蠅種群下十一種物種蛹期翅膀與成蟲腦部的轉錄體，鑑識出影響翅斑發育與展翅行為的GRNs與其在各物種的差異與變化。經由這一系列比較轉錄體分析，我們期望進一步了解GRNs在性狀功能聯結的起源與功能性性狀的分化和變異中，其連接關係和連接點如何改變，並且在性狀演化過程中，如何維持兩個性狀的聯結。 ;The changes of gene regulation have become the norm in the Evo-Devo of simple traits, but not much has been explored in the interplays of gene regulatory networks, GRNs, in functionally-related traits. Nonetheless, the evolution of functional relatedness in two or more traits that serve as a cohesive unit acted on by natural or sexual selection is commonly observed. In order to elucidate the mechanisms better reflect complexity of trait development, I propose to investigate the genic basis and GRNs in the evolution of two male-specific functionally-related traits, wing spot (as a morphological trait) and wing display (as a behavioral trait) in the Oriental Drosophila melanogaster species group, which include the well-studied species, D. melanogaster, in many aspects relevant to this study. By the mean of comparative genomics and comparative transcriptomes using two NGS technologies with complementary merits, the underlying genetic mechanisms for the co-option of these two functionally-related traits will be first investigated in detail in a crossable species pair in which one, D. elegans, possesses both traits and the other one, D. gunungcola, lacks both traits. The transcriptome analysis of pupal wings and adult brains with other conventional means will be employed to identify and validate of molecular divergence that are important for wing spot development and decision making of wing display at DNA sequence and transcription levels. Then the evolutionary dynamics of GRNs for wing spots and wing display will be investigated by using comparative transcriptome analysis on the gene expression levels in pupal wings and adult brains across 11 species in the studied lineage. Throughout the study of comparative transcriptomes with supplementary experiments in RT-qPCR, RNA in situ, and transgenic fly analysis, I anticipate to unveil the GRN subcircuits and their co-options in the origin of functional related traits, the conservation and flexibility of connections among GRN nodes, the genetic and driving mechanisms to retain the coupling of functional related traits. |
