适应性进化的理论和分子基础是进化生物学研究的前沿。依据经典的进化理论，Red Queen hypothesis，受环境中不断演变的生物/非生物因素驱动，适应性进化是持续进化的动态过程，从中演化出短暂适应性特征。为了适应不断变化的环境，基因组在适应性进化过程中是否体现出短暂适应性？背后的分子机制是什么？目前仍不清楚。申请者前期工作发现从头起源（de novo）miRNA因适应性进化而起源，但原有适应性特征因环境改变已消失，暗示了基因组短暂适应性的存在。本研究拟在前期工作基础上，在果蝇近缘种中探究de novo miRNA序列、表达和功能的快速进化，在基因组进化水平论证短暂适应性的存在及演化模式。此外，申请者将解析不同近缘种间miRNA介导的多基因调控网络进化规律，从调控网络进化角度阐述其短暂适应性的分子机理。本课题将为理解适应性进化基本理论，阐明适应性进化过程基因调控网络的演化规律提供参考。

The theory and molecular basis of adaptive evolution are the leading edge of evolutionary biology. According to the classical theory of organismal evolution, Red Queen hypothesis, driven by the evolving biological/abiotic factors in the environment, organisms evolve continually to adapt to the changing world, from which transient adaptive traits evolve. Do the genomes need to evolve transient adaptive traits in the process of adaptive evolution in order to adapt to the changing environment? What is the underline molecular mechanism? These questions still remain unknown. The applicant's previous work found that de novo miRNAs are fixed in genome by adaptive evolution, but their original adaptive traits have disappeared due to environmental changes, suggesting the existence of transient adaptation. Based on previous works, this study will explore the rapid evolution of sequence, expression and function of de novo miRNA in closely related species of Drosophila, demonstrating the existence and evolutionary dynamic of transient adaption at the level of genic evolution. Furthermore, we will analyze the evolution of miRNA-mediated multi-gene regulatory networks in closely related species of Drosophila, elucidating the molecular mechanism of transient adaptation from from the perspective of regulatory network evolution. This study will provide important hints for understanding the basic theory of genomic adaptive evolution and elucidate the principle of gene regulatory networks evolution during the process of adaptive evolution.