南瓜实蝇在西南“天空之岛”的空间拓展及定殖的机理研究

The “sky island” in southwest China is a natural laboratory for studying the interrelationship between environmental heterogeneity and biodiversity. The important invasive insect pest, Bactrocera tau, has a strong adaptability and wide distribution and poses a threat to the biodiversity and ecosystem in this area. This study focuses on the scientific issue of the interrelationship between environmental heterogeneity and geographic population differentiation of B. tau and the aim is to explore the role of Isolation By Environment (IBE) in the process of microevolution of B. tau. Firstly, ecology method is used to construct the spatial pattern of spatial niche differentiation of B. tau, and the relationship between spatial niche and bioclimatic factors was analyzed. About 20 representative geographical populations were selected, and their genetic diversity and genetic differentiation were revealed by molecular marker analysis. Base on the above analysis, 5 geographical populations with larger genetic differences are selected and compared in adaptive differentiation under extreme temperature, including the difference of their stress-resistant small molecules, stress-resistant enzyme activity and the expression of the heat shock protein gene sHSPs21 by using physiological, biochemical and molecular biological methods to examine the genetic differentiation among five populations. Eventually, the landscape genetics mechanism of the spacial expansion and colonization of B. tau in “sky island” in southwest China will be clarified. This study has scientific significance for the macroscopic and microscopic combined insect landscape genetics, and also contributes to the sustainable management of B. tau.

西南“天空之岛”是研究环境异质性和生物多样性相互关系的天然实验室。重要入侵害虫-南瓜实蝇适应性强，分布范围广，对该区域的生物多样性和生态系统构成威胁。本研究围绕环境异质性和南瓜实蝇地理种群分化相互关系这一科学问题，探索环境适应性隔离（IBE）对南瓜实蝇种群微进化的作用。首先采用生态学方法构建空间生态位地理格局，分析空间生态位分化与生物气候因子关系。对20个左右有代表性的地理种群，采用分子标记分析揭示其遗传多样性和遗传分化。最后选取遗传差异较大的5个左右地理种群，采用生理生化和分子生物学手段，比较极端温度胁迫下的适应性分化，包括低温胁迫下抗寒性小分子代谢差异及抗逆性酶活性变异、高温胁迫下小热激蛋白基因sHSPs21的差异化表达，对南瓜实蝇5个地理种群的遗传分化进行检验，揭示其分布拓展和定殖的景观遗传学机理。本研究对宏观和微观相结合的昆虫景观遗传学研究有科学意义，也有助于南瓜实蝇的可持续治理。

南瓜实蝇Bactrocera tau Hendel，是世界上最具毁灭性的入侵实蝇害虫之一，被世界上许多国家列为重要的检疫性害虫。南瓜实蝇可为害葫芦科、茄科等80余种寄主植物。近年来，南瓜实蝇在西南“天空之岛”的分布范围逐渐扩大，发生和危害呈现明显上升势头，对该地区的生物多样性和生态系统构成严重威胁。本研究紧紧围绕西南“天空之岛”区域范围内环境异质性和南瓜实蝇地理种群分化相互关系这一科学问题。首先构建了空间生态位地理格局，分析空间生态位分化与生物气候因子关系。进而揭示了不同地理种群空间遗传结构，进一步比较了不同地理种群在极端低温下的生理适应性分化和热激蛋白基因的差异化表达。揭示了环境适应性隔离（IBE）对南瓜实蝇种群在微进化进程中的作用。通过本研究发现，陕西汉中种群的由于对较高纬度和较低温度的适应，产生了较为明显的分化。而云南元江种群和四川攀枝花种群表现出对高温的适应性分化。云南昆明、贵州安顺等云南高原种群表现出对高原气候的适应性分化。