家蚕的野生祖先来源和起源地是家蚕起源与进化研究中最基本的科学问题，也是养蚕学上一个重大的基础科学问题。大量已有研究明确了家蚕的野生祖先是中国野桑蚕和起源于中国，但直接祖先型种群和确切起源地仍不清楚。前期小样本的线粒体基因组研究发现，中国野桑蚕的群体间存在地理分化；家蚕的母系野生祖先来自中国北方野桑蚕群体；中国南方地区很可能不是家蚕的起源地。这些新发现为进一步探讨家蚕的直接母系野生祖先和确切起源地提供了机会。因此，项目将采用线粒体基因组扫描和大样本策略，查明中国野桑蚕的群体遗传结构和地理分化；结合家蚕地方品种线粒体基因组信息，基于系统发育分析确定家蚕的直接母系野生祖先来自哪个种群；基于种群基因组学分析和养蚕历史考察明确家蚕的确切起源地。这是首次从野桑蚕地理遗传结构和系统发育基因组学的角度来审视家蚕的直接母系野生祖先和确切起源地，将为野桑蚕资源保护和利用、家蚕驯化和品种改良等研究奠定基础。

The evolutionary origin of the domestic silkworm, Bombyx mori, is one of the most important basic scientific issue for seriology and life science. The direct wild ancestor and the geographic origin area where the domestication event occurred are the two key questions on the evolutionary origin of the domestic silkworm. Plenty of previous studies have confirmed that the wild ancestor of the domestic silkworm is the wild silkworm, Chinese Bombyx mandarina, rather than Japanese B. mandarina, and the domestication event occurred in China; however, the direct wild ancestors and more exact place(s) the domestication event(s) happened are still unclear. ..Our recent study based on small sample of whole mitochondrial genome of silkworms happened to discover the presence of two genetically distinctive subtypes in Chinese B. mandarina populations, corresponding to northern Chinese B. mandarina and southern Chinese B. mandarina, respectively, according to the geographical dividing line between northern and southern China. We also found that the direct maternal wild ancestor of B. mori is derived from northern Chinese B. mamdarina, rather than southern Chinese B. mamdarina, thus excluding the possibility of the early domestication event in southern China. Our findings provide us an access to re-investigate the direct maternal wild ancestor and the geographic origin area of the domestic silkworm ..Thus, this research proposal will use the strategies for whole mitochondrial genome scanning and large sample data, from Chinese B. mandarina populations and B. mori local strains, and then (i) to investigate the population genetic structure and geographical differentiation of Chinese B. mandarina populations, (ii) together with the assessment of the genetic structure of B. mori local strains, to re-define the direct maternal wild ancestor of the domestic silkworm by mitochondrial phylogenomics analysis, (iii) to ascertain the geographic origin of the domestic silkworm by population mitochondrial genomics analysis and the ancient texts for silkworm rearing. ..This research proposal is the first time to re-assess the direct maternal wild ancestor and geographic origin of the domestic silkworm, the two key questions for study on the evolutionary origin, by systematic analysis of the geographical genetic structure of Chinese B. mandarina and mitochondrial phylogenomics. The results will provide insights into conservation and ultilization of wild silkworm resources, domestication and improvement of the domestic silkworm.