A silkworm's genetic diary
The silkworm, Bombyx mori, is an insect completely reliant on humans for its survival. It cannot fly, has poor vision, and lacks the camouflage of its wild ancestor, Bombyx mandarina. This dependency is the result of at least 5,000 years of selective breeding that began in China. This long history of domestication has left clear marks on the silkworm's genome. Compared to its wild relative, B. mori has a larger body, grows faster, and produces a significantly bigger cocoon. This process also reduced its genetic diversity by 33-49% compared to wild populations, a common effect of domestication.
The story of how this domesticated insect spread from China is written in its DNA. Phylogenetic analysis confirms that silkworm populations in Uzbekistan have a close genetic relationship with those in China, indicating they were introduced via the ancient Silk Road. Mitochondrial DNA (mtDNA), which is inherited maternally, is a powerful tracer for these ancient routes. The mtDNA of silkworms in the Boysun region shows that their ancestors were Chinese silkworms brought to this area around 1,700 years ago. These lineages established a new center for sericulture far from its origin point.