The domestication history of silkworms is unravelled in a paper published online this week in Nature Ecology & Evolution.
The cocoons of silkworms form one of the world’s most prized materials. However, the detailed history behind silkworm domestication remains ambiguous.
Shuai Zhan and colleagues analysed genetic material from 137 silkworm strains from China, Europe, Japan and India. The authors confirm that silkworms were domesticated in China 5,000 years ago from a wild ancestor, Bombyx mandarina. They also find evidence for multiple dispersal events along the Silk Road, the famous trade route of antiquity between China, South Asia and Europe. Subsequently, distinctive and improved strains were bred in both China and Japan.
In addition, the authors find selection for genes relating to cocoon-silk creation: for example, genes that have roles in the metabolism of nitrogen and amino acids, both of which are important for silk protein production. They also find evidence for different adaptations between the geographic regions where silkworms are farmed, including circadian rhythm changes, larger cocoons, and increased number of breeding cycles in tropical environments.