Biogeographic scenarios of Bombus flavescens through time A the most recent ancestor of B. flavescens dispersed through Southeast Asia or Sundaland around 1 Ma (orange) B the Malaysian population was isolated on the highland of the peninsula due to the temperature rising around 1 Ma (blue), at that time, the populations in Taiwan and Philippines were connected to the mainland populations (orange) C the bridge between the mainland and Taiwan was submerged, the Taiwan-Philippines populations were isolated around 0.5 Ma (purple) D at present day, B. flavescens populations distribute in the subtropical of Southeast Asia, China and Himalaya (yellow), on the Highlands of Malay peninsula (blue), and the islands of Taiwan and the Philippines (purple).