Abstract:Due to the change of the fundamental and realized niche, an invasive alien species (IAS) often shifts niches after it has established successfully and spread widely at the invaded region. Usually the direct evidence of the niche shift is difficult to achieve. The ecological niche models (ENMs) can be employed to predict the potential distribution of an invasive species in the invaded area based on the niche requirement of the species in its origin areas, given that its niche conserved when invaded in another region. Some indirect evidences of niche shift during biological invasion were found by comparing the difference between predicted and actual distribution in the invaded areas. The potential distribution of Ageratum conyzoides, a regional serious invaded weed in China, is predicted in non-native regions based on the niches require in its origin area using ENMs. The previous results showed that the distribution of A.conyzoides in non-native regions such as Asia-pacific region and Africa region could be well predicted by using ENMs, but there was a remarkable difference between predicted and actual distribution in China. A.conyzoides occurs widely in the south area of Yangzhi River, but the potential distribution of A.conyzoides predicted by ENMs only focuses in a small areas such as Yunan, Hainan and Taiwan provinces. The result of these investigations suggests that the climate niche of A.conyzoides has shifted after it invaded to China.