CBSE Class 12-science Answered

(i) The alien species became invasive and caused extinction or decline of indigenous species. For example, the Nile perch introduced into Lake Victoria in East Africa led to the extinction of more than 200 species of cichlid fish in the lake.

(ii) Loss of habitat and fragmentation drive animals and plants to extinction. For example, as the Amazon forest is cut and cleared for cultivating soya beans or for conversion of grasslands for raising beef cattle by which many species are affected.