This problem
of invasive species is a worldwide issue, second only to habitat
destruction as
a threat to biodiversity.
   
      The
Galápagos Archipelago contains some of the most unusual and
fascinating species in the world. 95% of its original plant and animal
species still survive.
   
      Hawaii is thought
to have lost over 50% of its original biodiversity since the first
arrival of humans 1,500 years ago.