Latin America is known as home to some of the Earth's greatest
concentrations of biodiversity (Heywood and Watson, 1995;
Harcourt and Sayer, 1996). Seven of the world's most diverse and
threatened areas are in Latin America and the Caribbean (Myers
et al., 2000). Of these, three rank among the world's five most
critical hotspots. The tropical Andes qualifies as one of the
world's two hyper-hot areas for its exceptional numbers of
endemic plants and endemic vertebratesthe highest in the world.
Maintenance of this diversity depends on the continued existence
of representative areas of natural ecosystems (Fearnside and
Ferraz, 1995; Fearnside, 1999). Dinerstein et al. (1995) have
divided Latin America into 191 terrestrial "ecoregions" and
collated information on the biodiversity importance and degree
of risk of each in a systematic fashion to establish priorities
for conservation. Many ecosystems already are at risk, without
additional stresses expected from climatic change: 48% of all
ecoregions are critical (1