Com­plex geol­o­gy and var­ied topog­ra­phy have giv­en rise to a diver­si­ty of ecosys­tems and species unmatched in the insu­lar Caribbean and cre­at­ed one of the most bio­log­i­cal­ly diverse trop­i­cal island sites on earth. Many of the under­ly­ing rocks are tox­ic to plants so species have had to adapt to sur­vive in these hos­tile con­di­tions. This unique process of evo­lu­tion has result­ed in the devel­op­ment of many new species and the park is one of the most impor­tant sites in the West­ern Hemi­sphere for the con­ser­va­tion of endem­ic flo­ra. Endemism of ver­te­brates and inver­te­brates is also very high.