BIODIVERSITY HOTSPOTS Biodiversity hotspots, areas with a high number of endemic but threatened or endangered species, cover a small percentage of land and water areas but hold more than 40–50% of all plant and vertebrate endemic animal species. Most hotspots are located in tropical biomes or in isolated terrestrial ecosystems such as mountains or islands. Even small disturbances can threaten endemic species who populate specialized niches in these hotspots.