Moreover, experience has shown that species' survival depends on the preservation of their habitats. Conflict over use of the earth's remaining natural wildlands will increase the focus on measuring, evaluating, and preserving biodiversity. Each taxonomic group usually receives equal value in estimating biodiversity, but certain species are sometimes assigned greater value. For example, the tuatara of New Zealand is an endangered lizardlike reptile with no close relatives. Because it is more genetically distinct than any species of true lizard, it contributes more to the diversity of the world's fauna.
Some species maintain the diversity of particular habitats.
These include the sea otter off the Pacific Coast of North America, which maintains diversity in subtidal waters by preying on sea urchins that would otherwise graze kelp forests to near extinction, thus removing the habitat for invertebrates and fishes.