 Note that the ethics of animal liberation or animal rights and biocentrism are both individualistic in that their various moral concerns are directed towards individuals only—not ecological wholes such as species, populations, biotic communities, and ecosystems. None of these is sentient, a subject-of-a-life, or a teleological-center-of-life, but the preservation of these collective entities is a major concern for many environmentalists. Moreover, the goals of animal liberationists, such as the reduction of animal suffering and death, may conflict with the goals of environmentalists. For example, the preservation of the integrity of an ecosystem may require the culling of feral animals or of some indigenous animal populations that threaten to destroy fragile habitats. So there are disputes about whether the ethics of animal liberation is a proper branch of environmental ethics (see Callicott 1980, 1988, Sagoff 1984, Jamieson 1998, Crisp 1998 and Varner 2000).