 Biological diversity, or biodiversity, is the sum total of all living things—the immense richness and variation of the living world. Biodiversity can be considered at many levels of biological variation, ranging from genetic variability within a species, to the biota of some selected region of the globe, to the number of evolutionary lineages and the degree of distinctness among them, to the diversity of ecosystems and biomes on Earth. (Groom et al. 2006: 27)