For example, oxygen given off by plants, as a by-product of photosynthesis, is in turn used by all respiring organisms. Scientists are unsure as to how many species of plants and animals exist on the Earth. Biologists support that there are at least 4 to 12 million different species. Some believe that the number of species could be as high as 100 million or more. There is a variation among these species of plants and animals, which is referred to as biological diversity.
Biodiversity is one of Earth s most ecologically important natural resources.
There are three types of diversity encompassed within the term biological diversity. First is genetic diversity , the genetic variety that exists within a species. This is represented by the different populations that together make-up a particular species. The second group is species diversity ,simply the different number of species that exist. Finally, there is ecosystem diversity , the variety that is exhibited within and between ecosystems.