These range from tiny algae to humpback whales, from zoo plankton to towering eucalyptus trees. Our knowledge about the number of species that live on Earth is even more vague. Estimates range from 5 to 30 million or more, though one well accepted estimate is 13.6 million. Scientists have only classified about 1.7 million species so far. Genetic diversity Genetic diversity is the variety of genes within species.
Individual genes are the most basic unit of biodiversity.
Made up of DNA sequences on chromosomes, genes encode information templates for specific body functions and characteristics. The different shape, features and colours among dogs, or the different hair and eye colour in humans are examples of genetic diversity. Genetic diversity also produces easily seen differences in many native Australian species, such as the White cheeked Rosella, which have yellow head plumage in north Queensland, red head plumage in southern Australia, and black head plumage in Northern Territory. The total number of different genes distributed among Australian species is unknown but thought to be in the millions. The number of genes contained by different groups of species varies a great deal.