Magnitude of biodiversity
How many species are there?
The current estimate of life on earth is thought to be around 11 million species worldwide, but other estimates range up to 50 million species depending on predictive models used. Essentially, however, we really do not know even the magnitude of our natural heritage resources. This is called the 'The Taxonomic Impediment'. It refers to the still monumental task to discover and define species within the three Domains of Life, as species continue to become extinct at an accelerated rate.
Achieving even an adequate knowledge of these living genetic resources is a huge task. So far only about 1.9 million species have been described. These mostly concern the larger, more conspicuous species of vertebrates, plants, microorganisms and invertebrates. But the vertebrates, like mammals and birds, comprise only about 1% of life’s diversity, and hence this is why the invertebrates are sometimes called 'The Other 99%'.
Each year about 10 to 15 thousand new species are published worldwide, of which around 75% are invertebrates, yet for some megadiverse invertebrate groups, like the insects, the task appears to be never-ending. And then there is the biodiversity of the past, the science of palaeontology. Species alive today undoubtedly represent only a very small proportion of those that once used to live on this planet.
About 150,000 species are described for Australia so far, but with estimates of about 0.5-0.6 million species in total. This maybe a gross underestimate, however, considering the highly diverse invertebrates, microfungi, and especially micro-organisms, such that we may possibly know less than 25% of our all our native species.
Even so, Australia is considered one of only nineteen megadiverse countries in the world, with a large proportion of endemic species. These include about 85% of our insects and flowering plants; 84% of mammals; 45% of birds; and 89% of inshore and freshwater fishes unique to the Australian continent and island territories.
Australia is also unique because it is one of only two of these megadiverse countries that have a developed and stable economic base; a relatively high standard of education; and an established research infrastructure.
Biodiversity and endemism is high in Australia because:
- It is big (with 70,000km continental coastline, 8.6 million km2 continental marine territory; 16.1 million km2 oceanic jurisdiction).
- It spans a broad range of climatic zones and therefore has many ecosystems (60 marine bioregions, all 5 oceanic climatic zones, tropics to polar, intertidal to the abyssal plains).
- It is a very old continent, once part of the ancient Gondwanan supercontinent, with a subsequent mixing of species from the Gondwanan and Tethyan faunas following continental split.
Queensland has Australia’s greatest biodiversity, characterised especially by some iconic ecosystems recognised internationally as World Heritage Areas and defined by their living and fossil biodiversity. Queensland has 19 of Australia’s 80 terrestrial bioregions, 17 of the 60 marine bioregions, and 5 of the 13 world heritage-listed sites (comprising 36 million hectares). These include the rainforests of the Wet Tropics, coral reefs of the Great Barrier Reef, Fraser Island and other islands of the Great Sandy Region, and the Riversleigh fossil field.
Queensland ecosystems contain about 70% of Australia's mammals, 80% of its birds, 50% of its reptiles and frogs; but we know far less about the potentially millions of terrestrial and marine invertebrate species. This is a major reason why the Queensland Museum devotes considerable research resources to discovering and naming the still largely unknown invertebrate faunas.
Queensland also has more than 8000 known flowering plants, gymnosperms and fern species and vegetation, ranging from heaths and temperate woodland to tropical rainforests, with Queensland's flora more substantially known than its fauna.