Biodiversity is the variety of life in the world and the variety of ecosystems present as well. It may not seem important on it’s effects, however, the following two quotes explain the need to maintain biodiversity; “Biodiversity boosts ecosystem productivity where each species, no matter how small, all have an important role to play”(Shah, 2014); “At least 40 per cent of the world’s economy and 80 per cent of the needs of the poor are derived from biological resources. In addition, the richer the diversity of life, the greater the opportunity for medical discoveries, economic development, and adaptive responses to such new challenges as climate change”(Shah, 2014). The easiest way to maintain biodiversity is reduce the risk of extinction. Australian megafauna used to be once thriving species which roamed on the land for thousands of years, however, most of the Australian megafauna suddenly became extinct. There are many theories on how the extinction of these megafauna occurred, however, these theories can not be proven absolutely right. By using the knowledge of the theories of Australian megafauna extinctions, we can become capable of preventing extinctions in the present and future by creating sustainable practices using this knowledge to help maintain our biodiversity.
Megalania(scientific name Varanus Priscus) is an extinct species of megafauna which was similar to a giant goanna or monitor lizard that lived in Australia during the Pleistocene Epoch, from 1.8 million years age to 40000 years ago. Megalania is thought to be about 3-5.5 metres long(Australian Museum, 2015 & Proc Natl Acad Sci U.S.A, 2009). Megalania’s weight is thought to about 575 kilograms(Proc Natl Acad Sci U.S.A, 2009). Furthermore, similar to its relative, the Komodo Dragon, Megalania had a venomous bite(Dinopedia, 2016). Megalania lived in a broad range of habitats, which included open forests, woodlands and perhaps grasslands(Australian Museum, 2015). It has been found with fossils of large animals such as kangaroos, which suggests that Megalania may have fed on large mammals, including deer, wild pigs and goats(Australian Museum, 2015).
There are many theories why Megalania became extinct, and these theories can help us increase biodiversity between us. There are two such theories why Megalania could have became extinct, these being that climate and geographical changes made food and water harder to find, and that humans hunted Megalania to extinction.
During the late 19th and 20th century, many believed that the extinction of many Australian Megafauna was due to the drying climate at the end of the Pleistocene. The Pleistocene was generally believed to have a cool and wet climate, with luxuriant vegetation which was essential in supporting large animals. Once the Australian continent converted into drier plains with sparse vegetation, larger species such as Megalania, are thought to have failed to have become adapted to the new environmental change(Monroe, 2006). Sir Richard Owen (1861) believes that “large species would be more susceptible to these changes because they required more food and water”(Monroe, 2006). Monroe (2011) also states that there was a sudden change in climate in Australia around 20000 years before the current era. Monroe (2011) describes the climate as being very different during the Late Pleistocene, and described that “…Australia received half the present rainfall and the winds were double their present strength…[and]up to 80% of the continent being covered by wind-blown sand.” Furthermore, other larger megafauna, including 14 species of sthenurines(large, single toed, flattened claw kangaroo) died out in the Late Pleistocene as well(Elias & Schreve, 2007). This supports Owen’s claims that larger species would have more difficulty adapting to changing climates, however, most other large species have been thought to have become extinct due to other reasons, such as hunting(Salleh, 2009). To support the claims that theory is true, the diet of Megalania is thought to have been carnivorous and a scavenger, and its prey included rhinoceros-sized creatures such as Diprotodon optatum, and other large megafauna(Australian Museum, 2016; Museum of Victoria, 2016 & National Geographic, 2014). Since most megafauna became extinct at this time, Megalania most likely lost it’s prey, and therefore could not sustain itself. It is evident that this theory is likely due to the evidence given about the climate of the Late Pleistocene and the diet of Megalania, however, this theory does not support the claim how other large herbivore megafauna species became extinct as well.
Human activity has also been thought to have been a theory for the extinction of Megalania. Large megafauna such as Megalania have been thought to have been hunted to extinction, especially due to their slow speed. Sir Richard Owen (1861) believes a ‘rude primitive human race’ from Europe had contributed to the extinction of many large animals, as these humans had been found with the remains of extinct mammals(Monroe, 2006). According to Sir Richard Owen (1877), no other adequate cause is plausible other than the hostility of humans. Owen also noted how the large size of the animals such as Megalania would cause them to move too slowly when escaping. However, this theory is flawed. Indigenous population densities across Australia were most likely too low at the time to cause a full extinction according to Figure 1.2, which shows the aboriginal population density and hunting efficiency required to stop animals this large
Human activity is considered to have a role in megafauna extinction, but not hunting to extinction in some cases. Another perspective given by Moismann, J. & Martin, P. (1975) is that “human populations colonise a certain geographical area only supporting unexploited megafauna.” This will cause megafauna in some species to become affected by the colonisation due to hunting, but will also be affected because of loss of habitat(Late Pleistocene Extinctions Australia, 2011). Overall, this theory is likely if including the fact that human activity does cause loss of habitat, and that hunting is not just one human problem.
Currently, there are many issues which affect the biodiversity of animals due to human activities which are leading to an increase of the number of species become extinct. Major issue that arise today include climate change and habitat destruction, and these problems can be countered through the use of sustainable practices