 Why are the animals in Australia so unique? You've got the kangaroo and wallaby, marsupials that carry their young in a handy pouch, the cute but lazy koala, and the weirdest of all, a beaked egg-laying mammal called the duck-billed platypus. In this video, you will learn how these weird and wonderful animals are formed in the process of speciation. Speciation is the formation of a new and distinct species in the course of evolution. Many millions of years ago, the continents that we know today were all joined together in one supercontinent known as Pangaea. Over several hundred million years, these continents slowly drifted apart from each other. When Australia finally separated from the other continents, its animals and plants were cut off from those on other land masses. This isolation is the first step in the formation of new species. It splits the species into two different gene pools. As the animals and plant groups on the Australian continent drifted away from their relations, they became isolated from other populations of their species, because the sea acted as a barrier. Each gene pool was now exposed to different conditions, like climate, food and competition. This is the second step in speciation. Some animals and plants that were not well adapted to the new conditions died, whereas those that were best adapted survived. Through the process of natural selection, the gene pool changed and the organisms became more and more different from those left behind. This is the third step in speciation. Eventually, these differences became so great that isolated populations are unable to interbreed and a new species is formed. This is the final step in speciation. There are many other examples. The lemurs and boba trees in Madagascar that became isolated from continental Africa. All the famous giant turtles and unique flightless cormorants of the Galopagos Islands that were isolated from South America. Their ancestors arrived either by flight, swimming or on natural rafts from the nearest mainland. Some of the species presented here are highly specialized. If their environment changes due to human or natural influence, they may become extinct. Like the Tasmanian tiger, a stripy dog-like animal which became extinct when humans entered its habitat and started over-hunting it. These are examples of speciation happening because of physical barriers. Members of the same species can also be separated due to biological or behavioral barriers. Birds of the same species but living in slightly different areas may over time develop different mating rituals or different mating songs. And so, the females are only attracted to rituals of the males from their area. Similarly, species living in different areas may face different climates or different food pressures. And so their mating seasons may end up being out of sync with other members of their species. This happened to two species of toad in North America. Over time, both of these resulted in speciation and are known as reproductive isolation. So remember, the amazing variety of flora and fauna that we have in our world is due to the process of speciation, the formation of a new and distinct species in the course of evolution.