Why are there so many more marsupial species in Australia compared to other continents?
In: 17
The theory is that most mammals used to be marsupials a long long time ago. And at that time animals were able to get to what is now Australia either by walking or even swimming short distances. Over time the Australian continent moved further and further away from the mainland and the animals on it became isolated. The mammals in other parts of the world eventually began evolving away from being marsupials, while the animals in Australia remained that way, possibly due to lack of contact with humans until relatively late in their evolution.
The really short answer is: no competition. Marsupials exist elsewhere, but they share their ranges with large placental mammals who either eat them, or eat their food.
Because Australia was geographically isolated from the rest of the world since before placental mammals outcompeted marsupials in other parts of the world (like in the Americas). So it’s not a case of “there’s so many”, because they were the only mammals present there in the first place and just filled all the normal niches, but rather “they survived so long”.
Latest Answers