Diversity in the world: diversity gradients and islands

Our planet is home to many different beings. They live scattered almost all over the world, but their distribution is not uniform and therefore, while there are places full of species, in many others we can only find a few species of few groups. What causes these distribution differences? Why are there more fun sites than others? Here are the possible answers to these questions. 400
Babesleak
Eusko Jaurlaritzako Industria, Merkataritza eta Turismo Saila