What question did charles darwin try to answer?

Why do different organisms live in different places Why do different regions have different organisms

It was during this voyage that he began to consider the issue with which his name is most often associated, namely the origin and evolution of species, including humans. He proposed that species evolved gradually by a combination of random mutation and natural selection over a long period of geological history. Thus the main questions he asked and answered concerned how species evolved and obtained their current forms.