The most populous nation in Africa is Nigeria, with 177 million people. The second most populous is Ethiopia with almost 87 million people.
Tunisia
China is the most populated nation in the world.
If you mean populated by the various animals it is because the environment can support so many different types of species.
Indonesia.
India is the most populated democratic nation with 1.1 billion inhabitants.
Nigeria Nigeria
China
Germany with about 83,000,000
The most densely populated sovereign nation is Monaco, with a population density of 16754.
Rainbow Nation.
Nigeria at around 146 million.