Biogeographical studies use information for various fields, such as evolutionary biology, geography, geology, and climate science to determine how organisms evolved through time and how the moving of tectonic plates resulting in forming continents, mountain ranges and islands has affected their distribution.
Studies in this field explain how organisms that now live on different continents are very closely related and how the flora and fauna of islands are connected to one of the closest continents etc.
Answer: The different layers are a result of lighter parts (such as the continental crust) settling at the surface level and heavier parts (such as iron and nickel in the core) settling in the middle. The layers separate by density, otherwise known as compositional layering. The earth did not always have these layers, as it had to undergo cooling to form some of them (like the continental crust).
Mature DNA cells do NOT contain DNA.
