1. Charles Darwin was an...

2. Darwin was not the first to develop a theory of...
3.The type of tortoise, mockingbird, and finch that live on each of the Galápagos Islands was slightly different; Darwin later figured out that some varieties were different enough to be classified as different...
4.Darwin noticed that there was a relationship between each

species and its environment, and that organisms that were best adapted to their environment would be more likely to survive and reproduce. This concept is known as natural selection.