Darwin's 4 fields of study in his book "On the Origin of Species"?

Question

What were the 4 fields of study that Darwin gathered evidence from in his book "On the Origin of Species" and what was the focus of each area of study?

Answer 1

major scientific concepts · Natural selection; the struggle for existence; variation and adaptation; heredity; species formation

scientific arguments · Hereditary variation is the cause of species development; the struggle for existence defines advantageous variation; natural selection is the mechanism for evolution; geographical isolation influences the divergence of species

http://www.sparknotes.com/lit/origin/fac...

Answer 2

http://en.wikipedia.org/wiki/Origin_of_s...

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