Problem:
Question 1: According to Darwin's Principles, what pre-conditions are required if a population is to evolve by natural selection?
Question 2: What was Darwin's model for heredity, and how did it weaken his argument that natural selection was the only adequate explanation for adaptation?
Question 3: What are the possible explanations for the existence of several different alleles in a population? (e.g., why hasn't one been fixed and the other gone extinct?).
Please Explain don't just write the answer.