Some of the following titles might be available as ebooks•
Population genetics: A concise guide. John Gillespie.The Johns Hopkins University Press (1997)•
Population genetics. J. S. Gale. Wiley (1980)•
Evolutionary genetics. John Maynard-Smith. Oxford University Press (1998)•
The growth of biological thought. Ernst Mayr. Harvard University Press (1985)•
Guns, germs and steel. Jared Diamond. W. W. Norton (2007)•
Evolutionary theory: Mathematical and conceptual foundations. Sean Rice. Oxford University Press (2004)