viii CONTENTS 



15. Means and Methods of Evolutionary Change 330 



16. Natural Selection IN Action 364 



17. Genetic Factors in the Origin of Diversity 375 



18. Genetic Change and Evolutionary Change 403 



19. Population Genetics and Evolutionary Change 427 



20. Natural Selection: I 450 



21. Natural Selection: II 484 



22. What of It? An Open Letter to Students 508 

 Index 525 



