The Origin of Species Chapter 4 Part 3 - Natural Selection

In which the gradual accumulation of slight variations in widely diffused and common species leads to the divergence and multiplication of forms, ultimately producing new varieties, species, and even genera through the persistent action of natural selection and extinction. This process, likened to a branching tree, explains the complex interrelations and classifications of living beings, while acknowledging that organisational advancement occurs variably according to an organism’s adaptation to its particular conditions.