Darwin's Postulates 1. The ability of a population to expand is infinite, but the ability of any environment to support populations is always finite. Organisms within populations vary, and this variation affects the ability of individuals to survive and reproduce. - since populations can out grow their resource supply, it follows that some individuals will survive and reproduce, while others will not. The variations are transmitted from parents to offspring. - thus, advantageous traits will become more common in succeeding generations. Evolution is undirected variation.
Variation is random.
The process can produce new species of organisms if populations of that species are separated. The data of this example comes from Rosemary and Peter Grant, two biologists who have conducted a modern study of Darwin's Finches to demonstrate how Darwin's Postulates lead to evolutionary change. Criticism of Evolution by Natural Selection. This sequence illustrates two points 1. The evolution of complex structures seems a bit risky, since it requires a whole sequence of evolutionary changes to be selectively advantageous.