AP BIOLOGY

Detailed explanation-1: -Darwin coined the term fitness to refer to an organism’s relative ability to survive and produce fertile offspring. Nature selects the variations that are most useful. Therefore, he called this type of selection natural selection.

Detailed explanation-2: -The term Darwinian fitness refers to the capacity of a variant type to invade and displace the resident population in competition for available resources.

Detailed explanation-3: -The Darwinian fitness of a genotype of predator or parasite is measured by the average reproductive success of an individual of that genotype. Often, reproductive success is enhanced by consuming more prey, or extracting more resource from a host and thereby reducing its chance of survival.

Detailed explanation-4: -In the first four editions of On the Origin of Species, Darwin had used the phrase “natural selection". In Chapter 4 of the 5th edition of The Origin published in 1869, Darwin implies again the synonym: “Natural Selection, or the Survival of the Fittest".