The person generally credited with originating the theory of evolution by natural selection is 1. A. B. C. D. E. Charles Barkley. Because elephants reproduce more slowly than mice, the mice have higher fitness. There is no fitness associated with a phenotype, only with the underlying genotype. An individual animal's fitness tends to increase as it gets older.
Fitness is calculated from both probability of survival and number of mates.
8. requires inherited phenotypic variation within a population.