The offspring, also, will thus have a better chance of surviving, for, of the many individuals of a species which are periodically born, but a small number survive. What this means is that the concept of natural selection results as an inevitable outcome of the acceptance of certain biological facts. Fact 1 . Natural populations have enormous excess fecundity. Fact 2 .
Population sizes remain stable.
Fact 3 . Limitation of resources. A severe struggle for existence must occur. Fact 4 . An abundance of variation exists among individuals of a species.