Variations within a population
Mutation is the important " starter " of the adaptive change engendered by natural selection. Variation is key to selection and without variation in organisms there would be nothing to select from for the survival and reproductive success of the organism against the immediate environment.
Randomness.
the fitest survive
Overproduction
Because natural selection only preserves incremental beneficial traits to the organism and many different areas of the organism are undergoing mutation and natural selection at the same time against the backdrop of the immediate environment. If a population of organisms, subject to allele change due to natural selection, is not in a changing environment, or split in a allopatric event, then adaptive change will be very slow, or will not happen at all and selection will winnow those variants and stabilizing selection is taking place. Regression to the mean of phenotype.
Variation in the organisms under selection. In both artificial selection and natural selection there must be heritable variations that have the possibility of being in the case of artificial selection what the selector wants in the organism and in thje case of natural selection survivability and reproductive advantages.
Natural Selection :)
Natural selection.
Reproductive isolation through sexual selection is often an important factor in speciation. This type of natural selection can lead to the evolution of reproductive barriers that prevent individuals from different populations from successfully interbreeding, ultimately resulting in the formation of distinct species.
Without genetic diversity, natural selection cannot occur
acidic and alkaline
Genetic variation is important for natural selection to drive evolution because it provides the raw material for natural selection to act upon. Without genetic variation, there would be no diversity in traits for natural selection to favor or eliminate, and evolution would not be possible.