Following general conditions are necessary for natural selection to occur in population:
- More organisms are born than can survive.
- Organisms vary in their characteristics, even within a species.
- Differences in reproduction and survival are due to variation among organisms.
According to Charles Darwin's theory of evolution by natural selection, organisms that possess heritable traits that enable them to better adapt to their environment compared with other members of their species will be more likely to survive, reproduce, and pass more of their genes on to the next generation.
Galapagos Finches: The Galapagos finches studied by Darwin on his famous voyage are probably the most common example of natural selection.