Understanding:
5.2.U7: Natural selection increases the frequency of characteristics that make individuals better adapted and decreases the frequency of other characteristics leading to changes within the species. Objective:
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The theory of natural selection was posited by Charles Darwin (and also Alfred Wallace) who described it as ‘survival of the fittest’
The process of natural selection occurs in response to a number of conditions:
- According to this theory, it is not necessarily the strongest or most intelligent that survives, but the ones most responsive to change
- Since the better adapted individuals of a species are the ones that survive, reproduce and pass their genes on to the next generation, these alleles will become more frequent within the population. The same would hold true for individuals that are less suited to an environment. These individuals will reproduce less frequently and die more often, thus decreasing the frequency of their alleles within a population. These changes happen over many generations
The process of natural selection occurs in response to a number of conditions:
- Inherited Variation – There is genetic variation within a population which can be inherited
- Competition – There is a struggle for survival (species tend to produce more offspring than the environment can support)
- Selection – Environmental pressures lead to differential reproduction within a population
- Adaptations – Individuals with beneficial traits will be more likely to survive and pass these traits on to their offspring
- Evolution – Over time, there is a change in allele frequency within the population gene pool
Process of Natural Selection