Natural selection is a theory developed by Charles Darwin

• Individuals whose physical and behavioral characteristics are best adapted to their environment (habitat) have better chances of reproducing and passing on their DNA to future generations.

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Class Starter1. Describe the theory of natural selection in your

own words. _______________________________________________________________________________________________________________

2. Explain how the same members of a species can develop different traits. ____________________________________________________________________________________________________________________________________________________

Example of Natural Selection- 2 variations of the peppered moth

• light variation is best adapted to living in the country (it camouflages with the birch trees)

• dark variation is best adapted to living near factories (where tree trunks have turned black due to the factory smoke)

Light Peppered Moth- best adapted to living in the country

Black peppered moth-best adapted to living near factories

How did the black moth come to be?

The black moth arose as a result of a genetic mutation in the gene responsible for wing

colour.

How do members of the same species develop different traits?

1. Genetic Mutations

– Every time your DNA replicates in order to make new cells it can make mistakes

– These mistakes result in changes to your DNA and thus changes to your physical traits.

– A new trait might be more successful in a specific environment, causing it to become more frequent in the population

Genetic Mutations

How do members of the same species develop different traits?

2. Sexual reproduction:

–Parents pass on their traits to their offspring through their DNA.

– Each offspring inherits a different combination of their mother and father’s genetic information (genes).

Different Combinations of Genes

How do members of the same species develop different traits?

• Certain offspring may be born with a combination of genes that is more successful than his/her parents or siblings.

• This will make the individual ‘more fit’ and therefore more likely to survive in their environment and pass on their DNA to future generations.