1. Natural selection

2. Learning intentions
To understand the process of natural selection

3. Natural Selection There are four main ideas behind natural selection:
There is variation of inherited characteristics in a species and some of these will increase the chances of surviving in a particular environment
In the struggle to survive, those members with favourable traits will have an increased chance of surviving in a particular environment

4. Natural Selection There are four main ideas behind natural selection:
Surviving members have an increased chance of reproducing and passing on their inherited traits to their offspring
4. Over time and many generations, organisms will possess traits that are better suited to their environment and increase their chances of survival

5. Natural selection
3 main elements:
Variation
Selection
Competition

6. Variation
Evolution says that more individuals are produced than the environment can support
These individuals will vary
Individuals with variations that help them reproduce will pass those variations onto their offspring

7. Selection Organisms are a part of their environments
Environments contain living (biotic) and non-living (abiotic) elements
These elements can potentially affect which variations are successful
If so, they are called selective agents

8. Competition Every individual needs food, water and a mate to reproduce
Individuals in a population compete with each other over these resources
They also need to compete to avoid predators

9. Mutations
Mutations can be one of the key sources of adaptations in nature:
Antibiotic resistant bacteria
Myxomitosis
Pesticide resistant insects

10. Inheritance
The genes we inherit from our parents are another source of adaptation in nature:
Peppered moths
Giraffes
Rhinoceros beetle

11. Inheritance vs. mutation
Inheritance adaptations occur over a long time, but have less potential to go wrong
Mutational adaptations occur much faster, but can often leave the organism much less likely to reproduce than without the mutation, such as with Down’s syndrome