3.38: Explain Darwin’s Theory of Evolution by Natural Selection

EVOLUTION: Cumulative change in heritable characteristics of a population across successive generations

NATURAL SELECTION: Process where organisms that are better adapted to an environment will survive and reproduce to pass on genes to next generation

DARWIN’S THEORY:

• Individuals in a Species show a range of variation caused by differences in genes
• Individuals with characteristics better adapted to the environment have a higher chance of survival, allowing thme to reproduce
• These genes are passed onto their offspring, showing evolution of species via natural selection

HOW NATURAL SELECTION OCCURS:

NATURAL SELECTION

Diagram showing the Evolution of Snails via Natural Selection

EXPLANATION: Organisms within the population will show variation via mutations Mutated organism that has characteristics allowing them to be better adapted to the environment will have higher a chance of survival Hence, they will reproduce to pass on these beneficial mutations to offspring As a result, offspring will carry the same beneficial gene, allowing the population over time to be better adapted to environment - evolution via natural selection

USING DIAGRAM: Snails will undergo mutation to show variation in characteristics Snail with mutated gene that codes for white shell is better adapted to environment due to camouflage, therefore increasing chances of survival Hence, they will reproduce to pass on these beneficial mutations to offspring As a result, offspring will carry the same beneficial gene - shown through increase in snails with white shells Over time, population of snails with white shells will increase as they are better adapted to environment - evolution via natural selection