Darwin’s 4 Main Postulates • 1. Individuals, even siblings, in a population vary (there is variation) • 2. These variations can be passed to offspring (are inherited)
Darwin’s 4 Main Postulates • 3. More offspring are produced than the environment can support, so there is competition for resources (from Malthus) • 4. Those individuals whose characteristics make them best suited to the environment (fitness) live and reproduce and have more offspring (survival of the fittest).
Individuals do not evolve, populations evolve! • Evolution is change in the genes of a population over time. • Both gene frequency (how common a gene is) and gene expression (whether it is turned on or off) can change.
Journal Questions • #2 - If I had a third child and he/she was born with seven fingers, would that be an example of evolution? If so, why? If not necessarily, what would be necessary for this to be considered an example of evolution, and what factors might influence this? • #3 - Thoughts/Reflections