* Evolution is about changes in allele frequencies: Evolution is fundamentally about changes in the relative frequencies of different versions of genes (alleles) within a population.
* Individuals don't evolve: An individual organism's genetic makeup is fixed. While an individual might develop traits during its lifetime (e.g., building muscle), these changes aren't passed on to offspring.
* Populations are the level where allele frequencies change: Evolutionary change happens when the frequency of certain alleles increases or decreases in a population over generations. This can occur through:
* Mutation: New alleles arise, introducing variation.
* Genetic drift: Random changes in allele frequencies due to chance events, especially in small populations.
* Gene flow: The movement of alleles between populations.
* Natural selection: Differential survival and reproduction of individuals with certain traits, leading to changes in allele frequencies.
Therefore, while an individual organism can be the subject of evolution, it's not the unit of evolution itself. Evolution occurs within populations over multiple generations.
