* Phenotype is the expression of the genotype: The genotype, the genetic makeup of an individual, provides the instructions for building and maintaining the organism. However, it's the phenotype that results from these instructions, and it's this phenotype that is exposed to the pressures of the environment.
* Environmental pressures act on the phenotype: Natural selection is driven by environmental pressures, such as competition for resources, predation, disease, and climate. These pressures exert selective forces on the phenotype, favoring individuals with traits that increase their chances of survival and reproduction.
* Survival and reproduction are based on phenotype: Individuals with advantageous phenotypes are more likely to survive, reproduce, and pass on their genes to the next generation. This is how natural selection leads to evolution.
Example: Imagine a population of rabbits with two fur colors: brown and white. If the environment is a forest, brown rabbits have a survival advantage because their camouflage helps them avoid predators. This means brown rabbits are more likely to survive and reproduce, passing on their genes for brown fur to their offspring. This leads to an increase in the frequency of brown rabbits in the population.
In summary:
* Natural selection is about the differential survival and reproduction of individuals in a population.
* Survival and reproduction are based on how well an individual's phenotype interacts with the environment.
* While the genotype ultimately dictates the phenotype, natural selection acts directly on the expressed characteristics of the phenotype.
