B.7(D) Supporting
Natural selection
Darwin's theory was based on the mechanism of natural selection, which explains how populations can evolve in such a way that they become better suited to their environments over time.
Natural selection acting on mice population over time.
Individuals have variations within their heritable traits. Some variations make an individual better suited to survive and reproduce in their environment.
If this continues over generations, these favorable adaptations (the heritable features that aid survival and reproduction) will become more and more common in the population.
The population will not only evolve (change in its genetic makeup and inherited traits), but will evolve in such a way that it becomes adapted, or better-suited, to its environment.
Genetic Variation
Genetic variation is a measure of the variation that exists in the genetic makeup of individuals within population.
Key Points
Genetic variation is an important force in evolution as it allows natural selection to increase or decrease frequency of alleles already in the population.
Genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism’s offspring).
Genetic variation is advantageous to a population because it enables some individuals to adapt to the environment while maintaining the survival of the population.
https://courses.lumenlearning.com/boundless-biology/chapter/population-genetics/
Check Your Understanding
Does natural selection change an individual or a population over time?
Explain how natural selection would effect a population of insects treated with a pesticide.
Practice answering the following STAAR questions
