Natural Selection

Natural Selection: Natural selection is the process through which certain traits become more prevalent in a population over time due to their advantageous effects on survival and reproduction. It occurs when individuals with traits better suited to their environment are more likely to survive and reproduce, thereby passing those traits on to the next generation.

Basic Example of Natural Selection

• Example Using Frogs:

  • A habitat scenario with frogs of varying colors (darker green/brown vs. lighter green).

  • Predators can more easily spot lighter frogs, leading to a situation where darker frogs survive more effectively.

  • Darker frogs have a better survival rate and thus higher biological fitness, measured by offspring count.

• Genetic Transmission:

  • Surviving darker frogs pass down their DNA to offspring.

  • Over generations, a higher frequency of darker frogs may evolve in this environment; evolution is thus a change over time through natural selection.

Importance of Genetic Variation

• Recessive Alleles:

  • The lighter color allele may persist as a recessive trait in the gene pool.

  • Genetic diversity can be maintained through mutations and genetic recombination (crossing over).

• Randomness of Mutations:

  • Variation and mutations occur randomly; organisms cannot will or control their traits.

  • Random mutations can be neutral, beneficial, or harmful affecting fitness.