Biology Variation and Natural Selection

Variation in Biology

• Variation is the differences between individuals within the same species.
• Variation can be continuous or discontinuous.
• Continuous variation traits take on any value within a range (e.g., height, weight). The graph of continuous data is a smooth bell curve.
• Discontinuous variation traits fall into distinct categories (e.g., blood type, flower color). The graph of discontinuous data is a step-like shape.
• Examples of continuous variation include height, mass, finger length.
• Examples of discontinuous variation include blood group (A, B, AB, O), gender (male, female), ability to roll tongue (yes/no).

Causes of Variation

• Genetic variation: differences in genes due to mutations, sexual reproduction, and gene flow.
• Environmental variation: differences caused by environmental factors (e.g., temperature, nutrition).
• Variations in phenotypes can be due to;
  • Genes (Genetic)
  • Environment (Environmental).

Natural Selection

• In any environment, individuals with the best adaptive features are most likely to survive and reproduce.
• This leads to natural selection.
• Individuals within a species vary genetically.
• When organisms reproduce, more offspring are produced than can be supported by the environment.
• This leads to competition for resources (food, mates).
• Individuals with characteristics best suited to the environment have a higher chance of survival and reproduction.
• Beneficial alleles are passed to offspring at a higher rate than unfavorable alleles
• This results in more individuals with traits better suited to the environment in the next generation.
• This theory, developed by Charles Darwin, is known as "survival of the fittest."

Adaptation

• Adaptation is the process resulting from natural selection, by which populations become more suited to their environment over many generations.
• Adaptations enhance survival by better fitting organisms to their environment.
• Examples of adaptation include camouflage, helpful structural features, and physiological adaptations.

Explore the concepts of variation in biology, including the differences between individuals within the same species. This quiz covers continuous and discontinuous variation, the causes of variation, and the role of natural selection in shaping phenotypes.