Biology Variation Overview

Study Notes

Variation is the differences between individuals of the same species.
Variation can be continuous or discontinuous.
Continuous Variation: Traits that can take any value within a range (e.g., height, weight). Measurements are usually taken on a scale.
Discontinuous Variation: Traits that fall into distinct categories (e.g., blood type, flower color).

Graphs of continuous variation data produce smooth bell curves, reflecting the small degrees of difference.
Graphs of discontinuous variation data produce step-like shapes.
Examples of continuous variation: height, mass, finger length.
Examples of discontinuous variation: blood type (A, B, AB, O), gender (male/female), ability to roll tongue (yes/no).

Genetic Variation: Differences in genes due to mutations, sexual reproduction, and gene flow.
Environmental Variation: Differences caused by environmental factors like temperature, nutrition, sunlight (affecting plant growth), and diet (affecting animal size).

Organisms with best adaptive features are more likely to survive and reproduce.
Individuals within a species show variation, resulting from differences in genes.
When organisms reproduce, more offspring are produced than the environment can support leading to competition.
Individuals best suited to their environments survive and reproduce more successfully.
Alleles for advantageous characteristics are passed on at a higher rate.
Eventually, there will be more individuals with better-adapted traits in subsequent generations.
Natural selection is also known as "survival of the fittest."

Environmental factors can affect the expression of traits.
Examples include the effect of sunlight on plant growth and the influence of diet on animal size.

Phenotype is determined by genetics and environment, together.
Examples of genetic variation in humans: blood group, eye color, gender, ability to roll tongue.

Adaptation is the process by which populations become better suited to their environment over generations, resulting from natural selection.
Camouflage is an example of adaptation in prey species helping them avoid predators.