Variation: Mutations and Environmental Effects
Individuals of the same species are not identical. This lesson separates genetic and environmental sources of variation, explains how mutations create new DNA variants, and shows why most phenotypes reflect interaction between inherited information and conditions.
Learning goals
- define the central terms precisely
- connect molecular, organismal and population evidence
- apply the ideas to unfamiliar biological cases
Core concepts
Variation is the set of measurable differences among individuals of the same species or population.
A mutation is a lasting change in a DNA sequence; it can be neutral, harmful, or beneficial in a particular context.
A mutagen is a physical, chemical, or biological factor that increases the probability of DNA damage and mutation.
Inherited variation comes from genetic differences that can pass through reproductive cells to offspring.
Environmental variation results when conditions such as nutrition, light, temperature, or activity alter phenotype without changing the inherited DNA sequence.
Continuous variation forms a range of values with many intermediates and is often influenced by many genes plus environment.