There Are Two Main Types of Variation
- Variation is one of the defining features of life.
- No two individuals are exactly alike, even within the same species.
- These differences are shaped by genetics, environment, or the interaction of both, and can be separated into two types:
- Continuous variation and discrete variation.
What Is Continuous Variation?
Definition
Continuous variation
Continuous variation describes traits that exhibit a range of phenotypes without distinct categories.
- This type of variation is often represented as a bell-shaped curve, with most individuals displaying intermediate traits and fewer at the extremes.
- Continuous traits are typically influenced by multiple genes (polygenic inheritance) and environmental factors.
Skin color in humans, which varies from very light to very dark, with countless shades in between.
What Is Discrete Variation?
Definition
Discrete variation
Discrete variation involves traits that fall into distinct, separate categories.
ABO blood groups, where individuals are type A, B, AB, or O, with no intermediates.
Continuous Traits and the Bell Curve
- Continuous variation results in a range of phenotypes, often forming a normal distribution curve.
- Traits like height, body mass, and wrist circumference are examples.
Applying Measures of Central Tendency
- Scientists use measures like mean, median, and mode to analyze continuous traits:
