What is covariation?

What is covariation?

• A. How two traits vary together in a population
• B. How a single trait varies over time
• C. The difference between two population means
• D. The sum of two variances

Answer: (A)

Covariation refers to how two traits vary together across individuals in a population. It’s measured by covariance and often summarized with correlation, which shows whether the traits tend to increase together (positive covariation), vary in opposite directions (negative covariation), or show no consistent relationship (near zero). This concept matters in breeding because a positive covariation means selecting for one trait can produce a correlated gain in the other, while a negative covariation can limit how much you improve both traits at once. Covariation arises from genetic relationships like pleiotropy or linkage and from shared environmental effects. It’s not about how a single trait changes over time (that’s temporal variance), not about the difference between population means, and not about the sum of variances.

Covariation refers to how two traits vary together across individuals in a population. It’s measured by covariance and often summarized with correlation, which shows whether the traits tend to increase together (positive covariation), vary in opposite directions (negative covariation), or show no consistent relationship (near zero). This concept matters in breeding because a positive covariation means selecting for one trait can produce a correlated gain in the other, while a negative covariation can limit how much you improve both traits at once. Covariation arises from genetic relationships like pleiotropy or linkage and from shared environmental effects. It’s not about how a single trait changes over time (that’s temporal variance), not about the difference between population means, and not about the sum of variances.