Systematic vs. Non-Systematic Forces

Which of the following is NOT a systematic force affecting gene frequency in a population?

Correct Answer: Random Genetic Drift

From the notes: Forces affecting Hardy-Weinberg equilibrium are of two types:

1. Systematic Forces (from notes)

Act in both large AND small populations; can be predicted in both amount and direction.

• Mutation: Slowest — rate ~10⁻⁵ per locus per generation. Ultimate source of all new variation.
• Migration (Gene flow): Predictable in amount AND direction. Δq = m(qm – q)
• Selection: Fastest force to change gene frequency.

2. Dispersive Force (from notes)

Acts only in small populations; can be predicted only in amount, NOT in direction.

• Random Genetic Drift (Sewall Wright effect): Random fluctuation in gene frequency in small populations. NOT a systematic force. ✔