Calculating narrow-sense heritability (h2) through truncation selection,
using ovipositor length as an example.
- Mean ovipositor length in generation 1 is
x0 (12 mm)
- Truncate (cut off) the population by assuming only females with ovipositors greater than 14 mm can breed.
- Mean ovipositor length of breeding females is
x1 (17 mm).
- Selection differential
S = x1 - x0 = 5 mm.
- Mean ovipositor length in generation 2 is
x2 (12.5 mm)
- Response to selection
R = x2 - x0 = 0.5 mm,
- Narrow-sense heritability
h2 = R/S = 0.1.
A high narrow-sense heritability indicates high genetic component in behaviors such as group
size.