Fig. 2
Collective-level heritability of size is greater than particle-level heritability for size. In a, we hold the effect of the environment fixed (standard deviation σ′ = 0.25) and vary the degree of developmental instability for particle size σ: 10− 4 (purple), 0.0625 (blue), 0.125 (green), 0.1875 (yellow), 0.25 (red). In the absence of developmental instability for size, collective and cell-level heritabilities are identical. Greater developmental instability increases relative collective-level heritability. b Here, we hold developmental instability fixed at σ = 0.25, and vary between-collective environmental effects on cell size from σ′ = 10− 4 (purple) to 0.25 (red). When developmental instability is nonzero, larger collectives improve collective-level heritability. We ran ten replicates of each parameter combination and simulated populations for nine generations of growth