Fig. 4

Relative heritability of collective size to cell size when the number of cells per collective varies. When the coefficient of variation for cell number per collective (CV_N) is low, collective-level heritability is always higher than cell-level heritability, but this advantage is undercut by increased variation in cell number. The ratio of collective- to cell-level heritability is maximized when developmental variation in cell size (σ) is large and variation in the number of cells per collective is zero. The pink contour denotes a ratio of collective-level to cell-level heritability of 1. In these simulations, we consider collectives with a genetic mean of 32 cells grown for seven generations. The colormap denotes collective-level heritability divided by cell-level heritability for size across 1024 σ, CV_N combinations