Figure 1.

The evolution of developmentally plastic and unconditional helping behaviours in patches that contain 0 ≤ n_h ≤ 5 helpers in early life, for three different values of juvenile dispersal d (a). When helping is developmentally plastic, individuals develop higher levels of help in patches where helpers are present in early life (n_h > 0) relative to patches where help in early life is absent (n_h = 0). (b) The corresponding relatedness coefficients, showing that relatedness is higher in patches with more helpers, as these are more productive (hence making it more likely that philopatric offspring claim breeding spots). Note that when d = 0.6, unconditional helping does not evolve; hence we only have n_h = 0. The corresponding line in (a) is hence only drawn for the purpose of illustration, while we do not depict a corresponding relatedness coefficient for d = 0.6 and unconditional helping. See also electronic supplementary material, figure S1 for n_h,max ∈ {3, 10, 20} and figure S5 when productivity increases in a decelerating (rather than linear) fashion with increasing numbers of helpers. Parameters: n_b = 2, ϕ₀ = 1, ϕ₁ = 5, ϕ₂ = 1, n_h,max = 5. (Online version in colour.)