Table 1.

Stability of two preferences dependent on the joint cost of choice θ

	Joint cost of choice θ	p1	p2
(a)	0.1	stable	stable
	0.2	stable	stable
	0.3	stable	stable
	0.4	stable	stable
	0.5	stable	cycles
	0.6	stable	cycles
	0.7	stable	cycles
(b)	0.1	stable	cycles
	0.2	stable	cycles
	0.3	stable	cycles
	0.4	stable	cycles
	0.5	stable	cycles
	0.6	cycles	cycles
	0.7	cycles	cycles

(a) One male ornament t₁ is subject to strong mutation bias u₁ = 0.001 and the other t₂ to weak small mutation bias u₂ = 0.00001. The cost of choice b = 0.001. (b) Mutation bias is just sufficient for stable evolution of p₁ but causes cyclic evolution of p₂ (u₁ = 0.0001, u₂ = 0.00001). The cost of choice was b = 0.0023, which just satisfies Eq. 4. Other parameter values were the same in both female and male traits G_t = G_p = 0.5, a = 0.4, b = 0.001, c = 0.04, λ = 1. Simulations were started with p₁, p₂, t₁, and t₂ at high values and ran until stability or obvious cyclic behavior was observed (≈10,000 generations).