Increasing the fraction of trait-lethals increases the degree of specialization. Solid line: (σ1,σ2) = (10, 1), dashed line: (σ1,σ2) = (1, 0.1). Each datum is the mean of 10 simulations ± std. dev., except for zero and 70% trait-lethals, which are for 20 simulations. log λ=-4, N=1000, μ=0.05. Error bars are s.e.m.