Figure 2

Final distributions of bacteria after time interval τ = 1000 starting from a random distribution, with d = 0.001, for various response dynamics. Represented are the left-swimming L (blue), the right-swimming R (red), and the tumbling population S (yellow). Only the population in -5 >x > 5 is shown. The distribution of attractant is shown with a solid black line. A: high sensitivity negative adaptive response, α₀ = 0.01, λ = 100.0, β = 100.0, corresponding to the thick red curve in Figure 4. B: low sensitivity positive linear response, α₀ = 0.01, λ = 1.7, β = 0.01, corresponding to the thin blue curve in Figure 4; C: low sensitivity negative adaptive response, α₀ = 0.01, λ = 1.7, β = 0.01, corresponding to the thin orange curve in Figure 4; D: low sensitivity hybrid response, α₀ = 0.01, λ_Lin = 1.1, λ_Adapt = 0.6, β = 0.01, corresponding to the thin green line in Figure 4; Note the change in scale in A. Asymmetry of the curves is due to the non-zero attractant velocity. All three low sensitivity responses, including the adaptive response, are characterised by a large fraction of tumbling bacteria co-localised with the attractant, even if the tumbling population is not large in regions far from the attractant.