We developed a three-dimensional Filippov piecewise-smooth population system characterizing aphid–ladybug–ant interactions, in which a threshold-based switching function describes the transition of aphids between pure reproduction and honeydew-excreting ant-recruitment strategies. In conventional numerical simulations of ecological models, sustained oscillations are often identified directly as steady-state limit cycles. Within the framework of non-smooth dynamical systems, the sliding dynamics, equilibrium classification, and stability of the model were analyzed. Time-series simulations, maximum Lyapunov exponent scans, and semi-logarithmic amplitude-decay analysis revealed that the long-lasting damped oscillations of the system are long transients rather than genuine limit cycles, which can be easily misjudged as steady-state oscillations under finite simulation time. The system exhibited monostable and bistable behaviors within the parameter domains examined, and the long transients were jointly induced by the weak stability of equilibria and the geometric constraints of the piecewise switching structure; the threshold switching, rather than any adaptive optimization, shaped the transient population dynamics. These findings highlight the distinction between transient evolution and genuine steady-state behavior in threshold-regulated ecosystems and provide reliable references for the numerical identification of such dynamics.
Citation: Zheqi Tao, Yi Yang, Changcheng Xiang. Long-transient behaviors and dynamical misjudgment in a Filippov piecewise-smooth population model[J]. AIMS Mathematics, 2026, 11(11): 36356-36378. doi: 10.3934/math.20261407
We developed a three-dimensional Filippov piecewise-smooth population system characterizing aphid–ladybug–ant interactions, in which a threshold-based switching function describes the transition of aphids between pure reproduction and honeydew-excreting ant-recruitment strategies. In conventional numerical simulations of ecological models, sustained oscillations are often identified directly as steady-state limit cycles. Within the framework of non-smooth dynamical systems, the sliding dynamics, equilibrium classification, and stability of the model were analyzed. Time-series simulations, maximum Lyapunov exponent scans, and semi-logarithmic amplitude-decay analysis revealed that the long-lasting damped oscillations of the system are long transients rather than genuine limit cycles, which can be easily misjudged as steady-state oscillations under finite simulation time. The system exhibited monostable and bistable behaviors within the parameter domains examined, and the long transients were jointly induced by the weak stability of equilibria and the geometric constraints of the piecewise switching structure; the threshold switching, rather than any adaptive optimization, shaped the transient population dynamics. These findings highlight the distinction between transient evolution and genuine steady-state behavior in threshold-regulated ecosystems and provide reliable references for the numerical identification of such dynamics.
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$ (a) $ three-dimensional state-space trajectory plot in $ (x, y_n, y_m) $ space; $ (b) $ time Series plot; $ (c) $ phase projection plot in $ (x, y_n) $ space. Parameters of system (2.1): $ K = 10 $, $ a_n = 0.7 $, $ b = 0.1 $, $ c = 0.5 $, $ \mu_n = 0.18 $, $ \mu_m = 0.18 $, $ \eta_1 = 0.8 $, $ \eta_2 = 0.9 $, $ \alpha = 0.5 $, $ \delta = 0.12 $, $ r = 4 $, $ \gamma = 3.5 $, $ \beta = 0.5 $
$ (a) $ three-dimensional state-space trajectory plot in $ (x, y_n, y_m) $ space; $ (b) $ time Series plot; $ (c) $ phase projection plot in $ (x, y_n) $ space. Parameters of system (2.1): $ K = 10 $, $ a_n = 0.8 $, $ b = 0.1 $, $ c = 0.5 $, $ \mu_n = 0.18 $, $ \mu_m = 0.18 $, $ \eta_1 = 0.8 $, $ \eta_2 = 0.9 $, $ \alpha = 0.5 $, $ \delta = 0.12 $, $ r = 4 $, $ \gamma = 3.5 $, $ \beta = 0.5 $
$ (a) $ three-dimensional state-space trajectory plot in $ (x, y_n, y_m) $ space; $ (b) $ time Series plot; $ (c) $ phase projection plot in $ (x, y_n) $ space. Parameters of system (2.1): $ K = 10 $, $ a_n = 0.7 $, $ b = 0.1 $, $ c = 0.5 $, $ \mu_n = 0.20 $, $ \mu_m = 0.18 $, $ \eta_1 = 0.8 $, $ \eta_2 = 0.9 $, $ \alpha = 0.5 $, $ \delta = 0.12 $, $ r = 4 $, $ \gamma = 3.5 $, $ \beta = 0.5 $
$ (a) $ three-dimensional state-space trajectory plot in $ (x, y_n, y_m) $ space; $ (b) $ time Series plot; $ (c) $ phase projection plot in $ (x, y_n) $ space. Parameters of system (2.1): $ K = 10 $, $ a_n = 0.9 $, $ b = 0.1 $, $ c = 0.5 $, $ \mu_n = 0.20 $, $ \mu_m = 0.18 $, $ \eta_1 = 0.8 $, $ \eta_2 = 0.9 $, $ \alpha = 0.5 $, $ \delta = 0.12 $, $ r = 2.6 $, $ \gamma = 2 $, $ \beta = 0.5 $
$ (a) $ three-dimensional state-space trajectory plot in $ (x, y_n, y_m) $ space; $ (b) $ time Series plot; $ (c) $ phase projection plot in $ (x, y_n) $ space. Parameters of system (2.1): $ K = 10 $, $ a_n = 0.7 $, $ b = 0.1 $, $ c = 0.5 $, $ \mu_n = 0.18 $, $ \mu_m = 0.18 $, $ \eta_1 = 0.8 $, $ \eta_2 = 0.9 $, $ \alpha = 0.5 $, $ \delta = 0.12 $, $ r = 4 $, $ \gamma = 3.5 $, $ \beta = 0.5 $. Simulation time $ T = 150 $
$ (a) $ three-dimensional state-space trajectory plot in $ (x, y_n, y_m) $ space; $ (b) $ time Series plot; $ (c) $ phase projection plot in $ (x, y_n) $ space. Parameters of system (2.1): $ K = 10 $, $ a_n = 0.8 $, $ b = 0.1 $, $ c = 0.5 $, $ \mu_n = 0.18 $, $ \mu_m = 0.18 $, $ \eta_1 = 0.8 $, $ \eta_2 = 0.9 $, $ \alpha = 0.5 $, $ \delta = 0.12 $, $ r = 4 $, $ \gamma = 3.5 $, $ \beta = 0.5 $. Simulation time $ T = 150 $
two-dimensional parameter scan of the maximum Lyapunov exponent over the plane $ (\beta, \gamma)\in[0.2, 0.4]\times[1, 4] $ (a uniform $ 200\times 200 $ grid). Parameters of system (2.1): $ K = 10 $, $ a_n = 0.95 $, $ b = 0.1 $, $ c = 0.5 $, $ \mu_n = 0.18 $, $ \mu_m = 0.18 $, $ \eta_1 = 0.8 $, $ \eta_2 = 0.9 $, $ \alpha = 0.5 $, $ \delta = 0.12 $, $ r = 4 $
Semi-logarithmic decay curve of oscillation amplitude. The vertical dotted lines mark the stopping instants $ T = 150 $, $ 400 $, $ 1000 $, and $ 3000 $. Parameters of system (2.1): $ \tau = 1280 $: $ K = 10 $, $ a_n = 0.9 $, $ b = 0.1 $, $ c = 0.5 $, $ \mu_n = 0.1 $, $ \mu_m = 0.18 $, $ \eta_1 = 0.8 $, $ \eta_2 = 0.9 $, $ \alpha = 0.5 $, $ \delta = 0.12 $, $ r = 4 $, $ \gamma = 3.5 $, $ \beta = 0.5 $; $ \tau = 155 $: $ K = 10 $, $ a_n = 0.9 $, $ b = 0.1 $, $ c = 0.5 $, $ \mu_n = 0.2 $, $ \mu_m = 0.18 $, $ \eta_1 = 0.8 $, $ \eta_2 = 0.9 $, $ \alpha = 0.5 $, $ \delta = 0.12 $, $ r = 2.6 $, $ \gamma = 3.5 $, $ \beta = 0.5 $; $ \tau = 435 $: $ K = 10 $, $ a_n = 0.95 $, $ b = 0.1 $, $ c = 0.5 $, $ \mu_n = 0.18 $, $ \mu_m = 0.18 $, $ \eta_1 = 0.8 $, $ \eta_2 = 0.9 $, $ \alpha = 0.5 $, $ \delta = 0.12 $, $ r = 4 $, $ \gamma = 3 $, $ \beta = 0.3 $