Competition modes determine ecosystem stability in rock–paper–scissors games

Contrasting effects of dispersal network heterogeneity on ecosystem stability in rock-paper-scissors games

“…Specifically, the NFD can decrease the average fitness of individuals when they become more common (cf. Zhang et al, 2022). Thus, the NFD, which is more significant in more heterogeneous networks, can suppress the population growth of dominant species but promote the growth of rare species, thereby increasing the frequency of oscillations and stabilizing competitive dynamics.…”

“…To focus solely on the effect of species competition on ecosystem stability, we perform simulations as follows: (i) according to the typical assumption in previous work (Masuda and Konno, 2006;Rojas-Echenique and Allesina, 2011;Grilli et al, 2017;Nagatani et al, 2018;Calleja-Solanas et al, 2021;Zhang et al, 2022), initially all patches are populated with individuals randomly drawn from the three species; (ii) in each time step, we perform a competition event using the two interaction modes specified below; (iii) we repeat step (ii) for a long time, finding that 1,000 generations (1 generation = 10,000 time steps at N = 10,000 patches) are sufficient for the system to achieve steady state; (iv) at steady state, we record the number of individuals for each species and the spatial patterns at every generation.…”

“…Despite these advances, several lattice-based models (Laird and Schamp, 2008;Rojas-Echenique and Allesina, 2011;Zhang et al, 2022) have observed that local intransitive competition can reduce species coexistence compared to long-range competition, in stark contrast to current knowledge of local interactions stabilizing coexistence (Durrett and Levin, 1997;Huisman and Weissing, 1999;Czárán et al, 2002;Kerr et al, 2002;Calleja-Solanas et al, 2021). Rojas-Echenique and and Zhang et al (2022) attributed the opposite outcomes to different interaction modes, which can induce distinct stabilizing mechanisms in lattice-structured models. Indeed, species in diverse natural ecosystems might interact in different ways.…”

“…The classic, cyclic game of rock-paper-scissors usually leads to species' abundances neutrally cycling without converging to a stable equilibrium point, which is rarely observed in nature. To overcome this problem, many approaches have been proposed to explain the robust persistence of the cyclically competing system, such as higher-order interactions (Grilli et al, 2017) and spatially structured interactions (Durrett and Levin, 1997;Czárán et al, 2002;Rojas-Echenique and Allesina, 2011;Calleja-Solanas et al, 2021;Zhang et al, 2022). In particular, the latter mechanism of local structured interactions stabilizing coexistence has been documented experimentally (Kerr et al, 2002).…”

“…Indeed, species in diverse natural ecosystems might interact in different ways. For example, there are two typical interaction modes often observed in nature: seedlings of tree species or propagules of grass species compete to fill gaps, while animal species fight directly for colony sites (Rojas-Echenique and Calleja-Solanas et al, 2021;Zhang et al, 2022). However, the effects of these different interaction modes, in combination with spatial heterogeneity in dispersal networks mentioned above, have not been well integrated into our general understanding of how stable coexistence emerges in cyclic competition.…”