Interspecific information use facilitates species coexistence in ecosystems

TL;DR

This work tackles the longstanding question of how biodiversity persists despite the competitive exclusion principle (CEP). It introduces a dimensionless predator–resource model that embeds interspecific information use into chasing-pair dynamics, showing that two consumer species can stably coexist on a single resource when information from one species enhances the other's search efficiency, mathematically reflected by a modified encounter rate $a_1 = a'_1 \left[ 1 + \dfrac{l_2 C_2}{K_2 + C_2} \right]$. The authors demonstrate that the zero-growth surfaces for the three species can intersect at a common fixed point (or yield a limit cycle in some cases), thereby relaxing CEP under both abiotic and biotic resource regimes and proving robustness to stochastic fluctuations via SSA. The model quantitatively recapitulates empirical patterns across diverse systems, including seabird foraging associations and classic insect experiments that previously contradicted CEP, suggesting a general mechanism by which information-mediated predator interactions sustain biodiversity. These findings bridge behavioral ecology and biodiversity theory, with potential extensions to microbial quorum sensing and broader ecological contexts.

Abstract

Explaining how competing species coexist remains a central question in ecology. The well-known competitive exclusion principle (CEP) states that two species competing for the same resource cannot stably coexist, and more generally, that the number of consumer species is bounded by the number of resource species at steady state. However, the remarkable species diversity observed in natural ecosystems, exemplified by the paradox of the plankton, challenges this principle. Here, we show that interspecific social information use among predators provides a mechanism that fundamentally relaxes the constraints of competitive exclusion. A model of predation dynamics that incorporates interspecific information use naturally explains coexistence beyond the limits imposed by CEP. Our model quantitatively reproduces two classical experiments that contradicts the CEP and captures coexistence patterns documented in natural ecosystems, offering a general mechanism for the maintenance of biodiversity in ecological communities.

Figures (10)

• Figure 1: Interspecific information use facilitates coexistence beyond the CEP limit. (A) Schematic illustration of two consumer species competing for a single resource. Green arrows indicate the energy (biomass) flow within the trophic interaction.(B) Model incorporating interspecific information use based on the schematic in (A), where consumer species $C_1$ use social information from $C_2$ to enhance its resource-searching efficiency.(C-D) Temporal dynamics of two consumer species competing for a single abiotic resource. (E-F) Positive steady-state solutions derived from the equilibrium equations (see Eqs. \ref{['eq1']}-\ref{['eq3']}): $\dot{R}=0$ (orange surface), $\dot{C_1}=0$ (blue surface), and $\dot{C_2}=0$ (green surface), representing the zero-growth isoclines. The red dot denotes the stable fixed point. The dotted curves in (D) indicate the analytical steady-state abundances (denoted by superscript '(A)'). See SM Sec. VI and Table S1 for simulation details of Figs. 1–3.
• Figure 2: Coexistence modes and corresponding parameter regions. (A-D) Representative coexistence trajectories in state space. (A) Abiotic resource case: the coexistence equilibrium (green dot) serves as a global attractor. (B-D) Biotic resource cases: in (B) and (C), the coexistence equilibria (green dots) remain globally stable, whereas in (D) the equilibrium (yellow dot) loses stability, and trajectories converge to a stable limit cycle. (E-F) Parameter regions supporting coexistence in the ODE studies. The parameter space bounded by the blue and red surfaces corresponds to stable coexistence. $\Delta$ is defined as $\Delta = {{\left( {{D_1} - {D_2}} \right)} \mathord{\left/{\newline} \right. \nulldelimiterspace} {{D_2}}}$ in (F).
• Figure 3: Interspecific information use explains experimental observations that contradict the CEP. (A-B) Representative temporal dynamics simulated using ODEs and SSA. (C) Comparison of SSA results with field survey data shows that two seabird species, Black legged Kittiwakes and Murres, coexist on the same cliff surfaces Hatch1988Hatch1989. Information used by Black legged Kittiwakes facilitates prey detection by Murres, helping to explain this phenomenon. (D-E) SSA simulations reproduce two classical experiments that violate the CEP. Two Tribolium species or two Drosophila species coexist with a single resource type in each experiment Park1954Ayala1969. In (C–E), the relative root mean square errors (rRMSEs) between SSA simulations and experimental data are as follows: Murres, 0.09; Black legged Kittiwakes, 0.13; T. confusum, 0.18; T. castaneum, 0.18; D. serrata Grp1, 0.15; and D. serrata Grp2, 0.15. (F) Comparison of time averaged relative population abundances between SSA results and experimental data Park1954Hatch1988Hatch1989Ayala1969. All data points lie close to the dashed line, where theoretical results equal experimental observations. The Pearson correlation coefficients between experimental data and SSA and ODE results are 0.998 and 0.997, respectively. See SM Sec.V and VI for details of the SSA simulations.
• Figure S1: ODE results for two consumer species competing for a single biotic resource type. (A-B) Time courses of two consumer species competing for a single biotic resource species. (C-D)Positive solutions to the steady-state equations (see Eqs.1-3): $\dot R = 0$ (orange surface), $\dot C_1 = 0$ (blue surface), and $\dot C_2 = 0$ (green surface), representing the zero-growth isoclines. The red dot represents the stable fixed point. The dotted curves in (D) correspond to the analytical steady-state abundances, labeled with the superscript '(A)'. See SM Sec. VI and Table S1 for simulation details of Figs. S1–2.
• Figure S2: The SSA and ODE simulations results including resource dynamics.(A) Coexistence dynamics between Kittiwakes and Murres within a seabird community under a single biotic resource.(B) Coexistence dynamics of flour beetles (T. confusum and T. castaneum) under a single abiotic resource. (C–D) Abundance variations of two Drosophila serrata groups (Grp1 and Grp2) and other minor taxa when sharing a single abiotic resource. The parameter settings and simulation methods: (A) and Fig.3C are identical; (B) and Fig.3D are identical; The relevant settings for (C) and (D) are described in Fig.3E.