Dispersal network heterogeneity promotes species coexistence in hierarchical competitive communities

Assessing mutualistic metacommunity capacity by integrating spatial and interaction networks

We develop a spatially realistic model of mutualistic metacommunities that exploits the joint structure of spatial and interaction networks. Assuming that all species have the same colonisation and extinction parameters, this model exhibits a sharp transition between stable non-null equilibrium states and a global extinction state. This behaviour allows defining a threshold on colonisation/extinction parameters for the long-term metacommunity persistence. This threshold, the 'metacommunity capacity', extends the metapopulation capacity concept and can be calculated from the spatial and interaction networks without needing to simulate the whole dynamics. In several applications we illustrate how the joint structure of the spatial and the interaction networks affects metacommunity capacity. It results that a weakly modular spatial network and a power-law degree distribution of the interaction network provide the most favourable configuration for the long-term persistence of a mutualistic metacommunity. Our model that encodes several explicit ecological assumptions should pave the way for a larger exploration of spatially realistic metacommunity models involving multiple interaction types.

Heterogeneous dispersal networks to improve biodiversity science

Dispersal has a key role in shaping spatial patterns of biodiversity, yet its spatial heterogeneity is often overlooked in biodiversity analyses and management strategies. Properly parameterised heterogeneous dispersal networks capture the complex interplay between landscape structure and species-specific dispersal capacities. However, this heterogeneity is recurrently neglected when studying the processes underlying biodiversity variation. To address this gap, we introduce a conceptual framework detailing the fundamental processes driving dispersal heterogeneity and its effects on biodiversity dynamics. We propose methods to parameterise heterogeneous dispersal networks, facilitating their integration into commonly used quantitative frameworks for biodiversity analyses. By considering the architecture of heterogeneous dispersal networks, we demonstrate their critical role in guiding biodiversity management strategies.

Complex patch geometry promotes species coexistence through a reverse competition-colonization trade-off

Explaining the maintenance of diverse species assemblages is a central goal of ecology and conservation. Recent coexistence mechanisms highlight the role of dispersal as a source of the differences that allow similar species to coexist. Here, we propose a new mechanism for species coexistence that is based on dispersal differences, and on the geometry of the habitat patch. In a finite habitat patch with complex boundaries, species with different dispersal abilities will arrange themselves in stable, concentric patterns of dominance. Species with superior competitive and dispersal abilities will dominate the interior of the patch, with inferior species at the periphery. We demonstrate and explain the mechanism on a simple one-dimensional domain, and then on two-dimensional habitat patches with realistic geometries. Finally, we use metrics from landscape ecology to demonstrate that habitat patches with more complex geometries can more easily support coexistence. The factors that underpin this new coexistence mechanism-different dispersal abilities and habitat patches with complex geometries-are common to many marine and terrestrial ecosystems, and it is therefore possible that the mechanism is a common factor supporting diverse species assemblages.

Maintenance of biodiversity in multitrophic metacommunities: Dispersal mode matters

Although metacommunity models generally formulate dispersal as a random, passive process, mounting evidence suggests that dispersal can be an active process depending on species fitness over the landscape, particularly in multitrophic communities. How different dispersal modes (i.e. from random to increasingly fitness-dependent dispersal) modulate the effect of dispersal on biodiversity remains unclear. Here, we used a metacommunity model of food webs to investigate the effects of dispersal and habitat heterogeneity on biodiversity and how these effects may be dependent on dispersal mode. Our results showed that compared to isolated systems, random dispersal increased local food web diversity ( α $$ \upalpha $$ diversity) but decreased across-community dissimilarity ( β $$ \upbeta $$ diversity) and regional food web diversity ( γ $$ \upgamma $$ diversity), consistent with findings from competitive metacommunity models. However, fitness-dependency could alter the effects of dispersal on biodiversity. Both β $$ \upbeta $$ and γ $$ \upgamma $$ diversity increased with the strength of fitness-dependency of dispersal, while α $$ \upalpha $$ diversity peaked at intermediate fitness-dependency. Notably, strong fitness-dependent dispersal maintained levels of β $$ \upbeta $$ and γ $$ \upgamma $$ diversity similar to those observed in isolated systems. Thus, random dispersal and isolation (i.e. no dispersal) can be considered as two extremes along the continuum of fitness-dependent dispersal, in terms of their effects on biodiversity. Moreover, both biodiversity-habitat heterogeneity and biodiversity-habitat connectivity relationships depended on the dispersal mode. Strikingly, under random dispersal, γ $$ \upgamma $$ diversity decreased with habitat heterogeneity and connectivity, but under strong fitness-dependent dispersal, it increased with habitat heterogeneity and remained unchanged as habitat connectivity increased. Our study highlights the context dependence of dispersal effects on biodiversity in heterogeneous landscapes. Our findings have useful implications for biodiversity conservation and landscape management, where management strategies should account for different modes of dispersal across taxa, thus different responses of biodiversity to habitat heterogeneity and connectivity.

Technological innovation facilitates the practice of "three-dimensional ecology"

The development of "three-dimensional ecology" reveals refreshing phenomena and challenges us to use three-dimensional information for studying animal perception. We created a new processing framework to quantify the shielding effect using a reconstructed environmental structure. The framework achieves three objectives: 1) the observed is introduced, 2) the observed space size can be flexibly dealt with, and 3) three-dimensional attributes are assigned to the environmental structure. Our processing framework is an applicable method to "three-dimensional ecology" based on the three-dimensional attributes of physical structures. We advocate for greater emphasis on "three-dimensional ecology" to recreate realistic animal living conditions and better reveal their behaviors.

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

Intransitive competition, typically represented by the classic rock-paper-scissors game, provides an endogenous mechanism promoting species coexistence. As well known, species dispersal and interaction in nature might occur on complex patch networks, with species interacting in diverse ways. However, the effects of different interaction modes, combined with spatial heterogeneity in patch connectivities, have not been well integrated into our general understanding of how stable coexistence emerges in cyclic competition. We thus incorporate network heterogeneity into the classic rock-paper-scissors game, in order to compare ecosystem stability under two typical modes of interaction: species compete to fill empty sites, and species seize each other’s colony sites. On lattice-structured regular networks, the two interaction modes produce similar stability patterns through forming conspecific clusters to reduce interspecific competition. However, for heterogeneous networks, the interaction modes have contrasting effects on ecosystem stability. Specifically, if species compete for colony sites, increasing network heterogeneity stabilizes competitive dynamics. When species compete to fill empty sites, an increase in network heterogeneity leads to larger population fluctuations and therefore a higher risk of stochastic extinctions, in stark contrast to current knowledge. Our findings strongly suggest that particular attention should be devoted to testing which mode of interaction is more appropriate for modeling a given system.

LiDAR Reveals the Process of Vision-Mediated Predator–Prey Relationships

Exploring the processes of interspecific relationships is crucial to understanding the mechanisms of biodiversity maintenance. Visually detecting interspecies relationships of large mammals is limited by the reconstruction accuracy of the environmental structure and the timely detection of animal behavior. Hence, we used backpack laser scanning (BLS) to reconstruct the high-resolution three-dimensional environmental structure to simulate the process of a predator approaching its prey, indicating that predator tigers would reduce their visibility by changing their behavior. Wild boars will nibble off about 5m of branches around the nest in order to create better visibility around the nest, adopting an anti-predation strategy to detect possible predators in advance. Our study not only points out how predator–prey relationships are affected by visibility as the environment mediates it, but also provides an operable framework for exploring interspecific relationships from a more complex dimension. Finally, this study provides a new perspective for exploring the mechanisms of biodiversity maintenance.

Multilayer network structure enhances the coexistence of competitive species

The concept of a multiplex network can be used to characterize the dispersal paths and states of different species in a patch habitat system. The multiplex network is one of three types of multilayer networks. In this study, the effect of a multiplex network on the long-term stable coexistence of species is investigated using the concept of metapopulation. Based on the mean field approximation, the stability analysis of a two-species system shows that, compared to the single layer network, the multiplex network is more conducive to the stable coexistence of species when one species has a stronger colonization ability. That is, in such a patch habitat system, if the dispersal paths of the stronger species are different than those of the weaker species, then the larger the heterogeneity of the dispersal network of the stronger species is, the more likely the long-term stable coexistence of species. This result provides a different perspective for understanding the biodiversity in heterogeneous habitats.