Biology subjects

Barabas, G.

Publications and source records attributed to Barabas, G..

9 recordsLinked to original sources

bioRxiv2026

Maximum trophic level predicts food webs susceptibility to coextinctions

As ecosystems face a growing number of threats, coextinctions (resultant extinctions following a primary extinction) are expected to proliferate. However, less is known about the conditions under which coextinctions could outpace primary extinctions. Because coextinctions often occur through lost species interactions, we posit that aspects of food web structure and complexity can help predict differences in vulnerability to coextinction across ecosystems. To test this, we leverage Bayesian network models to assess the extent to which variation in ecosystem vulnerability to coextinction varies with food web structure. We find that food webs with high maximum trophic level are most vulnerable to coextinction, and that maximum trophic level is a better predictor than other aspects of food web structure, such as species richness or trophic connectance. Extending this approach, we also find that maximum trophic level uncovers the relative vulnerability of ecosystem services to species coextinction across 12 empirical food webs.

ecology↗

bioRxiv2026

Weak dispersal and landscape size inevitably promote local biodiversity in heterogeneous metacommunities of competing species

We provide a general theoretical explanation for a longstanding result in spatial ecology: weak dispersal among habitat patches promotes local biodiversity. Using analytical approximations of spatial Lotka-Volterra competition models, we show that species persistence in heterogeneous landscapes can be expressed as a function of regional abundance and local invasion growth rates. We further demonstrate that local multispecies coexistence is governed by the feasibility domain, linking spatial coexistence to a structural property of nonspatial competitive systems. Together, these results explain why weak dispersal increases local species richness and why this effect strengthens with landscape size. We test these predictions using numerical simulations and find that the theory breaks down only when both dispersal and competitive interactions are very strong, in which case dispersal has a unimodal effect on coexistence. In contrast, landscape size retains a positive effect on coexistence whenever an effect is detectable. We then apply the theory to long-term data from a natural Daphnia metacommunity. We detect strong preemptive competition among species and find no detectable effect of dispersal rate on local coexistence, whereas species co-occurrence increases with local landscape size, as predicted by theory. Together, our results identify how dispersal, interaction strength, and landscape size jointly regulate biodiversity in competitive systems.

ecology↗

bioRxiv2025

Indirect effects cause decline in ecosystem service delivery: a case study in the Barents Sea

Ecosystem services are important for the well-being of human societies. At the same time, the ecosystems providing the services are under constant pressure from anthropogenic activities, causing loss of biodiversity. Since all species are connected to each other via interaction networks, the loss of one species can trigger additional, secondary extinctions. However, the consequences of these secondary extinctions for ecosystem services are not known. Here we address this gap by coupling threats to species and their interaction networks, and these networks to ecosystem service provisioning. We use a highly resolved food web dataset of the Barents Sea, and simulate secondary extinctions using Bayesian networks. We explore a range of assumptions on how the loss of service-providing species translates to the disintegration of the services they provide. We find that activation of threats cause secondary extinctions of service-providing as well as supporting species which negatively affect ecosystem services, and that the magnitude of these effects are highly dependent on the sensitivity of consumers to resource loss as well as service robustness. We also show that the indirect effects from species interactions causes substantial decreases in service provisioning. Understanding the linkages between ecological threats, species interactions in ecological networks and ecosystem service provisioning will be an important tool for guiding management strategies for effective ecosystem service management.

ecology↗

bioRxiv2025

Label invariance: a guiding principle for ecological models

Ecological models, though diverse in form, are strengthened when they obey guiding principles. We formalize and advocate for a foundational principle we call "label invariance", which says that a models dynamics must remain the same when identical individuals are arbitrarily grouped into distinct sub-populations. This principle is a necessary consequence of trait continuity--the observation that ecological interactions change continuously as organisms become more similar. Violation of label invariance often implies a hidden, intrinsic niche differentiation between species, which may obscure the mechanisms of biodiversity maintenance. We provide a general framework for constructing both deterministic and stochastic models that follow label invariance. We further demonstrate its utility as a complementary, non-statistical tool for empirical model selection. In sum, label invariance provides an important test for evaluating existing ecological models and a guide for developing new ones, promoting clarity in model assumptions from the outset.

ecology↗

bioRxiv2025

Destabilizing effects of eco-evolutionary feedback on community stability and the role of climate change

What underpins the stability of natural systems is a central topic in ecology for decades. Evidence from simple communities with few species shows that eco-evolutionary feedback has the potential to stabilize community dynamics. Here, we show that these findings may not hold in more complex natural systems with many species. We first simulated an eco-evolutionary model of producer-herbivores dynamics, and found destabilizing, rather than stabilizing effect of the eco-evolutionary feedback (i.e. an increasing Lyapunov exponent). We then analyzed 11 long term monitoring data sets of natural aquatic communities, containing the temporal dynamics of a key individual-level trait (body mass) and of population densities. This analysis matched the model results and further showed that warming tends to make eco-evolutionary feedback even more destabilizing. Our results indicate that eco-evolutionary feedback may play a role in destabilizing community dynamics and the climate may mediate the magnitude.

evolutionary biology↗

bioRxiv2024

Variation in precipitation drives differences in interactions and short-term transient instability between grassland functional groups: a stage-structured community approach

Climate change is expected to increase the frequency and severity of precipitation extremes, causing droughts and flooding. Consequently, grassland communities are forecasted to become increasingly unstable. To predict grassland responses, we need empirical information together with models that reliably extrapolate community dynamics from those observations. However, such prediction is challenging because community models typically simulate long-term (asymptotic) performance, and thus potentially neglect their short-term (transient) performance. Here, we use data from a precipitation experiment performed over eight years to model both short- and long-term responses of three functional groups - grasses, legumes, and non-leguminous forbs - to precipitation extremes. We use multi-functional-group Integral Projection Models and pseudospectral theory, to track grassland community dynamics. We show that the percentage-cover-stage-structure of functional groups shapes their transient instability, and that inter-functional-group interactions are competitive under increased precipitation but facilitative under decreased precipitation. IPMs and pseudospectra enable forecasting of how functional-group-stage-structure drives responses to climatic extremes.

ecology↗

bioRxiv2022

Evolutionary effects of individual variation and dimensionality of higher-order interactions on the robustness of species coexistence

Although the eco-evolutionary effects of individual variation for species coexistence are still widely debated, theoretical evidence appears to support a negative impact on coexistence. Mechanistic models of eco-evolutionary effects of individual variation focus largely on pairwise interactions, while the dynamics of communities where both pairwise and higher-order interactions (HOIs) are pervasive are not known. In addition, most studies have focused on effects of high dimensional HOIs on species coexistence when in reality such HOIs could be highly structured and low-dimensional, as species interactions could primarily be mediated through phenotypic traits. Here, combining quantitative genetics and Lotka-Volterra equations, we explored the eco-evolutionary effects of individual variation on the patterns of species coexistence in a competitive community dictated by pairwise interactions and HOIs. Specifically, we compare six different models in which HOIs were modelled to be trait-mediated (low-dimensional) or random (high-dimensional) and evaluated its impact on robustness of species coexistence in the presence of different levels of individual variation. Across the six different models, we found that individual variation did not promote species coexistence, irrespective of whether interactions were pairwise or were of higher-order. However, individual trait variation could stabilize communities to external perturbation more so when interactions were of higher order. When compared across models, species coexistence is promoted when HOIs strengthen pairwise intraspecific competition more so than interspecific competition, and when HOIs act in a hierarchical manner. Additionally, across the models, we found that species traits tend to cluster together when individual variation in the community was low. We argue that, while individual variation can influence community patterns in many different ways, they more often lead to fewer species coexisting together.

ecology↗

bioRxiv2020

The evolution of trait variance creates a tension between species diversity and functional diversity

It seems intuitive that species diversity promotes functional diversity. For example, more plant species imply more diverse leaf chemistry and thus more kinds of food for herbivores. Here we argue that the evolution of functional trait variance challenges this view. We show that trait-based eco-evolutionary processes force species to evolve narrower trait breadths in tightly packed communities, in their effort to avoid competition with neighboring species. This effect is so strong as to reduce overall trait space coverage, overhauling the expected positive relationship between species- and functional diversity. Empirical data from Galápagos land snail communities proved consistent with this claim. As a consequence, trait data from species-poor communities may misjudge functional diversity in species-rich ones, and vice versa.Competing Interest StatementThe authors have declared no competing interest.View Full Text

ecology↗

bioRxiv2020

The importance of species interactions in spatially explicit eco-evolutionary community dynamics under climate change

Eco-evolutionary dynamics are essential in shaping the biological response of communities to ongoing climate change. Here we develop a spatially explicit eco-evolutionary framework which integrates evolution, dispersal, and species interactions within and between trophic levels. This allows us to analyze how these processes interact to shape species- and community-level dynamics under climate change. Additionally, we incorporate the heretofore unexplored feature that species interactions themselves might change due to increasing temperatures and affect the impact of climate change on ecological communities. The new modeling framework captures previously reported ecological responses to climate change, and also reveals two new key results. First, interactions between trophic levels as well as temperature-dependent competition within a trophic level mitigate the negative impact of climate change on global biodiversity, emphasizing the importance of understanding biotic interactions in shaping climate change impact. Second, using a trait-based perspective, we found a strong negative relationship between the within-community variation in preferred temperatures and the capacity to respond to climate change. Communities resulting from different ecological interaction structures form distinct clusters along this relationship, but varying species abilities to disperse and adapt to new temperatures leave it unaffected.

ecology↗