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opencc-zeroMar 2024View details →

Fast-slow traits predict competition network structure and its response to resources and enemies

Plants interact in complex networks but how network structure depends on resources, natural enemies, and species resource-use strategy remains poorly understood. Here, we quantified competition networks among 18 plants varying in fast-slow strategy, by testing how increased nutrient availability and reduced foliar pathogens affected intra- and inter-specific interactions. Our results show that nitrogen and pathogens altered several aspects of network structure, often in unexpected ways due to fast and slow-growing species responding differently. Nitrogen addition increased competition asymmetry in slow-growing networks, as expected, but decreased it in fast-growing networks. Pathogen reduction made networks more even and less skewed because pathogens targeted weaker competitors. Surprisingly, pathogens and nitrogen dampened each other's effect. Our results show that plant growth strategy is key to understanding how competition responds to resources and enemies, a prediction from classic theories that has rarely been tested by linking functional traits to competition networks.

opencc-zeroJul 2021View details →

Molecular signatures of resource competition: Clonal interference favors ecological diversification and can lead to incipient speciation

Microbial ecosystems harbor an astonishing diversity that can persist for long times. To understand how such diversity is structured and maintained, ecological and evolutionary processes need to be integrated at similar timescales. Here, we study a model of resource competition that allows for evolution via de novo mutation, and focus on rapidly adapting asexual populations with large mutational inputs, as typical of many bacteria species. We characterize the adaptation and diversification of an initially maladapted population and show how the eco-evolutionary dynamics are shaped by the interaction between simultaneously emerging lineages – clonal interference. We find that in large populations, more intense clonal interference can foster diversification under sympatry, increasing the probability that phenotypically and genetically distinct clusters coexist. In smaller populations, the accumulation of deleterious and compensatory mutations can push further the diversification process and kick-start speciation. Our findings have implications beyond microbial populations, providing novel insights about the interplay between ecology and evolution in clonal populations.

FIG. 6 in Dietary behaviour and competition for vegetal resources in two Early Miocene pecoran ruminants from Central Spain

FIG. 6. — Histograms showing the percentage of high and low occlusal relief and of each type of cusp shape for the Spanish taxa with living species and with fossil populations of Andegameryx Ginsburg, 1971 and Procervulus Gaudry, 1877 from Europe. Dental mesowear data of living taxa taken from Fortelius & Solounias (2000). Data of German taxa and fossil Procervulus ginsburgi Azanza, 1993 taken from Kaiser & RÖssner (2007) and DeMiguel et al. (2008), respectively. Abbreviations: see Material and methods.

FIG. 5 in Dietary behaviour and competition for vegetal resources in two Early Miocene pecoran ruminants from Central Spain

FIG. 5. — Mesowear features of selected teeth of: A, B, AAGR; C, D, PAGR; E, F, PMOR; G, H, PAB1. Scale bar: 1 cm. Abbreviations: see Material and methods.

FIG. 1 in Dietary behaviour and competition for vegetal resources in two Early Miocene pecoran ruminants from Central Spain

FIG. 1. — Location of the studied localities in the Iberian Chain (Central Spain). Ágreda and Moratilla are placed in the Calatayud basin, and Alto de Ballester 1 in the Rubielos de Mora basin.

FIG. 3 in Dietary behaviour and competition for vegetal resources in two Early Miocene pecoran ruminants from Central Spain

FIG. 3. — Histogram showing the density of scratches and pits for the Spanish taxa with living species and with Procervulus from other Spanish localities. Dental microwear data of living taxa and Procervulus taken from Solounias et al. (2000) and DeMiguel (2008, 2010), respectively. Abbreviations: see Material and methods.

FIG. 2 in Dietary behaviour and competition for vegetal resources in two Early Miocene pecoran ruminants from Central Spain

FIG. 2. — ESEM photomicrographs of share facets of the population of: A, AAGR; B, PAGR; C, PMOR; D, PAB1. Scale bars: 100 μm. Abbreviations: see Material and methods.

opencc-zeroMay 2024View details →

Data from: Pollinator competition and the contingency of nectar depletion during an early spring resource pulse

Concerns about competition between pollinators are predicated on the assumption of floral resource limitation. Floral resource limitation, however, is a complex phenomenon involving the interplay of resource production by plants, resource demand by pollinators, and exogenous factors — like weather conditions — that constrain both plants and pollinators. In this study, we examine nectar limitation during the mass flowering of rosaceous fruit trees in early spring. Our study is set in the same region as a previous study that found extremely severe nectar limitation in summer grasslands. We use this seasonal contrast to evaluate two alternative hypotheses concerning the seasonal dynamics of floral resource limitation: either (H1) rates of resource production and consumption are matched through seasonal time to maintain a consistent degree of resource limitation or (H2) a mismatch of high floral resource production and low pollinator activity in early spring creates a period of relaxed resource limitation that intensifies later in the year. We found generally much lower depletion in our study compared to the near 100% depletion found in the summer study, but depletion rates varied markedly through diel time and across sampling days, with afternoon depletion rates sometimes exceeding 80%. In some cases, there were also pronounced differences in depletion rate across simultaneously sampled floral species, indicating different degrees of nectar exploitation. These findings generally support the seasonal mismatch hypothesis (H2) but underscore the complex contingency of nectar depletion. The challenge of future work is to discern how the fluctuation of resource limitation across diel, inter-diel, and seasonal time scales translates into population-level fitness outcomes for pollinators.

publicJul 2021View details →

Molecular signatures of resource competition: Clonal interference favors ecological diversification and can lead to incipient speciation

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publicMay 2024View details →

Data from: Pollinator competition and the contingency of nectar depletion during an early spring resource pulse

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publicMay 2025View details →

Data and code for: Moisture and competition constrain ephemeral resource quality for burying beetle reproduction

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publicMar 2024View details →

Fast-slow traits predict competition network structure and its response to resources and enemies

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opencc-zeroMay 2020View details →

Data from: Contrasting per-gram competitive and soil resource effects in grasses and woody plants

1. Plant species differ in their competitive effects by decreasing resource availability via uptake, but in some cases may increase resource availability via non-uptake pathways. Here we explore differences between grasses and woody plants in their competitive effects, and relate these to differences in resource effects. 2. We grew five species each of grasses and woody plants in monocultures for eight years. In the final two growing seasons, competitive effects were measured by growing transplants in all monocultures and in plots without neighbours. 3. Total competitive effects were significantly greater for woody plants than grasses. In contrast, the competitive effect per gram of grasses was about 17 times greater than that of woody plants. 4. For grasses, soil water and soil available N decreased significantly with increasing biomass. In contrast, for woody plants, soil water and soil available N increased significantly with increasing biomass. The results suggest that the intense per-gram competitive effects in grasses is related to the uptake of soil resources, and that the significantly lower per-gram competitive effects of woody plants may be related to their positive effects on soil resources. 5. Synthesis. The results link differences in competitive effects between grasses and woody plants to differences in the direction of their effects on soil resources. These differences may contribute to the entrainment of negative feedback in grasslands, excluding trees by means of strong competition, and the entrainment of positive feedback beneath woody plants establishing in grasslands, resulting in a state change from grassland to woody vegetation.

opencc-zeroJan 2020View details →

Competition for resources can promote the divergence of social learning phenotypes

Social learning occurs when animals acquire knowledge or skills by observing or interacting with others, and is the fundamental building block of culture. Within populations, some individuals use social learning more frequently than others, but why social learning phenotypes differ among individuals is poorly understood. We modelled the evolution of social learning frequency in a system where foragers compete for resources and there are many different foraging options to learn about. Social learning phenotypes diverged when some options offered much better rewards than others and expected rewards changed moderately quickly over time. When options offered similar rewards or when rewards changed slowly, a single social learning phenotype evolved. This held for fixed and simple conditional social learning rules. Sufficiently complex conditional social learning rules prevented the divergence of social learning phenotypes under all conditions. Our results explain how competition can promote the divergence of social learning phenotypes.

zenodo36/100

Resource competition predicts assembly of in vitro gut bacterial communities

Microbiota dynamics arise from a plethora of interspecies interactions, including resource competition, cross-feeding, and pH modulation. The individual contributions of these mechanisms are challenging to untangle, especially in natural or complex laboratory environments where the landscape of resource competition is unclear. Here, we developed a framework to estimate the extent of multi-species niche overlaps by combining metabolomics data of individual species, growth measurements in pairwise spent media, and mathematical models. When applied to an in vitro model system of human gut commensals in complex media, our framework revealed that a simple model of resource competition described most pairwise interactions. By grouping metabolomic features depleted by the same set of species, we constructed a coarse-grained consumer-resource model that predicted assembly compositions to reasonable accuracy. Moreover, deviations from model predictions enabled us to identify and incorporate into the model additional interactions, including pH-mediated effects and cross-feeding, which improved model performance. In sum, our work provides an experimental and theoretical framework to dissect microbial interactions in complex in vitro environments.

opencc-by-4.0Jan 2023View details →

opencc-zeroOct 2021View details →

Preferential allocation of benefits and resource competition among recipients allows coexistence of symbionts within hosts

Functionally variable symbionts commonly co-occur including within the roots of individual plants, in spite of arguments from simple models of the stability of mutualism that predict competitive exclusion among symbionts. We explore this paradox by evaluating the dynamics generated by symbiont competition for plant resources, and the plant's preferential allocation to the most beneficial symbiont, using a system of differential equations representing the densities of mutualistic and non-mutualistic symbionts and the level of preferentially allocated and non-preferentially allocated resources for which the symbionts compete. We find that host preferential allocation and costs of mutualism generate resource specialization that makes the coexistence of beneficial and non-beneficial symbionts possible. Furthermore, coexistence becomes likely due to negative physiological feedbacks in host preferential allocation. We find that biologically realistic models of plant physiology and symbiont competition predict that the coexistence of beneficial and non-beneficial symbionts should be common in root symbioses, and that the density and relative abundance of mutualists should increase in proportion to the needs of the host.

opencc-zeroApr 2022View details →

Collective foraging: Experimentally-increased competition decreases group performance exploiting a permanent resource

Foraging collectively offers advantages, such as access to social information on food locations, but it may also intensify competition for local resources. Social information may be most advantageous during ecologically challenging conditions, when food sources are scarce or unpredictable, which predicts more collective foraging during such conditions. Alternatively, higher within-group competition when resources are scarce might destabilize social groups and reduce collective foraging. To evaluate these effects, we experimentally decreased the number and predictability of food sources (feeders with ad libitum seeds) available to wild-caught common waxbills (Estrilda astrild) living in a large open-air mesocosm. Compared to control periods, in the treatment with few food sources competitive aggressiveness at feeders increased, the social network became more fragmented, with on average weaker associations between individuals, and foraging groups became smaller. Foraging groups also spent less time per visit to the feeding area, individuals spent less time at the feeders per group visit and had to make more visits to the feeding area per day, all of which indicate less efficient exploitation of the food sources. These effects were also observed when the number of feeders changed unpredictably across days. Even though the collective behaviour of waxbills appeared to exacerbate, rather than mitigate, the ecological challenges of reduced or unpredictable food sources, we suggest that, in nature, this increased aggressiveness and fragmentation of the social network may function adaptively as an early trigger to explore alternative foraging locations before local food sources are severely depleted.