Publications
The development of ecological systems along paths of least resistance
Jie Deng., Otto X. Cordero, Tadashi Fukami, Simon A. Levin, Robert M. Pringle, Ricard Solé, Serguei Saavedra. BioRxiv: 10.1101/2024.06.24.600194.
Short summary: Classic ecological theory holds that ecological systems develop following a sequenced orderly process that generally proceeds from fast-growing to slow-growing taxa and depends on life-history trade-offs. Here, we show that this developmental order camn be understood as the path with the least environmental resistance for survival of the component species and hence favored by probability alone.
Fundamental constraints to the logic of living systems
Ricard Solé, Christopher P. Kempes, Bernat Corominas-Murtra , Manlio De Domenico , Artemy Kolchinsky, Michael Lachmann, Eric Libby , Serguei Saavedra, Eric Smith, David Wolpert . Preprints 2024, 2024060891 (2024).
Short summary: It has been argued that the historical nature of evolution makes it a highly path-dependent process. At the same time, there is ample evidence that convergence and constraints strongly limit the domain of the potential design principles that evolution can achieve. Are these limitations relevant in shaping the fabric of the possible? Here, we argue that fundamental constraints are associated with the logic of living matter.
[pre-print] [journal]
Integrating metabolic scaling and coexistence theories
Serguei Saavedra. José Ignacio Arroyo, Jie Deng, Pablo A. Marquet, Christopher P. Kempes. BioRxiv: 10.1101/2023.02.28.530509 (2024).
Short summary: We provide a tractable and scalable framework to link metabolic scaling relationships at the population level and the persistence of ecological communities under environmental uncertainty. Specifically, this framework focuses on exploring the dependence of community feasibility on body size. This integration can open up new opportunities to increase our understanding of how metabolic scaling relationships at the population level have evolved to optimize process at the community level.
Structured community transitions explain the switching capacity of microbial systems
Chengyi Long, Jie Deng, Jen Nguyen, Yang-Yu Liu, Eric J. Alm, Ricard Solé, Serguei Saavedra. Proc. Natl. Acad. Sci. USA 121: e2312521121 (2024).
Short summary: Following a structuralist approach, we introduce a conceptual, mathematical, and practical framework to demonstrate that the relatively high switching capacity of microbial systems can be explained by structured community transitions that increase the dependency on the current community. We corroborate our theory using temporal data of human and ocean microbiota, opening the opportunity to enhance our understanding of a wide array of microbial systems.
[paper] [journal] [code] [commentary]
Protection from harvesting promotes energetically efficient structures in marine communities
Andrea Tabi, Luis J. Gilarranz, Spencer A. Wood, Jennifer A. Dunne, Serguei Saavedra. PLoS Computational Biology 19: e1011742 (2023).
Short summary: Combining scaling metabolic theory and a nonparametric causal inference analysis based on a global dataset of marine communities, we show that protection from harvesting leads fish communities towards top-heavy structures (larger fishes are more abundant compared to smaller fishes). We show theoretically that in top-heavy structures the efficiency of energy transfer across trophic levels is higher than in bottom-heavy structures.
On the limits to invasion prediction using coexistence outcomes
Jie Deng, Washington Taylor, Simon A. Levin, Serguei Saavedra. J. of Theoretical Biology 577: 111674 (2023)
Short summary: Coexistence outcomes have been widely used to predict invasion outcomes. Therefore, It is central to understand the limits to this predictability. We provide this translation under a geometric and probabilistic Lotka-Volterra framework. We show that while survival probability can be fairly closely translated into colonization probability, the translation is less precise between community persistence and community augmentation, and worse between exclusion probability and replacement probability.
Assembly archetypes in ecological communities
Hugo Flores-Arguedas, Omar Antolin-Camarena, Serguei Saavedra, Marco Tulio Angulo. J. of the Royal Society Interface 20: 20230349 (2023).
Short summary: We combine a novel mathematical formalism based on Category Theory with experimental data to show that similar "assembly archetypes" exist at the larger organization scale of ecological communities when assembling a species pool across diverse environmental contexts, particularly when species interactions are highly structured. We applied our formalism to clinical data discovering two assembly archetypes that differentiate between healthy and unhealthy human gut microbiota.
Feasibility in MacArthur's consumer-resource model
Andrea Aparicio, Tong Wang, Serguei Saavedra, Yang-Yu Liu. J. of Theoretical Ecology 16: 225-238 (2023).
Short summary: Theoretically, for mechanistic models such as MacArthur’s consumer-resource model, most of the efforts have concentrated on proving the stability of an equilibrium assuming that it is feasible, but overlooking the conditions that ensure its feasibility. Here we address this gap by finding the range of conditions that lead to a feasible equilibrium of MacArthur’s consumer-resource model and study how changes in the system’s structural and parametric properties affect those ranges.
Understanding the state-dependent impact of species correlated responses on community sensitivity to perturbations
Lucas P. Medeiros, Serguei Saavedra. Ecology 104: e4115 (2023).
Short summary: Understanding how communities respond to perturbations requires us to consider not only changes in the abundance of individual species, but also correlated changes that can emerge through interspecific effects. We demonstrate that species correlations change considerably across time and continuously alternate between reducing and having no impact on community sensitivity. Importantly, these alternating impacts depend on the abundance of particular species and can be detected even from noisy time series.
Rapid monitoring of ecological persistence
Chuliang Song, Benno I. Simmons, Marie-Josée Fortin, Andrew Gonzalez, Christopher N. Kaiser-Bunbury, Serguei Saavedra. Proc. Natl. Acad. Sci. USA 120: e2211288120 (2023).
Short summary: We show that the persistence of small subnetworks in isolation — that is, their persistence when considered separately from the larger network of which they are a part — is a reliable probabilistic indicator of the persistence of the network as a whole. Empirically, we show that our theoretical predictions are supported by data on invaded networks in restored and unrestored areas, even in the presence of environmental variability.
Plant-insect chemical communication in ecological communities: an information-theory perspective
Pengjuan Zu, Reinaldo García-García, Meredith Schuman, Serguei Saavedra, Carlos Melián. J. of Systematics and Evolution 63: 445-453 (2023)
Short summary: We propose an interdisciplinary framework based on information theory to investigate mechanisms shaping cross-species communication at the community level. We use plants and insects, the cornerstones of most ecosystems, as a showcase; and focus on chemical communication as the key communication channel.
Ranking species based on sensitivity to perturbations under non-equilibrium community dynamics
Lucas P. Medeiros, Stefano Allesina, Vasilis Dakos, George Sugihara, Serguei Saavedra. Ecology Letters 26: 170-183 (2022)
Short summary: We introduce two data-driven approaches (expected sensitivity and eigenvector rankings) based on the time-varying Jacobian matrix to rank species over time according to their sensitivity to perturbations on abundances. We find that the most sensitive species are not always the ones with the most rapidly changing or lowest abundance, which are typical criteria used to monitor populations.
Understanding the impact of third-party species on pairwise coexistence
Jie Deng, Washington Taylor, Serguei Saavedra. PLoS Computuational Biology 18: e1010630 (2022)
Short summary: The focus has been on the persistence probability of an entire multispecies community (formed of either two or more species). However, the methodological and philosophical question has always been whether we can observe the entire community and, if not, what the conditions are under which an observed subset of the community can persist as part of a larger multispecies system. Here, we derive long-term (using analytical calculations) and short-term (using simulations and experimental data) system-level indicators of the effect of third-party species on the coexistence probability of a pair (or subset) of species under unknown environmental conditions.
Multispecies coexistence in fragmented landscapes
Mingyu Luo, Shaopeng Wang, Serguei Saavedra, Dieter Ebert, Florian Altermatt. Proc. Natl. Acad. Sci. USA 119: e2201503119 (2022)
Short summary: We develop a spatially explicit metacommunity model of multiple competing species and derive analytical criteria for their coexistence in fragmented heterogeneous landscapes. Specifically, we propose measures of niche and fitness differences for metacommunities, which clarify how spatial dynamics and habitat configuration interact with local competition to determine coexistence of species.
Towards a system-level causative knowledge of pollinator communities
Serguei Saavedra, Ignasi Bartomeus, Oscar Godoy, Rudolf P. Rohr, Pengjuan Zu. Phil. Transactions Royal Society B: 377: 20210159 (2022)
Short summary: How to make interventions successful at the system level remains extremely challenging due to the complex nature of species interactions and the various unknown or unmeasured confounding ecological factors. We propose that this knowledge can be derived by following a probabilistic systems analysis using nonparametric causal inference. We provide an illustration with pollinator communities to show how to extract system-level causal knowledge from observational data.
Feasibility conditions of ecological models: unfolding links between model parameters
Mohammad AlAdwani, Serguei Saavedra. Ecological Modelling 466: 109900 (2022)
Short summary: It has been impossible to derive analytic expressions of the behavior of a system if the isocline equations have five or more roots, which can be easily reached even in 2-species models. We propose a general formalism to obtain the set of analytical conditions of feasibility for any polynomial population dynamics model of any dimension without the need to solve for the equilibrium locations.
Synthesizing the effects of individual-level variation on coexistence
Simon M. Stump, Chuliang Song, Serguei Saavedra Jonathan M. Levine, David A. Vasseur. Ecological Monographs 92: e01493 (2022)
Short summary: We review recent work and propose a new conceptual framework to explain how ITV affects coexistence between two species. We re-examine 10 studies on ITV and coexistence, along with four novel models, and show that our framework can explain why ITV promotes coexistence in some models and undermines coexistence in others. Bottom line, separate intrinsic growth rates from interspecific effects.
Untangling the complexity of priority effects in multispecies communities
Chuliang Song, Tadashi Fukami, Serguei Saavedra. Ecology Letters 24: 2301-2313 (2021).
Short summary: Here, we provide a graph-based, non-parametric, theoretical framework for understanding the predictability of community assembly as affected by priority effects. We discuss how this theoretical framework can guide new experimental studies.
Generalizing game-changing species across microbial communities
Jie Deng, Marco Tulio Angulo, Serguei Saavedra. ISME Communications 1: 22 (2021)
Short summary: We integrate tractable theoretical systems with tractable experimental systems to find general conditions under which non-resident species can change the collection of resident communities---game-changing species. Despite the strong context-dependency of microbial communities, we show that under an appropriate integration, it is possible to unveil regularities that can then be potentially extended to understand the changing behavior of complex natural communities.
Merging dynamical and structural indicators to measure resilience in multispecies systems
Lucas P. Medeiros, Chuliang Song, Serguei Saavedra. J. of Animal Ecology 90: 2027-2040 (2021).
Short summary: We provide a framework grounded on dynamical and structural stability to link recovery from small perturbations on species abundances (i.e., dynamical indicators) with resistance to parameter perturbations of any magnitude (i.e., structural indicators). We use theoretical and experimental multispecies systems to show that the faster the recovery from abundance perturbations, the higher the resistance to parameter perturbations.
Coexistence holes characterize the assembly and disassembly of multispecies systems
Marco Tulio Angulo, Aaron Kelley, Luis Montejano, Chuliang Song, Serguei Saavedra. Nature Ecology & Evolution 5: 1091-1101 (2021).
Short summary: Here we introduce a novel hypergraph-based formalism that fully captures the structure of coexistence in multispecies systems. Our formalism uncovers that, below its limits, coexistence in ecological systems has ubiquitous discontinuities that we call “coexistence holes." By highlighting discontinuities in the form of coexistence holes, our work provides a new platform to uncover the order and structure of the assembly and disassembly of ecological systems.
Understanding the emergence of contingent and deterministic exclusion in multispecies communities
Chuliang Song, Lawrence Uricchio, Erin A. Mordecai, Serguei Saavedra. Ecology Letters 24: 2155-2168 (2021).
Short summary: We provide a general theoretical approach to explain both the emergence and sources of competitive exclusion in multispecies communities. We find a shift from contingent exclusion to dominance with increasing numbers of competing species.
The impact of colonization history on the composition of ecological systems
Nannan Zhao, Serguei Saavedra, Yang-Yu Liu Physical Review E 108: 052403 (2021)
Short summary: We show that the probability that community composition is dominated by colonization history is modulated by community size, species connectivity, and the variation of intrinsic growth rates across species.
Bridging parametric and nonparametric measures of species interactions unveils new insights of non-equilibrium dynamics
Chuliang Song, Serguei Saavedra. Oikos 130: 1027-1034 (2021)
Short summary: We revisit species interactions measured as constant direct effects (typically used in parametric approaches) and local aggregated effects (typically used in nonparametric approaches). We show when these measures can be linked, demonstrate fundamental differences between them, and illustrate how they can be combined to gain further insights about non-equilibrium ecological dynamics and higher-order interactions
Experimental evidence of the importance of multi-trophic structure for species persistence
Ignasi Bartomeus, Serguei Saavedra, Rudolf P. Rohr, Oscar Godoy. Proc. Natl. Acad. Sci. USA 118: e2023872118 (2021).
Short summary: We integrate a mathematical approach and detailed experiments in plant-pollinator communities to demonstrate the need to jointly account for species interactions within and across trophic levels when estimating the ability of species to persist. We show that experimentally preventing some species to interact can modify the rest of the interactions and affect idiosyncratically the probability of species persistence.
Observed ecological communities are formed by species combinations that are among the most likely to persist under changing environments
Lucas P. Medeiros, Karina Boege, Ek del-Val, Alejandro Zaldivar-Riverón, Serguei Saavedra. The American Naturalist 197: E17-E29 (2021).
Short summary: Despite the rich biodiversity found in nature, it is unclear the extent to which some combinations of interacting species while conceivable in a given place and time may never be realized. Here, we show that the specific combinations of interacting species that emerge from the ecological dynamics within regional species pools are not all equally likely to be seen, rather they are among the most likely to persist under changing environments.
Ecological models: higher complexity in, higher feasibility out
Mohammad AlAdwani, Serguei Saavedra. J. of the Royal Sociey Interface 17: 20200607 (2020).
Short summary: Does the explanatory power of a model come from the general form of its polynomial or from a more realistic description of multispecies systems? We show that the probability of generating a feasible system in a model is an increasing function of its complexity, regardless of the specific mechanism invoked. Our results reveal that conclusions regarding the relevance of mechanisms embedded in complex models must be evaluated in relation to the expected explanatory power of their polynomial forms.
Structural forecasting of species persistence under changing environments
Serguei Saavedra, Lucas P. Medeiros, Mohammad AlAdwani. Ecology Letters 23: 1511-1521 (2020).
Short summary: We propose a probabilistic approach rooted on the statistical concepts of ensemble theory applied to statistical mechanics and on the mathematical concepts of structural stability applied to population dynamics models---what we call structural forecasting. We use this new approach to estimate a probability of persistence for single species, to understand and interpret this probability conditional on the information we have concerning a system, and to provide accurate out-of-sample predictions of species persistence without the need of extensive amounts of data.
Species multidimensional effects explain idiosyncratic responses of communities to environmental change
Andrea Tabi, Frank Pennekamp, Florian Altermatt, Roman Alther, Emanuel Fronhofer, Katherine Horgan, Elvira Machler, Mikael Pontarp , Owen Petchey, Serguei Saavedra. Nature Ecology & Evolution 4: 1036-1043 (2020).
Short summary: We show that, as the asymmetry of the feasibility domain increases, the relationship between species abundance when grown together and when grown in isolation weakens. We then show that microbial communities experiencing different temperature environments exhibit patterns consistent with this theory.
Information arms race explains plant-herbivore chemical communication in ecological communities
Pengjuan Zu, Karina Boege, Ek del-Val, Meredith Schuman, Philip Stevenson, Alejandro Zaldivar-Riverón, Serguei Saavedra. Science 368: 1377-1381 (2020).
Short summary: By integrating information theory with chemical ecology and community ecology, we show that a stable information structure of plant volatile organic compounds (VOCs) can emerge from a conflicting information process between plants and herbivores. We corroborate this information arms-race theory with field data recording plant-VOC associations and herbivore-plant interactions in a tropical dry forest.
[paper] [code] [journal] [perspective]
Telling ecological networks apart by their structure: an environment-dependent approach
Chuliang Song, Serguei Saavedra. PLoS Computational Biology 16: e1007787 (2020).
Short summary: We show that the association between ecological interactions and network architectures exists, but cannot be fully understood without attention to the environmental conditions acting upon them.
Disentangling the effects of external perturbations on coexistence and priority effects
Chuliang Song, Rudolf P. Rohr, David Vasseur, Serguei Saavedra. J. of Ecology 108: 1677-1689 (2020).
Short summary: We combine Modern Coexistence Theory and the Structural Approach to disentangle the tolerance in coexistence and priority effects of a pair of competing species when subject to perturbations in intrinsic growth rates and competition strengths. We reveal the emergence of a key trade-off: increasing the tolerance to perturbations in intrinsic growth rates typically decreases the tolerance in competition strengths, and vice versa.
Towards a probabilistic understanding about the context-dependency of species interactions
Chuliang Song, Sarah Von Ahn, Rudolf P. Rohr, Serguei Saavedra. Trends in Ecology & Evolution 35: 384-396 (2020).
Short summary: We propose an overarching theoretical framework, by integrating probabilistic and structural approaches, to establish null expectations about switches of interaction classes across environmental contexts. As a proof of concept, we show how this integration reconciles the observations that mutualisms have tended to persist in nature despite being the most likely to switch in experiments.
Assessing the predictability of nonlinear dynamics under smooth parameter changes
Simone Cenci, Lucas P. Medeiros, George Sugihara, Serguei Saavedra. J. of the Royal Society Interface 17: 20190627 (2020).
Short summary: We show that the predictability of nonlinear dynamics is associated with the local structural stability--a better predictor than the largest Lyapunov exponent. Moreover, we demonstrate that forecasts from locally structurally unstable states can produce significantly large prediction errors.
On the consequences of the interdependence of stabilizing and equalizing mechanisms
Chuliang Song, György Barabás, Serguei Saavedra. The American Naturalist 194: 627-639 (2019).
Short summary: We show that the stabilizing and equalizing mechanisms exhibit a complex interdependence, which can change the direction of their effect on coexistence. However, by seeing them as aggregated effects (rather than underlying causes) of coexistence, we may increase our understanding of ecological dynamics.
Is the addition of higher-order interactions in ecological models increasing our understanding of ecological dynamics?
Mohammad AlAdwani, Serguei Saavedra. Mathematical Biosciences 315: 108222 (2019).
Short summary: Our results show that while adding higher-order interactions in ecological models may be good for prediction purposes, they cannot provide additional explanatory power of ecological dynamics if model parameters are not ecologically restricted.
Nonparametric estimation of the structural stability of non-equilibrium community dynamics
Simone Cenci, Serguei Saavedra. Nature Ecology & Evolution 3: 912-918 (2019).
Short summary: We develop a data-driven nonparametric framework to estimate the time-varying tolerance of non-equilibrium community dynamics to environmental perturbations, i.e., their local structural stability.
Beware z-scores
Chuliang Song, Rudolf P. Rohr, Serguei Saavedra. J. of Animal Ecology 88: 808-809 (2019).
Short summary: This paper helps as a reminder about not using z-scores (related to p-values in statistics) to compare ecological networks when having different sizes and different constraints, such as a maximum value of nestedness.
Regularized S-map for inference and forecasting with noisy ecological time series
Simone Cenci, George Sugihara, Serguei Saavedra. Methods in Ecology & Evolution 10: 650-660 (2019).
Short summary: We show that an appropriate choice of a regularization scheme for the S-map, alongside an accurate choice of the kernel functions, can significantly improve the in-sample inference of Jacobian coefficients and the out-of-sample forecast of species abundances in the presence of process noise.
Uncertainty quantification of the effects of biotic interactions on community dynamics from nonlinear time series
Simone Cenci, Serguei Saavedra. J. of the Royal Society Interface 15: 20180695 (2018).
Short summary: We develop an novel method to quantify the expected effect and the uncertainty associated with the effect of biotic interactions on community dynamics from non-equilibrium ecological time-series data. Our method is able to detect the most informative time intervals for each biotic interaction within a multivariate time series.
Structural stability as a consistent predictor of phenological events
Chuliang Song, Serguei Saavedra. Proc. Royal Society B 285: 20180767 (2018).
Short summary: We show that measures based on the notion of structural stability can synthesize the expected variation of environmental conditions tolerated by a community, and explain more consistently the phenological changes observed in ecological communities.
Structural changes within trophic levels are constrained by within-family assembly rules at lower trophic levels
Chuliang Song, Florian Altermatt, Ian Pearse, Serguei Saavedra. Ecology Letters 21: 1221-1228 (2018).
Short summary: Using the registry of the last 2000 years of plant introductions and their novel herbivores encountered in Central Europe, we find that the order of arrival of closely-related (but not of distantly-related) plant species constrained the structural changes within the trophic level formed by herbivore species across the observation period.
A guideline to study the feasibility domain of multi-trophic and changing ecological communities
Chuliang Song, Rudolf P. Rohr, Serguei Saavedra. J. of Theoretical Biology 45: 30-36 (2018).
Short summary: Here, we present a step-by-step quantitative guideline providing illustrative examples, computational code, and mathematical proofs to study systematically the feasibility domain of communities under changes of interactions and subject to different constraints on the trophic energy flows.
Rethinking the importance of the structure of ecological networks under an environment-dependent framework
Simone Cenci, Chuliang Song, Serguei Saavedra. Ecology & Evolution 8: 6852-6859 (2018).
Short summary: We show that the importance of a network structure depends on the environmental conditions faced by a community at any given point in time. We discuss a research agenda to systematically investigate the importance of ecological networks under an environment-dependent framework
Towards the integration of niche and network theories
Oscar Godoy, Ignasi Bartomeus, Rudolf P. Rohr, Serguei Saavedra. Trends in Ecology & Evolution 33: 287-300 (2018)
Short summary: Here we call for the integration of niche and network theories to reach new frontiers of knowledge exploring how interactions within and across trophic levels promote species coexistence.
Structural stability of nonlinear population dynamics
Simone Cenci, Serguei Saavedra. Physical Review E 97: 012401 (2018)
Short summary: We show that the approach used to investigate the structural stability of the classic Lotka-Volterra dynamics can be applied to a much larger class of nonlinear models. We also show how the structural approach can be applied to stochastic dynamical systems.
Will a small randomly-assembled community be feasible and stable?
Chuliang Song, Serguei Saavedra. Ecology 99: 743-751 (2018)
Short summary: We show that the current contrasting answers to this relatively simple question are due to the underestimation of the association of the parameter space of intrinsic growth rates with the feasibility and stability properties of small randomly-assembled communities.
Estimating the effect of the reorganization of interactions on the adaptability of species to changing environments
Simone Cenci, Ana Montero-Castaño, Serguei Saavedra. J. of Theoretical Biology 437: 115-125 (2018).
Short summary: We introduce the concept of the adaptation space of a group of species based on a feasibility analysis of a population dynamics model. We define the adaptation space of a group as the set of environmental conditions that can be made compatible with its persistence thorough the reorganization of interactions among species within the group. We validate this new concept on empirical data.
[paper] [code + data] [journal]
Comparing species interaction networks along environmental gradients
Loïc Pelliser, Camille Albouy, Jordi Bascompte, Nina Farwig, Catherine Graham, Michel Loreau, Maria Maglianesi, Carlos Melián, Camille Pitteloud, Tomas Roslin, Rudolf P. Rohr, Serguei Saavedra, Wilfred Thuiller, Guy Woodward, Niklaus Zimmermann, Dominique Gravel. Biological Reviews 93: 785-800 (2018).
Short summary: we review studies investigating variation in network structures along environmental gradients, highlighting how methodological decisions about standardization can influence their conclusions.
Why are some plant-pollinator networks more nested than others?
Chuliang Song, Rudolf P. Rohr, Serguei Saavedra. J. of Animal Ecology 86: 1417-1424 (2017).
Short summary: In line with theory on structural stability of species coexistence in mutualistic systems, we show that higher levels of nestedness are associated with highly changing or seasonal environments. We show that the previous lack of agreement on this relationship came from an extended practice of using standardize measures of nestedness (z-scores) that cannot be compared across different networks.
[paper] [code + data] [journal]
Reorganization of interaction networks modulates the persistence of species in late successional stages
Serguei Saavedra, Simone Cenci, Ek del-Val, Karina Boege, Rudolf P. Rohr. J. of Animal Ecology 86: 1136-1146 (2017)
Short summary: We introduce novel quantitative tools based on feasibility analysis to reveal how changes of species interactions among resident species inhibit the likelihood of persistence of colonizing species in late successional stages (despite the invariability of global network properties).
[paper] [code + data] [journal]
A structural approach for understanding multispecies coexistence
Serguei Saavedra, Rudolf P. Rohr, Jordi Bascompte, Oscar Godoy, Nathan J. B. Kraft, Jonathan M. Levine Ecological Monographs 87: 470-486 (2017)
Short summary: We derive novel feasibility metrics analogous to stabilizing niche differences and fitness differences that measure the range of conditions compatible with multispecies coexistence, incorporating the effects of indirect interactions emerging in diverse systems.
Fungal-host diversity among mycoheterotrophic plants increases proportionally to their fungal-host overlap
Sofia I. F. Gomes, Vincent S. F. T. Merckx, Serguei Saavedra. Ecology & Evolution 7: 3623-3630 (2017)
Short summary: This paper illustrates how species coexistence in consumer-resource communities can be better understood by looking at the two sides of the ecological interactions.
Persist or produce: a community trade-off tuned by species evenness
Rudolf P. Rohr*, Serguei Saavedra*, Guadalupe Peralta, Carol M. Frost, Louis-Félix Bersier, Jordi Bascompte, Jason M. Tylianakis. The American Naturalist 188:411-422 (2016)
Short summary: Using feasibility analysis in a competition system, we confirm that species evenness can be used as a general indicator of the risk of future extinctions in a community, however, evenness cannot be used as an indicator of the level of biomass production.
[paper] [code + data] [journal]
Nested species interactions promote feasibility over stability during the assembly of a pollinator community
Serguei Saavedra, Rudolf P. Rohr, Jens M. Olesen, Jordi Bascompte. Ecology & Evolution 6:997-1007 (2016)
Short summary: To what extent the persistence of ecological networks depend on their stability? This study demonstrates that mutualistic communities favor feasibility over stability through the nested architecture of species interactions.
[paper] [code + data] [journal]
Seasonal species interactions minimize the impact of species turnover on the likelihood of community persistence
Serguei Saavedra, Rudolf P. Rohr, Miguel A. Fortuna, Nuria Selva, Jordi Bascompte. Ecology 97: 865-873 (2016)
Short summary: How do species cope with strong periodic environmental variations? This study shows that seasonal changes of species interactions can act as a mechanism to maintain similar feasibility properties across time (homeostasis) despite disturbances. [Cover of April's Issue]
[paper] [code + data] [journal]
How structurally stable are global socioeconomic systems?
Serguei Saavedra, Rudolf P. Rohr, Luis J. Gilarranz, Jordi Bascompte. J. Royal Society Interface 11: 20140693 (2014).
Short summary: This study provides a feasibility guideline to calculate the tolerance to demographic perturbations in competition (resource-utilization) systems.
On the structural stability of mutualistic systems
Rudolf P. Rohr*, Serguei Saavedra*, Jordi Bascompte. Science 345: 1253497 (2014).
Short summary: This study provides a feasibility methodology to calculate the tolerance to environmental perturbations in mutualistic systems. Our findings suggest that the nested architecture of mutualistic interaction networks (the one observed in nature) provides the largest tolerance to perturbations. (*co-first authors)
Stock fluctuations are correlated and amplified across networks of interlocking directorates
Serguei Saavedra, Luis J. Gilarranz, Rudolf P. Rohr, Michael Schnabel, Brian Uzzi, Jordi Bascompte. EPJ Data Science 3: 30 (2014).
Short summary: This study shows that the fewer degrees of separation between two corporations in the interlocking network, the stronger the temporal correlation between their stock price returns. We show how this has important implications during financial crashes.
Estimating the tolerance of species to the effects of global environmental change
Serguei Saavedra, Rudolf P. Rohr, Vasilis Dakos, Jordi Bascompte. Nature Communications 4: 2350 (2013).
Short summary: The ranking of species in terms of their survival probability depends on both the type of perturbations experienced by the community and the parameters defining the strength and architecture of interspecific interactions.
"Disentangling nestedness" disentangled
Serguei Saavedra, Daniel B. Stouffer. Nature 500: E1-E2 (2013).
Short summary: All else being equal, our results here illustrate that, the greater the nestedness of a community, the greater is that community’s persistence.
Foraging under conditions of short-term exploitative competition: The case of stock traders
Serguei Saavedra, R. Dean Malmgren, Nicholas Switanek, Brian Uzzi. Proc. Royal Society B 280: 20122901 (2013).
Short summary: Financial traders tend to maximize gains under short-term intervals but miss long-term opportunities.
Is coaching experience associated with effective use of timeouts in basketball?
Serguei Saavedra, Satyam Mukherjee, James P. Bagrow. Scientific Reports 2: 676 (2012).
Short summary: While we find that timeouts play a small role in the scoring dynamics, coaches early in their careers benefit more from timeouts than later in their careers.
Strong contributors to network persistence are the most vulnerable to extinction
Serguei Saavedra, Daniel B. Stouffer, Brian Uzzi , Jordi Bascompte. Nature 478: 233-235 (2011).
Short summary: Under a lack of environmental variation, species do not contribute equally to the network architecture nor to the persistence of the community.
Synchronicity, instant messaging and performance among financial traders
Serguei Saavedra, Kathleen Hagerty, Brian Uzzi. Proc. Natl. Acad. Sci. USA 108: 5296-5301 (2011).
Short summary: A higher than expected synchronous trading activity signals a window of opportunity in the financial market.
Tracking traders' understanding of the market using e-communication data
Serguei Saavedra, Jordi Duch, Brian Uzzi. PLoS ONE 6: e26705 (2011).
Short summary: Changes in traders' words used in online communication can be used as early-warning signals of strong market fluctuations.
Common Organizing Mechanisms in Ecological and Socio-economic Networks
Serguei Saavedra, Brian Uzzi, Felix Reed-Tsochas. arXiv: 1110.0376 (2011)
Short summary: We show that ecological networks can be carefully used to increase our understanding of socioeconomic networks and vice versa.
Cooperation under indirect reciprocity and imitative trust
Serguei Saavedra, David Smith and Felix Reed-Tsochas. PLoS ONE 5: e13475 (2010).
Short summary: We find that when information about someone's reputation is limited, trusting the action of third parties towards that individual favors collective cooperation.
Mutually-antagonistic interactions in baseball networks
Serguei Saavedra, Scott Powers, Trent McCotter, Mason A. Porter, Peter J. Mucha. Physica A 389: 1131-1141 (2010).
Short summary: We provide a transparent algorithm to rank the performance of baseball players across time based on pitcher-batter match-ups.
A simple model of bipartite cooperation for ecological and organizational networks
Serguei Saavedra, Felix Reed-Tsochas, Brian Uzzi. Nature 457: 463-466 (2008).
Short summary: We show that both ecological and socioeconomic networks are heavily characterized by hierarchical and complementary processes.
Asymmetric disassembly and robustness in declining networks
Serguei Saavedra, Felix Reed-Tsochas, Brian Uzzi. Proc. Natl. Acad. Sci. USA 105: 16466-16471 (2008).
Short summary: During community decline, interactions between generalist and specialist are favored avoiding a total and early collapse of the community.
Identifying the underlying structure and dynamic interactions in a voting network
Serguei Saavedra, Janet Efstathiou, Felix Reed-Tsochas. Physica A 377: 672-678 (2007).
Short summary: We propose a network approach to measure the unbiased performance of songs.
*Copyright Notice* This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author’s copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder.