About

We are a team of quantitative ecologists at the Department of Ecology and Evolutionary Biology, UCLA. We develop rigorous theory through interdisciplinary tools, devise monitoring-applicable metrics, and validate these approaches with empirical data from a broad range of ecosystems.

Research topics

• Computer Science
• Ecology
• Artificial Intelligence
• Biology
• Sociology
• Data science
• Epistemology
• Mathematics
• Environmental science
• Environmental resource management

Selected publications

• What have we learned from empirical applications of modern coexistence theory?

  DRYAD · 2026-04-21

  datasetOpen access

  We reviewed empirical applications of modern coexistence theory in ecology. The files and code in this repository show the 84 studies that met our criteria for inclusion along with the data we collected about each study, such as study setting, methodology, and the coexistence metrics quantified. The R code allows users to reproduce the simple analyses we conducted using these data.

  PublisherDOI

• Author response for "The Equilibrium Conundrum"

  2025-09-15

  peer-review
  PublisherDOI

• Label invariance: a guiding principle for ecological models

  bioRxiv (Cold Spring Harbor Laboratory) · 2025-07-19 · 1 citations

  preprintOpen accessSenior authorCorresponding

  Abstract 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 model’s 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.

  PublisherOA PDFDOI

• Author response for "The Equilibrium Conundrum"

  2025-07-09

  peer-review
  PublisherDOI

• Species interactions are internally constrained despite large climatic variability

  bioRxiv (Cold Spring Harbor Laboratory) · 2025-10-28

  preprintOpen access

  Abstract Understanding how vital rates and species interactions vary over time is crucial for predicting community responses to environmental change. Considerable progress has been made in understanding the drivers of variation in vital rates. However, the question of whether interactions are highly plastic and context-dependent, or strongly constrained by internal (e.g., species traits and composition) and/or external factors (e.g., environmental conditions) remains unclear. We applied a theoretical approach based on the feasibility domain —the range of conditions allowing coexistence— to a nine-year dataset of time-changing interactions between annual plants under large variability in annual precipitation. Using subcommunities of three species, we found that species interactions are strongly constrained, forming a “core-periphery” structure of consistently feasible combinations across years. This main finding means that species sample repeatedly a restricted range of opportunities for coexistence. Similar findings were obtained for subcommunities of four species. Crucially, the constraints to variation in biotic interactions are determined by species identity (internal constraints) rather than precipitation or temporal autocorrelation (external environmental factors). Furthermore, we found a contrasting effect of precipitation on the feasibility of subcommunities. While wetter years increase similarity between subcommunities and reduce the overall feasible range, drier years increase dissimilarity between subcommunities and increase the probability of coexistence when the conditions seem harsher. These findings suggest that constraints to biotic interactions tend to be alike across species in wetter years, but more context dependency occurs across species in drier years. Our findings challenge the assumption of highly plastic species interactions even in a highly dynamic system of annual plants. Our results also highlight the critical importance of internal constraints generated by species identity in mediating community persistence and predicting community responses to environmental change.

  PublisherOA PDFDOI

• A geometric approach to beta diversity

  Ecological Monographs · 2025-02-01 · 1 citations

  article1st authorCorresponding

  Abstract Beta diversity—the variation among community compositions in a region—is a fundamental measure of biodiversity. Most classic measures have posited that beta diversity is maximized when each community has a distinct, nonoverlapping set of species. However, this assumption overlooks the ecological significance of species interactions and non‐additivity in ecological systems, where the function and behavior of species depend on other species in a community. Here, we introduce a geometric approach to measure beta diversity as the hypervolume of the geometric embedding of a metacommunity. Besides considering compositional distinctiveness as in classic metrics, this geometric measure explicitly incorporates species associations and captures the idea that adding a unique, species‐rich community to a metacommunity increases beta diversity. We show that our geometric measure is closely linked to and naturally extends previous information‐ and variation‐based measures. Additionally, we provide a unifying geometric framework for widely adopted extensions of beta diversity. Applying our geometric measures to empirical data, we address two long‐standing questions in beta diversity research—the latitudinal pattern of beta diversity and the effect of sampling effort—and present novel ecological insights that were previously obscured by the limitations of classic approaches. In sum, our geometric approach offers a new and complementary perspective on beta diversity, is immediately applicable to existing data, and holds promise for advancing our understanding of the complex relationships between species composition, ecosystem functioning, and stability.

  PublisherDOI

• Rigorous validation of ecological models against empirical time series

  Nature Ecology & Evolution · 2025-10-27 · 3 citations

  article1st authorCorresponding
  PublisherDOI

• Assembly Graph as the Rosetta Stone of Ecological Assembly

  Environmental Microbiology · 2025-01-01 · 10 citations

  reviewOpen access1st authorCorresponding

  Ecological assembly-the process of ecological community formation through species introductions-has recently seen exciting theoretical advancements across dynamical, informational, and probabilistic approaches. However, these theories often remain inaccessible to non-theoreticians, and they lack a unifying lens. Here, I introduce the assembly graph as an integrative tool to connect these emerging theories. The assembly graph visually represents assembly dynamics, where nodes symbolise species combinations and edges represent transitions driven by species introductions. Through the lens of assembly graphs, I review how ecological processes reduce uncertainty in random species arrivals (informational approach), identify graphical properties that guarantee species coexistence and examine how the class of dynamical models constrain the topology of assembly graphs (dynamical approach), and quantify transition probabilities with incomplete information (probabilistic approach). To facilitate empirical testing, I also review methods to decompose complex assembly graphs into smaller, measurable components, as well as computational tools for deriving empirical assembly graphs. In sum, this math-light review of theoretical progress aims to catalyse empirical research towards a predictive understanding of ecological assembly.

  PublisherOA PDFDOI

• The Equilibrium Conundrum

  Ecology Letters · 2025-11-01 · 3 citations

  articleOpen access

  The idea that natural systems tend to be at equilibrium dates back to the origin of the field of ecology and continues to underlie most ecological theory. However, empirical evidence for equilibrium dynamics in nature and in experiments is surprisingly elusive. Here, we address this conundrum by first exploring the history of equilibrium in ecological theory and the evidence for equilibrium dynamics in natural systems. We then search the literature to quantify how empiricists deal with equilibrium in their research and address barriers to integrating the concept of equilibrium into empirical work by providing step-by-step instructions for determining whether a population is at equilibrium. Next, we lay out three ways that equilibrium is embedded in theory, and for each, outline when meeting the equilibrium assumption in empirical tests is critical for scientific inference, and when it may be possible to relax this assumption. And finally, we present concrete steps that empiricists and theoreticians can each take in order to meet in the middle when it comes to equilibrium. We hope that this paper will stimulate new discussions from researchers from across the theory-empirical divide about this longstanding issue.

  PublisherOA PDFDOI

• Author response for "Trophic tug-of-war: Coexistence mechanisms within and across trophic levels"

  2024-02-26

  peer-review1st authorCorresponding
  PublisherDOI

Frequent coauthors

• Serguei Saavedra

  41 shared

• Marie‐Josée Fortin

  11 shared

• Andrew Gonzalez

  McGill University

  11 shared

• György Barabás

  Linköping University

  9 shared

• Marco Tulio Angulo

  Universidad Nacional Autónoma de México

  9 shared

• Luis Montejano

  Universidad Rovira i Virgili

  9 shared

• A. Kelley

  Universidad Nacional Autónoma de México

  9 shared

• Benno I. Simmons

  University of Exeter

  7 shared