The Macroevolution Unit studies how biological diversity is structured through deep time by integrating fossils, biomechanics, phylogenetics, population genomics, community ecology, and theory. Our goal is to understand why similar ecological and evolutionary patterns emerge repeatedly across lineages, habitats, and geological eras, and to identify the processes that govern diversification, innovation, and extinction.
At the center of our work is the Diversity–Reset Framework, a system-level model that views macroevolution as a sequence of recurrent ecological cycles. Ecosystems fill with species and functional types; they are disrupted by environmental change or extinction; and they reorganize as surviving or newly evolved lineages re-establish ecological structure. These cycles create the long-term patterns observed in both the fossil record and living communities: pulses of innovation, functional convergence, limits to diversification, and repeated assembly of familiar ecological roles.
Rather than treating deep time, modern biodiversity, and theoretical models as separate domains, we use each to illuminate a different component of this cycle. By combining mechanistic and historical perspectives, our Unit aims to generate a predictive and empirically grounded account of how diversity originates, saturates, and restructures through time.
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Conceptual Framework
Macroevolution as a Complex System
Understanding macroevolution requires more than documenting patterns through time.
It requires explaining why those patterns emerge.
Our lab approaches macroevolution as a complex adaptive system shaped by the interaction of:
• ecological limits,
• extinction and environmental disturbance,
• functional and biomechanical constraints,
• developmental architecture, and
• historical contingency.
These forces operate across multiple scales—from traits and organisms to ecosystems and global events—and their interactions generate the large-scale structure of biodiversity.
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The Diversity–Reset Framework
We are developing a unified theoretical model, the Diversity–Reset Framework, which formalizes how diversity accumulates, saturates, collapses, and re-organizes over deep time.
The core principles are:
1. Ecological Filling
Lineages diversify until ecological and functional space becomes saturated.
Biomechanics and development constrain the shapes that organisms can occupy, while competition restricts the roles they can perform.
2. Disruption
Mass extinction, environmental change, or biotic turnover periodically destabilize established ecosystems.
These resets eliminate competitors, collapse structure, and open functional space.
3. Reorganization
Following a reset, surviving or invading lineages radiate rapidly—often in parallel across regions—rebuilding ecological structure with recurrent designs.
Novelty arises, but within the boundaries set by physics, development, and inherited architectures.
4. Recurrence
Because constraints and ecological rules are stable through time, macroevolution shows repeated patterns:
similar body plans, similar ecological roles, and similar diversity trajectories reappear even as lineages turn over.
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Integrating Data and Mechanism
A complete theory of macroevolution must connect mechanism to pattern.
We therefore integrate:
• fossils, which record long-term dynamics, constraint, and extinction;
• living fishes, which reveal performance, ecology, and real community structure;
• biomechanics, which defines physical limits and viable designs;
• development, which shapes trait modularity and innovation;
• phylogenetics, which captures diversification and imbalance;
• genomics, which reveals population structure, biogeography, and historical connectivity.
No single dataset can explain macroevolution.
Together, they allow us to build mechanistic models that unify short-term process with long-term pattern.
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What This Enables
This framework allows us to address fundamental questions:
• Why does diversity rise and fall in predictable cycles?
• Why do some lineages persist while others vanish?
• Why do similar ecological and functional designs reappear across millions of years?
• How do extinctions restructure ecosystems?
• How do constraints channel the emergence of novelty?
• Why does macroevolution look “law-like” despite being driven by contingent events?
Our research seeks not only to describe these phenomena, but to explain them—to identify the mechanisms that generate deep-time structure.
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Why Fishes?
Fishes provide a uniquely powerful model system because hydrodynamics and biomechanics tightly couple body form, performance, ecology, and evolutionary trajectory. Fossils extend this record across half a billion years, allowing direct tests of general principles of diversification, constraint, and turnover.
But fishes are not the goal—they are a lens through which we generalize macroevolutionary dynamics across clades and ecosystems.
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How Our Projects Connect
Although our Unit spans diverse biological systems, each project contributes to a shared conceptual structure. The Diversity–Reset Framework provides the map; the following research areas supply the evidence and mechanisms.
Early Vertebrates and the Fossil Record: Origins of Novelty and Constraint
Work on Paleozoic fishes shows how novel body plans arise, diversify, and respond to ecological disruption. These deep-time case studies reveal the functional limits and opportunities that shape radiations, helping us understand how innovation persists (or disappears) during reset cycles.
Biomechanics and Functional Morphology: The Physical Basis of Ecological Space
Biomechanical modeling and experimental analyses identify how performance, hydrodynamics, and morphology constrain ecological opportunity. This work defines the boundaries of functional and phenotypic space—the “rules” that determine how far lineages can diversify within each ecological cycle.
Alpha Taxonomy and Systematics: Establishing the Diversity Landscape
Foundational species descriptions and distributional data anchor every component of our work. Taxonomy and systematics define the biological units of diversification, reveal hidden or cryptic diversity, refine classifications, and map species ranges. These efforts are essential for interpreting diversification rates, functional trait evolution, and biogeographic assembly within the Diversity–Reset Framework.
Without reliable species-level data, patterns of innovation, ecological saturation, and reset dynamics cannot be meaningfully interpreted.
Trait Evolution and Ecological Structure in Modern Fishes
Analyses of feeding mode, body shape, habitat use, and behavior in Indo-Pacific fishes show how ecological space fills and re-fills in real time. These modern communities provide a natural laboratory for studying saturation, coexistence, and functional turnover across environmental gradients.
Population Genomics and Biogeography: Divergence and Community Assembly
Genome-scale datasets reveal how historical connectivity, demographic structure, and geographic boundaries shape diversification and community formation. These processes determine how reset cycles unfold regionally and how ecological roles are redistributed among lineages. Genomic patterns also complement systematics by helping validate species boundaries and clarify the evolutionary context of new taxa.
Developmental Data and the Origins of Variation
Comparative developmental data show how morphological novelties arise and which aspects of form are developmentally constrained. Linking development to biomechanics and fossil patterns allows us to identify which innovations are likely to succeed during ecological resets, and which are limited by underlying developmental architecture.
Theory and Modeling: Formalizing Reset Dynamics
Mathematical and computational models integrate data from fossils, genomics, development, and ecology to test core predictions of the Diversity–Reset Framework. This includes quantifying innovation, measuring ecological saturation, modeling turnover, and identifying conditions under which similar ecological structures reappear.
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A Unified Approach
Each component—taxonomy, fossils, biomechanics, development, traits, genomes, and theory—addresses a different part of the same macroevolutionary cycle. Together, they allow us to ask integrated questions:
• How do innovations arise, and why do some persist across ecological disruptions?
• What limits diversification within ecological and functional space?
• How do species boundaries, geographic structure, and developmental variation shape ecological opportunity?
• Why do similar ecological strategies reappear after extinction events?
• How do communities rebuild following environmental turnover?
• Under what conditions does macroevolution produce repeated patterns through time?
By connecting evidence across scales, our Unit aims to explain not only what happened in the history of life, but why macroevolutionary structure re-emerges again and again.