About

The Fuxjager Lab studies the physiological and evolutionary bases of complex animal behavior. We combine numerous techniques and approaches, ranging from field work in the Amazon to molecular work at the bench. The Lab is located at Brown University in the Department of Ecology, Evolution, and Organismal Biology (EEOB).

Research topics

• Evolutionary biology
• Biology
• Genetics
• Neuroscience
• Psychology
• Ecology
• Computational biology
• Communication

Selected publications

• An Illustrative Case for Muscular Fatigue Resistance Underlying Exaggerated Begging in Avian Brood Parasites

  The American Naturalist · 2026-02-09

  articleSenior author
  PublisherDOI

• Correction: Neuromuscular coordination of movement and breathing forges a hammer-like mechanism for woodpecker drilling

  Journal of Experimental Biology · 2026-01-15

  articleOpen accessSenior author

  There was an error in J. Exp. Biol. (2025) 228, jeb251167 (doi:10.1242/jeb.251167).During preparation of the figures for publication, after peer review, the authors inadvertently used an incorrect version of Fig. 2D that duplicated one of the bar graphs. Specifically, the purple bar graph representing the iliotibialis cranialis (IC) muscle is a duplicate of the blue bar graph representing the musculus depressor caudae (MDc) muscle. The corrected and original panel are shown below.Both the online full-text and PDF versions of the article have been updated. The authors apologise to the readers for this error. This correction does not affect the results, interpretation or conclusions of the study and all analyses, code and statistics reported in the paper and supplementary materials are correct.

  PublisherOA PDFDOI

• Hormonal and neuromuscular regulation of courtship displays

  Elsevier eBooks · 2025-01-01

  book-chapterSenior author
  PublisherDOI

• Dynamic Sexual Dichromatism Promotes Rapid Mate Recognition in an Explosive Breeding Toad

  Ichthyology & Herpetology · 2025-09-02

  articleOpen access

  Many species reproduce by participating in explosive breeding events, where hundreds of individuals converge at specific locations for a short time period to mate. During these spectacular aggregations, many males must actively search and compete for a limited number of females. One idea is that sexual selection in explosive breeding species favors the evolution of communication strategies facilitating easy detection of males and females. As such, the emergence of dynamic sexual dichromatism, a reversible change of body coloration of one sex, might act as a visual signal promoting rapid mate recognition in dense breeding aggregations. We tested this idea in Asian Common Toads (Duttaphrynus melanostictus), an explosive breeder in which males quickly turn from brown to bright yellow for up to two days during mating. Thus, we first explored whether color differences of brown and yellow are sufficient to be perceived and distinguished by toads using a color vision model. In a set of behavioral experiments, we then tested the interactions of male toads with a yellow (resembling a breeding male) and a brown (resembling a female) 3D model toad to determine the functional significance of yellow male coloration during mating. Finally, we compared male body color, morphological parameters, and body condition of mated and non-mated males to investigate if these traits are influenced by securing a mate or female mate choice. Our results show that dynamic yellow coloration displayed by males can be easily discriminated against brown female conspecifics from a toad's point of view. During model experiments, males had twice as much physical contact with brown models and clasped them 40 times more often than yellow models. Coloration and several morphological traits did not differ between mated and non-mated males; hence, securing a mating partner was not influenced by variations in color or morphology. Our study supports the idea that dynamic sexual dichromatism repeatedly evolved as a visual signal mediating fast mate recognition in tropical and temperate anuran species solving a common problem in time-limited, dense breeding aggregations, by minimizing same-sex harassment and mismatch.

  PublisherDOI

• Relative amplitude modulation in woodpecker drums shows species-specific patterns

  Animal Behaviour · 2025-05-27 · 1 citations

  articleOpen access

  Amplitude is one of several components that comprise multicomponent acoustic signals. We aimed to study relative amplitude modulation over the duration of an acoustic signal that woodpeckers produce to defend their territories, the drum. Woodpecker drumming is a tractable system for this type of analysis because drum recordings are readily available through public databases and the physical mechanism for amplitude generation is easily observable and modelled. Accordingly, we characterized relative amplitude modulation of drums from eight woodpecker species by fitting models to the amplitude modulation pattern and found that species' modulation patterns (1) showed consistency within species and (2) differed between species. Functionally, relative amplitude modulation could showcase motor skill when individuals reach peak amplitude quickly or maintain a high amplitude. Alternatively, amplitude modulation could be used to evaluate individual quality through consistently repeating drums without mistakes. Our findings highlight the importance of studying both the mechanical production and functional role of multicomponent signals to understand how a signalling system works. • The drums of some woodpeckers exhibit species-specific relative amplitude patterns. • Drum amplitude and impact force are proportional with a positive relationship. • The drumming system may leverage mechanical constraints to highlight motor skill.

  PublisherDOI

• Genomic resources for comparative analyses of obligate avian brood parasitism

  bioRxiv (Cold Spring Harbor Laboratory) · 2025-08-15

  preprintOpen access

  Examples of convergent evolution, wherein distantly related organisms evolve similar traits, including behaviors, underscore the adaptive power of natural selection. In birds, obligate brood parasitism, and the associated loss of parental care behaviors, has evolved independently in seven different lineages, though little is known about the genetic basis of the complex suite of traits associated with this rare life history strategy. We generated genome assemblies for ten brood parasitic species plus eight species representatives of their parental/nesting outgroups. This includes nine long-read chromosome-level assemblies, with scaffold N50 sizes ranging from 38.1 to 72.6 MB, and gene representation completeness measures >97%. Leveraging this new catalog of avian genomes, we constructed clade-level alignments that reveal variation in chromosomal synteny, provide first-time or improved annotations of protein- coding and non-coding genes, and define cross-species ortholog reference sets. We also refine estimates for the timing of the seven independent origins of brood parasitism, ranging from recent events such as 1.6 to 4.5 million years ago in Molothrus cowbirds to much earlier origins over 30 million years ago in two of the three cuckoo lineages. These genomic resources lay the foundation for investigating the genetic and genomic underpinnings of brood parasitism, including the loss of parental care, shifts in mating systems, perhaps resulting in heightened sperm competition, elevated annual fecundity, improved spatial cognition related to nest-finding, and the diverse adaptations shaped by intense coevolution with host species.

  PublisherOA PDFDOI

• Endocrine and skeletal muscle physiology optimizing avian migratory capabilities

  Journal of Avian Biology · 2025-11-01 · 2 citations

  articleOpen access

  The long‐distance migrations of thousands of bird species and their billions of individuals are feats of astounding physiological specialization and plasticity. Whereas numerous organ systems require modification to achieve successful fueling and navigation capabilities, given their overarching importance for movement and contribution to body mass, skeletal muscles are subject to exceptional performance optimization and anatomical plasticity. To express the appropriate changes throughout the complicated life history of migration, while remaining in synchrony with the environment, skeletal muscles must receive preparatory signals and express transcriptional and biochemical modifications required for full expression of the migratory phenotype. In all likelihood, these muscles must also temporally signal their state and needs to other organ systems. By considering other well‐studied avian skeletal muscle systems, this review explores how endocrine signaling likely impacts skeletal muscles involved in migration and, conversely, how those muscles might relay their condition elsewhere throughout the bird's body. Systems biology offers exceptional modeling for capturing this complex biology.

  PublisherOA PDFDOI

• Behavioral Strategizing Among Animals: A Systems Approach

  Integrative and Comparative Biology · 2025-06-27 · 1 citations

  articleSenior author

  Examples of behavioral strategizing exist throughout the animal kingdom, but the quantification and analysis of these complex behavioral patterns remain a challenge. Classic research in this realm often relies either on methods that intentionally simplify complexity or that focus on a subset of abundant behaviors. Unfortunately, these approaches can sometimes eliminate informative details of behavioral strategizing. Here, we demonstrate the utility of a systems-based approach to characterize behavioral patterns in a way that captures the complexity of behavioral strategies and tactics while supporting the generation of relevant, system-specific hypotheses. We accomplish this aim by building upon classic ideas of strategy and tactic, refocusing the theory on behavioral traits, and extending the framework to make sense of patterns of behavior use. In doing so, we outline a more expansive definition of the behavioral tactic, and we provide a methodological roadmap for quantifying multi-behavior and multi-agent tactics. Our goal is to craft a framework for the study of behavioral patterns and encourage researchers to embrace the complexity in their systems. To this end, we provide a case study of territoriality in downy woodpeckers as proof of concept for a network-based systems approach to understanding behavioral strategies.

  PublisherDOI

• Deep-time gene expression shift reveals an ancient change in avian muscle phenotypes

  PLoS Genetics · 2025-04-11 · 1 citations

  articleOpen access

  Gene duplication is an important process of molecular evolutionary change, though identifying these events and their functional implications remains challenging. Studies on gene duplication more often focus on the presence of paralogous genes within the genomes and less frequently explore shifts in expression. We investigated the evolutionary history of calsequestrin (CASQ), a crucial calcium-binding protein in the junctional sarcoplasmic reticulum of muscle tissues. CASQ exists in jawed vertebrates as subfunctionalized paralogs CASQ1 and CASQ2 expressed primarily in skeletal and cardiac muscles, respectively. We used an enhanced sequence dataset to support initial duplication of CASQl in a jawed fish ancestor prior to the divergence of cartilaginous fishes. Surprisingly, we find CASQ2 is the predominant skeletal muscle paralog in birds, while CASQ1 is either absent or effectively nonfunctional. Changes in the amino acid composition and electronegativity of avian CASQ2 suggest enhancement to calcium-binding properties that preceded the loss of CASQ1. We identify this phenomenon as CASQ2 "synfunctionalization," where one paralog functionally replaces another. While additional studies are needed to fully understand the dynamics of CASQ1 and CASQ2 in bird muscles, the long and consistent history of CASQ subfunctions outside of birds indicate a substantial evolutionary pressure on calcium-cycling processes in muscle tissues, likely connected to increased avian cardiovascular and metabolic demands. Our study provides an important insight into the molecular evolution of birds and shows how gene expression patterns can be comparatively studied across phylum-scale deep time to reveal key evolutionary events.

  PublisherDOI

• Repeated evolutionary turnover of vertebrate skeletal muscle myosins

  Proceedings of the Royal Society B Biological Sciences · 2025-10-28

  preprintOpen access

  Myosin heavy chain proteins are essential for muscle contraction and nearly every physiological function in animals, but their diversity and evolution outside mammals are largely unknown. We comprehensively model the evolutionary history of 1201 heavy-chain myosins from across Chordata. We find that skeletal muscle myosins are located in a conserved tandem gene array in all vertebrate species, but repeated gene duplication-loss turnover has surprisingly led to an independently evolved set of core skeletal muscle myosins in each major vertebrate group. Despite these separate derivations of these myosin subfamilies, each major vertebrate group exhibits tissue-specific patterns of subfamily expression and specialized myosin subfamily expression in extreme muscles. Our results show that muscle evolution across vertebrates is not based on conserved one-to-one orthologous motor myosins, as might be expected for such a core structural protein family. Instead, we find that skeletal muscle myosins have evolved as a shifting cluster of genes that is constantly changing and diversifying to balance maintainance of core physiological processes and innovation of new physiological possibilities.

  PublisherDOI

Recent grants

• COLLABORATIVE RESEARCH: Neuroendocrine basis of gestural display evolution

  NSF · $346k · 2017–2019

• IRES Track 1: Neurobiology and evolution of frog dance displays in Austria and India

  NSF · $300k · 2020–2025

• COLLABORATIVE RESEARCH: Neuroendocrine basis of gestural display evolution

  NSF · $286k · 2019–2021

Frequent coauthors

• Barney A. Schlinger

  University of California, Los Angeles

  44 shared

• Eric R. Schuppe

  Cornell University

  37 shared

• Meredith C. Miles

  Providence College

  30 shared

• Eliot T. Miller

  28 shared

• Nigel K. Anderson

  Brown University

  24 shared

• Michaela Hau

  University of Konstanz

  24 shared

• Maren N. Vitousek

  Cornell University

  23 shared

• Doris Preininger

  University of Vienna

  22 shared

Labs

• Fuxjager LabPI