About

Dr. Kory M. Evans is an Assistant Professor in the Department of BioSciences at Rice University. His academic background encompasses ichthyology, comparative anatomy, and phylogenetic comparative methods. Dr. Evans integrates these methodologies to advance the understanding of the evolution and development of complex biological systems, using the fish skull as a primary model system. His research focuses on the ontogeny and development of functional and evolutionary modules within fish skulls, with particular attention to the development of damselfish jaws. Through this work, Dr. Evans aims to elucidate the developmental and functional relationships that shape morphological structures in ray-finned fishes, contributing to broader insights in evolutionary biology and functional morphology.

Research topics

• Biology
• Ecology
• Machine Learning
• Evolutionary biology
• Computer Science
• Artificial Intelligence
• Fishery
• Paleontology
• Genetics
• Anatomy
• Zoology

Selected publications

• Caribbean fish feces are an environmental hotspot of viable Symbiodiniaceae

  Frontiers in Microbiology · 2026-02-12

  articleOpen access

  Approximately 85% of stony coral species initially acquire their nutritional symbionts (Family Symbiodiniaceae) from the environment (horizontal transmission). Recent studies have identified live Symbiodiniaceae cells in the feces of coral-eating (corallivorous) and herbivore/detritivore fish, and thus these fish could vector Symbiodiniaceae to prospective stony coral hosts. However, nearly all data on viable Symbiodiniaceae cell densities in fish feces are from Pacific reefs. This study quantifies the density and diversity of viable Symbiodiniaceae cells in the feces of six Caribbean corallivore and herbivore/detritivore fish species in the U.S. Virgin Islands, enabling comparisons of consumer-symbiont pathways between ocean basins. Caribbean fish feces contained an average of 5 million viable Symbiodiniaceae cells ml −1 , comparable to previously reported values for Pacific corallivores. However, unlike on Pacific reefs, where Symbiodiniaceae cell densities varied in feces by fish trophic group, in the Caribbean, high densities of Symbiodiniaceae cells were documented in fish feces across feeding categories. In Caribbean herbivore/detritivore feces, high Symbiodiniaceae densities likely reflect observed, yet unexpected, feeding by these fishes on corals. Contributions of sloughed diseased coral tissue to detritus on U.S. Virgin Islands reefs may have also increased the number of Symbiodiniaceae cells consumed by detritivorous fishes. Symbiodiniaceae genera Symbiodinium , Breviolum , Cladocopium , Durusdinium , and Fugacium were detected in Caribbean fish feces. These findings demonstrate that corallivore and herbivore/detritivore fish feces constitute environmental hotspots of viable Symbiodiniaceae on Caribbean reefs.

  PublisherOA PDFDOI

• Divergent morphologies with convergent performance in the mandible of pelagiarian fishes

  bioRxiv (Cold Spring Harbor Laboratory) · 2025-01-29

  preprintOpen access

  Abstract Mandibles represent a key evolutionary innovation that enabled jawed vertebrates to adapt and diversify in response to a range of food sources. Using a phylogenetic comparative approach, we explore the phenotypic disparity and mechanical properties of the lower jaw in Pelagiaria, a morphologically diverse but relatively small clade of open-ocean fishes which are hypothesized to have radiated near the Cretaceous/Paleogene (K/Pg) mass extinction event. We found that body elongation and diet are not significantly correlated with jaw shape, but that habitat depth and tooth type are. Mechanical advantage (MA) is significantly correlated with mandible shape, with jaw-closing MA being most strongly correlated. Pelagiarian jaw shapes fall broadly into six morphotypes, of which two show significantly higher closing MA than other groups, despite differing substantially in shape. The high morphological disparity of pelagiarian mandible shape was established very early in their evolutionary history, and high levels of disparity have been maintained over tens of millions of years; this is consistent with the hypothesis that Pelagiaria represents an ancient adaptive radiation. Our results demonstrate both the mechanical and morphological diversity of the pelagiarian mandible and highlight the crucial role that morphological diversification has played in the trophic radiation of this clade.

  PublisherDOI

• Cranial modularity drives phenotypic diversification and adaptive radiation of Antarctic icefishes

  Proceedings of the National Academy of Sciences · 2025-09-29 · 2 citations

  articleSenior author

  Modularity among traits is thought to drive morphological evolution and diversification, with more modular species often showing greater morphological disparity and faster evolutionary rates. However, recent studies suggest this pattern is not universal, as higher integration can sometimes be linked to faster rates of evolution. In adaptive radiation, modularity likely facilitates morphological divergence, but its specific role in trait diversification within these events remains uncertain. Antarctic icefishes (Perciformes: Notothenioidei) have undergone adaptive radiation in the frigid Southern Ocean, yet the role of modularity in their craniofacial evolution remains poorly understood. Emerging from a common ancestor 22 Mya, these fishes developed unique morpho-physiological adaptations, such as antifreeze glycoproteins, that contributed to their evolutionary success, but the contribution of cranial modularity to their diversification is still unexplored. Here, we analyze skull shape across 172 perciform species using micro-CT scanning and geometric morphometrics to investigate the tempo and mode of skull evolution in 80 notothenioids versus 92 perciform relatives. Notothenioids exhibit considerable cranial shape diversity, with skull shapes ranging from short to long faces. Fast rates of skull shape evolution occurred in smaller subclades following the emergence of cranial elongation, a derived trait within notothenioids. They also exhibit elevated evolutionary modularity relative to their perciform relatives, with reduced covariation among skeletal elements over time, likely corresponding with Miocene cooling events and the formation of the Antarctic Circumpolar Current. We propose that greater phenotypic modularity in notothenioid skulls represents a pivotal innovation, facilitating their evolutionary response to new ecological opportunities in the Antarctic.

  PublisherDOI

• What happens to the ocean if we take out all the fish? A marine ecologist explains the complex roles fish play in their ecosystem

  2024-01-08

  article1st authorCorresponding
  PublisherDOI

• Freshwater Habitats Promote Rapid Rates of Phenotypic Evolution in Sculpin Fishes (Perciformes: Cottoidea)

  The American Naturalist · 2024-06-13 · 9 citations

  articleSenior author

  AbstractInvasions of freshwater habitats by marine fishes provide exceptional cases of habitat-driven biological diversification. Freshwater habitats make up less than 1% of aquatic habitats but contain ∼50% of fish species. However, while the dominant group of freshwater fishes (Otophysi) is older than that of most marine fishes (Percomorphaceae), it is less morphologically diverse. Classically, scientists have invoked differences in the tempo and/or mode of evolution to explain such cases of unequal morphological diversification. We tested for evidence of these phenomena in the superfamily Cottoidea (sculpins), which contains substantial radiations of marine and freshwater fishes. We find that the morphology of freshwater sculpins evolves faster but under higher constraint than that of marine sculpins, causing widespread convergence in freshwater sculpins and more morphological disparity in marine sculpins. The endemic freshwater sculpins of Lake Baikal, Siberia, are exceptions that demonstrate elevated novelty akin to that of marine sculpins. Several tantalizing factors may explain these findings, such as differences in habitat stability and/or habitat connectivity between marine and freshwater systems.

  PublisherDOI

• Phylogenomics reveals the deep ocean as an accelerator for evolutionary diversification in anglerfishes

  bioRxiv (Cold Spring Harbor Laboratory) · 2023-10-30 · 2 citations

  preprintOpen access

  ABSTRACT Colonization of a novel habitat is often followed by radiation in the wake of ecological opportunity. Alternatively, some habitats should be inherently more constraining than others if the challenges of that environment have few evolutionary solutions. We examined the push-and-pull of these factors on evolution following habitat transitions, using anglerfishes (Lophiiformes) as a model. Deep-sea fishes are notoriously difficult to study, and poor sampling has limited progress thus far. Here we present a new phylogeny of anglerfishes with unprecedented taxonomic sampling (1,092 loci and 40% of species), combined with three-dimensional phenotypic data from museum specimens obtained with micro-CT scanning. We use these datasets to examine the tempo and mode of phenotypic and lineage diversification using phylogenetic comparative methods, comparing lineages in shallow and deep benthic versus bathypelagic habitats. Our results show that anglerfishes represent a surprising case where the bathypelagic lineage has greater taxonomic and phenotypic diversity than coastal benthic relatives. This defies expectations based on ecological principles since the bathypelagic zone is the most homogeneous habitat on Earth. Deep-sea anglerfishes experienced rapid lineage diversification concomitant with colonization of the bathypelagic zone from a continental slope ancestor. They display the highest body, skull and jaw shape disparity across lophiiforms. In contrast, reef-associated taxa show strong constraints on shape and low evolutionary rates, contradicting patterns suggested by other shallow marine fishes. We found that Lophiiformes as a whole evolved under an early burst model with subclades occupying distinct body shapes. We further discuss to what extent the bathypelagic clade is a secondary adaptive radiation, or if its diversity can be explained by non-adaptive processes.

  PublisherOA PDFDOI

• Sexual Dimorphism in the Electric Knifefish Sternarchogiton labiatus (Gymnotiformes: Apteronotidae) with a Hypermorphic Snout and Oral Jaws

  Ichthyology & Herpetology · 2023-11-01 · 1 citations

  article

  Secondary sexual dimorphism is relatively common in the ghost knifefishes (Gymnotiformes: Apteronotidae), with males of several species growing greatly elongated snouts (e.g., Compsaraia samueli, Parapteronotus hasemani ), while others develop enlarged, protruding teeth on either the lower jaw ( Sternarchorhynchus spp.) or both jaws ( Sternarchogiton nattereri ). Of the four known species of Sternarchogiton , sexual dimorphism has so far only been reported in S. nattereri . Here we report that in an additional species, S. labiatus , mature males possess similar enlarged, external teeth on the dentary and premaxilla. We document this condition in three specimens collected during the high-water spawning season from the río Nanay near Iquitos, Peru. We analyze this morphology using high-resolution X-ray microcomputed tomography. Additionally, we use genetic sequence data to demonstrate that specimens bearing external teeth are genetically indistinguishable from those with the phenotype of S. labiatus . Finally, we review and summarize the current knowledge of sexual dimorphism within the Apteronotidae.

  PublisherDOI

• A New Era of Morphological Investigations: Reviewing Methods for Comparative Anatomical Studies

  Integrative Organismal Biology · 2023-01-01 · 22 citations

  reviewOpen access

  The increased use of imaging technology in biological research has drastically altered morphological studies in recent decades and allowed for the preservation of important collection specimens alongside detailed visualization of bony and soft-tissue structures. Despite the benefits associated with these newer imaging techniques, there remains a need for more "traditional" methods of morphological examination in many comparative studies. In this paper, we describe the costs and benefits of the various methods of visualizing, examining, and comparing morphological structures. There are significant differences not only in the costs associated with these different methods (monetary, time, equipment, and software), but also in the degree to which specimens are destroyed. We argue not for any one particular method over another in morphological studies, but instead suggest a combination of methods is useful not only for breadth of visualization, but also for the financial and time constraints often imposed on early-career research scientists.

  PublisherOA PDFDOI

• Evolutionary Patterns of Modularity in the Linkage Systems of the Skull in Wrasses and Parrotfishes

  Integrative Organismal Biology · 2023-01-01 · 6 citations

  articleOpen access

  The concept of modularity is fundamental to understanding the evolvability of morphological structures and is considered a central framework for the exploration of functionally and developmentally related subsets of anatomical traits. In this study, we explored evolutionary patterns of modularity and integration in the 4-bar linkage biomechanical system of the skull in the fish family Labridae (wrasses and parrotfish). We measured evolutionary modularity and rates of shape diversification of the skull partitions of three biomechanical 4-bar linkage systems using 205 species of wrasses (family: Labridae) and a three-dimensional geometric morphometrics data set of 200 coordinates. We found support for a two-module hypothesis on the family level that identifies the bones associated with the three linkages as being a module independent from a module formed by the remainder of the skull (neurocranium, nasals, premaxilla, and pharyngeal jaws). We tested the patterns of skull modularity for four tribes in wrasses: hypsigenyines, julidines, cheilines, and scarines. The hypsigenyine and julidine groups showed the same two-module hypothesis for Labridae, whereas cheilines supported a four-module hypothesis with the three linkages as independent modules relative to the remainder of the skull. Scarines showed increased modularization of skull elements, where each bone is its own module. Diversification rates of modules show that linkage modules have evolved at a faster net rate of shape change than the remainder of the skull, with cheilines and scarines exhibiting the highest rate of evolutionary shape change. We developed a metric of linkage planarity and found the oral jaw linkage system to exhibit high planarity, while the rest position of the hyoid linkage system exhibited increased three dimensionality. This study shows a strong link between phenotypic evolution and biomechanical systems, with modularity influencing rates of shape change in the evolution of the wrasse skull.

  PublisherOA PDFDOI

• Mosaic Evolution of the Skull in Labrid Fishes Involves Differences in Both Tempo and Mode of Morphological Change

  Systematic Biology · 2022 · 43 citations

  Senior authorCorresponding
  • Biology
  • Evolutionary biology
  • Anatomy

  Modularity is a ubiquitous feature of organismal design that plays an important role in structuring patterns of morphological diversification. Modularity can facilitate evolutionary changes by allowing subsets of traits to coevolve as integrated units and follow quasi-independent evolutionary trajectories, a pattern that may be particularly consequential in the case of highly complex morphological structures. Here we examine modularity in a complex and highly kinetic structure, the teleost skull, and ask if a modular organization of the skull has influenced the diversification dynamics of the shapes of its osteological components across the labrid phylogeny. We compiled one of the largest 3D morphological data sets of fishes to date and used geometric morphometrics to quantify patterns of cranial shape evolution across 184 species of wrasses (Labridae). We then tested several hypotheses of modularity inspired by functional and developmental relationships between cranial bones and compared phenotypic rates among modules. We also compared the fit of models of trait evolution for the entire skull and the various articulated bones that it comprises. Our analyses indicated strong support for a 2-module hypothesis, one that encompasses the oral and pharyngeal jaws and another module comprised of the neurocranium, hyoid apparatus, and operculum. This functional hypothesis yielded one of the highest significant rate differentials across modules, yet we also found that the best-fitting models of trait evolution differed among skull bones. These results suggest that modularity can influence morphological diversification in complex biological structures via differences in both the tempo and mode of evolutionary change. [3D geometric morphometrics, cranial morphology, evolutionary modularity, Labridae, phenotypic rates, structural complexity.].

  PublisherDOI

Frequent coauthors

• James S. Albert

  University of Louisiana at Lafayette

  12 shared

• Olivier Larouche

  University of Houston

  7 shared

• Maxwell J. Bernt

  Susquehanna University

  7 shared

• Prosanta Chakrabarty

  7 shared

• Aaron H. Fronk

  University of Louisiana at Lafayette

  6 shared

• Elizabeth Christina Miller

  6 shared

• Keiffer Williams

  Clemson University

  5 shared

• Ricardo Betancur‐R

  Scripps Institution of Oceanography

  4 shared

Labs

• EVANS LABPI

  Dr. Kory M. Evans Assistant Professor | Department of BioSciences | Rice University My background is in ichthyology, comparative anatomy, and phylogenetic comparative methods. I integrate these methods to better understand the evolution and development of complex systems using the fish skull as a model system

Education

• Ph. D candidate, Biology

  University of Louisiana at Lafayette