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Laird MF, Ross CF, Kang V, Konow N. Introduction: food processing and nutritional assimilation in animals. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220559. [PMID: 37839455 PMCID: PMC10577032 DOI: 10.1098/rstb.2022.0559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Accepted: 09/11/2023] [Indexed: 10/17/2023] Open
Abstract
How animals process and absorb nutrients from their food is a fundamental question in biology. Despite the continuity and interaction between intraoral food processing and post-oesophageal nutritional extraction, these topics have largely been studied separately. At present, we lack a synthesis of how pre- and post-oesophageal mechanisms of food processing shape the ability of various taxa to effectively assimilate nutrients from their diet. The aim of this special issue is to catalyse a unification of these distinct approaches as a functional continuum. We highlight questions that derive from this synthesis, as well as technical advances to address these questions. At present, there is also a skew toward vertebrates in studies of feeding form-function mechanics; by including perspectives from researchers working on both vertebrates and invertebrates, we hope to stimulate integrative and comparative research on food processing and nutritional assimilation. Below, we discuss how the papers in this issue contribute to these goals in three areas: championing a functional-comparative approach, quantifying performance and emphasizing the effects of life history, and food substrate and extrinsic factors in current and future studies of oral food processing and nutritional assimilation. This article is part of the theme issue 'Food processing and nutritional assimilation in animals'.
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Affiliation(s)
- Myra F. Laird
- Department of Basic and Translational Sciences, University of Pennsylvania, Philadelphia, PA 19104-6243, USA
| | - Callum F. Ross
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL 60637, USA
| | - Victor Kang
- Department of Bioengineering, Imperial College London, London SW7 2AZ, UK
| | - Nicolai Konow
- Department of Biological Sciences, University of Massachusetts, Lowell, MA 01854, USA
- UMass Movement Center, University of Massachusetts, Lowell, MA 01854, USA
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Cama B, Ehlers S, Szczerbowski D, Thomas-Oates J, Jiggins CD, Schulz S, McMillan WO, Dasmahapatra KK. Exploitation of an ancestral pheromone biosynthetic pathway contributes to diversification in Heliconius butterflies. Proc Biol Sci 2022; 289:20220474. [PMID: 35892212 PMCID: PMC9326301 DOI: 10.1098/rspb.2022.0474] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
During courtship, male butterflies of many species produce androconial secretions containing male sex pheromones (MSPs) that communicate species identity and affect female choice. MSPs are thus likely candidates as reproductive barriers, yet their role in speciation remains poorly studied. Although Heliconius butterflies are a model system in speciation, their MSPs have not been investigated from a macroevolutionary perspective. We use GC/MS to characterize male androconial secretions in 33 of the 69 species in the Heliconiini tribe. We found these blends to be species-specific, consistent with a role in reproductive isolation. We detected a burst in blend diversification rate at the most speciose genus, Heliconius; a consequence of Heliconius and Eueides species using a fatty acid (FA) metabolic pathway to unlock more complex blends than basal Heliconiini species, whose secretions are dominated by plant-like metabolites. A comparison of 10 sister species pairs demonstrates a striking positive correlation between blend dissimilarity and range overlap, consistent with character displacement or reinforcement in sympatry. These results demonstrate for the first time that MSP diversification can promote reproductive isolation across this group of butterflies, showcasing how implementation of an ancestral trait, the co-option of the FA metabolic pathway for pheromone production, can facilitate rapid speciation.
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Affiliation(s)
- Bruna Cama
- Department of Biology, University of York, Heslington YO10 5DD, UK
| | - Stephanie Ehlers
- Institute of Organic Chemistry, Technische Universität Braunschweig, Hagenring 30, Braunschweig 38106, Germany
| | - Daiane Szczerbowski
- Institute of Organic Chemistry, Technische Universität Braunschweig, Hagenring 30, Braunschweig 38106, Germany
| | - Jane Thomas-Oates
- Department of Chemistry, University of York, Heslington YO10 5DD, UK
| | - Chris D. Jiggins
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - Stefan Schulz
- Institute of Organic Chemistry, Technische Universität Braunschweig, Hagenring 30, Braunschweig 38106, Germany
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Martinez CM, Tovar AJ, Wainwright PC. A novel intramandibular joint facilitates feeding versatility in the sixbar distichodus. J Exp Biol 2022; 225:273910. [PMID: 34989395 DOI: 10.1242/jeb.243621] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 12/23/2021] [Indexed: 11/20/2022]
Abstract
The intramandibular joint (IMJ) is a secondary point of movement between the two major bones of the lower jaw. It has independently evolved in several groups of teleost fishes, each time representing a departure from related species in which the mandible functions as a single structure rotating only at the quadratomandibular joint (QMJ). In this study, we examine kinematic consequences of the IMJ novelty in a freshwater characiform fish, the herbivorous Distichodus sexfasciatus. We combine traditional kinematic approaches with trajectory-based analysis of motion shapes to compare patterns of prey capture movements during substrate biting, the fish's native feeding mode, and suction of prey from the water column. We find that the IMJ enables complex jaw motions and contributes to feeding versatility by allowing the fish to modulate its kinematics in response to different prey and to various scenarios of jaw-substrate interaction. Implications of the IMJ include context-dependent movements of lower versus upper jaws, enhanced lower jaw protrusion, and the ability to maintain contact between the teeth and substrate throughout the jaw closing or biting phase of the motion. The IMJ in D. sexfasciatus appears to be an adaptation for removing attached benthic prey, consistent with its function in other groups that have evolved the joint. This study builds on our understanding of the role of the IMJ during prey capture and provides insights into broader implications of the innovative trait.
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Affiliation(s)
- Christopher M Martinez
- Department of Ecology and Evolutionary Biology, University of California, Irvine, CA 92697, USA.,Department of Evolution and Ecology, University of California, Davis, CA 95616, USA
| | - Angelly J Tovar
- Department of Evolution and Ecology, University of California, Davis, CA 95616, USA
| | - Peter C Wainwright
- Department of Evolution and Ecology, University of California, Davis, CA 95616, USA
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Influence of historical changes in tropical reef habitat on the diversification of coral reef fishes. Sci Rep 2021; 11:20731. [PMID: 34671048 PMCID: PMC8528860 DOI: 10.1038/s41598-021-00049-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 09/28/2021] [Indexed: 11/11/2022] Open
Abstract
Past environmental changes are expected to have profoundly impacted diversity dynamics through time. While some previous studies showed an association between past climate changes or tectonic events and important shifts in lineage diversification, it is only recently that past environmental changes have been explicitly integrated in diversification models to test their influence on diversification rates. Here, we used a global reconstruction of tropical reef habitat dynamics during the Cenozoic and phylogenetic diversification models to test the influence of (i) major geological events, (ii) reef habitat fragmentation and (iii) reef area on the diversification of 9 major clades of tropical reef fish (Acanthuridae, Balistoidea, Carangoidea, Chaetodontidae, Haemulinae, Holocentridae, Labridae, Pomacentridae and Sparidae). The diversification models revealed a weak association between paleo-habitat changes and diversification dynamics. Specifically, the fragmentation of tropical reef habitats over the Cenozoic was found to be a driver of tropical reef fish diversification for 2 clades. However, overall, our approach did not allow the identification of striking associations between diversification dynamics and paleo-habitat fragmentation in contrast with theoretical model's predictions.
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Hodge JR, Song Y, Wightman MA, Milkey A, Tran B, Štajner A, Roberts AS, Hemingson CR, Wainwright PC, Price SA. Constraints on the Ecomorphological Convergence of Zooplanktivorous Butterflyfishes. Integr Org Biol 2021; 3:obab014. [PMID: 34377941 PMCID: PMC8341894 DOI: 10.1093/iob/obab014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Whether distantly related organisms evolve similar strategies to meet the demands of a shared ecological niche depends on their evolutionary history and the nature of form-function relationships. In fishes, the visual identification and consumption of microscopic zooplankters, selective zooplanktivory, is a distinct type of foraging often associated with a suite of morphological specializations. Previous work has identified inconsistencies in the trajectory and magnitude of morphological change following transitions to selective zooplanktivory, alluding to the diversity and importance of ancestral effects. Here we investigate whether transitions to selective zooplanktivory have influenced the morphological evolution of marine butterflyfishes (family Chaetodontidae), a group of small-prey specialists well known for several types of high-precision benthivory. Using Bayesian ancestral state estimation, we inferred the recent evolution of zooplanktivory among benthivorous ancestors that hunted small invertebrates and browsed by picking or scraping coral polyps. Traits related to the capture of prey appear to be functionally versatile, with little morphological distinction between species with benthivorous and planktivorous foraging modes. In contrast, multiple traits related to prey detection or swimming performance are evolving toward novel, zooplanktivore-specific optima. Despite a relatively short evolutionary history, general morphological indistinctiveness, and evidence of constraint on the evolution of body size, convergent evolution has closed a near significant amount of the morphological distance between zooplanktivorous species. Overall, our findings describe the extent to which the functional demands associated with selective zooplanktivory have led to generalizable morphological features among butterflyfishes and highlight the importance of ancestral effects in shaping patterns of morphological convergence.
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Affiliation(s)
- J R Hodge
- Department of Biological Sciences, Clemson University, Clemson, SC 29634, USA
- Department of Evolution and Ecology, University of California, Davis, Davis, CA 95616, USA
| | - Y Song
- Department of Evolution and Ecology, University of California, Davis, Davis, CA 95616, USA
- Department of Biomedical Engineering, The Chinese University of Hong Kong, Hong Kong
| | - M A Wightman
- Department of Evolution and Ecology, University of California, Davis, Davis, CA 95616, USA
- Harbor Branch Oceanographic Institute, Florida Atlantic University, Fort Pierce, FL 34946, USA
| | - A Milkey
- Department of Evolution and Ecology, University of California, Davis, Davis, CA 95616, USA
| | - B Tran
- Department of Evolution and Ecology, University of California, Davis, Davis, CA 95616, USA
| | - A Štajner
- Department of Evolution and Ecology, University of California, Davis, Davis, CA 95616, USA
| | - A S Roberts
- Department of Evolution and Ecology, University of California, Davis, Davis, CA 95616, USA
| | - C R Hemingson
- College of Science and Engineering, James Cook University, Townsville, QLD 4811, Australia
| | - P C Wainwright
- Department of Evolution and Ecology, University of California, Davis, Davis, CA 95616, USA
| | - S A Price
- Department of Biological Sciences, Clemson University, Clemson, SC 29634, USA
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Olsson KH, Martin CH, Holzman R. Hydrodynamic Simulations of the Performance Landscape for Suction-Feeding Fishes Reveal Multiple Peaks for Different Prey Types. Integr Comp Biol 2020; 60:1251-1267. [PMID: 32333778 PMCID: PMC7825097 DOI: 10.1093/icb/icaa021] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The complex interplay between form and function forms the basis for generating and maintaining organismal diversity. Fishes that rely on suction-feeding for prey capture exhibit remarkable phenotypic and trophic diversity. Yet the relationships between fish phenotypes and feeding performance on different prey types are unclear, partly because the morphological, biomechanical, and hydrodynamic mechanisms that underlie suction-feeding are complex. Here we demonstrate a general framework to investigate the mapping of multiple phenotypic traits to performance by mapping kinematic variables to suction-feeding capacity. Using a mechanistic model of suction-feeding that is based on core physical principles, we predict prey capture performance across a broad range of phenotypic trait values, for three general prey types: mollusk-like prey, copepod-like prey, and fish-like prey. Mollusk-like prey attach to surfaces, copepod-like prey attempt to escape upon detecting the hydrodynamic disturbance produced by the predator, and fish-like prey attempt to escape when the predator comes within a threshold distance. This approach allowed us to evaluate suction-feeding performance for any combination of six key kinematic traits, irrespective of whether these trait combinations were observed in an extant species, and to generate a multivariate mapping of phenotype to performance. We used gradient ascent methods to explore the complex topography of the performance landscape for each prey type, and found evidence for multiple peaks. Characterization of phenotypes associated with performance peaks indicates that the optimal kinematic parameter range for suction-feeding on different prey types are narrow and distinct from each other, suggesting different functional constraints for the three prey types. These performance landscapes can be used to generate hypotheses regarding the distribution of extant species in trait space and their evolutionary trajectories toward adaptive peaks on macroevolutionary fitness landscapes.
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Affiliation(s)
- Karin H Olsson
- Department of Zoology, Tel Aviv University, Tel Aviv 69978, Israel
- Inter-University Institute for Marine Sciences, Eilat 8810302, Israel
| | - Christopher H Martin
- Department of Integrative Biology, University of California, Berkeley, CA 94720, USA
- Museum of Vertebrate Zoology, University of California, Berkeley, CA 94720, USA
| | - Roi Holzman
- Department of Zoology, Tel Aviv University, Tel Aviv 69978, Israel
- Inter-University Institute for Marine Sciences, Eilat 8810302, Israel
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Trait evolution is reversible, repeatable, and decoupled in the soldier caste of turtle ants. Proc Natl Acad Sci U S A 2020; 117:6608-6615. [PMID: 32152103 PMCID: PMC7104247 DOI: 10.1073/pnas.1913750117] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The scope of adaptive phenotypic change within a lineage is shaped by how functional traits evolve. Castes are defining functional traits of adaptive phenotypic change in complex insect societies, and caste evolution is expected to be phylogenetically conserved and developmentally constrained at broad phylogenetic scales. Yet how castes evolve at the species level has remained largely unaddressed. Turtle ant soldiers (genus Cephalotes), an iconic example of caste specialization, defend nest entrances by using their elaborately armored heads as living barricades. Across species, soldier morphotype determines entrance specialization and defensive strategy, while head size sets the specific size of defended entrances. Our species-level comparative analyses of morphotype and head size evolution reveal that these key ecomorphological traits are extensively reversible, repeatable, and decoupled within soldiers and between soldier and queen castes. Repeated evolutionary gains and losses of the four morphotypes were reconstructed consistently across multiple analyses. In addition, morphotype did not predict mean head size across the three most common morphotypes, and head size distributions overlapped broadly across all morphotypes. Concordantly, multiple model-fitting approaches suggested that soldier head size evolution is best explained by a process of divergent pulses of change. Finally, while soldier and queen head size were broadly coupled across species, the level of head size disparity between castes was decoupled from both queen head size and soldier morphotype. These findings demonstrate that caste evolution can be highly dynamic at the species level, reshaping our understanding of adaptive morphological change in complex social lineages.
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Price SA, Friedman ST, Corn KA, Martinez CM, Larouche O, Wainwright PC. Building a Body Shape Morphospace of Teleostean Fishes. Integr Comp Biol 2020; 59:716-730. [PMID: 31241147 DOI: 10.1093/icb/icz115] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
We present a dataset that quantifies body shape in three dimensions across the teleost phylogeny. Built by a team of researchers measuring easy-to-identify, functionally relevant traits on specimens at the Smithsonian National Museum of Natural History it contains data on 16,609 specimens from 6144 species across 394 families. Using phylogenetic comparative methods to analyze the dataset we describe the teleostean body shape morphospace and identify families with extraordinary rates of morphological evolution. Using log shape ratios, our preferred method of body-size correction, revealed that fish width is the primary axis of morphological evolution across teleosts, describing a continuum from narrow-bodied laterally compressed flatfishes to wide-bodied dorsoventrally flattened anglerfishes. Elongation is the secondary axis of morphological variation and occurs within the more narrow-bodied forms. This result highlights the importance of collecting shape on three dimensions when working across teleosts. Our analyses also uncovered the fastest rates of shape evolution within a clade formed by notothenioids and scorpaeniforms, which primarily thrive in cold waters and/or have benthic habits, along with freshwater elephantfishes, which as their name suggests, have a novel head and body shape. This unprecedented dataset of teleostean body shapes will enable the investigation of the factors that regulate shape diversification. Biomechanical principles, which relate body shape to performance and ecology, are one promising avenue for future research.
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Affiliation(s)
- S A Price
- Department of Biological Sciences, Clemson University, Clemson, SC 29634, USA
| | - S T Friedman
- Department of Evolution and Ecology, University of California Davis, Davis, CA 95616, USA
| | - K A Corn
- Department of Evolution and Ecology, University of California Davis, Davis, CA 95616, USA
| | - C M Martinez
- Department of Evolution and Ecology, University of California Davis, Davis, CA 95616, USA
| | - O Larouche
- Department of Biological Sciences, Clemson University, Clemson, SC 29634, USA
| | - P C Wainwright
- Department of Evolution and Ecology, University of California Davis, Davis, CA 95616, USA
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Evans KM, Kim LY, Schubert BA, Albert JS. Ecomorphology of Neotropical Electric Fishes: An Integrative Approach to Testing the Relationships between Form, Function, and Trophic Ecology. Integr Org Biol 2019; 1:obz015. [PMID: 33791530 PMCID: PMC7671154 DOI: 10.1093/iob/obz015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The relationship between form and function is thought to play an integral role in structuring broad-scale patterns of morphological evolution and resource utilization. In ecomorphological studies, mechanical performance is widely understood to constrain the evolution of form and function. However, the relationship between form, function, and resource utilization is less clear. Additionally, seasonal fluctuations in resource availability may further complicate patterns of resource use. How organisms cope with these complexities, and the effect of these factors on broadscale patterns of morphological evolution is also poorly understood. Here we use three-dimensional geometric morphometrics, biomechanics, stable isotope analysis, and gut-content analysis to study trophic evolution in a clade of riverine-adapted electric fishes from a region with high seasonal variability; the Amazon River. We find significant and phylogenetically structured relationships among measures of trophic ecology and skull shape. We also recover a significant relationship between the mechanical advantage of the mandible and trophic position, where species feeding at higher trophic levels have narrower jaws with lower mechanical advantages, and species feeding at lower trophic levels have deeper jaws with higher mechanical advantages. Our results indicate that selection is driving the evolution of mandible shape and performance toward specialization on different trophic ecologies.
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Affiliation(s)
- K M Evans
- College of Food, Agricultural and Natural Resource Sciences, University of Minnesota, 1987 Upper Buford Circle, St. Paul, MN 55108, USA
| | - L Y Kim
- Department of Biology, University of Louisiana at Lafayette, P.O. Box 42451, Lafayette, LA 70504, USA
| | - B A Schubert
- School of Geosciences, University of Louisiana at Lafayette, P.O. Box 43705, Lafayette, LA 70504, USA
| | - J S Albert
- Department of Biology, University of Louisiana at Lafayette, P.O. Box 42451, Lafayette, LA 70504, USA
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Huby A, Lowie A, Herrel A, Vigouroux R, Frédérich B, Raick X, Kurchevski G, Godinho AL, Parmentier E. Functional diversity in biters: the evolutionary morphology of the oral jaw system in pacus, piranhas and relatives (Teleostei: Serrasalmidae). Biol J Linn Soc Lond 2019. [DOI: 10.1093/biolinnean/blz048] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Abstract
Serrasalmid fishes form a highly specialized group of biters that show a large trophic diversity, ranging from pacus able to crush seeds to piranhas capable of cutting flesh. Their oral jaw system has been hypothesized to be forceful, but variation in bite performance and morphology with respect to diet has not previously been investigated. We tested whether herbivorous species have higher bite forces, larger jaw muscles and more robust jaws than carnivorous species. We measured in vivo and theoretical bite forces in 27 serrasalmid species. We compared the size of the adductor mandibulae muscle, the jaw mechanical advantages, the type of jaw occlusion, and the size and shape of the lower jaw. We also examined the association between bite performance and functional morphological traits of the oral jaw system. Contrary to our predictions, carnivorous piranhas deliver stronger bites than their herbivorous counterparts. The size of the adductor mandibulae muscle varies with bite force and muscles are larger in carnivorous species. Our study highlights an underestimated level of functional morphological diversity in a fish group of exclusive biters. We provide evidence that the trophic specialization towards carnivory in piranhas results from changes in the configuration of the adductor mandibulae muscle and the lower jaw shape, which have major effects on bite performance and bite strategy.
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Affiliation(s)
- Alessia Huby
- Laboratory of Functional and Evolutionary Morphology, University of Liège, Liège, Belgium
| | - Aurélien Lowie
- Laboratory of Functional and Evolutionary Morphology, University of Liège, Liège, Belgium
- Evolutionary Morphology of Vertebrates, Ghent University, Gent, Belgium
| | - Anthony Herrel
- UMR7179 MNHN/CNRS, National Museum of Natural History, Paris, France
- Evolutionary Morphology of Vertebrates, Ghent University, Gent, Belgium
| | - Régis Vigouroux
- HYDRECO GUYANE, Laboratory Environment of Petit Saut, Kourou, French Guiana
| | - Bruno Frédérich
- Laboratory of Functional and Evolutionary Morphology, University of Liège, Liège, Belgium
| | - Xavier Raick
- Laboratory of Functional and Evolutionary Morphology, University of Liège, Liège, Belgium
| | - Gregório Kurchevski
- Fish Passage Center, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | | | - Eric Parmentier
- Laboratory of Functional and Evolutionary Morphology, University of Liège, Liège, Belgium
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11
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Reef fish functional traits evolve fastest at trophic extremes. Nat Ecol Evol 2018; 3:191-199. [DOI: 10.1038/s41559-018-0725-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2018] [Accepted: 10/21/2018] [Indexed: 12/11/2022]
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12
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Konow N, Price S, Abom R, Bellwood D, Wainwright P. Decoupled diversification dynamics of feeding morphology following a major functional innovation in marine butterflyfishes. Proc Biol Sci 2018; 284:rspb.2017.0906. [PMID: 28768889 DOI: 10.1098/rspb.2017.0906] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Accepted: 06/26/2017] [Indexed: 11/12/2022] Open
Abstract
The diversity of fishes on coral reefs is influenced by the evolution of feeding innovations. For instance, the evolution of an intramandibular jaw joint has aided shifts to corallivory in Chaetodon butterflyfishes following their Miocene colonization of coral reefs. Today, over half of all Chaetodon species consume coral, easily the largest concentration of corallivores in any reef fish family. In contrast with Chaetodon, other chaetodontids, including the long-jawed bannerfishes, remain less intimately associated with coral and mainly consume other invertebrate prey. Here, we test (i) if intramandibular joint (IMJ) evolution in Chaetodon has accelerated feeding morphological diversification, and (ii) if cranial and post-cranial traits were affected similarly. We measured 19 cranial functional morphological traits, gut length and body elongation for 33 Indo-Pacific species. Comparisons of Brownian motion rate parameters revealed that cranial diversification was about four times slower in Chaetodon butterflyfishes with the IMJ than in other chaetodontids. However, the rate of gut length evolution was significantly faster in Chaetodon, with no group-differences for body elongation. The contrasting patterns of cranial and post-cranial morphological evolution stress the importance of comprehensive datasets in ecomorphology. The IMJ appears to enhance coral feeding ability in Chaetodon and represents a design breakthrough that facilitates this trophic strategy. Meanwhile, variation in gut anatomy probably reflects diversity in how coral tissues are procured and assimilated. Bannerfishes, by contrast, retain a relatively unspecialized gut for processing invertebrate prey, but have evolved some of the most extreme cranial mechanical innovations among bony fishes for procuring elusive prey.
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Affiliation(s)
- Nicolai Konow
- Department of Biological Sciences, University of Massachusetts Lowell, Lowell, MA 01852, USA
| | - Samantha Price
- Department of Evolution and Ecology, UC Davis, Davis, CA 95616, USA.,Department of Biological Sciences, Clemson University, Clemson, SC 29634, USA
| | - Richard Abom
- School of Marine and Tropical Biology, James Cook University, Townsville, Queensland 4811, Australia
| | - David Bellwood
- School of Marine and Tropical Biology, James Cook University, Townsville, Queensland 4811, Australia.,ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland 4811, Australia
| | - Peter Wainwright
- Department of Evolution and Ecology, UC Davis, Davis, CA 95616, USA
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