1
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Torgersen KT, Bouton BJ, Hebert AR, Kleyla NJ, Plasencia X, Rolfe GL, Tagliacollo VA, Albert JS. Phylogenetic structure of body shape in a diverse inland ichthyofauna. Sci Rep 2023; 13:20758. [PMID: 38007528 PMCID: PMC10676429 DOI: 10.1038/s41598-023-48086-5] [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: 08/21/2023] [Accepted: 11/22/2023] [Indexed: 11/27/2023] Open
Abstract
Body shape is a fundamental metric of animal diversity affecting critical behavioral and ecological dynamics and conservation status, yet previously available methods capture only a fraction of total body-shape variance. Here we use structure-from-motion (SFM) 3D photogrammetry to generate digital 3D models of adult fishes from the Lower Mississippi Basin, one of the most diverse temperate-zone freshwater faunas on Earth, and 3D geometric morphometrics to capture morphologically distinct shape variables, interpreting principal components as growth fields. The mean body shape in this fauna resembles plesiomorphic teleost fishes, and the major dimensions of body-shape disparity are similar to those of other fish faunas worldwide. Major patterns of body-shape disparity are structured by phylogeny, with nested clades occupying distinct portions of the morphospace, most of the morphospace occupied by multiple distinct clades, and one clade (Acanthomorpha) accounting for over half of the total body shape variance. In contrast to previous studies, variance in body depth (59.4%) structures overall body-shape disparity more than does length (31.1%), while width accounts for a non-trivial (9.5%) amount of the total body-shape disparity.
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Affiliation(s)
| | | | - Alyx R Hebert
- Department of Biology, University of Louisiana, Lafayette, USA
| | - Noah J Kleyla
- Department of Biology, University of Louisiana, Lafayette, USA
| | | | - Garrett L Rolfe
- Department of Biology, University of Louisiana, Lafayette, USA
| | | | - James S Albert
- Department of Biology, University of Louisiana, Lafayette, USA
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2
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Daniels J, Sainz G, Katija K. New Method for Rapid 3D Reconstruction of Semi-Transparent Underwater Animals and Structures. Integr Org Biol 2023; 5:obad023. [PMID: 37521145 PMCID: PMC10372866 DOI: 10.1093/iob/obad023] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 04/20/2023] [Indexed: 08/01/2023] Open
Abstract
Morphological features are the primary identifying properties of most animals and key to many comparative physiological studies, yet current techniques for preservation and documentation of soft-bodied marine animals are limited in terms of quality and accessibility. Digital records can complement physical specimens, with a wide array of applications ranging from species description to kinematics modeling, but options are lacking for creating models of soft-bodied semi-transparent underwater animals. We developed a lab-based technique that can live-scan semi-transparent, submerged animals, and objects within seconds. To demonstrate the method, we generated full three-dimensional reconstructions (3DRs) of an object of known dimensions for verification, as well as two live marine animals-a siphonophore and an amphipod-allowing detailed measurements on each. Techniques like these pave the way for faster data capture, integrative and comparative quantitative approaches, and more accessible collections of fragile and rare biological samples.
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Affiliation(s)
| | - Giovanna Sainz
- Monterey Bay Aquarium Research Institute, Moss Landing, CA, 95039, USA
| | - Kakani Katija
- Monterey Bay Aquarium Research Institute, Moss Landing, CA, 95039, USA
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3
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Buser TJ, Kee VE, Terry RC, Summers AP, Sidlauskas BL. Taurus of the Tidepool? Inferring the Function of Cranial Weapons in Intertidal Sculpins (Pisces: Cottoidea: Oligocottinae). ICHTHYOLOGY & HERPETOLOGY 2023. [DOI: 10.1643/i2022044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
Affiliation(s)
- Thaddaeus J. Buser
- Department of Fisheries, Wildlife and Conservation Sciences, Oregon State University, Corvallis, Oregon; (VEK) ; and (BLS)
. ORCID: (BLS) 0000-0003-0597-4085
| | - Victoria E. Kee
- Department of Fisheries, Wildlife and Conservation Sciences, Oregon State University, Corvallis, Oregon; (VEK) ; and (BLS)
. ORCID: (BLS) 0000-0003-0597-4085
| | - Rebecca C. Terry
- Department of Integrative Biology, Oregon State University, Corvallis, Oregon; . ORCID: 0000-0002-9803-6292
| | - Adam P. Summers
- Department of Biology and SAFS, University of Washington, Friday Harbor Laboratories, Friday Harbor, Washington; . ORCID: 0000-0003-1930-9748
| | - Brian L. Sidlauskas
- Department of Fisheries, Wildlife and Conservation Sciences, Oregon State University, Corvallis, Oregon; (VEK) ; and (BLS)
. ORCID: (BLS) 0000-0003-0597-4085
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4
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Evans KM, Larouche O, West JL, Gartner SM, Westneat MW. Burrowing constrains patterns of skull shape evolution in wrasses. Evol Dev 2023; 25:73-84. [PMID: 35971630 DOI: 10.1111/ede.12415] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 07/08/2022] [Accepted: 07/12/2022] [Indexed: 01/13/2023]
Abstract
The evolution of behavioral and ecological specialization can have marked effects on the tempo and mode of phenotypic evolution. Head-first burrowing has been shown to exert powerful selective pressures on the head and body shapes of many vertebrate and invertebrate taxa. In wrasses, burrowing behaviors have evolved multiple times independently, and are commonly used in foraging and predator avoidance behaviors. While recent studies have examined the kinematics and body shape morphology associated with this behavior, no study to-date has examined the macroevolutionary implications of burrowing on patterns of phenotypic diversification in this clade. Here, we use three-dimensional geometric morphometrics and phylogenetic comparative methods to study the evolution of skull shape in fossorial wrasses and their relatives. We test for skull shape differences between burrowing and non burrowing wrasses and evaluate hypotheses of shape convergence among the burrowing wrasses. We also quantify rates of skull shape evolution between burrowing and non burrowing wrasses to test for whether burrowing constrains or accelerates rates of skull shape evolution in this clade. We find that while burrowing and non burrowing wrasses exhibit similar degrees of morphological disparity, for burrowing wrasses, it took nearly twice as long to amass this disparity. Furthermore, while the disparities between groups are evenly matched, we find that most burrowing species are confined to a particular region of shape space with most species exhibiting narrower heads than many non-burrowing species. These results suggest head-first burrowing constrains patterns of skull shape diversification in wrasses by potentially restricting the range of phenotypes that can perform this behavior.
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Affiliation(s)
- Kory M Evans
- Department of Bioscience, Rice University, Houston, Texas, USA
| | | | - JoJo L West
- Department of Bioscience, Rice University, Houston, Texas, USA
| | - Samantha M Gartner
- Department of Organismal Biology and Anatomy, University of Chicago Biological Sciences Division, Chicago, Illinois, USA
| | - Mark W Westneat
- Department of Organismal Biology and Anatomy, University of Chicago Biological Sciences Division, Chicago, Illinois, USA
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5
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Taphorn DC, Liverpool E, Lujan NK, DoNascimiento C, Hemraj DD, Crampton WGR, Kolmann MA, Fontenelle JP, de Souza LS, Werneke DC, Ram M, Bloom DD, Sidlauskas BL, Holm E, Lundberg JG, Sabaj MH, Bernard C, Armbruster JW, López-Fernández H. Annotated checklist of the primarily freshwater fishes of Guyana. PROCEEDINGS OF THE ACADEMY OF NATURAL SCIENCES OF PHILADELPHIA 2022. [DOI: 10.1635/053.168.0101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
| | - Elford Liverpool
- Department of Biology, Faculty of Natural Sciences, University of Guyana, Turkeyen, East Coast Demerara, 413741, Georgetown, Guyana.
| | - Nathan K. Lujan
- Department of Natural History, Royal Ontario Museum, 100 Queen's Park, Toronto, Ontario, M5S 2C6, Canada and Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, M5S 3B2, Canada
| | - Carlos DoNascimiento
- Universidad de Antioquia, Grupo de Ictiología, Instituto de Biología, Calle 67 No. 53-108, Medellín, Antioquia, Colombia
| | - Devya D. Hemraj
- Centre for the Study of Biological Diversity, Department of Biology, Faculty of Natural Sciences, University of Guyana, Turkeyen Campus, Greater Georgetown, Guyana
| | | | - Matthew A. Kolmann
- Department of Biology, University of Louisville, Louisville, KY, 40292, USA
| | - João Pedro Fontenelle
- University of Toronto, Institute of Forestry and Conservation, 33 Willcocks St. Office 4004, M5S 3E8, Toronto, ON, Canada
| | - Lesley S. de Souza
- Field Museum of Natural History, 1400 S. Lake Shore, Chicago, IL, 60605 USA
| | - David C. Werneke
- Department of Biological Sciences, 101 Rouse, Auburn University, Auburn, AL, 36849, USA
| | - Mark Ram
- Department of Biology, Faculty of Natural Sciences, University of Guyana, Turkeyen Campus, Greater Georgetown, Guyana
| | - Devin D. Bloom
- Department of Biological Sciences and Institute of the Environment & Sustainability, Western Michigan University, Kalamazoo, MI, 49008-5410, USA
| | - Brian L. Sidlauskas
- Oregon State University, Department of Fisheries, Wildlife and Conservation Sciences, 104 Nash Hall, Corvallis, Oregon, 97331-3803 USA and Department of Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, Dist
| | - Erling Holm
- Department of Natural History, Royal Ontario Museum, 100 Queen's Park, Toronto, Ontario, M5S 2C6, Canada
| | - John G. Lundberg
- The Academy of Natural Sciences of Drexel University, 1900 Benjamin Franklin Parkway, Philadelphia, PA, 19103, USA
| | - Mark H. Sabaj
- The Academy of Natural Sciences of Drexel University, 1900 Benjamin Franklin Parkway, Philadelphia, PA, 19103, USA
| | - Calvin Bernard
- Department of Biology, Faculty of Natural Sciences, University of Guyana, Turkeyen Campus, Greater Georgetown, Guyana
| | | | - Hernán López-Fernández
- Department of Ecology and Evolutionary Biology and Museum of Zoology, University of Michigan, 1105 North University Ave. Ann Arbor, MI, 48109, USA
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6
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Wynd B, Abdala F, Nesbitt SJ. Ontogenetic growth in the crania of Exaeretodon argentinus (Synapsida: Cynodontia) captures a dietary shift. PeerJ 2022; 10:e14196. [PMID: 36299507 PMCID: PMC9590418 DOI: 10.7717/peerj.14196] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 09/15/2022] [Indexed: 01/26/2023] Open
Abstract
Background An ontogenetic niche shift in vertebrates is a common occurrence where ecology shifts with morphological changes throughout growth. How ecology shifts over a vertebrate's lifetime is often reconstructed in extant species-by combining observational and skeletal data from growth series of the same species-because interactions between organisms and their environment can be observed directly. However, reconstructing shifts using extinct vertebrates is difficult and requires well-sampled growth series, specimens with relatively complete preservation, and easily observable skeletal traits associated with ecologies suspected to change throughout growth, such as diet. Methods To reconstruct ecological changes throughout the growth of a stem-mammal, we describe changes associated with dietary ecology in a growth series of crania of the large-bodied (∼2 m in length) and herbivorous form, Exaeretodon argentinus (Cynodontia: Traversodontidae) from the Late Triassic Ischigualasto Formation, San Juan, Argentina. Nearly all specimens were deformed by taphonomic processes, so we reconstructed allometric slope using a generalized linear mixed effects model with distortion as a random effect. Results Under a mixed effects model, we find that throughout growth, E. argentinus reduced the relative length of the palate, postcanine series, orbits, and basicranium, and expanded the relative length of the temporal region and the height of the zygomatic arch. The allometric relationship between the zygomatic arch and temporal region with the total length of the skull approximate the rate of growth for feeding musculature. Based on a higher allometric slope, the zygoma height is growing relatively faster than the length of the temporal region. The higher rate of change in the zygoma may suggest that smaller individuals had a crushing-dominated feeding style that transitioned into a chewing-dominated feeding style in larger individuals, suggesting a dietary shift from possible faunivory to a more plant-dominated diet. Dietary differentiation throughout development is further supported by an increase in sutural complexity and a shift in the orientation of microwear anisotropy between small and large individuals of E. argentinus. A developmental transition in the feeding ecology of E. argentinus is reflective of the reconstructed dietary transition across Gomphodontia, wherein the earliest-diverging species are inferred as omnivorous and the well-nested traversodontids are inferred as herbivorous, potentially suggesting that faunivory in immature individuals of the herbivorous Traversodontidae may be plesiomorphic for the clade.
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Affiliation(s)
- Brenen Wynd
- Department of Geosciences, Virginia Tech, Blacksburg, VA, United States of America
| | - Fernando Abdala
- CONICET-Fundación Miguel Lillo, Unidad Ejecutora Lillo, San Miguel de Tucumán, Tucumán, Argentina,Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa
| | - Sterling J. Nesbitt
- Department of Geosciences, Virginia Tech, Blacksburg, VA, United States of America
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7
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Gerstenhaber C, Knapp A. Sexual selection leads to positive allometry but not sexual dimorphism in the expression of horn shape in the blue wildebeest, Connochaetes taurinus. BMC Ecol Evol 2022; 22:107. [PMID: 36089581 PMCID: PMC9464394 DOI: 10.1186/s12862-022-02060-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 08/22/2022] [Indexed: 11/30/2022] Open
Abstract
Sexual selection is thought to be an important driver of adaptation, speciation and extinction. Empirically testing these predictions across macroevolutionary timescales first requires an understanding of the morphology of secondary sexual traits in extant taxa. We used three-dimensional geometric morphometrics to analyse a large sample of the skull of the blue wildebeest, Connochaetes taurinus, in which horns are found in both sexes but only used in intrasexual competition in males. We show that the horns fit several predictions of secondary sexual traits; overall skull shape is significantly correlated with size (R2 = 0.38, p = 0.001), and the sexually selected horns show drastically higher growth rates and variation than any other skull element, supporting previous findings. We also find that despite showing significant sexual dimorphism in shape and size (R2 = 0.21, p = 0.001), allometric growth trajectories of sexes are identical (R2 = 0.01, p = 0.635) and dimorphism is not readily detectable without prior knowledge of sex, and is not possible when shape is corrected for size. Our results show that even with strong sexual selection operating in only one sex, the expression of secondary sexual traits may show characteristic and indistinguishable patterns of growth and variance in both sexes.
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8
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Freiler MK, Proffitt MR, Smith GT. Electrocommunication signals and aggressive behavior vary among male morphs in an apteronotid fish, Compsaraia samueli. J Exp Biol 2022; 225:275495. [DOI: 10.1242/jeb.243452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 05/17/2022] [Indexed: 11/20/2022]
Abstract
Within-species variation in male morphology is common among vertebrates and is often characterized by dramatic differences in behavior and hormonal profiles. Males with divergent morphs also often use communication signals in a status-dependent way. Weakly electric knifefish are an excellent system for studying variation in male morphology and communication and its hormonal control. Knifefish transiently modulate the frequency of their electric organ discharge (EOD) during social encounters to produce chirps and rises. In the knifefish Compsaraia samueli, males vary extensively in jaw length. EODs and their modulations (chirps and rises) have never been investigated in this species, so it is unclear whether jaw length is related to the function of these signals. We used three behavioral assays to analyze EOD modulations in male C. samueli: (1) artificial playbacks, (2) relatively brief, live agonistic dyadic encounters, and (3) long-term overnight recordings. We also measured circulating levels of two androgens, 11-ketotestosterone and testosterone. Chirp structure varied within and across individuals in response to artificial playback, but was unrelated to jaw length. Males with longer jaws were more often dominant in dyadic interactions. Chirps and rises were correlated with and preceded attacks regardless of status, suggesting these signals function in aggression. In longer-term interactions, chirp rate declined after one week of pairing, but was unrelated to male morphology. Levels of circulating androgens were low and not predictive of jaw length or EOD signal parameters. These results suggest that communication signals and variation in male morphology are linked to outcomes of non-breeding agonistic contests.
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Affiliation(s)
- Megan K. Freiler
- Department of Biology, Indiana University, 1001 E. 3rd St., Bloomington, IN, 47405, USA
- Center for the Integrative Study of Animal Behavior, Indiana University, 409 N. Park Ave., Bloomington, IN, 47405, USA
| | - Melissa R. Proffitt
- Department of Biology, Indiana University, 1001 E. 3rd St., Bloomington, IN, 47405, USA
- Center for the Integrative Study of Animal Behavior, Indiana University, 409 N. Park Ave., Bloomington, IN, 47405, USA
| | - G. Troy Smith
- Department of Biology, Indiana University, 1001 E. 3rd St., Bloomington, IN, 47405, USA
- Center for the Integrative Study of Animal Behavior, Indiana University, 409 N. Park Ave., Bloomington, IN, 47405, USA
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9
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Peixoto LAW, de Pinna M. Patterns of diversification and phylogenetic structure in the dorsolateral head musculature of Neotropical electric eels (Ostariophysi: Gymnotiformes), with a myological synonymy. NEOTROPICAL ICHTHYOLOGY 2022. [DOI: 10.1590/1982-0224-2021-0009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Abstract The present study offers a broad comparative analysis of the dorsolateral head musculature in the Gymnotiformes, with detailed descriptions and illustrations of the dorsolateral head muscles of 83 species representing combined all valid genera. Results permit a detailed assessment of primary homologies and taxonomically-relevant variation across the order. This provides the basis for a myological synonymy, which organizes 33 previously proposed names for 15 recognized muscles. Morphological variation derived from dorsolateral head musculature was coded into 56 characters. When analyzed in isolation, that set of characters results in Gymnotidae as the sister group of remaining gymnotiforms, and all other currently recognized families as monophyletic groups. In a second analysis, myological characters were concatenated with other previously proposed characters into a phenotypic matrix. Results of that analysis reveal new myological synapomorphies for nearly all taxonomic categories within Gymnotiformes. A Partitioned Bremer Support (PBS) was used to asses the significance of comparative myology in elucidating phylogenetic relationships. PBS values show strongly non-uniform distributions on the tree, with positive scores skewed towards more inclusive taxa, and negative PBS values concentrated on less inclusive clades. Our results provide background for future studies on biomechanical constraints evolved in the early stages of gymnotiform evolution.
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10
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Cohen HE, Kane EA. Biting kinematics do not differ between ecologically divergent populations of Trinidadian guppies. J Zool (1987) 2021. [DOI: 10.1111/jzo.12924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- H. E. Cohen
- Department of Biology Georgia Southern University Statesboro GA USA
| | - E. A. Kane
- Department of Biology University of Louisiana at Lafayette Lafayette LA USA
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11
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Egan JP, Buser TJ, Burns MD, Simons AM, Hundt PJ. Patterns of Body Shape Diversity and Evolution in Intertidal and Subtidal Lineages of Combtooth Blennies (Blenniidae). Integr Org Biol 2021; 3:obab004. [PMID: 33937629 PMCID: PMC8077888 DOI: 10.1093/iob/obab004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Marine intertidal zones can be harsher and more dynamic than bordering subtidal zones, with extreme and temporally variable turbulence, water velocity, salinity, temperature, and dissolved oxygen levels. Contrasting environmental conditions and ecological opportunities in subtidal versus intertidal habitats may generate differing patterns of morphological diversity. In this study we used phylogenetic comparative methods, measurements of body length, and two-dimensional landmarks to characterize body shape and size diversity in combtooth blennies (Ovalentaria: Blenniidae) and test for differences in morphological diversity between intertidal, subtidal, and supralittoral zones. We found that subtidal combtooth blennies have significantly higher body shape disparity and occupy a region of morphospace three times larger than intertidal lineages. The intertidal morphospace was almost entirely contained within the subtidal morphospace, showing that intertidal combtooth blennies did not evolve unique body shapes. We found no significant differences in body size disparity between tidal zones, no correlations between body shape and tidal zone or body size and tidal zone, and no body shape convergence associated with tidal zone. Our findings suggest that a subset of combtooth blenny body shapes are suitable for life in both subtidal and intertidal habitats. Many species in regions of morphospace unique to subtidal combtooth blennies exhibit distinct microhabitat use, which suggests subtidal environments promoted morphological diversification via evolutionary microhabitat transitions. In contrast, limited intertidal body shape diversity may be due to strong selective pressures that constrained body shape evolution and environmental filtering that prevented colonization of intertidal zones by certain subtidal body shapes.
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Affiliation(s)
- Joshua P Egan
- Department of Biological Sciences, Western Michigan University, 2375 West Michigan Ave, Kalamazoo, MI 49006, USA
| | - Thaddaeus J Buser
- Department of Fisheries and Wildlife, Oregon State University, 104 Nash Hall, 2820 SW Campus Way, Corvallis, OR 97331, USA
| | - Michael D Burns
- Cornell Lab of Ornithology, Cornell University Museum of Vertebrates, 159 Sapsucker Woods Road, Ithaca, NY 14850, USA
| | - Andrew M Simons
- Bell Museum of Natural History, University of Minnesota, 100 Ecology, 1987 Upper Buford Saint Paul, MN 55108, USA.,Department of Fisheries, Wildlife and Conservation Biology, University of Minnesota, 2003 Upper Buford Circle, Saint Paul, Minnesota 55108, USA
| | - Peter J Hundt
- Bell Museum of Natural History, University of Minnesota, 100 Ecology, 1987 Upper Buford Saint Paul, MN 55108, USA.,Department of Fisheries, Wildlife and Conservation Biology, University of Minnesota, 2003 Upper Buford Circle, Saint Paul, Minnesota 55108, USA
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12
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Peixoto LAW, Datovo A, Menezes NA, de Santana CD. A new species of sexually dimorphic and rheophilic ghost knifefish (Apteronotidae: Gymnotiformes) from the Amazon basin. JOURNAL OF FISH BIOLOGY 2021; 98:803-816. [PMID: 33247436 DOI: 10.1111/jfb.14629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 11/03/2020] [Accepted: 11/24/2020] [Indexed: 06/12/2023]
Abstract
A new species of ghost knifefish, Apteronotus, is described from high-energy environments in the Rios Mapuera and Trombetas (at Cachoeira Porteira waterfalls), Brazil. X-ray microcomputed tomography (μCT scan) was used to access the internal anatomy of the type series. The new species is distinguished from all congeners by the anteriormost position of the anus, with its posterior margin extending less than one eye diameter beyond the vertical through the caudal limit of the posterior nostril, the low number of anal-fin rays (117-125) and the reduced number of branchiostegal rays (three). A series of modifications associated with secondary sexual dimorphism on the preorbital region of mature males are depicted and discussed. In addition, comments on homologies of the branchiostegal rays in Apteronotidae are provided.
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Affiliation(s)
| | - Aléssio Datovo
- Museu de Zoologia da Universidade de São Paulo, São Paulo, Brazil
| | | | - Carlos David de Santana
- Division of Fishes, Department of Vertebrate Zoology, MRC-159, National Museum of Natural History, Smithsonian Institution, Washington, District of Columbia, USA
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13
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Knapp A, Knell RJ, Hone DWE. Three-dimensional geometric morphometric analysis of the skull of Protoceratops andrewsi supports a socio-sexual signalling role for the ceratopsian frill. Proc Biol Sci 2021; 288:20202938. [PMID: 33529562 PMCID: PMC7893235 DOI: 10.1098/rspb.2020.2938] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 01/12/2021] [Indexed: 12/19/2022] Open
Abstract
Socio-sexual selection is predicted to be an important driver of evolution, influencing speciation, extinction and adaptation. The fossil record provides a means of testing these predictions, but detecting its signature from morphological data alone is difficult. There are, nonetheless, some specific patterns of growth and variation which are expected of traits under socio-sexual selection. The distinctive parietal-squamosal frill of ceratopsian dinosaurs has previously been suggested as a socio-sexual display trait, but evidence for this has been limited. Here, we perform a whole-skull shape analysis of an unprecedentedly large sample of specimens of Protoceratops andrewsi using a high-density landmark-based geometric morphometric approach to test four predictions regarding a potential socio-sexual signalling role for the frill. Three predictions-low integration with the rest of the skull, significantly higher rate of change in size and shape during ontogeny, and higher morphological variance than other skull regions-are supported. One prediction, sexual dimorphism in shape, is not supported, suggesting that sexual differences in P. andrewsi are likely to be small. Together, these findings are consistent with mutual mate choice or selection for signalling quality in more general social interactions, and support the hypothesis that the frill functioned as a socio-sexual signal in ceratopsian dinosaurs.
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Affiliation(s)
- A. Knapp
- Department of Earth Sciences, The Natural History Museum, London, UK
- Department of Organismal Biology, Queen Mary University of London, London, UK
| | - R. J. Knell
- Department of Organismal Biology, Queen Mary University of London, London, UK
| | - D. W. E. Hone
- Department of Organismal Biology, Queen Mary University of London, London, UK
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14
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Albert JS, Tagliacollo VA, Dagosta F. Diversification of Neotropical Freshwater Fishes. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2020. [DOI: 10.1146/annurev-ecolsys-011620-031032] [Citation(s) in RCA: 76] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Neotropical freshwater fishes (NFFs) constitute the most diverse continental vertebrate fauna on Earth, with more than 6,200 named species compressed into an aquatic footprint <0.5% of the total regional land-surface area and representing the greatest phenotypic disparity and functional diversity of any continental ichthyofauna. Data from the fossil record and time-calibrated molecular phylogenies indicate that most higher taxa (e.g., genera, families) diversified relatively continuously through the Cenozoic, across broad geographic ranges of the South American platform. Biodiversity data for most NFF clades support a model of continental radiation rather than adaptive radiation, in which speciation occurs mainly in allopatry, and speciation and adaptation are largely decoupled. These radiations occurred under the perennial influence of river capture and sea-level oscillations, which episodically fragmented and merged portions of adjacent river networks. The future of the NFF fauna into the Anthropocene is uncertain, facing numerous threats at local, regional, and continental scales.
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Affiliation(s)
- James S. Albert
- Department of Biology, University of Louisiana at Lafayette, Louisiana 70504, USA
| | | | - Fernando Dagosta
- Faculty of Biological and Environmental Sciences, Universidade Federal da Grande Dourados, Brazil 79825-070
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15
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Saitta ET, Stockdale MT, Longrich NR, Bonhomme V, Benton MJ, Cuthill IC, Makovicky PJ. An effect size statistical framework for investigating sexual dimorphism in non-avian dinosaurs and other extinct taxa. Biol J Linn Soc Lond 2020. [DOI: 10.1093/biolinnean/blaa105] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Abstract
Despite reports of sexual dimorphism in extinct taxa, such claims in non-avian dinosaurs have been rare over the last decade and have often been criticized. Since dimorphism is widespread in sexually reproducing organisms today, under-reporting in the literature might suggest either methodological shortcomings or that this diverse group exhibited highly unusual reproductive biology. Univariate significance testing, especially for bimodality, is ineffective and prone to false negatives. Species recognition and mutual sexual selection hypotheses, therefore, may not be required to explain supposed absence of sexual dimorphism across the grade (a type II error). Instead, multiple lines of evidence support sexual selection and variation of structures consistent with secondary sexual characteristics, strongly suggesting sexual dimorphism in non-avian dinosaurs. We propose a framework for studying sexual dimorphism in fossils, focusing on likely secondary sexual traits and testing against all alternate hypotheses for variation in them using multiple lines of evidence. We use effect size statistics appropriate for low sample sizes, rather than significance testing, to analyse potential divergence of growth curves in traits and constrain estimates for dimorphism magnitude. In many cases, estimates of sexual variation can be reasonably accurate, and further developments in methods to improve sex assignments and account for intrasexual variation (e.g. mixture modelling) will improve accuracy. It is better to compare estimates for the magnitude of and support for dimorphism between datasets than to dichotomously reject or fail to reject monomorphism in a single species, enabling the study of sexual selection across phylogenies and time. We defend our approach with simulated and empirical data, including dinosaur data, showing that even simple approaches can yield fairly accurate estimates of sexual variation in many cases, allowing for comparison of species with high and low support for sexual variation.
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Affiliation(s)
- Evan T Saitta
- Life Sciences Section, Integrative Research Center, Field Museum of Natural History, Chicago, IL, USA
| | | | - Nicholas R Longrich
- Department of Biology and Biochemistry and Milner Centre for Evolution, University of Bath, Bath, UK
| | - Vincent Bonhomme
- Institut des sciences de l’évolution, Université de Montpellier, Montpellier, France
| | | | - Innes C Cuthill
- School of Biological Sciences, University of Bristol, Bristol, UK
| | - Peter J Makovicky
- Department of Earth and Environmental Sciences, University of Minnesota, Minneapolis, MN, USA
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