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Nweeia MT. Biology and Cultural Importance of the Narwhal. Annu Rev Anim Biosci 2024; 12:187-208. [PMID: 38358838 DOI: 10.1146/annurev-animal-021122-112307] [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] [Indexed: 02/17/2024]
Abstract
Though narwhal have survived multiple ice ages, including 2.5 Ma and the last interglacial period with warming temperatures, Arctic climate change during the Anthropocene introduces new challenges. Despite their evolutionary connection to Arctic Pleistocene fossils, narwhal archeocete ancestors from the Pliocene (Bohaskaia monodontoides) and Miocene (Denebola and Odobenocetopsidae) inhabited warm waters. Narwhal Arctic adaptation holds valuable insights into unique traits, including thin skin; extreme diving capacity; and a unique straight, spiraled, and sensory tooth organ system. Inaccessible weather, ice conditions, and darkness limit scientific studies, though Inuit knowledge adds valuable observations of narwhal ecology, biology, and behavior. Existing and future studies in myriad fields of physical, chemical, biological, and genetic science, combined and integrated with remote sensing and imaging technologies, will help elucidate narwhal evolution, biology, and adaptation. When integrated with Qaujimajatuqangit, "the Inuit way of knowing," these studies help describe interesting biologic expressions of the narwhal.
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Affiliation(s)
- Martin T Nweeia
- Department of Restorative Dentistry and Biomaterials Sciences, Harvard School of Dental Medicine, Boston, Massachusetts, USA;
- Arctic Studies Center, Smithsonian Institution, Washington, DC, USA
- Department of Vertebrate Zoology, Canadian Museum of Nature, Ottawa, Ontario, Canada
- Zoonomia Consortium, Broad Institute of Harvard/MIT, Boston, Massachusetts, USA
- Polar Institute, The Wilson Center, Washington, DC, USA
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2
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Yu G, Wong BH, Painting CJ, Li H, Yu L, Zhang Z, Zhang S, Li D. Males armed with big weapons win fights at limited cost in ant-mimicking jumping spiders. Curr Zool 2024; 70:98-108. [PMID: 38476142 PMCID: PMC10926263 DOI: 10.1093/cz/zoac101] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 12/18/2022] [Indexed: 03/14/2024] Open
Abstract
A core assumption of sexual selection theory is that sexually selected weapons, specialized morphological structures used directly in male contests, can improve an individual's reproductive success but only if the bearer can overcome associated costs, the negative effects on the bearer's fitness components. However, recent studies have shown that producing and wielding exaggerated weapons may not necessarily be costly. Rather, some traits can be selected for supporting, or compensating for, the expense of producing and wielding such exaggerated weapons. In the ant-mimicking jumping spider Myrmarachne gisti, exaggerated chelicerae are borne only by adult males and not females, showing sexual dimorphism and steep positive allometry with body size. Here, we determine the potential benefits of bearing exaggerated chelicerae during male contests and explore the potential for costs in terms of prey-capture efficiency and compensation between chelicera size and neighboring trait size. While males with longer chelicerae won most of their male-male contests, we found no significant differences in prey-capture efficiency between males and females regardless of whether prey was winged or flightless. Males' elongated chelicerae thus do not impede their efficiency at capturing prey. Furthermore, we found that the sizes of all neighboring traits are positively correlated with chelicera size, suggesting that these traits may be under correlational selection. Taken together, our findings suggest that M. gisti males armed with the exaggerated chelicerae that function as weapons win more fights at limited cost for performance in prey capture and compensate for neighboring structures.
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Affiliation(s)
- Guocheng Yu
- State Key Laboratory of Biocatalysis and Enzyme Engineering and Centre for Behavioral Ecology and Evolution, School of Life Sciences, Hubei University, Wuhan 430062, China
| | - Boon Hui Wong
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore
| | - Christina J Painting
- Te Aka Mātuatua School of Science, University of Waikato, Private Bag 3105, Hamilton 3240, New Zealand
| | - Hongze Li
- State Key Laboratory of Biocatalysis and Enzyme Engineering and Centre for Behavioral Ecology and Evolution, School of Life Sciences, Hubei University, Wuhan 430062, China
| | - Long Yu
- State Key Laboratory of Biocatalysis and Enzyme Engineering and Centre for Behavioral Ecology and Evolution, School of Life Sciences, Hubei University, Wuhan 430062, China
| | - Zengtao Zhang
- State Key Laboratory of Biocatalysis and Enzyme Engineering and Centre for Behavioral Ecology and Evolution, School of Life Sciences, Hubei University, Wuhan 430062, China
| | - Shichang Zhang
- State Key Laboratory of Biocatalysis and Enzyme Engineering and Centre for Behavioral Ecology and Evolution, School of Life Sciences, Hubei University, Wuhan 430062, China
| | - Daiqin Li
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore
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Ji J, Shi Q, Zhang K, Chen L, Zhu X, Li D, Gao X, Niu L, Wang L, Luo J, Cui J. Sexually dimorphic morphology, feeding behavior and gene expression profiles in cotton aphid Aphis gossypii. PEST MANAGEMENT SCIENCE 2023; 79:5152-5161. [PMID: 37642384 DOI: 10.1002/ps.7718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2023] [Revised: 05/23/2023] [Accepted: 08/29/2023] [Indexed: 08/31/2023]
Abstract
BACKGROUND Sexual dimorphism exists in most insects; however, less is known about sexual dimorphism in aphids. In this study, we identified sexually dimorphic differences in morphology, feeding behavior and gene expression between sexual females and males of the cotton aphid through electron microscopy, electrical penetration graph techniques and RNA sequencing. RESULTS All males were alate with a slender reddish-yellow body and abdominal yellow-black stripes, whereas all sexual females were apterous with a pudgy green body. Sensillum types on the antennae were identical between the two sexes, although males had more sensilla, possibly because the antennae are significantly longer in males compared with sexual females. In terms of feeding behavior, males spent more time probing mesophyll cells and the phloem sieve, and salivating into the phloem sieve. By contrast, sexual females spent more time ingesting xylem sap. In total, 510 and 724 genes were specifically expressed in sexual females and males, respectively, and were significantly enriched in signaling pathways related to reproduction for sexual females (e.g. ovarian steroidogenesis, oxytocin signaling pathway) and energy and flight for males (e.g. thermogenesis, insulin signaling pathway). Moreover, 8551 differentially expressed genes were identified between the two sexes, of which the 3720 upregulated genes in sexual females were mostly enriched in signaling pathways of metabolism and energy, such as thermogenesis and the citrate cycle. CONCLUSION This study provides insight into sexual dimorphism in aphids and lays a foundation for revealing the molecular mechanism underlying differences between the two sexes in cotton aphid. © 2023 Society of Chemical Industry.
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Affiliation(s)
- Jichao Ji
- Zhengzhou Research Base, National Key Laboratory of Cotton Bio-breeding and Integrated Utilization, School of Agricultural Sciences, Zhengzhou University, Zhengzhou, China
- National Key Laboratory of Cotton Bio-breeding and Integrated Utilization, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang, China
- Western Agricultural Research Center, Chinese Academy of Agricultural Sciences, Changji, China
| | - Qingyu Shi
- National Key Laboratory of Cotton Bio-breeding and Integrated Utilization, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang, China
| | - Kaixin Zhang
- Zhengzhou Research Base, National Key Laboratory of Cotton Bio-breeding and Integrated Utilization, School of Agricultural Sciences, Zhengzhou University, Zhengzhou, China
- National Key Laboratory of Cotton Bio-breeding and Integrated Utilization, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang, China
- Western Agricultural Research Center, Chinese Academy of Agricultural Sciences, Changji, China
| | - Lulu Chen
- College of Agronomy, Xinjiang Agricultural University, Urumqi, China
| | - Xiangzhen Zhu
- Zhengzhou Research Base, National Key Laboratory of Cotton Bio-breeding and Integrated Utilization, School of Agricultural Sciences, Zhengzhou University, Zhengzhou, China
- National Key Laboratory of Cotton Bio-breeding and Integrated Utilization, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang, China
- Western Agricultural Research Center, Chinese Academy of Agricultural Sciences, Changji, China
| | - Dongyang Li
- Zhengzhou Research Base, National Key Laboratory of Cotton Bio-breeding and Integrated Utilization, School of Agricultural Sciences, Zhengzhou University, Zhengzhou, China
- National Key Laboratory of Cotton Bio-breeding and Integrated Utilization, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang, China
- Western Agricultural Research Center, Chinese Academy of Agricultural Sciences, Changji, China
| | - Xueke Gao
- Zhengzhou Research Base, National Key Laboratory of Cotton Bio-breeding and Integrated Utilization, School of Agricultural Sciences, Zhengzhou University, Zhengzhou, China
- National Key Laboratory of Cotton Bio-breeding and Integrated Utilization, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang, China
- Western Agricultural Research Center, Chinese Academy of Agricultural Sciences, Changji, China
| | - Lin Niu
- Zhengzhou Research Base, National Key Laboratory of Cotton Bio-breeding and Integrated Utilization, School of Agricultural Sciences, Zhengzhou University, Zhengzhou, China
- National Key Laboratory of Cotton Bio-breeding and Integrated Utilization, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang, China
- Western Agricultural Research Center, Chinese Academy of Agricultural Sciences, Changji, China
| | - Li Wang
- Zhengzhou Research Base, National Key Laboratory of Cotton Bio-breeding and Integrated Utilization, School of Agricultural Sciences, Zhengzhou University, Zhengzhou, China
- National Key Laboratory of Cotton Bio-breeding and Integrated Utilization, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang, China
- Western Agricultural Research Center, Chinese Academy of Agricultural Sciences, Changji, China
| | - Junyu Luo
- Zhengzhou Research Base, National Key Laboratory of Cotton Bio-breeding and Integrated Utilization, School of Agricultural Sciences, Zhengzhou University, Zhengzhou, China
- National Key Laboratory of Cotton Bio-breeding and Integrated Utilization, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang, China
- Western Agricultural Research Center, Chinese Academy of Agricultural Sciences, Changji, China
| | - Jinjie Cui
- Zhengzhou Research Base, National Key Laboratory of Cotton Bio-breeding and Integrated Utilization, School of Agricultural Sciences, Zhengzhou University, Zhengzhou, China
- National Key Laboratory of Cotton Bio-breeding and Integrated Utilization, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang, China
- Western Agricultural Research Center, Chinese Academy of Agricultural Sciences, Changji, China
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Coste A, Fordyce RE, Loch C. A new dolphin with tusk-like teeth from the late Oligocene of New Zealand indicates evolution of novel feeding strategies. Proc Biol Sci 2023; 290:20230873. [PMID: 37312551 PMCID: PMC10265015 DOI: 10.1098/rspb.2023.0873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 05/24/2023] [Indexed: 06/15/2023] Open
Abstract
All extant toothed whales (Cetacea, Odontoceti) are aquatic mammals with homodont dentitions. Fossil evidence from the late Oligocene suggests a greater diversity of tooth forms among odontocetes, including heterodont species with a variety of tooth shapes and orientations. A new fossil dolphin from the late Oligocene of New Zealand, Nihohae matakoi gen. et sp. nov., consisting of a near complete skull, earbones, dentition and some postcranial material, represents this diverse dentition. Several preserved teeth are horizontally procumbent, including all incisors and canines. These tusk-like teeth suggest adaptive advantages for horizontally procumbent teeth in basal dolphins. Phylogenetic analysis places Nihohae among the poorly constrained basal waipatiid group, many with similarly procumbent teeth. Features of N. matakoi such as its dorsoventrally flattened and long rostrum, long mandibular symphysis, unfused cervical vertebrae, lack of attritional or occlusal wear on the teeth and thin enamel cover suggest the rostrum and horizontally procumbent teeth were used to injure and stun prey though swift lateral head movements, a feeding mode that did not persist in extant odontocetes.
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Affiliation(s)
- Ambre Coste
- Department of Geology, University of Otago, Dunedin, New Zealand
| | - R. Ewan Fordyce
- Department of Geology, University of Otago, Dunedin, New Zealand
| | - Carolina Loch
- Faculty of Dentistry, University of Otago, Dunedin, New Zealand
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5
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Sizing up swords: Correlated evolution of antlers and tusks in ruminants. J MAMM EVOL 2022. [DOI: 10.1007/s10914-022-09628-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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7
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Palaoro AV, García-Hernández S, Buzatto BA, Machado G. Function predicts the allometry of contest-related traits, but not sexual or male dimorphism in the amazonian tusked harvestman. Evol Ecol 2022. [DOI: 10.1007/s10682-022-10152-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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8
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Ackermans NL, Varghese M, Wicinski B, Torres J, De Gasperi R, Pryor D, Elder GA, Gama Sosa MA, Reidenberg JS, Williams TM, Hof PR. Unconventional animal models for traumatic brain injury and chronic traumatic encephalopathy. J Neurosci Res 2021; 99:2463-2477. [PMID: 34255876 PMCID: PMC8596618 DOI: 10.1002/jnr.24920] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 06/09/2021] [Accepted: 06/24/2021] [Indexed: 12/11/2022]
Abstract
Traumatic brain injury (TBI) is one of the main causes of death worldwide. It is a complex injury that influences cellular physiology, causes neuronal cell death, and affects molecular pathways in the brain. This in turn can result in sensory, motor, and behavioral alterations that deeply impact the quality of life. Repetitive mild TBI can progress into chronic traumatic encephalopathy (CTE), a neurodegenerative condition linked to severe behavioral changes. While current animal models of TBI and CTE such as rodents, are useful to explore affected pathways, clinical findings therein have rarely translated into clinical applications, possibly because of the many morphofunctional differences between the model animals and humans. It is therefore important to complement these studies with alternative animal models that may better replicate the individuality of human TBI. Comparative studies in animals with naturally evolved brain protection such as bighorn sheep, woodpeckers, and whales, may provide preventive applications in humans. The advantages of an in-depth study of these unconventional animals are threefold. First, to increase knowledge of the often-understudied species in question; second, to improve common animal models based on the study of their extreme counterparts; and finally, to tap into a source of biological inspiration for comparative studies and translational applications in humans.
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Affiliation(s)
- Nicole L Ackermans
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Center for Anatomy and Functional Morphology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Merina Varghese
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Bridget Wicinski
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Joshua Torres
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Rita De Gasperi
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- General Medical Research Service, James J. Peters Department of Veterans Affairs Medical Center, Bronx, NY, USA
| | - Dylan Pryor
- General Medical Research Service, James J. Peters Department of Veterans Affairs Medical Center, Bronx, NY, USA
| | - Gregory A Elder
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Ronald M. Loeb Center for Alzheimer's Disease, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Neurology Service, James J. Peters Department of Veterans Affairs Medical Center, Bronx, NY, USA
| | - Miguel A Gama Sosa
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- General Medical Research Service, James J. Peters Department of Veterans Affairs Medical Center, Bronx, NY, USA
| | - Joy S Reidenberg
- Center for Anatomy and Functional Morphology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Terrie M Williams
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, CA, USA
| | - Patrick R Hof
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Ronald M. Loeb Center for Alzheimer's Disease, Icahn School of Medicine at Mount Sinai, New York, NY, USA
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Simone Y, van der Meijden A. Armed stem to stinger: a review of the ecological roles of scorpion weapons. J Venom Anim Toxins Incl Trop Dis 2021; 27:e20210002. [PMID: 34527038 PMCID: PMC8425188 DOI: 10.1590/1678-9199-jvatitd-2021-0002] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 03/18/2021] [Indexed: 12/24/2022] Open
Abstract
Scorpions possess two systems of weapons: the pincers (chelae) and the stinger (telson). These are placed on anatomically and developmentally well separated parts of the body, that is, the oral appendages and at the end of the body axis. The otherwise conserved body plan of scorpions varies most in the shape and relative dimensions of these two weapon systems, both across species and in some cases between the sexes. We review the literature on the ecological function of these two weapon systems in each of three contexts of usage: (i) predation, (ii) defense and (iii) sexual contests. In the latter context, we will also discuss their usage in mating. We first provide a comparative background for each of these contexts of usage by giving examples of other weapon systems from across the animal kingdom. Then, we discuss the pertinent aspects of the anatomy of the weapon systems, particularly those aspects relevant to their functioning in their ecological roles. The literature on the functioning and ecological role of both the chelae and the telson is discussed in detail, again organized by context of usage. Particular emphasis is given on the differences in morphology or usage between species or higher taxonomic groups, or between genders, as such cases are most insightful to understand the roles of each of the two distinct weapon systems of the scorpions and their evolutionary interactions. We aimed to synthesize the literature while minimizing conjecture, but also to point out gaps in the literature and potential future research opportunities.
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Affiliation(s)
- Yuri Simone
- CIBIO Research Centre in Biodiversity and Genetic Resources, InBIO, Porto, Portugal
| | - Arie van der Meijden
- CIBIO Research Centre in Biodiversity and Genetic Resources, InBIO, Porto, Portugal
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Inferring the mating system in the burrowing shrimp Lepidophthalmus bocourti (Decapoda, Axiidea, Callichiridae) from the social structure and sexual dimorphism. Behav Ecol Sociobiol 2021. [DOI: 10.1007/s00265-021-03031-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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11
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Detection of foraging behavior from accelerometer data using U-Net type convolutional networks. ECOL INFORM 2021. [DOI: 10.1016/j.ecoinf.2021.101275] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Louis M, Skovrind M, Garde E, Heide-Jørgensen MP, Szpak P, Lorenzen ED. Population-specific sex and size variation in long-term foraging ecology of belugas and narwhals. ROYAL SOCIETY OPEN SCIENCE 2021; 8:202226. [PMID: 33972883 PMCID: PMC8074634 DOI: 10.1098/rsos.202226] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Intraspecific variation in resource use by individuals of different age, sex or size may reflect differing energetic requirements and physiological constraints. Males and females often show differences in diet owing to sexual size dimorphism, different life histories and/or habitat use. Here, we investigate how sex and size influence the long-term foraging ecology of belugas and narwhals in Greenland, using stable isotopes of carbon and nitrogen from bone collagen. We show that males have a higher trophic level and a larger ecological niche than females in West Greenland belugas and in East Greenland narwhals. In addition, for these two populations, we find that δ 15N increases with size, particularly in males. We hypothesize that sexual size dimorphism together with strong maternal investment drive these differences. By contrast, we find no differences in foraging ecology between sexes in West Greenland narwhals and observe no influence of size on trophic level. This may reflect the influence of interspecific competition in West Greenland, where the distributions of belugas and narwhals overlap, and/or geographical resource partitioning among different summer aggregations of narwhals. Our results suggest that sex and size variations in diet are population dependent, and probably the result of varying ecological interactions.
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Affiliation(s)
- Marie Louis
- Globe Institute, University of Copenhagen, Denmark
| | | | - Eva Garde
- Greenland Institute of Natural Resources, Copenhagen, Denmark
| | | | - Paul Szpak
- Trent University, Peterborough, Ontario, Canada
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Fülöp A, Lukács D, Fábián PI, Kocsis B, Csöppü G, Bereczki J, Barta Z. Sex-specific signalling of individual personality by a mutual plumage ornament in a passerine. Behav Ecol Sociobiol 2021. [DOI: 10.1007/s00265-021-02971-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Abstract
The significance of colour signals in species with strong sexual dimorphism and/or elaborated visual ornaments is rather well-understood. Less attention has, however, been devoted to study colour signals in species with weak or no apparent sexual dimorphism. In such species, an interesting possibility arises as both sexes can bear the same colour ornament(s) (i.e. sexes are mutually ornamented), but their signalling value might differ in males and females. We aimed to explore this possibility by investigating the phenotypic correlates of the black bib, a melanin-based plumage ornament, in the Eurasian tree sparrow (Passer montanus). More specifically, we studied the sex-dependent relationships between bib size and three aspects of individuals’ phenotype: body condition (i.e. size-corrected body mass), physiology (i.e. cellular innate immunity/inflammation status, expressed through total leucocyte counts, and chronic physiological stress, expressed through the ratio of heterophils to lymphocytes) and individual personality (i.e. activity in a novel environment). We found that bib size was not associated with body condition and cellular innate immunity/inflammation status, but was positively related to physiological stress levels independent of sex. Furthermore, bib size was negatively associated with activity in males but positively in females. Our findings bring important correlative evidence that mutual ornamental traits may have sex-specific signalling value.
Significance statement
The signalling role of elaborated colourful ornaments, that are usually possessed only by males in sexually dimorphic species, is well-established. The function of various colour traits which are borne by both sexes (i.e. mutual ornaments), however, is less obvious. Do they have a signalling value in both sexes? If yes, do they signal the same information in males and females? Or, most intriguingly, can they convey different information in the two sexes? To test these alternatives, we studied the signalling value of the black bib, a melanin-based mutual plumage ornament, in Eurasian tree sparrows (Passer montanus). Apart from being correlated with chronic stress in both sexes, bib size was positively related to activity in females but negatively in males. Our results suggest that the information content of the same colour trait in males and females can be different in mutually ornamented species.
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14
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Nasoori A. Tusks, the extra-oral teeth. Arch Oral Biol 2020; 117:104835. [PMID: 32668361 DOI: 10.1016/j.archoralbio.2020.104835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 06/25/2020] [Accepted: 06/25/2020] [Indexed: 10/23/2022]
Abstract
OBJECTIVE The present review aims to: a) describe the features that support tusks in extra-oral position, and b) represent distinctive features of tusks, which provide insights into tusks adaptation to ambient conditions. DESIGN A comprehensive review of scientific literature relevant to tusks and comparable dental tissues was conducted. RESULTS The oral cavity provides a desirable condition which is conducive to tooth health. Therefore, it remains questionable how the bare (exposed) tusks resist the extra-oral conditions. The common features among tusked mammals indicate that the structural (e.g. the peculiar dentinal alignment), cellular (e.g. low or lack of cell populations in the tusk), hormonal (e.g. androgens), and behavioral traits have impact on a tusk's preservation and occurrence. CONCLUSIONS Understanding of bare mineralized structures, such as tusks and antlers, and their compatibility with different environments, can provide important insight into oral biology.
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Affiliation(s)
- Alireza Nasoori
- Graduate School of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-ku, Sapporo, 060-0818, Japan.
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Graham ZA, Garde E, Heide-Jørgensen MP, Palaoro AV. The longer the better: evidence that narwhal tusks are sexually selected. Biol Lett 2020; 16:20190950. [PMID: 32183636 PMCID: PMC7115180 DOI: 10.1098/rsbl.2019.0950] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Accepted: 02/24/2020] [Indexed: 01/14/2023] Open
Abstract
Once thought to be the magical horn of a unicorn, narwhal tusks are one of the most charismatic structures in biology. Despite years of speculation, little is known about the tusk's function, because narwhals spend most of their lives hidden underneath the Arctic ice. Some hypotheses propose that the tusk has sexual functions as a weapon or as a signal. By contrast, other hypotheses propose that the tusk functions as an environmental sensor. Since assessing the tusks function in nature is difficult, we can use the morphological relationships of tusk size with body size to understand this mysterious trait. To do so, we collected morphology data on 245 adult male narwhals over the course of 35 years. Based on the disproportional growth and large variation in tusk length we found, we provide the best evidence to date that narwhal tusks are indeed sexually selected. By combining our results on tusk scaling with known material properties of the tusk, we suggest that the narwhal tusk is a sexually selected signal that is used during male-male contests.
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Affiliation(s)
- Zackary A. Graham
- School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA
| | - Eva Garde
- Greenland Institute of Natural Resources, Box 570, DK-3900 Nuuk, Greenland
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