1
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Healey HM, Penn HB, Small CM, Bassham S, Goyal V, Woods MA, Cresko WA. Single Cell RNA Sequencing Provides Clues for the Developmental Genetic Basis of Syngnathidae's Evolutionary Adaptations. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.08.588518. [PMID: 38645265 PMCID: PMC11030337 DOI: 10.1101/2024.04.08.588518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/23/2024]
Abstract
Seahorses, pipefishes, and seadragons are fishes from the family Syngnathidae that have evolved extraordinary traits including male pregnancy, elongated snouts, loss of teeth, and dermal bony armor. The developmental genetic and cellular changes that led to the evolution of these traits are largely unknown. Recent syngnathid genomes revealed suggestive gene content differences and provide the opportunity for detailed genetic analyses. We created a single cell RNA sequencing atlas of Gulf pipefish embryos to understand the developmental basis of four traits: derived head shape, toothlessness, dermal armor, and male pregnancy. We completed marker gene analyses, built genetic networks, and examined spatial expression of select genes. We identified osteochondrogenic mesenchymal cells in the elongating face that express regulatory genes bmp4, sfrp1a, and prdm16. We found no evidence for tooth primordia cells, and we observed re-deployment of osteoblast genetic networks in developing dermal armor. Finally, we found that epidermal cells expressed nutrient processing and environmental sensing genes, potentially relevant for the brooding environment. The examined pipefish evolutionary innovations are composed of recognizable cell types, suggesting derived features originate from changes within existing gene networks. Future work addressing syngnathid gene networks across multiple stages and species is essential for understanding how their novelties evolved.
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Affiliation(s)
- Hope M Healey
- Institute of Ecology and Evolution, University of Oregon
| | - Hayden B Penn
- Institute of Ecology and Evolution, University of Oregon
| | - Clayton M Small
- Institute of Ecology and Evolution, University of Oregon
- School of Computer and Data Science, University of Oregon
| | - Susan Bassham
- Institute of Ecology and Evolution, University of Oregon
| | - Vithika Goyal
- Institute of Ecology and Evolution, University of Oregon
| | - Micah A Woods
- Institute of Ecology and Evolution, University of Oregon
| | - William A Cresko
- Institute of Ecology and Evolution, University of Oregon
- Knight Campus for Accelerating Scientific Impact, University of Oregon
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2
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Pappert FA, Dubin A, Torres GG, Roth O. Navigating sex and sex roles: deciphering sex-biased gene expression in a species with sex-role reversal ( Syngnathus typhle). ROYAL SOCIETY OPEN SCIENCE 2024; 11:rsos.231620. [PMID: 38577217 PMCID: PMC10987989 DOI: 10.1098/rsos.231620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 02/02/2024] [Accepted: 03/11/2024] [Indexed: 04/06/2024]
Abstract
Sexual dimorphism, the divergence in morphological traits between males and females of the same species, is often accompanied by sex-biased gene expression. However, the majority of research has focused on species with conventional sex roles, where females have the highest energy burden with both egg production and parental care, neglecting the diversity of reproductive roles found in nature. We investigated sex-biased gene expression in Syngnathus typhle, a sex-role reversed species with male pregnancy, allowing us to separate two female traits: egg production and parental care. Using RNA sequencing, we examined gene expression across organs (brain, head kidney and gonads) at various life stages, encompassing differences in age, sex and reproductive status. While some gene groups were more strongly associated with sex roles, such as stress resistance and immune defence, others were driven by biological sex, such as energy and lipid storage regulation in an organ- and age-specific manner. By investigating how genes regulate and are regulated by changing reproductive roles and resource allocation in a model system with an unconventional life-history strategy, we aim to better understand the importance of sex and sex role in regulating gene expression patterns, broadening the scope of this discussion to encompass a wide range of organisms.
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Affiliation(s)
- Freya A. Pappert
- Marine Evolutionary Biology, Zoological Institute, Christian-Albrechts-Universität Kiel, Kiel24118, Germany
- Evolutionary Ecology of Marine Fishes, Helmholtz-Centre for Ocean Research Kiel (GEOMAR), Kiel24105, Germany
| | - Arseny Dubin
- Marine Evolutionary Biology, Zoological Institute, Christian-Albrechts-Universität Kiel, Kiel24118, Germany
| | - Guillermo G. Torres
- Institute of Clinical Molecular Biology (IKMB), University Hospital Schleswig-Holstein, Kiel University, Kiel24105, Germany
| | - Olivia Roth
- Marine Evolutionary Biology, Zoological Institute, Christian-Albrechts-Universität Kiel, Kiel24118, Germany
- Evolutionary Ecology of Marine Fishes, Helmholtz-Centre for Ocean Research Kiel (GEOMAR), Kiel24105, Germany
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3
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Schneider RF, Gunter HM, Salewski I, Woltering JM, Meyer A. Growth dynamics and molecular bases of evolutionary novel jaw extensions in halfbeaks and needlefishes (Beloniformes). Mol Ecol 2023; 32:5798-5811. [PMID: 37750351 DOI: 10.1111/mec.17143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 08/17/2023] [Accepted: 09/05/2023] [Indexed: 09/27/2023]
Abstract
Evolutionary novelties-derived traits without clear homology found in the ancestors of a lineage-may promote ecological specialization and facilitate adaptive radiations. Examples for such novelties include the wings of bats, pharyngeal jaws of cichlids and flowers of angiosperms. Belonoid fishes (flying fishes, halfbeaks and needlefishes) feature an astonishing diversity of extremely elongated jaw phenotypes with undetermined evolutionary origins. We investigate the development of elongated jaws in a halfbeak (Dermogenys pusilla) and a needlefish (Xenentodon cancila) using morphometrics, transcriptomics and in situ hybridization. We confirm that these fishes' elongated jaws are composed of distinct base and novel 'extension' portions. These extensions are morphologically unique to belonoids, and we describe the growth dynamics of both bases and extensions throughout early development in both studied species. From transcriptomic profiling, we deduce that jaw extension outgrowth is guided by populations of multipotent cells originating from the anterior tip of the dentary. These cells are shielded from differentiation, but proliferate and migrate anteriorly during the extension's allometric growth phase. Cells left behind at the tip leave the shielded zone and undergo differentiation into osteoblast-like cells, which deposit extracellular matrix with both bone and cartilage characteristics that mineralizes and thereby provides rigidity. Such bone has characteristics akin to histological observations on the elongated 'kype' process on lower jaws of male salmon, which may hint at common conserved regulatory underpinnings. Future studies will evaluate the molecular pathways that govern the anterior migration and proliferation of these multipotent cells underlying the belonoids' evolutionary novel jaw extensions.
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Affiliation(s)
- Ralf F Schneider
- Lehrstuhl für Zoologie und Evolutionsbiologie, Department of Biology, University of Konstanz, Konstanz, Germany
- Department of Marine Ecology, GEOMAR, Kiel, Germany
| | - Helen M Gunter
- Lehrstuhl für Zoologie und Evolutionsbiologie, Department of Biology, University of Konstanz, Konstanz, Germany
| | - Inken Salewski
- Lehrstuhl für Zoologie und Evolutionsbiologie, Department of Biology, University of Konstanz, Konstanz, Germany
| | - Joost M Woltering
- Lehrstuhl für Zoologie und Evolutionsbiologie, Department of Biology, University of Konstanz, Konstanz, Germany
| | - Axel Meyer
- Lehrstuhl für Zoologie und Evolutionsbiologie, Department of Biology, University of Konstanz, Konstanz, Germany
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4
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Jiang H, Zhao Z, Yu H, Lin Q, Liu Y. Evolutionary traits and functional roles of chemokines and their receptors in the male pregnancy of the Syngnathidae. MARINE LIFE SCIENCE & TECHNOLOGY 2023; 5:500-510. [PMID: 38045539 PMCID: PMC10689615 DOI: 10.1007/s42995-023-00205-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Accepted: 10/27/2023] [Indexed: 12/05/2023]
Abstract
Vertebrates have developed various modes of reproduction, some of which are found in Teleosts. Over 300 species of the Syngnathidae (seahorses, pipefishes and seadragons) exhibit male pregnancies; the males have specialized brood pouches that provide immune protection, nourishment, and oxygen regulation. Chemokines play a vital role at the mammalian maternal-fetal interface; however, their functions in fish reproduction are unclear. This study revealed the evolutionary traits and potential functions of chemokine genes in 22 oviparous, ovoviviparous, and viviparous fish species through comparative genomic analyses. Our results showed that chemokine gene copy numbers and evolutionary rates vary among species with different modes of reproduction. Syngnathidae lost cxcl13 and cxcr5, which are involved in key receptor-ligand pairs for lymphoid organ development. Notably, Syngnathidae have site-specific mutations in cxcl12b and ccl44, suggesting immune function during gestation. Moreover, transcriptome analysis revealed that chemokine gene expression varies among Syngnathidae species with different types of brood pouches, suggesting adaptive variations in chemokine functions among seahorses and their relatives. Furthermore, challenge experiments on seahorse brood pouches revealed a joint immune function of chemokine genes during male pregnancy. This study provides insights into the evolutionary diversity of chemokine genes associated with different reproductive modes in fish. Supplementary Information The online version contains supplementary material available at 10.1007/s42995-023-00205-x.
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Affiliation(s)
- Han Jiang
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301 China
- Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301 China
- University of Chinese Academy of Sciences, Beijing, 101400 China
| | - Zhanwei Zhao
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301 China
- Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301 China
- University of Chinese Academy of Sciences, Beijing, 101400 China
| | - Haiyan Yu
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301 China
- Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301 China
| | - Qiang Lin
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301 China
- Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301 China
- University of Chinese Academy of Sciences, Beijing, 101400 China
| | - Yali Liu
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301 China
- Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301 China
- University of Chinese Academy of Sciences, Beijing, 101400 China
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5
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Wilson AB, Whittington CM, Meyer A, Scobell SK, Gauthier ME. Prolactin and the evolution of male pregnancy. Gen Comp Endocrinol 2023; 334:114210. [PMID: 36646326 DOI: 10.1016/j.ygcen.2023.114210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 11/04/2022] [Accepted: 01/11/2023] [Indexed: 01/15/2023]
Abstract
Prolactin (PRL) is a multifunctional hormone of broad physiological importance, and is involved in many aspects of fish reproduction, including the regulation of live birth (viviparity) and both male and female parental care. Previous research suggests that PRL also plays an important reproductive role in syngnathid fishes (seahorses, pipefish and seadragons), a group with a highly derived reproductive strategy, male pregnancy - how the PRL axis has come to be co-opted for male pregnancy remains unclear. We investigated the molecular evolution and expression of the genes for prolactin and its receptor (PRLR) in an evolutionarily diverse sampling of syngnathid fishes to explore how the co-option of PRL for male pregnancy has impacted its evolution, and to clarify whether the PRL axis is also involved in regulating reproductive function in species with more rudimentary forms of male pregnancy. In contrast to the majority of teleost fishes, all syngnathid fishes tested carry single copies of PRL and PRLR that cluster genetically within the PRL1 and PRLRa lineages of teleosts, respectively. PRL1 gene expression in seahorses and pipefish is restricted to the pituitary, while PRLRa is expressed in all tissues, including the brood pouch of species with both rudimentary and complex brooding structures. Pituitary PRL1 expression remains stable throughout pregnancy, but PRLRa expression is specifically upregulated in the male brood pouch during pregnancy, consistent with the higher affinity of pouch tissues for PRL hormone during embryonic incubation. Finally, immunohistochemistry of brood pouch tissues reveals that both PRL1 protein and PRLRa and Na+/K+ ATPase-positive cells line the inner pouch epithelium, suggesting that pituitary-derived PRL1 may be involved in brood pouch osmoregulation during pregnancy. Our data provide a unique molecular perspective on the evolution and expression of prolactin and its receptor during male pregnancy, and provide the foundation for further manipulative experiments exploring the role of PRL in this unique form of reproduction.
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Affiliation(s)
- Anthony B Wilson
- Department of Biology, Brooklyn College, 2900 Bedford Avenue, Brooklyn, NY 11210, United States; The Graduate Center, City University of New York, 365 Fifth Avenue, New York, NY 10016, United States; Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich 8057, Switzerland; Department of Biology, University of Konstanz, Universitätsstrasse 10, 78457, Germany.
| | - Camilla M Whittington
- Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich 8057, Switzerland; Sydney School of Veterinary Science, University of Sydney, Sydney 2006, Australia; School of Life and Environmental Sciences, University of Sydney, Sydney 2006, Australia
| | - Axel Meyer
- Department of Biology, University of Konstanz, Universitätsstrasse 10, 78457, Germany
| | - Sunny K Scobell
- Department of Biology, Brooklyn College, 2900 Bedford Avenue, Brooklyn, NY 11210, United States
| | - Marie-Emilie Gauthier
- Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich 8057, Switzerland
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6
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Ramesh B, Small CM, Healey H, Johnson B, Barker E, Currey M, Bassham S, Myers M, Cresko WA, Jones AG. Improvements to the Gulf pipefish Syngnathus scovelli genome. GIGABYTE 2023; 2023:gigabyte76. [PMID: 36969711 PMCID: PMC10038202 DOI: 10.46471/gigabyte.76] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 02/03/2023] [Indexed: 02/22/2023] Open
Abstract
The Gulf pipefish Syngnathus scovelli has emerged as an important species for studying sexual selection, development, and physiology. Comparative evolutionary genomics research involving fishes from Syngnathidae depends on having a high-quality genome assembly and annotation. However, the first S. scovelli genome assembled using short-read sequences and a smaller RNA-sequence dataset has limited contiguity and a relatively poor annotation. Here, using PacBio long-read high-fidelity sequences and a proximity ligation library, we generate an improved assembly to obtain 22 chromosome-level scaffolds. Compared to the first assembly, the gaps in the improved assembly are smaller, the N75 is larger, and our genome is ~95% BUSCO complete. Using a large body of RNA-Seq reads from different tissue types and NCBI's Eukaryotic Annotation Pipeline, we discovered 28,162 genes, of which 8,061 are non-coding genes. Our new genome assembly and annotation are tagged as a RefSeq genome by NCBI and provide enhanced resources for research work involving S. scovelli..
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Affiliation(s)
- Balan Ramesh
- Department of Biological Sciences, University of Idaho, Moscow, ID 83844, USA
| | - Clay M. Small
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403, USA
- Presidential Initiative in Data Science, University of Oregon, Eugene, OR 97403, USA
| | - Hope Healey
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403, USA
| | - Bernadette Johnson
- Department of Biological Sciences, University of Idaho, Moscow, ID 83844, USA
| | - Elyse Barker
- Department of Biological Sciences, University of Idaho, Moscow, ID 83844, USA
| | - Mark Currey
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403, USA
| | - Susan Bassham
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403, USA
| | - Megean Myers
- Department of Biological Sciences, University of Idaho, Moscow, ID 83844, USA
| | - William A. Cresko
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403, USA
- Presidential Initiative in Data Science, University of Oregon, Eugene, OR 97403, USA
| | - Adam Gregory Jones
- Department of Biological Sciences, University of Idaho, Moscow, ID 83844, USA
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7
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Parker J, Dubin A, Schneider R, Wagner KS, Jentoft S, Böhne A, Bayer T, Roth O. Immunological tolerance in the evolution of male pregnancy. Mol Ecol 2023; 32:819-840. [PMID: 34951070 DOI: 10.1111/mec.16333] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 12/12/2021] [Accepted: 12/14/2021] [Indexed: 11/29/2022]
Abstract
The unique male pregnancy in pipefishes and seahorses ranges from basic attachment (pouch-less species: Nerophinae) of maternal eggs to specialized internal gestation in pouched species (e.g. Syngnathus and Hippocampus) with many transitions in between. Due to this diversity, male pregnancy offers a unique platform for assessing physiological and molecular adaptations in pregnancy evolution. These insights will contribute to answering long-standing questions of why and how pregnancy evolved convergently in so many vertebrate systems. To understand the molecular congruencies and disparities in male pregnancy evolution, we compared transcriptome-wide differentially expressed genes in four syngnathid species, at four pregnancy stages (nonpregnant, early, late and parturition). Across all species and pregnancy forms, metabolic processes and immune dynamics defined pregnancy stages, especially pouched species shared expression features akin to female pregnancy. The observed downregulation of adaptive immune genes in early-stage pregnancy and its reversed upregulation during late/parturition in pouched species, most notably in Hippocampus, combined with directionless expression in the pouch-less species, suggests immune modulation to be restricted to pouched species that evolved placenta-like systems. We propose that increased foeto-paternal intimacy in pouched syngnathids commands immune suppression processes in early gestation, and that the elevated immune response during parturition coincides with pouch opening and reduced progeny reliance. Immune response regulation in pouched species supports the recently described functional MHC II pathway loss as critical in male pregnancy evolution. The independent co-option of similar genes and pathways both in male and female pregnancy highlights immune modulation as crucial for the evolutionary establishment of pregnancy.
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Affiliation(s)
- Jamie Parker
- Marine Evolutionary Ecology, GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
| | - Arseny Dubin
- Marine Evolutionary Ecology, GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
| | - Ralf Schneider
- Marine Evolutionary Ecology, GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
| | - Kim Sara Wagner
- Marine Evolutionary Ecology, GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
| | - Sissel Jentoft
- Department of Biosciences, Centre for Ecological and Evolutionary Synthesis, University of Oslo, Oslo, Norway
| | - Astrid Böhne
- Center for Molecular Biodiversity Research, Zoological Research Museum Alexander Koenig, Bonn, Germany
| | - Till Bayer
- Marine Evolutionary Ecology, GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
| | - Olivia Roth
- Marine Evolutionary Ecology, GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
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8
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Skalkos ZMG, Van Dyke JU, Whittington CM. Distinguishing Between Embryonic Provisioning Strategies in Teleost Fishes Using a Threshold Value for Parentotrophy. Biomolecules 2023; 13:biom13010166. [PMID: 36671551 PMCID: PMC9856118 DOI: 10.3390/biom13010166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 12/20/2022] [Accepted: 12/24/2022] [Indexed: 01/15/2023] Open
Abstract
The source of embryonic nutrition for development varies across teleost fishes. A parentotrophy index (ratio of neonate: ovulated egg dry mass) is often used to determine provisioning strategy, but the methodologies used vary across studies. The variation in source and preservation of tissue, staging of embryos, and estimation approach impedes our ability to discern between methodological and biological differences in parentotrophy indices inter- and intra-specifically. The threshold value used to distinguish between lecithotrophy and parentotrophy (0.6-1) differs considerably across studies. The lack of a standardised approach in definition and application of parentotrophy indices has contributed to inconsistent classifications of provisioning strategy. Consistency in both methodology used to obtain a parentotrophy index, and in the classification of provisioning strategy using a threshold value are essential to reliably distinguish between provisioning strategies in teleosts. We discuss alternative methods for determining parentotrophy and suggest consistent standards for obtaining and interpreting parentotrophy indices.
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Affiliation(s)
- Zoe M. G. Skalkos
- School of Life and Environmental Sciences, The University of Sydney, Heydon-Laurence Building (A08), Sydney, NSW 2006, Australia
| | - James U. Van Dyke
- School of Agriculture, Biomedicine and Environment, La Trobe University, Wodonga, VIC 3690, Australia
| | - Camilla M. Whittington
- School of Life and Environmental Sciences, The University of Sydney, Heydon-Laurence Building (A08), Sydney, NSW 2006, Australia
- Correspondence:
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9
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Liu Y, Qu M, Jiang H, Schneider R, Qin G, Luo W, Yu H, Zhang B, Wang X, Zhang Y, Zhang H, Zhang Z, Wu Y, Zhang Y, Yin J, Zhang S, Venkatesh B, Roth O, Meyer A, Lin Q. Immunogenetic losses co-occurred with seahorse male pregnancy and mutation in tlx1 accompanied functional asplenia. Nat Commun 2022; 13:7610. [PMID: 36494371 PMCID: PMC9734139 DOI: 10.1038/s41467-022-35338-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 11/29/2022] [Indexed: 12/13/2022] Open
Abstract
In the highly derived syngnathid fishes (pipefishes, seadragons & seahorses), the evolution of sex-role reversed brooding behavior culminated in the seahorse lineage's male pregnancy, whose males feature a specialized brood pouch into which females deposit eggs during mating. Then, eggs are intimately engulfed by a placenta-like tissue that facilitates gas and nutrient exchange. As fathers immunologically tolerate allogenic embryos, it was suggested that male pregnancy co-evolved with specific immunological adaptations. Indeed, here we show that a specific amino-acid replacement in the tlx1 transcription factor is associated with seahorses' asplenia (loss of spleen, an organ central in the immune system), as confirmed by a CRISPR-Cas9 experiment using zebrafish. Comparative genomics across the syngnathid phylogeny revealed that the complexity of the immune system gene repertoire decreases as parental care intensity increases. The synchronous evolution of immunogenetic alterations and male pregnancy supports the notion that male pregnancy co-evolved with the immunological tolerance of the embryo.
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Affiliation(s)
- Yali Liu
- grid.9227.e0000000119573309CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 510301 Guangzhou, China ,grid.9227.e0000000119573309Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301 PR China ,grid.410726.60000 0004 1797 8419University of Chinese Academy of Sciences, 100101 Beijing, China
| | - Meng Qu
- grid.9227.e0000000119573309CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 510301 Guangzhou, China ,grid.9227.e0000000119573309Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301 PR China
| | - Han Jiang
- grid.9227.e0000000119573309CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 510301 Guangzhou, China ,grid.410726.60000 0004 1797 8419University of Chinese Academy of Sciences, 100101 Beijing, China
| | - Ralf Schneider
- grid.9764.c0000 0001 2153 9986Marine Evolutionary Ecology, Zoological Institute, Kiel University, 24118 Kiel, Germany
| | - Geng Qin
- grid.9227.e0000000119573309CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 510301 Guangzhou, China ,grid.9227.e0000000119573309Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301 PR China
| | - Wei Luo
- grid.9227.e0000000119573309CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 510301 Guangzhou, China
| | - Haiyan Yu
- grid.9227.e0000000119573309CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 510301 Guangzhou, China
| | - Bo Zhang
- grid.9227.e0000000119573309CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 510301 Guangzhou, China
| | - Xin Wang
- grid.9227.e0000000119573309CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 510301 Guangzhou, China ,grid.9227.e0000000119573309Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301 PR China
| | - Yanhong Zhang
- grid.9227.e0000000119573309CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 510301 Guangzhou, China ,grid.9227.e0000000119573309Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301 PR China
| | - Huixian Zhang
- grid.9227.e0000000119573309CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 510301 Guangzhou, China ,grid.9227.e0000000119573309Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301 PR China
| | - Zhixin Zhang
- grid.9227.e0000000119573309CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 510301 Guangzhou, China ,grid.412785.d0000 0001 0695 6482Graduate School of Marine Science and Technology, Tokyo University of Marine Science and Technology, Minato, Tokyo, Japan
| | - Yongli Wu
- grid.9227.e0000000119573309CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 510301 Guangzhou, China
| | - Yingyi Zhang
- grid.9227.e0000000119573309CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 510301 Guangzhou, China ,grid.410726.60000 0004 1797 8419University of Chinese Academy of Sciences, 100101 Beijing, China
| | - Jianping Yin
- grid.9227.e0000000119573309CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 510301 Guangzhou, China ,grid.9227.e0000000119573309Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301 PR China
| | - Si Zhang
- grid.9227.e0000000119573309CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 510301 Guangzhou, China ,grid.9227.e0000000119573309Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301 PR China
| | - Byrappa Venkatesh
- grid.418812.60000 0004 0620 9243Institute of Molecular and Cell Biology, A*STAR, 138673 Singapore, Singapore
| | - Olivia Roth
- grid.9764.c0000 0001 2153 9986Marine Evolutionary Ecology, Zoological Institute, Kiel University, 24118 Kiel, Germany
| | - Axel Meyer
- grid.9811.10000 0001 0658 7699Department of Biology, University of Konstanz, 78464 Konstanz, Germany
| | - Qiang Lin
- grid.9227.e0000000119573309CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 510301 Guangzhou, China ,grid.9227.e0000000119573309Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301 PR China ,grid.410726.60000 0004 1797 8419University of Chinese Academy of Sciences, 100101 Beijing, China
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10
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Whittington CM, Buddle AL, Griffith OW, Carter AM. Embryonic specializations for vertebrate placentation. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210261. [PMID: 36252220 PMCID: PMC9574634 DOI: 10.1098/rstb.2021.0261] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 02/28/2022] [Indexed: 12/20/2022] Open
Abstract
The vertebrate placenta, a close association of fetal and parental tissue for physiological exchange, has evolved independently in sharks, teleost fishes, coelacanths, amphibians, squamate reptiles and mammals. This transient organ forms during pregnancy and is an important contributor to embryonic development in both viviparous and oviparous, brooding species. Placentae may be involved in transport of respiratory gases, wastes, immune molecules, hormones and nutrients. Depending on the taxon, the embryonic portion of the placenta is comprised of either extraembryonic membranes (yolk sac or chorioallantois) or temporary embryonic tissues derived via hypertrophy of pericardium, gill epithelium, gut, tails or fins. These membranes and tissues have been recruited convergently into placentae in several lineages. Here, we highlight the diversity and common features of embryonic tissues involved in vertebrate placentation and suggest future studies that will provide new knowledge about the evolution of pregnancy. This article is part of the theme issue 'Extraembryonic tissues: exploring concepts, definitions and functions across the animal kingdom'.
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Affiliation(s)
- Camilla M. Whittington
- School of Life and Environmental Sciences, The University of Sydney, Heydon-Laurence A08, New South Wales 2006, Australia
| | - Alice L. Buddle
- School of Life and Environmental Sciences, The University of Sydney, Heydon-Laurence A08, New South Wales 2006, Australia
| | - Oliver W. Griffith
- Department of Biological Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
| | - Anthony M. Carter
- Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, J. B. Winsloews Vej 21, 5000 Odense, Denmark
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11
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Holt WV, Fazeli A, Otero-Ferrer F. Sperm transport and male pregnancy in seahorses: An unusual model for reproductive science. Anim Reprod Sci 2022; 246:106854. [PMID: 34579988 DOI: 10.1016/j.anireprosci.2021.106854] [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: 05/21/2021] [Revised: 09/14/2021] [Accepted: 09/15/2021] [Indexed: 12/14/2022]
Abstract
The Syngnathidae (seahorses and pipefishes) are a group of teleost fishes in which, uniquely, developing embryos are hosted throughout pregnancy by males, using a specialized brood pouch situated on the abdomen or tail. Seahorses have evolved the most advanced form of brood pouch, whereby zygotes and embryos are intimately connected to the host's circulatory system and also bathed in pouch fluid. The pouch is closed to the external environment and has to perform functions such as gaseous exchange, removal of waste and maintenance of appropriate osmotic conditions, much like the mammalian placenta. Fertilization of the oocytes occurs within the brood pouch, but unlike the mammalian situation the sperm transport mechanism from the ejaculatory duct towards the pouch is unclear, and the sperm: egg ratio (about 5:1) is possibly the least of any vertebrate. In this review, there is highlighting of the difficulty of elucidating the sperm transport mechanism, based on studies of Hippocampus kuda. The similarities between seahorse pouch function and the mammalian placenta have led to suggestions that the pouch provides important nutritional support for the developing embryos, supplementing the nutritional functions of the yolk sac provided by the oocytes. In this review, there is a description of the recent evidence in support of this hypothesis, and also emphasis, as in mammals, that embryonic development depends on nutritional support from the placenta-like pouch at important stages of the gestational period ("critical windows").
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Affiliation(s)
- William V Holt
- Academic Unit of Reproductive and Developmental Medicine, Department of Oncology and Metabolism, University of Sheffield, Level 4, Jessop Wing, Tree Root Walk, Sheffield S10 2SF, UK.
| | - Alireza Fazeli
- Institute of Veterinary Medicine and Animal Sciences, Estonian University of Life Sciences, Tartu, Estonia; Department of Pathophysiology, Institute of Biomedicine and Translational Medicine, Faculty of Medicine, Tartu University, Tartu, Estonia; Academic Unit of Reproductive and Developmental Medicine, Department of Oncology and Metabolism, Medical School, University of Sheffield, Sheffield, UK
| | - Francisco Otero-Ferrer
- University Institute of Sustainable Aquaculture and Marine Ecosystems (IU ECOAQUA) Scientific and Technological Marine Park, University of Las Palmas de Gran Canaria, 35200, Spain
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12
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Dudley J, Paul J, Teh V, Mackenzie T, Butler T, Tolosa J, Smith R, Foley M, Dowland S, Thompson M, Whittington C. Seahorse brood pouch morphology and control of male parturition in Hippocampus abdominalis. Placenta 2022; 127:88-94. [DOI: 10.1016/j.placenta.2022.07.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Revised: 07/07/2022] [Accepted: 07/18/2022] [Indexed: 11/30/2022]
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13
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Xiao W, Chen Z, Zhang Y, Wu Y, Jiang H, Zhang H, Qu M, Lin Q, Qin G. Hepcidin Gene Co-Option Balancing Paternal Immune Protection and Male Pregnancy. Front Immunol 2022; 13:884417. [PMID: 35529860 PMCID: PMC9073008 DOI: 10.3389/fimmu.2022.884417] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Accepted: 03/24/2022] [Indexed: 11/13/2022] Open
Abstract
Viviparity has originated independently more than 150 times in vertebrates, while the male pregnancy only emerged in Syngnathidae fishes, such as seahorses. The typical male pregnancy seahorses have closed sophisticated brood pouch that act as both uterus and placenta, representing an excellent model system for studying the evolutionary process of paternal immune protection. Phylogenetic analysis indicated that the hampII gene family has multiple tandem duplicated genes and shows independent lineage-specific expansion in seahorses, and they had the highest ratio of nonsynonymous substitutions to synonymous substitutions (dN/dS) in the seahorse phylogenetic branch. The expression levels of hampIIs in the brood pouch placenta were significantly higher during pregnancy than non-pregnancy. Both LPS stimulation test in vivo and cytotoxicity test in vitro proved the immunological protection function of hampIIs against pathogen infection in seahorse. Besides, seahorse hampII peptides exhibit weaker antibacterial function, but stronger agglutination and free endotoxin inhibition. We assumed that the modified immunological function seemed to be a trade-off between the resistance to microbial attack and offspring protection. In brief, this study suggests that the rapid co-option of hampIIs contributes to the evolutionary adaption to paternal immune care during male pregnancy.
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Affiliation(s)
- Wanghong Xiao
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
- University of the Chinese Academy of Sciences, Beijing, China
| | - Zelin Chen
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China
| | - Yanhong Zhang
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
| | - Yongli Wu
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China
| | - Han Jiang
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China
| | - Huixian Zhang
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China
| | - Meng Qu
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China
| | - Qiang Lin
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
- University of the Chinese Academy of Sciences, Beijing, China
- *Correspondence: Geng Qin, ; Qiang Lin,
| | - Geng Qin
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
- *Correspondence: Geng Qin, ; Qiang Lin,
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14
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Foster CSP, Van Dyke JU, Thompson MB, Smith NMA, Simpfendorfer CA, Murphy CR, Whittington CM. Different genes are recruited during convergent evolution of pregnancy and the placenta. Mol Biol Evol 2022; 39:6564414. [PMID: 35388432 PMCID: PMC9048886 DOI: 10.1093/molbev/msac077] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The repeated evolution of the same traits in distantly related groups (convergent evolution) raises a key question in evolutionary biology: do the same genes underpin convergent phenotypes? Here we explore one such trait, viviparity (live birth), which qualitative studies suggest may indeed have evolved via genetic convergence. There are >150 independent origins of live birth in vertebrates, providing a uniquely powerful system to test the mechanisms underpinning convergence in morphology, physiology, and/or gene recruitment during pregnancy. We compared transcriptomic data from eight vertebrates (lizards, mammals, sharks) that gestate embryos within the uterus. Since many previous studies detected qualitative similarities in gene use during independent origins of pregnancy, we expected to find significant overlap in gene use in viviparous taxa. However, we found no more overlap in uterine gene expression associated with viviparity than we would expect by chance alone. Each viviparous lineage exhibits the same core set of uterine physiological functions, yet, contrary to prevailing assumptions about this trait, we find that none of the same genes are differentially expressed in all viviparous lineages, or even in all viviparous amniote lineages. Therefore, across distantly related vertebrates, different genes have been recruited to support the morphological and physiological changes required for successful pregnancy. We conclude that redundancies in gene function have enabled the repeated evolution of viviparity through recruitment of different genes from genomic 'toolboxes', which are uniquely constrained by the ancestries of each lineage.
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Affiliation(s)
- Charles S P Foster
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, Australia.,School of Medical Sciences, University of New South Wales, Sydney, NSW, Australia
| | - James U Van Dyke
- School of Molecular Sciences, La Trobe University, Albury-Wodonga campus, VIC, Australia
| | - Michael B Thompson
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, Australia
| | - Nicholas M A Smith
- School of Biological Sciences, University of Queensland, Brisbane, QLD, Australia
| | - Colin A Simpfendorfer
- College of Science and Engineering, James Cook University, Townsville, Queensland, Australia
| | - Christopher R Murphy
- School of Medical Sciences and The Bosch Institute, University of Sydney, Sydney, NSW, Australia
| | - Camilla M Whittington
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, Australia
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15
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Stiller J, Short G, Hamilton H, Saarman N, Longo S, Wainwright P, Rouse GW, Simison WB. Phylogenomic analysis of Syngnathidae reveals novel relationships, origins of endemic diversity and variable diversification rates. BMC Biol 2022; 20:75. [PMID: 35346180 PMCID: PMC8962102 DOI: 10.1186/s12915-022-01271-w] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Accepted: 03/04/2022] [Indexed: 12/03/2022] Open
Abstract
Background Seahorses, seadragons, pygmy pipehorses, and pipefishes (Syngnathidae, Syngnathiformes) are among the most recognizable groups of fishes because of their derived morphology, unusual life history, and worldwide distribution. Despite previous phylogenetic studies and recent new species descriptions of syngnathids, the evolutionary relationships among several major groups within this family remain unresolved. Results Here, we provide a reconstruction of syngnathid phylogeny based on genome-wide sampling of 1314 ultraconserved elements (UCEs) and expanded taxon sampling to assess the current taxonomy and as a basis for macroevolutionary insights. We sequenced a total of 244 new specimens across 117 species and combined with published UCE data for a total of 183 species of Syngnathidae, about 62% of the described species diversity, to compile the most data-rich phylogeny to date. We estimated divergence times using 14 syngnathiform fossils, including nine fossils with newly proposed phylogenetic affinities, to better characterize current and historical biogeographical patterns, and to reconstruct diversification through time. We present a phylogenetic hypothesis that is well-supported and provides several notable insights into syngnathid evolution. We found nine non-monophyletic genera, evidence for seven cryptic species, five potentially invalid synonyms, and identified a novel sister group to the seahorses, the Indo-Pacific pipefishes Halicampus macrorhynchus and H. punctatus. In addition, the morphologically distinct southwest Pacific seahorse Hippocampus jugumus was recovered as the sister to all other non-pygmy seahorses. As found in many other groups, a high proportion of syngnathid lineages appear to have originated in the Central Indo-Pacific and subsequently dispersed to adjoining regions. Conversely, we also found an unusually high subsequent return of lineages from southern Australasia to the Central Indo-Pacific. Diversification rates rose abruptly during the Middle Miocene Climate Transition and peaked after the closure of the Tethys Sea. Conclusions Our results reveal a previously underappreciated diversity of syngnathid lineages. The observed biogeographic patterns suggest a significant role of the southern Australasian region as a source and sink of lineages. Shifts in diversification rates imply possible links to declining global temperatures, the separation of the Atlantic and Pacific faunas, and the environmental changes associated with these events. Supplementary Information The online version contains supplementary material available at 10.1186/s12915-022-01271-w.
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Affiliation(s)
- Josefin Stiller
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, USA. .,Centre for Biodiversity Genomics, University of Copenhagen, 2100, Copenhagen, Denmark.
| | - Graham Short
- Ichthyology, Australian Museum, Sydney, Australia.,Ichthyology, California Academy of Sciences, San Francisco, USA.,Ichthyology, Burke Museum of Natural History and Culture, Seattle, USA
| | | | - Norah Saarman
- Department of Biology and Ecology Center, Utah State University, Logan, Utah, USA
| | - Sarah Longo
- Department of Biological Science, Towson University, Towson, MD, 21252, USA
| | - Peter Wainwright
- Department of Evolution & Ecology, University of California, Davis, USA
| | - Greg W Rouse
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, USA
| | - W Brian Simison
- Center for Comparative Genomics, California Academy of Sciences, San Francisco, USA
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16
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Harada A, Shiota R, Okubo R, Yorifuji M, Sogabe A, Motomura H, Hiroi J, Yasumasu S, Kawaguchi M. Brood pouch evolution in pipefish and seahorse based on histological observation. Placenta 2022; 120:88-96. [DOI: 10.1016/j.placenta.2022.02.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Revised: 02/09/2022] [Accepted: 02/20/2022] [Indexed: 12/17/2022]
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17
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Zhang H, Liu Y, Qin G, Lin Q. Identification of neurohypophysial hormones and the role of VT in the parturition of pregnant seahorses ( Hippocampus erectus). Front Endocrinol (Lausanne) 2022; 13:923234. [PMID: 35966100 PMCID: PMC9372264 DOI: 10.3389/fendo.2022.923234] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Accepted: 07/06/2022] [Indexed: 11/26/2022] Open
Abstract
Neurohypophysial hormones regulate the reproductive behavior of teleosts; however, their role in the gestation and parturition of ovoviviparous fishes with male pregnancy (syngnathids) remains to be demonstrated. In the present study, the complementary DNA (cDNA) sequences of arginine vasotocin (VT) and isotocin (IT) from the lined seahorse (Hippocampus erectus) were cloned and identified. We observed that the mature core peptides of seahorse VT and IT were conserved among teleosts. In the phylogenic tree, seahorse VT and IT were clustered independently with teleost VT and IT. The tissue distribution patterns of VT and IT were similar, and both were highly expressed in the brain, gills, and gonads. Interestingly, they were also expressed to some extent in the brood pouch. In situ hybridization revealed that VT and IT messenger RNA (mRNA) signals in the brain were mainly located in the preoptic area region of the hypothalamus. Intraperitoneal administration of the VT core peptide to pregnant seahorses induced premature parturition, stimulated gonadotropin release, increased serum estrogen levels, and decreased prolactin secretion. Moreover, VT injection upregulated the mRNA expression of the membrane estrogen receptor in the brood pouch. In summary, neurohypophysial hormones promote premature parturition by regulating estrogen synthesis through the hypothalamus-pituitary-gonad axis.
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Affiliation(s)
- Huixian Zhang
- Chinese Academy of Science (CAS) Key Laboratory of Tropical Marine Bio-resources and Ecology (LMB), Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yali Liu
- Chinese Academy of Science (CAS) Key Laboratory of Tropical Marine Bio-resources and Ecology (LMB), Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China
| | - Geng Qin
- Chinese Academy of Science (CAS) Key Laboratory of Tropical Marine Bio-resources and Ecology (LMB), Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China
| | - Qiang Lin
- Chinese Academy of Science (CAS) Key Laboratory of Tropical Marine Bio-resources and Ecology (LMB), Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China
- University of Chinese Academy of Sciences, Beijing, China
- *Correspondence: Qiang Lin,
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18
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Recknagel H, Carruthers M, Yurchenko AA, Nokhbatolfoghahai M, Kamenos NA, Bain MM, Elmer KR. The functional genetic architecture of egg-laying and live-bearing reproduction in common lizards. Nat Ecol Evol 2021; 5:1546-1556. [PMID: 34621056 DOI: 10.1038/s41559-021-01555-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Accepted: 08/20/2021] [Indexed: 02/07/2023]
Abstract
All amniotes reproduce either by egg-laying (oviparity), which is ancestral to vertebrates or by live-bearing (viviparity), which has evolved many times independently. However, the genetic basis of these parity modes has never been resolved and, consequently, its convergence across evolutionary scales is currently unknown. Here, we leveraged natural hybridizations between oviparous and viviparous common lizards (Zootoca vivipara) to describe the functional genes and genetic architecture of parity mode and its key traits, eggshell and gestation length, and compared our findings across vertebrates. In these lizards, parity trait genes were associated with progesterone-binding functions and enriched for tissue remodelling and immune system pathways. Viviparity involved more genes and complex gene networks than did oviparity. Angiogenesis, vascular endothelial growth and adrenoreceptor pathways were enriched in the viviparous female reproductive tissue, while pathways for transforming growth factor were enriched in the oviparous. Natural selection on these parity mode genes was evident genome-wide. Our comparison to seven independent origins of viviparity in mammals, squamates and fish showed that genes active in pregnancy were related to immunity, tissue remodelling and blood vessel generation. Therefore, our results suggest that pre-established regulatory networks are repeatedly recruited for viviparity and that these are shared at deep evolutionary scales.
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Affiliation(s)
- Hans Recknagel
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK.,Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Madeleine Carruthers
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK.,School of Biological Sciences, University of Bristol, Bristol, UK
| | - Andrey A Yurchenko
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK.,Inserm U981, Gustave Roussy Cancer Campus, Université Paris Saclay, Villejuif, France
| | - Mohsen Nokhbatolfoghahai
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK
| | - Nicholas A Kamenos
- School of Geographical and Earth Sciences, University of Glasgow, Glasgow, UK
| | - Maureen M Bain
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK
| | - Kathryn R Elmer
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK.
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19
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Lin T, Liu X, Zhang D. Does the female seahorse still prefer her mating partner after a period of separation? JOURNAL OF FISH BIOLOGY 2021; 99:1613-1621. [PMID: 34331361 DOI: 10.1111/jfb.14867] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 07/21/2021] [Accepted: 07/23/2021] [Indexed: 06/13/2023]
Abstract
For species showing sexual monogamy, once one male and one female form a mating pair bond, they will be faithful to each other in subsequent breeding events. However, if their pair bond is broken for some reason, do they continue to prefer their partner when they come together again for mating? In other words, can the broken pair bond of sexually monogamous species be repaired? This is an interesting question but not yet well answered. To address this question, in the present study we used the lined seahorse (Hippocampus erectus), a typical sexually monogamous species, to study the partner preference of a female individual who experienced a complete separation followed by a reunion with her partner. Our main findings are as follows: (i) The female seahorse no longer prefers her partner after a separation, whether it is a former partner or a recent partner. No preference for partner-males may indicate that the broken pair bond cannot be repaired. (ii) The female seahorse maintains sexual fidelity to her partner in the absence of separation. However, once the health of her partner decreases, the female will switch mate, and her courtship with the new partner can take place during the pregnancy of her original partner. The first finding may provide insight into whether monogamous species still have an opportunity to reselect a new partner in the future to correct their poor choice once they have mated with a low-quality partner. The answer is that they can still gain an opportunity as long as the pair bonds with their current partners are broken. The second finding may reveal the conditions and timing at which a female seahorse switches her mate. These findings help us better understand the mating system of the seahorse H. erectus.
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Affiliation(s)
- Tingting Lin
- Key Laboratory of East China Sea Fishery Resources Exploitation, Ministry of Agriculture, East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai, China
| | - Xin Liu
- Key Laboratory of East China Sea Fishery Resources Exploitation, Ministry of Agriculture, East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai, China
| | - Dong Zhang
- Key Laboratory of East China Sea Fishery Resources Exploitation, Ministry of Agriculture, East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai, China
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20
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Affiliation(s)
- Camilla M Whittington
- School of Life and Environmental Sciences, The University of Sydney, Camperdown, New South Wales, Australia.
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21
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Dudley JS, Hannaford P, Dowland SN, Lindsay LA, Thompson MB, Murphy CR, Van Dyke JU, Whittington CM. Structural changes to the brood pouch of male pregnant seahorses (Hippocampus abdominalis) facilitate exchange between father and embryos. Placenta 2021; 114:115-123. [PMID: 34517263 DOI: 10.1016/j.placenta.2021.09.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2021] [Revised: 08/10/2021] [Accepted: 09/01/2021] [Indexed: 11/16/2022]
Abstract
INTRODUCTION Embryonic growth and development require efficient respiratory gas exchange. Internal incubation of developing young thus presents a significant physiological challenge, because respiratory gas diffusion to embryos is impeded by the additional barrier of parental tissue between the embryo and the environment. Therefore, live-bearing species exhibit a variety of adaptations facilitating respiratory gas exchange between the parent (usually the mother) and embryos. Syngnathid fishes are the only vertebrates to exhibit male pregnancy, allowing comparative studies of the biology and evolution of internal incubation of embryos, independent of the female reproductive tract. Here, we examine the fleshy, sealed, seahorse brood pouch, and provide the first quantification of structural changes to this gestational organ across pregnancy. METHODS We used histological analysis and morphometrics to quantify the surface area for exchange across the brood pouch epithelium, and the structure of the vascular bed of the brood pouch. RESULTS We show dramatic remodelling of gestational tissues as pregnancy progresses, including an increase in tortuosity of the gestational epithelium, an increase in capillary density, and a decrease in diffusion distance between capillaries and the pouch lumen. DISCUSSION These changes produce an increased surface area and expansion of the vascular bed of the placenta that likely facilitates respiratory gas exchange. These changes mirror the remodelling of gestational tissue in viviparous amniotes and elasmobranchs, and provide further evidence of the convergence of adaptations to support pregnancy in live-bearing animals.
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Affiliation(s)
- J S Dudley
- The University of Sydney, School of Life and Environmental Sciences, Sydney, NSW, Australia; Macquarie University, Department of Biological Sciences, Faculty of Science and Engineering, Macquarie Park, NSW, Australia
| | - P Hannaford
- The University of Sydney, School of Life and Environmental Sciences, Sydney, NSW, Australia
| | - S N Dowland
- The University of Sydney, School of Medical Sciences (Anatomy and Histology), Sydney, NSW, Australia
| | - L A Lindsay
- The University of Sydney, School of Medical Sciences (Anatomy and Histology), Sydney, NSW, Australia
| | - M B Thompson
- The University of Sydney, School of Life and Environmental Sciences, Sydney, NSW, Australia
| | - C R Murphy
- The University of Sydney, School of Life and Environmental Sciences, Sydney, NSW, Australia; The University of Sydney, School of Medical Sciences (Anatomy and Histology), Sydney, NSW, Australia
| | - J U Van Dyke
- La Trobe University, Department of Pharmacy and Biomedical Sciences, School of Molecular Sciences, Wodonga, Victoria, Australia
| | - C M Whittington
- The University of Sydney, School of Life and Environmental Sciences, Sydney, NSW, Australia.
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22
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Qu M, Liu Y, Zhang Y, Wan S, Ravi V, Qin G, Jiang H, Wang X, Zhang H, Zhang B, Gao Z, Huysseune A, Zhang Z, Zhang H, Chen Z, Yu H, Wu Y, Tang L, Li C, Zhong J, Ma L, Wang F, Zheng H, Yin J, Witten PE, Meyer A, Venkatesh B, Lin Q. Seadragon genome analysis provides insights into its phenotype and sex determination locus. SCIENCE ADVANCES 2021; 7:eabg5196. [PMID: 34407945 PMCID: PMC8373133 DOI: 10.1126/sciadv.abg5196] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Accepted: 07/01/2021] [Indexed: 05/29/2023]
Abstract
The iconic phenotype of seadragons includes leaf-like appendages, a toothless tubular mouth, and male pregnancy involving incubation of fertilized eggs on an open "brood patch." We de novo-sequenced male and female genomes of the common seadragon (Phyllopteryx taeniolatus) and its closely related species, the alligator pipefish (Syngnathoides biaculeatus). Transcription profiles from an evolutionary novelty, the leaf-like appendages, show that a set of genes typically involved in fin development have been co-opted as well as an enrichment of transcripts for potential tissue repair and immune defense genes. The zebrafish mutants for scpp5, which is lost in all syngnathids, were found to lack or have deformed pharyngeal teeth, supporting the hypothesis that the loss of scpp5 has contributed to the loss of teeth in syngnathids. A putative sex-determining locus encoding a male-specific amhr2y gene shared by common seadragon and alligator pipefish was identified.
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Affiliation(s)
- Meng Qu
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 510301 Guangzhou, China
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), 511458 Guangzhou, China
| | - Yali Liu
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 510301 Guangzhou, China
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), 511458 Guangzhou, China
| | - Yanhong Zhang
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 510301 Guangzhou, China
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), 511458 Guangzhou, China
| | - Shiming Wan
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 510301 Guangzhou, China
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), 511458 Guangzhou, China
| | - Vydianathan Ravi
- Institute of Molecular and Cell Biology, A*STAR, 138673 Biopolis, Singapore
| | - Geng Qin
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 510301 Guangzhou, China
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), 511458 Guangzhou, China
| | - Han Jiang
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 510301 Guangzhou, China
- University of Chinese Academy of Sciences, 100101 Beijing, China
| | - Xin Wang
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 510301 Guangzhou, China
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), 511458 Guangzhou, China
| | - Huixian Zhang
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 510301 Guangzhou, China
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), 511458 Guangzhou, China
| | - Bo Zhang
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 510301 Guangzhou, China
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), 511458 Guangzhou, China
| | - Zexia Gao
- College of Fisheries, Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, 430070 Wuhan, China
| | - Ann Huysseune
- Department of Biology, Ghent University, Ledeganckstraat 35, B-9000 Ghent, Belgium
| | - Zhixin Zhang
- Graduate School of Marine Science and Technology, Tokyo University of Marine Science and Technology, Minato, Tokyo, Japan
| | - Hao Zhang
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 510301 Guangzhou, China
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), 511458 Guangzhou, China
| | - Zelin Chen
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 510301 Guangzhou, China
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), 511458 Guangzhou, China
| | - Haiyan Yu
- Biomarker Technologies Corporation, 101300 Beijing, China
| | - Yongli Wu
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 510301 Guangzhou, China
- University of Chinese Academy of Sciences, 100101 Beijing, China
| | - Lu Tang
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 510301 Guangzhou, China
- University of Chinese Academy of Sciences, 100101 Beijing, China
| | - Chunyan Li
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 510301 Guangzhou, China
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), 511458 Guangzhou, China
| | - Jia Zhong
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 510301 Guangzhou, China
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), 511458 Guangzhou, China
| | - Liming Ma
- Biomarker Technologies Corporation, 101300 Beijing, China
| | - Fengling Wang
- Biomarker Technologies Corporation, 101300 Beijing, China
| | - Hongkun Zheng
- Biomarker Technologies Corporation, 101300 Beijing, China
| | - Jianping Yin
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 510301 Guangzhou, China
| | - Paul Eckhard Witten
- Department of Biology, Ghent University, Ledeganckstraat 35, B-9000 Ghent, Belgium
| | - Axel Meyer
- Department of Biology, University of Konstanz, 78464 Konstanz, Germany.
| | - Byrappa Venkatesh
- Institute of Molecular and Cell Biology, A*STAR, 138673 Biopolis, Singapore.
| | - Qiang Lin
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 510301 Guangzhou, China.
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), 511458 Guangzhou, China
- University of Chinese Academy of Sciences, 100101 Beijing, China
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Female lined seahorses (Hippocampus erectus) recognize their mates based on olfactory cues. Behav Processes 2021; 189:104419. [PMID: 33991591 DOI: 10.1016/j.beproc.2021.104419] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 04/21/2021] [Accepted: 05/10/2021] [Indexed: 11/24/2022]
Abstract
Recognition of mates from others is crucial for monogamous species to maintain their long-term pair bonds. The seahorse is widely recognized as a monogamous species, and its mate recognition cue is still not well understood. In the present study, we used the lined seahorse (Hippocampus erectus) as an experimental animal and investigated the effect of blocking olfactory, visual or behavioral (i.e., greeting) cues on mate recognition. Our results show that as long as the female seahorse can smell her mate, she will remain faithful to her mate and persistently select her mate as her next mating partner, regardless of whether the visual and/or behavioral cues between her and her mate are blocked. This finding implies that olfaction is a critical cue for a female seahorse to recognize her mate.
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24
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Diversity of Seahorse Species (Hippocampus spp.) in the International Aquarium Trade. DIVERSITY 2021. [DOI: 10.3390/d13050187] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Seahorses (Hippocampus spp.) are threatened as a result of habitat degradation and overfishing. They have commercial value as traditional medicine, curio objects, and pets in the aquarium industry. There are 48 valid species, 27 of which are represented in the international aquarium trade. Most species in the aquarium industry are relatively large and were described early in the history of seahorse taxonomy. In 2002, seahorses became the first marine fishes for which the international trade became regulated by CITES (Convention for the International Trade in Endangered Species of Wild Fauna and Flora), with implementation in 2004. Since then, aquaculture has been developed to improve the sustainability of the seahorse trade. This review provides analyses of the roles of wild-caught and cultured individuals in the international aquarium trade of various Hippocampus species for the period 1997–2018. For all species, trade numbers declined after 2011. The proportion of cultured seahorses in the aquarium trade increased rapidly after their listing in CITES, although the industry is still struggling to produce large numbers of young in a cost-effective way, and its economic viability is technically challenging in terms of diet and disease. Whether seahorse aquaculture can benefit wild populations will largely depend on its capacity to provide an alternative livelihood for subsistence fishers in the source countries. For most species, CITES trade records of live animals in the aquarium industry started a few years earlier than those of dead bodies in the traditional medicine trade, despite the latter being 15 times higher in number. The use of DNA analysis in the species identification of seahorses has predominantly been applied to animals in the traditional medicine market, but not to the aquarium trade. Genetic tools have already been used in the description of new species and will also help to discover new species and in various other kinds of applications.
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25
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Home range use in the West Australian seahorse Hippocampus subelongatus is influenced by sex and partner’s home range but not by body size or paired status. J ETHOL 2021. [DOI: 10.1007/s10164-021-00698-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
AbstractGenetic monogamy is the rule for many species of seahorse, including the West Australian seahorse Hippocampus subelongatus. In this paper, we revisit mark-recapture and genetic data of H. subelongatus, allowing a detailed characterization of movement distances, home range sizes and home range overlaps for each individual of known sex, paired status (paired or unpaired) and body size. As predicted, we find that females have larger home ranges and move greater distances compared to males. We also confirm our prediction that the home ranges of pair-bonded individuals (members of a pair known to reproduce together) overlap more on average than home ranges of randomly chosen individuals of the opposite or same sex. Both sexes, regardless of paired status, had home ranges that overlapped with, on average, 6–10 opposite-sex individuals. The average overlap area among female home ranges was significantly larger than the overlap among male home ranges, probably reflecting females having larger home ranges combined with a female biased adult sex ratio. Despite a prediction that unpaired individuals would need to move around to find a mate, we find no evidence that unpaired members of either sex moved more than paired individuals of the same sex. We also find no effect of body size on home range size, distance moved or number of other individuals with which a home range overlapped. These patterns of movement and overlap in home ranges among individuals of both sexes suggest that low mate availability is not a likely explanation for the maintenance of monogamy in the West Australian seahorse.
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26
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Skalkos ZMG, Van Dyke JU, Whittington CM. Paternal nutrient provisioning during male pregnancy in the seahorse Hippocampus abdominalis. J Comp Physiol B 2020; 190:547-556. [PMID: 32617716 DOI: 10.1007/s00360-020-01289-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 04/22/2020] [Accepted: 06/18/2020] [Indexed: 02/06/2023]
Abstract
Vertebrates that incubate embryos on or within the body cavity exhibit diverse strategies to provide nutrients to developing embryos, ranging from lecithotrophy (solely yolk-provided nutrition) to substantial matrotrophy (supplemental nutrients from the mother before birth). Syngnathid fishes (seahorses, pipefishes and sea dragons) are the only vertebrates to exhibit male pregnancy. Therefore, they provide a unique opportunity for comparative evolutionary research, in examining pregnancy independent of the female reproductive tract. Here, we tested the hypothesis that the most complex form of syngnathid pregnancy involves nutrient transport from father to offspring. We compared the dry masses of newly fertilised Hippocampus abdominalis eggs with those of fully developed neonates to derive a patrotrophy index. The patrotrophy index of H. abdominalis was 1, indicating paternal nutrient supplementation to embryos during gestation. We also measured the lipid content of newly fertilised eggs and neonates and found that there was no significant decrease in lipid mass during embryonic development. Since lipids are likely to be the main source of energy during embryonic development, our results suggest that lipid yolk reserves being depleted by embryonic metabolism are replaced by the brooding father. The results of our study support the hypothesis that nutrient transport occurs in the most advanced form of male pregnancy in vertebrates.
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Affiliation(s)
- Zoe M G Skalkos
- School of Life and Environmental Sciences, The University of Sydney, Heydon-Laurence A08, Camperdown, NSW, 2006, Australia
| | - James U Van Dyke
- School of Molecular Sciences, College of Science, Health and Engineering, La Trobe University, Wodonga, VIC, Australia
| | - Camilla M Whittington
- School of Life and Environmental Sciences, The University of Sydney, Heydon-Laurence A08, Camperdown, NSW, 2006, Australia.
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