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Kaiser S, Stransky B, Jennings RM, Kihara TC, Brix S. Combining morphological and mitochondrial DNA data to describe a new species of Austroniscus Vanhöffen, 1914 (Isopoda, Janiroidea, Nannoniscidae) linking abyssal and hadal depths of the Puerto Rico Trench. Zootaxa 2023; 5293:401-434. [PMID: 37518475 DOI: 10.11646/zootaxa.5293.3.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Indexed: 08/01/2023]
Abstract
Hadal trenches are perceived as a unique deep-sea ecosystem with fundamentally different communities compared to the nearby abyss. So far, however, scarce information exists about how populations are genetically linked within a trench and about mechanisms for species divergence. The present study presents the morphological and molecular-genetic characterization and description of a new nannoniscid species within the genus Austroniscus Vanhöffen, 1914 obtained from abyssal and hadal depths of the Puerto Rico Trench, NW Atlantic. Samples were collected as part of the Vema-TRANSIT expedition onboard RV Sonne in January 2015. Because of the large depth differences between sampling locations (4,552-8,338 m), we expected to find different species within the genus inhabiting abyssal and hadal sites. Initial morphological examination using traditional light microscopy and Confocal Laser Scanning Microscopy was paired with subsequent molecular analysis based on mtDNA (COI and 16S). Contrary to our assumptions, combined morphological and molecular species delimitation analyses (sGMYC, mPTP, ABGD) revealed the presence of only one species spanning the abyssal and hadal seafloor of the Puerto Rico Trench. In addition, comparison with type material could show that this species belongs to a new species, Austroniscus brandtae n. sp., which is described herein. Incongruence between some species delimitation methods suggesting the presence of multiple species is interpreted as strong genetic population structuring within the trench, which is also supported by the analysis of the haplotype networks. The geographic and bathymetric distribution of Austroniscus species is discussed. The species described herein represents the first in the genus Austroniscus from the Atlantic Ocean and the deepest record of the genus to date, and hence significantly expanding previously known limits of its geographic and bathymetric range.
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Affiliation(s)
- Stefanie Kaiser
- University of Łódź; Faculty of Biology and Environmental Protection; Department of Invertebrate Zoology and Hydrobiology; Banacha St. 12/16; Łódź; 90-237; Poland; Senckenberg Research Institute; Department of Marine Zoology; Section Crustacea; Senckenberganlage 25; 60325 Frankfurt; Germany.
| | - Bente Stransky
- Museum of Nature; Leibniz Institute for the Analysis of Biodiversity Change (LIB); Centre for Taxonomy and Morphology; Martin- Luther-King-Platz 3; 20146 Hamburg; Germany.
| | - Robert M Jennings
- Temple University; Biology Department; 1900 North 12th Street; Philadelphia; PA 19122; USA.
| | - Terue Cristina Kihara
- Integrated Environmental Solutions UG-INES; c/o DZMB; Südstrand 44; 26382 Wilhelmshaven; Germany.
| | - Saskia Brix
- German Centre for Marine Biodiversity Research (DZMB); Senckenberg am Meer; Martin-Luther-King-Platz 3; 20146 Hamburg; Germany.
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Piertney SB, Wenzel M, Jamieson AJ. Large effective population size masks population genetic structure in Hirondellea amphipods within the deepest marine ecosystem, the Mariana Trench. Mol Ecol 2023; 32:2206-2218. [PMID: 36808786 DOI: 10.1111/mec.16887] [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: 08/26/2022] [Revised: 02/07/2023] [Accepted: 02/09/2023] [Indexed: 02/20/2023]
Abstract
The examination of genetic structure in the deep-ocean hadal zone has focused on divergence between tectonic trenches to understand how environment and geography may drive species divergence and promote endemism. There has been little attempt to examine localized genetic structure within trenches, partly because of logistical challenges associated with sampling at an appropriate scale, and the large effective population sizes of species that can be sampled adequately may mask underlying genetic structure. Here we examine genetic structure in the superabundant amphipod Hirondellea gigas in the Mariana Trench at depths of 8126-10,545 m. RAD sequencing was used to identify 3182 loci containing 43,408 single nucleotide polymorphisms (SNPs) across individuals after stringent pruning of loci to prevent paralogous multicopy genomic regions being erroneously merged. Principal components analysis of SNP genotypes resolved no genetic structure between sampling locations, consistent with a signature of panmixia. However, discriminant analysis of principal components identified divergence between all sites driven by 301 outlier SNPs in 169 loci and significantly associated with latitude and depth. Functional annotation of loci identified differences between singleton loci used in analysis and paralogous loci pruned from the data set and also between outlier and nonoutlier loci, all consistent with hypotheses explaining the role of transposable elements driving genome dynamics. This study challenges the traditional perspective that highly abundant amphipods within a trench form a single panmictic population. We discuss the findings in relation to eco-evolutionary and ontogenetic processes operating in the deep sea, and highlight key challenges associated with population genetic analysis in nonmodel systems with inherent large effective population sizes and genomes.
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Affiliation(s)
| | - Marius Wenzel
- School of Biological Sciences, University of Aberdeen, Aberdeen, UK
| | - Alan J Jamieson
- Minderoo-UWA Deep-Sea Research Centre, School of Biological Sciences and Oceans Institute, The University of Western Australia, Perth, Western Australia, Australia
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Weston JNJ, Jensen EL, Hasoon MSR, Kitson JJN, Stewart HA, Jamieson AJ. Barriers to gene flow in the deepest ocean ecosystems: Evidence from global population genomics of a cosmopolitan amphipod. SCIENCE ADVANCES 2022; 8:eabo6672. [PMID: 36288308 PMCID: PMC9604539 DOI: 10.1126/sciadv.abo6672] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The deepest marine ecosystem, the hadal zone, hosts endemic biodiversity resulting from geographic isolation and environmental selection pressures. However, the pan-ocean distribution of some fauna challenges the concept that the hadal zone is a series of isolated island-like habitats. Whether this remains true at the population genomic level is untested. We investigated phylogeographic patterns of the amphipod, Bathycallisoma schellenbergi, from 12 hadal features across the Pacific, Atlantic, Indian, and Southern oceans and analyzed genome-wide single-nucleotide polymorphism markers and two mitochondrial regions. Despite a cosmopolitan distribution, populations were highly restricted to individual features with only limited gene flow between topographically connected features. This lack of connectivity suggests that populations are on separate evolutionary trajectories, with evidence of potential cryptic speciation at the Atacama Trench. Together, this global study demonstrates that the shallower ocean floor separating hadal features poses strong barriers to dispersal, driving genetic isolation and creating pockets of diversity to conserve.
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Affiliation(s)
- Johanna N J Weston
- School of Natural and Environmental Sciences, Newcastle University, Newcastle Upon Tyne NE1 7RU, UK
| | - Evelyn L Jensen
- School of Natural and Environmental Sciences, Newcastle University, Newcastle Upon Tyne NE1 7RU, UK
| | - Megan S R Hasoon
- Faculty of Medical Sciences, Newcastle University, Newcastle Upon Tyne NE1 7RU, UK
| | - James J N Kitson
- School of Natural and Environmental Sciences, Newcastle University, Newcastle Upon Tyne NE1 7RU, UK
| | - Heather A Stewart
- British Geological Survey, Lyell Centre, Research Avenue South, Edinburgh EH14 4AP, UK
- School of Energy, Geoscience, Infrastructure and Society, Institute of Life and Earth Sciences, Heriot-Watt University, Edinburgh, UK, EH14 4AS, UK
| | - Alan J Jamieson
- Minderoo-UWA Deep-Sea Research Centre, School of Biological Sciences and Oceans Institute, The University of Western Australia (M090), 35 Stirling Highway, Perth, WA 6009
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Li W, Wang F, Jiang S, Pan B, Liu Q, Xu Q. Morphological and molecular evolution of hadal amphipod’s eggs provides insights into embryogenesis under high hydrostatic pressure. Front Cell Dev Biol 2022; 10:987409. [PMID: 36172273 PMCID: PMC9511220 DOI: 10.3389/fcell.2022.987409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 08/26/2022] [Indexed: 11/13/2022] Open
Abstract
Hadal zones are unique habitats characterized by high hydrostatic pressure (HHP) and scarce food supplies. The ability of eggs of species dwelling in hadal zones to develop into normal embryo under high hydrostatic pressure is an important evolutionary and developmental trait. However, the mechanisms underlying the development of eggs of hadal-dwelling species remain unknown due to the difficulty of sampling ovigerous females. Here, morphological and transcriptome analyses of eggs of the “supergiant” amphipod Alicella gigantea collected from the New Britain Trench were conducted. The morphology of A. gigantea eggs, including size, was assessed and the ultrastructure of the eggshell was investigated by scanning electron microscopy. Transcriptome sequencing and molecular adaptive evolution analysis of A. gigantea eggs showed that, as compared with shallow-water Gammarus species, genes exhibiting accelerated evolution and the positively selected genes were mostly related to pathways associated with “mitosis” and “chitin-based embryonic cuticle biosynthetic process”, suggesting that “normal mitosis maintenance” and “cuticle development and protection” are the two main adaptation strategies for survival of eggs in hadal environments. In addition, the concentration of trimethylamine oxide (TMAO), an important osmotic regulator, was significantly higher in the eggs of hadal amphipods as compared to those of shallow-water species, which might promote the eggs’ adaptation abilities. Morphological identification, evolutionary analysis, and the trimethylamine oxide concentration of A. gigantea eggs will facilitate a comprehensive overview of the piezophilic adaptation of embryos in hadal environments and provide a strategy to analyze embryogenesis under high hydrostatic pressure.
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Affiliation(s)
- Wenhao Li
- Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources, Ministry of Education, College of Marine Sciences, Shanghai Ocean University, Shanghai, China
- Shanghai Engineering Research Center of Hadal Science and Technology, College of Marine Sciences, Shanghai Ocean University, Shanghai, China
- Key Laboratory of Aquaculture Resources and Utilization, Ministry of Education, College of Fisheries and Life Sciences, Shanghai Ocean University, Shanghai, China
| | - Faxiang Wang
- Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources, Ministry of Education, College of Marine Sciences, Shanghai Ocean University, Shanghai, China
| | - Shouwen Jiang
- Key Laboratory of Aquaculture Resources and Utilization, Ministry of Education, College of Fisheries and Life Sciences, Shanghai Ocean University, Shanghai, China
| | - Binbin Pan
- Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources, Ministry of Education, College of Marine Sciences, Shanghai Ocean University, Shanghai, China
- Shanghai Engineering Research Center of Hadal Science and Technology, College of Marine Sciences, Shanghai Ocean University, Shanghai, China
| | - Qi Liu
- Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources, Ministry of Education, College of Marine Sciences, Shanghai Ocean University, Shanghai, China
| | - Qianghua Xu
- Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources, Ministry of Education, College of Marine Sciences, Shanghai Ocean University, Shanghai, China
- Shanghai Engineering Research Center of Hadal Science and Technology, College of Marine Sciences, Shanghai Ocean University, Shanghai, China
- National Distant-water Fisheries Engineering Research Center, Shanghai Ocean University, Shanghai, China
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Trimethylamine N-Oxide (TMAO) and Trimethylamine (TMA) Determinations of Two Hadal Amphipods. JOURNAL OF MARINE SCIENCE AND ENGINEERING 2022. [DOI: 10.3390/jmse10040454] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Hadal trenches are a unique habitat with high hydrostatic pressure, low temperature and scarce food supplies. Amphipods are the dominant scavenging metazoan species in this ecosystem. Trimethylamine (TMA) and trimethylamine oxide (TMAO) have been shown to play important roles in regulating osmotic pressure in mammals, hadal dwellers and even microbes. However, the distributions of TMAO and TMA concentrations of hadal animals among different tissues have not been reported so far. Here, the TMAO and TMA contents of eight tissues of two hadal amphipods, Hirondellea gigas and Alicella gigantea from the Mariana Trench and the New Britain Trench, were detected by using the ultrahigh performance liquid chromatography–mass spectrometry (UPLC-MS/MS) method. Compared with the shallow water Decapoda, Penaeus vannamei, the hadal amphipods possessed significantly higher TMAO concentrations and a similar level of TMA in all the detected tissues. A higher level of TMAO was detected in the external organs (such as the eye and exoskeleton) for both of the two hadal amphipods, which indicated that the TMAO concentration was not evenly distributed, although the same hydrostatic pressure existed in the outer and internal organs. Moreover, a strong positive correlation was found between the concentrations of TMAO and TMA in the two hadal amphipods. In addition, evolutionary analysis regarding FMO3, the enzyme to convert TMA into TMAO, was also conducted. Three positive selected sites in the conserved region and two specific mutation sites in two conserved motifs were found in the A. gigantea FMO3 gene. Combined together, this study supports the important role of TMAO for the environmental adaptability of hadal amphipods and speculates on the molecular evolution and protein structure of FMO3 in hadal species.
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