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Maturana CS, Biersma EM, Díaz A, González-Wevar C, Contador T, Convey P, Jackson JA, Poulin E. Survivors and colonizers: Contrasting biogeographic histories reconciled in the Antarctic freshwater copepod Boeckella poppei. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.1012852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Two main hypotheses have been proposed to explain the contemporary distribution of Antarctic terrestrial biota. We assess whether the current distribution of maritime Antarctic populations of the freshwater copepod Boeckella poppei is the result of (1) a post-Last Glacial Maximum (LGM) colonization, or whether (2) the species survived in regional glacial refugia throughout the LGM and earlier glaciations. Using 438 specimens from 34 different sampling sites across Southern South America, South Georgia, South Orkney Islands, South Shetland Islands, and the Antarctic Peninsula, we analyzed mitochondrial and nuclear sequences to uncover patterns of genetic diversity and population structure. We also performed median-joining haplotype network, phylogenetic reconstruction, and divergence time analyses. Finally, we evaluated past demographic changes and historical scenarios using the Approximate Bayesian Computation (ABC) method. Our data support the existence of two clades with different and contrasting biogeographic histories. The first clade has been present in maritime Antarctica since at least the mid-Pleistocene, with the South Orkney Islands the most likely refugial area. The second clade has a broader distribution including southern South America, South Georgia, South Shetland Islands, and the Antarctic Peninsula. The ABC method identified long-distance dispersal (LDD) colonization event(s) from southern South America to South Georgia and the maritime Antarctic after the LGM deglaciation, supporting more recent colonization of Antarctic locations. The current Antarctic and sub-Antarctic distribution of B. poppei is likely derived from two independent biogeographic events. The combination of both (1) post-LGM colonization from southern South America and (2) longer-term persistence in in situ regional refugia throughout glacial periods challenges current understanding of the biogeographic history of Antarctic freshwater biota. Re-colonization of ice-impacted Antarctic areas would have occurred following a LDD and Establishment model, pointing to the existence of possible post-dispersal barriers, despite widely assumed high passive dispersal capacity in freshwater invertebrates.
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Segovia NI, González-Wevar CA, Naretto J, Rosenfeld S, Brickle P, Hüne M, Bernal V, Haye PA, Poulin E. The right tool for the right question: contrasting biogeographic patterns in the notothenioid fish Harpagifer spp. along the Magellan Province. Proc Biol Sci 2022; 289:20212738. [PMID: 35382596 PMCID: PMC8984805 DOI: 10.1098/rspb.2021.2738] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Molecular-based analysis has become a fundamental tool to understand the role of Quaternary glacial episodes. In the Magellan Province in southern South America, ice covering during the last glacial maximum (20 ka) radically altered the landscape/seascape, speciation rates and distribution of species. For the notothenioid fishes of the genus Harpagifer, in the area are described two nominal species. Nevertheless, this genus recently colonized South America from Antarctica, providing a short time for speciation processes. Combining DNA sequences and genotyping-by-sequencing SNPs, we evaluated the role of Quaternary glaciations over the patterns of genetic structure in Harpagifer across its distribution in the Magellan Province. DNA sequences showed low phylogeographic structure, with shared and dominant haplotypes between nominal species, suggesting a single evolutionary unit. SNPs identified contrastingly two groups in Patagonia and a third well-differentiated group in the Falkland/Malvinas Islands with limited and asymmetric gene flow. Linking the information of different markers allowed us to infer the relevance of postglacial colonization mediated by the general oceanographic circulation patterns. Contrasting rough- and fine-scale genetic patterns highlights the relevance of combined methodologies for species delimitation, which, depending on the question to be addressed, allows discrimination among phylogeographic structure, discarding incipient speciation, and contemporary spatial differentiation processes.
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Affiliation(s)
- N I Segovia
- Departamento de Ciencias Ecológicas, Instituto Milenio de Ecología y Biodiversidad (IEB), Universidad de Chile. Las Palmeras 3425, Ñuñoa, Santiago, Chile.,Departamento de Biología Marina, Facultad de Ciencias del Mar, Universidad Católica del Norte, Larrondo 1281, Coquimbo, Chile.,Instituto Milenio en Socio-ecología Costera (SECOS), Coquimbo, Chile.,Instituto Milenio Biodiversidad de Ecosistemas Antárticos y subAntárticos (MI-BASE), Valdivia, Chile
| | - C A González-Wevar
- Departamento de Ciencias Ecológicas, Instituto Milenio de Ecología y Biodiversidad (IEB), Universidad de Chile. Las Palmeras 3425, Ñuñoa, Santiago, Chile.,Instituto Milenio Biodiversidad de Ecosistemas Antárticos y subAntárticos (MI-BASE), Valdivia, Chile.,Instituto de Ciencias Marinas y Limnológicas (ICML), Facultad de Ciencias, Universidad Austral de Chile, Casilla 567, Valdivia, Chile.,Centro de Investigación en Dinámicas de Ecosistemas de Altas Latitudes (Fondap IDEAL), Universidad Austral de Chile
| | - J Naretto
- Costa Humboldt, Puerto Varas, Los Lagos, Chile
| | - S Rosenfeld
- Departamento de Ciencias Ecológicas, Instituto Milenio de Ecología y Biodiversidad (IEB), Universidad de Chile. Las Palmeras 3425, Ñuñoa, Santiago, Chile.,Laboratorio de Ecosistemas Antárticos y sub-Antárticos, Universidad de Magallanes, Chile
| | - P Brickle
- South Atlantic Environmental Research Institute (SAERI), PO Box 609, Stanley Cottage, Port Stanley, Falkland Islands, UK
| | - M Hüne
- Departamento de Ciencias Ecológicas, Instituto Milenio de Ecología y Biodiversidad (IEB), Universidad de Chile. Las Palmeras 3425, Ñuñoa, Santiago, Chile.,Centro de Investigación para la Conservación de los Ecosistemas Australes (ICEA), Punta Arenas, Chile
| | - V Bernal
- Departamento de Ciencias Ecológicas, Instituto Milenio de Ecología y Biodiversidad (IEB), Universidad de Chile. Las Palmeras 3425, Ñuñoa, Santiago, Chile.,Instituto Milenio Biodiversidad de Ecosistemas Antárticos y subAntárticos (MI-BASE), Valdivia, Chile
| | - P A Haye
- Departamento de Biología Marina, Facultad de Ciencias del Mar, Universidad Católica del Norte, Larrondo 1281, Coquimbo, Chile.,Instituto Milenio en Socio-ecología Costera (SECOS), Coquimbo, Chile
| | - E Poulin
- Departamento de Ciencias Ecológicas, Instituto Milenio de Ecología y Biodiversidad (IEB), Universidad de Chile. Las Palmeras 3425, Ñuñoa, Santiago, Chile.,Instituto Milenio Biodiversidad de Ecosistemas Antárticos y subAntárticos (MI-BASE), Valdivia, Chile
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3
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Effects of seawater temperature and seasonal irradiance on growth, reproduction, and survival of the endemic Antarctic brown alga Desmarestia menziesii (Phaeophyceae). Polar Biol 2022. [DOI: 10.1007/s00300-021-02991-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
AbstractEndemic Antarctic macroalgae are especially adapted to live in extreme Antarctic conditions. Their potential biogeographic distribution niche is primarily controlled by the photoperiodic regime and seawater temperatures, since these parameters regulate growth, reproduction, and survival during the entire life cycle. Here we analyzed the upper survival temperature (UST) of juvenile sporophytes and the temperature range for sporophyte formation from gametophytes of Desmarestia menziesii, one of the dominant endemic Antarctic brown algal species. This process is a missing link to better evaluate the full biogeographical niche of this species. Two laboratory experiments were conducted. First, growth and maximum quantum yield of juvenile sporophytes were analyzed under a temperature gradient (0, 5, 10, 12, 13, 14, 15, and 16 °C) in a 16:8 h light:dark (LD) regime (Antarctic spring condition) for 2 weeks. Second, the formation of sporophytes from gametophytes (as a proxy of gametophyte reproduction) was evaluated during a 7 weeks period under a temperature gradient (0, 4, 8, 12, and 16 °C), and two different photoperiods: 6:18 h LD regime simulating winter conditions and a light regime simulating the Antarctic shift from winter to spring by gradually increasing the light period from 7.5:16.5 h LD (late winter) to 18.5:5.5 h LD (late spring). Sporophytes of D. menziesii were able to grow and survive up to 14 °C for 2 weeks without visible signs of morphological damage. Thus, this species shows the highest UST of all endemic Antarctic Desmarestiales species. In turn, gametophyte reproduction solely took place at 0 °C but not at 4–8 °C. The number of emerging sporophytes was six times higher under the light regime simulating the transition from winter to spring than under constant short day winter conditions. There was a negative relationship between the number of sporophytes formed and the gametophyte density at the beginning of the experiment, which provides evidence that gametophyte density exerts some control upon reproduction in D. menziesii. Results strongly indicate that although sporophytes and gametophytes may survive in warmer temperatures, the northernmost distribution limit of D. menziesii in South Georgia Islands is set by the low temperature requirements for gametophyte reproduction. Hence, global warming could have an impact on the distribution of this and other Antarctic species, by influencing their growth and reproduction.
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4
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OUP accepted manuscript. Zool J Linn Soc 2022. [DOI: 10.1093/zoolinnean/zlac032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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5
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Tonicelli GA, Croce ME, Díaz-Tapia P, Fredericq S, Freshwater DW, Gauna MC, Parodi ER, Verbruggen H, Hommersand MH. Meridionella gen. nov., a New Genus of Cystocloniaceae (Gigartinales, Rhodophyta) from the Southern Hemisphere, Including M. obtusangula comb. nov. and M. antarctica sp. nov. JOURNAL OF PHYCOLOGY 2021; 57:797-816. [PMID: 33450046 DOI: 10.1111/jpy.13127] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 10/28/2020] [Accepted: 10/29/2020] [Indexed: 06/12/2023]
Abstract
The classification of Cystoclonium obtusangulum has been questioned since the species was first described by Hooker and Harvey as Gracilaria? obtusangula. The objective of this study was to provide the first comprehensive taxonomic analysis of Cystoclonium obtusangulum, based on DNA sequences coupled with morphological observations made on syntype specimens and new collections. Sequence divergences of rbcL, UPA, and COI-5P, and maximum-likelihood phylogenies for rbcL and 18S demonstrated that specimens identified as Cystoclonium obtusangulum represent a clade of two distinct species that are distantly related to the generitype Cystoclonium purpureum. A new genus, Meridionella gen. nov., is proposed for this clade. The two species placed in this new genus were morphologically indistinguishable cryptic species, but have disjunct distributions, with Meridionella obtusangula comb. nov. found from temperate to cold coasts of South America and the Falkland Islands and Meridionella antarctica sp. nov., occurring in Antarctic waters. Vegetative and reproductive characters of Meridionella gen. nov. are described, and implications of our results for the biogeography of the family Cystocloniaceae are discussed.
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Affiliation(s)
- Gina A Tonicelli
- Instituto Argentino de Oceanografía, CONICET-UNS, Camino La carrindanga km 7.5, Bahía Blanca, 8000, Argentina
- Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, San Juan 670, Bahía Blanca, 8000, Argentina
| | - Maria Emilia Croce
- Instituto Argentino de Oceanografía, CONICET-UNS, Camino La carrindanga km 7.5, Bahía Blanca, 8000, Argentina
- Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, San Juan 670, Bahía Blanca, 8000, Argentina
| | - Pilar Díaz-Tapia
- Coastal Biology Research Group, Faculty of Sciences and Centre for Advanced Scientific Research (CICA), University of A Coruña, 15071, A Coruña, Spain
- Instituto Español de Oceanografía (IEO), Centro Oceanográfico de A Coruña, Apdo, 130, 15080, A Coruña, Spain
| | - Suzanne Fredericq
- Department of Biology, University of Louisiana at Lafayette, Lafayette, Louisiana, 70504-3602, USA
| | - David Wilson Freshwater
- Center for Marine Science, University of North Carolina at Wilmington, 5600 Marvin Moss Lane, Wilmington, North Carolina, 28409, USA
| | - Maria Cecilia Gauna
- Instituto Argentino de Oceanografía, CONICET-UNS, Camino La carrindanga km 7.5, Bahía Blanca, 8000, Argentina
- Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, San Juan 670, Bahía Blanca, 8000, Argentina
| | - Elisa R Parodi
- Instituto Argentino de Oceanografía, CONICET-UNS, Camino La carrindanga km 7.5, Bahía Blanca, 8000, Argentina
- Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, San Juan 670, Bahía Blanca, 8000, Argentina
| | - Heroen Verbruggen
- School of BioSciences, University of Melbourne, Melbourne, Victoria, 3010, Australia
| | - Max H Hommersand
- Department of Biology, University of North Carolina at Chapel Hill, Coker Hall, Chapel Hill, North Carolina, 27599-3280, USA
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González-Ballesteros N, Rodríguez-Argüelles MC, Lastra-Valdor M. Evaluation of the Antioxidant Capacities of Antarctic Macroalgae and Their Use for Nanoparticles Production. Molecules 2021; 26:1182. [PMID: 33672102 PMCID: PMC7926919 DOI: 10.3390/molecules26041182] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 02/16/2021] [Accepted: 02/20/2021] [Indexed: 12/19/2022] Open
Abstract
Macroalgae are sources of bioactive compounds that are interesting from both a chemical and a medical point of view. Although their use in biomedicine has increased significantly in recent years, tests conducted to date have been mostly related to species from temperate latitudes, with the potential application of Antarctic biodiversity being minor. The wide variety of algae species present on Antarctic coastal areas can be a source of new antioxidants. Bearing this in mind, the brown macroalgae Desmarestia antarctica (DA) and the red Iridaea cordata (IC) were selected for the preparation of aqueous extracts with the aim of analyzing their antioxidant activity. This analysis was performed by determining reducing power, total phenolic content, and 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity. Furthermore, both extracts were employed to synthesize gold and silver nanoparticles. The nanomaterials were fully characterized by means of UV-Visible spectroscopy, transmission electron microscopy, Z potential measurements, and Fourier transform infrared spectroscopy, which confirmed the formation of stable, spherical nanoparticles with mean diameters of 13.7 ± 3.1 and 17.5 ± 3.7 nm for Ag@DA and Ag@IC and 12.6 ± 1.9 and 12.3 ± 1.6 nm for Au@DA and Au@IC. Antioxidant assays were performed after the synthesis of the nanomaterials to evaluate their possible synergistic effect with the extracts. The results suggest that polysaccharides and proteins may play a key role in the process of reduction and stabilization. Finally, for the sake of comparison, the results obtained for the Antarctic macroalgae Desmarestia menziesii and Palmaria decipiens have also been considered in the present work.
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Affiliation(s)
| | | | - M. Lastra-Valdor
- Centro de Investigación Marina, Universidade de Vigo, 36331 Vigo, Spain;
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7
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Díaz A, Gérard K, González-Wevar C, Maturana C, Féral JP, David B, Saucède T, Poulin E. Genetic structure and demographic inference of the regular sea urchin Sterechinus neumayeri (Meissner, 1900) in the Southern Ocean: The role of the last glaciation. PLoS One 2018; 13:e0197611. [PMID: 29874287 PMCID: PMC5991379 DOI: 10.1371/journal.pone.0197611] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 05/04/2018] [Indexed: 01/10/2023] Open
Abstract
One of the most relevant characteristics of the extant Southern Ocean fauna is its resiliency to survive glacial processes of the Quaternary. These climatic events produced catastrophic habitat reductions and forced some marine benthic species to move, adapt or go extinct. The marine benthic species inhabiting the Antarctic upper continental shelf faced the Quaternary glaciations with different strategies that drastically modified population sizes and thus affected the amount and distribution of intraspecific genetic variation. Here we present new genetic information for the most conspicuous regular sea urchin of the Antarctic continental shelf, Sterechinus neumayeri. We studied the patterns of genetic diversity and structure in this broadcast-spawner across three Antarctic regions: Antarctic Peninsula, the Weddell Sea and Adélie Land in East Antarctica. Genetic analyses based on mitochondrial and nuclear markers suggested that S. neumayeri is a single genetic unit around the Antarctic continent. The species is characterized by low levels of genetic diversity and exhibits a typical star-like haplotype genealogy that supports the hypothesis of a single in situ refugium. Based on two mutation rates standardized for this genus, the Bayesian Skyline plot analyses detected a rapid demographic expansion after the Last Glacial Maximum. We propose a scenario of rapid postglacial expansion and recolonization of Antarctic shallow areas from a less ice-impacted refugium where the species survived the LGM. Considering the patterns of genetic diversity and structure recorded in the species, this refugium was probably located in East Antarctica.
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Affiliation(s)
- Angie Díaz
- Departamento de Zoología, Universida d de Concepción, Barrio Universitario s/n, Concepción, Chile
| | - Karin Gérard
- Facultad de Ciencias, Universidad de Magallanes, Bulnes, Punta Arenas, Chile
- Laboratorio de Ecología Molecular Antártica y Subantártica, Universidad de Magallanes, Punta Arenas, Chile
| | - Claudio González-Wevar
- Laboratorio de Ecología Molecular Antártica y Subantártica, Universidad de Magallanes, Punta Arenas, Chile
- Instituto de Ciencias Marinas y Limnológicas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile
- Instituto de Ecología y Biodiversidad (IEB), Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Las Palmeras, Ñuñoa, Santiago, Chile
| | - Claudia Maturana
- Instituto de Ecología y Biodiversidad (IEB), Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Las Palmeras, Ñuñoa, Santiago, Chile
| | - Jean-Pierre Féral
- UMR 7263—IMBE, Station Marine d’Endoume, Institut Méditerranéen de Biodiversité et d’Ecologie Marine et continentale, Chemin de la Batterie des Lions,Marseille, France
| | - Bruno David
- Biogéosciences, UMR CNRS 6282, Université de Bourgogne, boulevard Gabriel, Dijon, France
- Museum National d’Histoire Naturelle, Paris, France
| | - Thomas Saucède
- UMR 7263—IMBE, Station Marine d’Endoume, Institut Méditerranéen de Biodiversité et d’Ecologie Marine et continentale, Chemin de la Batterie des Lions,Marseille, France
| | - Elie Poulin
- Instituto de Ecología y Biodiversidad (IEB), Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Las Palmeras, Ñuñoa, Santiago, Chile
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8
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Comparative phylogeography of six red algae along the Antarctic Peninsula: extreme genetic depletion linked to historical bottlenecks and recent expansion. Polar Biol 2018. [DOI: 10.1007/s00300-017-2244-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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9
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Soler-Membrives A, Linse K, Miller KJ, Arango CP. Genetic signature of Last Glacial Maximum regional refugia in a circum-Antarctic sea spider. ROYAL SOCIETY OPEN SCIENCE 2017; 4:170615. [PMID: 29134072 PMCID: PMC5666255 DOI: 10.1098/rsos.170615] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Accepted: 09/18/2017] [Indexed: 05/16/2023]
Abstract
The evolutionary history of Antarctic organisms is becoming increasingly important to understand and manage population trajectories under rapid environmental change. The Antarctic sea spider Nymphon australe, with an apparently large population size compared with other sea spider species, is an ideal target to look for molecular signatures of past climatic events. We analysed mitochondrial DNA of specimens collected from the Antarctic continent and two Antarctic islands (AI) to infer past population processes and understand current genetic structure. Demographic history analyses suggest populations survived in refugia during the Last Glacial Maximum. The high genetic diversity found in the Antarctic Peninsula and East Antarctic (EA) seems related to multiple demographic contraction-expansion events associated with deep-sea refugia, while the low genetic diversity in the Weddell Sea points to a more recent expansion from a shelf refugium. We suggest the genetic structure of N. australe from AI reflects recent colonization from the continent. At a local level, EA populations reveal generally low genetic differentiation, geographically and bathymetrically, suggesting limited restrictions to dispersal. Results highlight regional differences in demographic histories and how these relate to the variation in intensity of glaciation-deglaciation events around Antarctica, critical for the study of local evolutionary processes. These are valuable data for understanding the remarkable success of Antarctic pycnogonids, and how environmental changes have shaped the evolution and diversification of Southern Ocean benthic biodiversity.
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Affiliation(s)
- Anna Soler-Membrives
- Unitat de Zoologia, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain
| | - Katrin Linse
- British Antarctic Survey, Natural Environmental Research Council, High Cross, Madingley Road, Cambridge CB30ET, UK
| | - Karen J. Miller
- Australian Institute of Marine Science, Indian Ocean Marine Research Centre Fairway, cnr Service Road 4, Crawley, Western Australia 6009, Australia
| | - Claudia P. Arango
- Biodiversity and Geosciences Program, Queensland Museum, PO Box 3300, South Brisbane, Queensland 4101, Australia
- Author for correspondence: Claudia P. Arango e-mail:
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González-Wevar CA, Rosenfeld S, Segovia NI, Hüne M, Gérard K, Ojeda J, Mansilla A, Brickle P, Díaz A, Poulin E. Genetics, Gene Flow, and Glaciation: The Case of the South American Limpet Nacella mytilina. PLoS One 2016; 11:e0161963. [PMID: 27598461 PMCID: PMC5012656 DOI: 10.1371/journal.pone.0161963] [Citation(s) in RCA: 12] [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: 05/27/2016] [Accepted: 08/15/2016] [Indexed: 02/01/2023] Open
Abstract
Glacial episodes of the Quaternary, and particularly the Last Glacial Maximum (LGM) drastically altered the distribution of the Southern-Hemisphere biota, principally at higher latitudes. The irregular coastline of Patagonia expanding for more than 84.000 km constitutes a remarkable area to evaluate the effect of Quaternary landscape and seascape shifts over the demography of near-shore marine benthic organisms. Few studies describing the biogeographic responses of marine species to the LGM have been conducted in Patagonia, but existing data from coastal marine species have demonstrated marked genetic signatures of post-LGM recolonization and expansion. The kelp-dweller limpet Nacella mytilina is broadly distributed along the southern tip of South America and at the Falkland/Malvinas Islands. Considering its distribution, abundance, and narrow bathymetry, N. mytilina represents an appropriate model to infer how historical and contemporary processes affected the distribution of intraspecific genetic diversity and structure along the southern tip of South America. At the same time, it will be possible to determine how life history traits and the ecology of the species are responsible for the current pattern of gene flow and connectivity across the study area. We conducted phylogeographic and demographic inference analyses in N. mytilina from 12 localities along Pacific Patagonia (PP) and one population from the Falkland/Malvinas Islands (FI). Analyses of the mitochondrial gene COI in 300 individuals of N. mytilina revealed low levels of genetic polymorphism and the absence of genetic differentiation along PP. In contrast, FI showed a strong and significant differentiation from Pacific Patagonian populations. Higher levels of genetic diversity were also recorded in the FI population, together with a more expanded genealogy supporting the hypothesis of glacial persistence of the species in these islands. Haplotype genealogy, and mismatch analyses in the FI population recognized an older and more complex demographic history than in PP. Demographic reconstructions along PP suggest a post-LGM expansion process (7.5 ka), also supported by neutrality tests, mismatch distribution and maximum parsimony haplotype genealogies. Migration rate estimations showed evidence of asymmetrical gene flow from PP to FI. The absence of genetic differentiation, the presence of a single dominant haplotype, high estimated migration rates, and marked signal of recent demographic growth, support the hypothesis of rapid post-glacial expansion in N. mytilina along PP. This expansion could have been sustained by larval and rafting-mediated dispersal of adults from northernmost populations following the Cape Horn Current System. Marked genetic differentiation between PP and FI could be explained through differences in their respective glacial histories. During the LGM, Pacific Patagonia (PP) was almost fully covered by the Patagonian Ice Sheet, while sheet coverage in the FI ice was restricted to small cirques and valleys. As previously recorded in the sister-species N. magellanica, the FI rather than represent a classical glacial refugium for N. mytilina, seems to represent a sink area and/or a secondary contact zone. Accordingly, historical and contemporary processes, contrasting glacial histories between the analyzed sectors, as well as life history traits constitute the main factors explaining the current biogeographical patterns of most shallow Patagonian marine benthic organisms.
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Affiliation(s)
- Claudio A. González-Wevar
- GAIA Antártica – Universidad de Magallanes, Departamento de Recursos Naturales, Bulnes 01890, Punta Arenas, Chile
- Instituto de Ecología y Biodiversidad (IEB), Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Las Palmeras # 3425, Ñuñoa, Santiago, Chile
- Laboratorio de Macroalgas Antárticas y Subantárticas, Universidad de Magallanes, casilla 113-D, Punta Arenas, Chile
| | - Sebastián Rosenfeld
- Instituto de Ecología y Biodiversidad (IEB), Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Las Palmeras # 3425, Ñuñoa, Santiago, Chile
- Laboratorio de Macroalgas Antárticas y Subantárticas, Universidad de Magallanes, casilla 113-D, Punta Arenas, Chile
| | - Nicolás I. Segovia
- Instituto de Ecología y Biodiversidad (IEB), Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Las Palmeras # 3425, Ñuñoa, Santiago, Chile
| | - Mathias Hüne
- Instituto de Ecología y Biodiversidad (IEB), Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Las Palmeras # 3425, Ñuñoa, Santiago, Chile
- Fundación Ictiológica, Providencia – Santiago, Chile
| | - Karin Gérard
- GAIA Antártica – Universidad de Magallanes, Departamento de Recursos Naturales, Bulnes 01890, Punta Arenas, Chile
- Laboratorio de Macroalgas Antárticas y Subantárticas, Universidad de Magallanes, casilla 113-D, Punta Arenas, Chile
| | - Jaime Ojeda
- Instituto de Ecología y Biodiversidad (IEB), Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Las Palmeras # 3425, Ñuñoa, Santiago, Chile
- Laboratorio de Macroalgas Antárticas y Subantárticas, Universidad de Magallanes, casilla 113-D, Punta Arenas, Chile
| | - Andrés Mansilla
- Instituto de Ecología y Biodiversidad (IEB), Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Las Palmeras # 3425, Ñuñoa, Santiago, Chile
- Laboratorio de Macroalgas Antárticas y Subantárticas, Universidad de Magallanes, casilla 113-D, Punta Arenas, Chile
| | - Paul Brickle
- South Atlantic Environmental Research Institute (SAERI), PO Box 609, Stanley Cottage, Stanley, Falkland Islands
| | - Angie Díaz
- Departamento de Zoología, Facultad de Ciencias Naturales y Oceanográficas, Universidad de Concepción, Concepción, Chile
| | - Elie Poulin
- Instituto de Ecología y Biodiversidad (IEB), Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Las Palmeras # 3425, Ñuñoa, Santiago, Chile
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