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Madeira P, Reddy MM, Assis J, Bolton JJ, Rothman MD, Anderson RJ, Kandjengo L, Kreiner A, Coleman MA, Wernberg T, De Clerck O, Leliaert F, Bandeira S, Ada AM, Neiva J, Pearson GA, Serrão EA. Cryptic diversity in southern African kelp. Sci Rep 2024; 14:11071. [PMID: 38745036 PMCID: PMC11093989 DOI: 10.1038/s41598-024-61336-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Accepted: 05/04/2024] [Indexed: 05/16/2024] Open
Abstract
The southern coast of Africa is one of the few places in the world where water temperatures are predicted to cool in the future. This endemism-rich coastline is home to two sister species of kelps of the genus Ecklonia maxima and Ecklonia radiata, each associated with specific thermal niches, and occuring primarily on opposite sides of the southern tip of Africa. Historical distribution records indicate that E. maxima has recently shifted its distribution ~ 70 km eastward, to sites where only E. radiata was previously reported. The contact of sister species with contrasting thermal affinities and the occurrence of mixed morphologies raised the hypothesis that hybridization might be occurring in this contact zone. Here we describe the genetic structure of the genus Ecklonia along the southern coast of Africa and investigate potential hybridization and cryptic diversity using a combination of nuclear microsatellites and mitochondrial markers. We found that both species have geographically discrete genetic clusters, consistent with expected phylogeographic breaks along this coastline. In addition, depth-isolated populations were found to harbor unique genetic diversity, including a third Ecklonia lineage. Mito-nuclear discordance and high genetic divergence in the contact zones suggest multiple hybridization events between Ecklonia species. Discordance between morphological and molecular identification suggests the potential influence of abiotic factors leading to convergent phenotypes in the contact zones. Our results highlight an example of cryptic diversity and hybridization driven by contact between two closely related keystone species with contrasting thermal affinities.
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Affiliation(s)
- Pedro Madeira
- CCMAR, University of Algarve, Gambelas, Faro, Portugal.
| | - Maggie M Reddy
- Department of Biological Sciences, University of Cape Town, Cape Town, 7701, South Africa.
| | - Jorge Assis
- CCMAR, University of Algarve, Gambelas, Faro, Portugal
- Faculty of Bioscience and Aquaculture, Nord Universitet, Bodø, Norway
| | - John J Bolton
- Department of Biological Sciences, University of Cape Town, Cape Town, 7701, South Africa.
| | - Mark D Rothman
- Department of Biological Sciences, University of Cape Town, Cape Town, 7701, South Africa.
- Department of Environment, Forestry and Fisheries, Private Bag X2, Vlaeberg, 8012, South Africa.
| | - Robert J Anderson
- Department of Biological Sciences, University of Cape Town, Cape Town, 7701, South Africa
| | - Lineekela Kandjengo
- Department of Fisheries and Ocean Sciences, University of Namibia, Sam Nujoma Campus, Henties Bay, Namibia
| | - Anja Kreiner
- National Marine Information and Research Centre, Ministry of Fisheries and Marine Resources, Swakopmund, Namibia
| | - Melinda A Coleman
- New South Wales Fisheries, National Marine Science Centre, 2 Bay Drive, Coffs Harbour, NSW, 2450, Australia
- National Marine Science Centre, Southern Cross University, 2 Bay Drive, Coffs Harbour, NSW, 2450, Australia
- UWA Oceans Institute and School of Biological Sciences, University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia
| | - Thomas Wernberg
- UWA Oceans Institute and School of Biological Sciences, University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia
| | - Olivier De Clerck
- Biology Department, Ghent University, Krijgslaan 281 S8, 9000, Ghent, Belgium
| | | | - Salomão Bandeira
- Department of Biological Sciences, Eduardo Mondlane University, Maputo, Mozambique
| | - Abdul M Ada
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, 70803, USA
| | - João Neiva
- CCMAR, University of Algarve, Gambelas, Faro, Portugal
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Salland N, Jensen A, Smale DA. The structure and diversity of macroinvertebrate assemblages associated with the understudied pseudo-kelp Saccorhiza polyschides in the Western English Channel (UK). MARINE ENVIRONMENTAL RESEARCH 2024; 198:106519. [PMID: 38678754 DOI: 10.1016/j.marenvres.2024.106519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2024] [Revised: 03/28/2024] [Accepted: 04/15/2024] [Indexed: 05/01/2024]
Abstract
We examined spatiotemporal variability in the structure of faunal assemblages associated with the warm-temperate pseudo-kelp Saccorhiza polyschides towards its range centre (Western English Channel, southwest UK), to better understand its role as a habitat-former in the northeast Atlantic. A total of 180 sporophytes and their associated fauna were sampled across three months, three sites, and two depths. Assemblage abundance and biomass varied markedly between three morpho-functional sporophyte components (i.e., holdfast, stipe, blade). We recorded rich and abundant macroinvertebrate assemblages, comprising nine phyla, 28 coarse taxonomic groups, and 57 species of molluscs, which consistently dominated assemblages. We observed pronounced seasonality in faunal assemblage structure, marked variability between sites and depths, and strong positive relationships between biogenic habitat availability and faunal abundance/biomass. S. polyschides sporophytes are short-lived and offer temporary, less-stable habitat compared with dominant perennial Laminaria species, so shifts in the relative abundances of habitat-formers will likely alter local biodiversity patterns.
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Affiliation(s)
- Nora Salland
- The Marine Biological Association of the United Kingdom, The Laboratory, Citadel Hill, PL1 2PB, Plymouth, UK; School of Ocean and Earth Science, University of Southampton, European Way, SO14 3ZH, Southampton, UK.
| | - Antony Jensen
- School of Ocean and Earth Science, University of Southampton, European Way, SO14 3ZH, Southampton, UK.
| | - Dan A Smale
- The Marine Biological Association of the United Kingdom, The Laboratory, Citadel Hill, PL1 2PB, Plymouth, UK.
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Filbee-Dexter K, Starko S, Pessarrodona A, Wood G, Norderhaug KM, Piñeiro-Corbeira C, Wernberg T. Marine protected areas can be useful but are not a silver bullet for kelp conservation. JOURNAL OF PHYCOLOGY 2024; 60:203-213. [PMID: 38546039 DOI: 10.1111/jpy.13446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Revised: 03/02/2024] [Accepted: 03/04/2024] [Indexed: 04/11/2024]
Abstract
Kelp forests are among the most valuable ecosystems on Earth, but they are increasingly being degraded and lost due to a range of human-related stressors, leading to recent calls for their improved management and conservation. One of the primary tools to conserve marine species and biodiversity is the establishment of marine protected areas (MPAs). International commitments to protect 30% of the world's ecosystems are gaining momentum, offering a promising avenue to secure kelp forests into the Anthropocene. However, a clear understanding of the efficacy of MPAs for conserving kelp forests in a changing ocean is lacking. In this perspective, we question whether strengthened global protection will create meaningful conservation outcomes for kelp forests. We explore the benefits of MPAs for kelp conservation under a suite of different stressors, focusing on empirical evidence from protected kelp forests. We show that MPAs can be effective against some drivers of kelp loss (e.g., overgrazing, kelp harvesting), particularly when they are maintained in the long-term and enforced as no-take areas. There is also some evidence that MPAs can reduce impacts of climate change through building resilience in multi-stressor situations. However, MPAs also often fail to provide protection against ocean warming, marine heatwaves, coastal darkening, and pollution, which have emerged as dominant drivers of kelp forest loss globally. Although well-enforced MPAs should remain an important tool to protect kelp forests, successful kelp conservation will require implementing an additional suite of management solutions that target these accelerating threats.
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Affiliation(s)
- Karen Filbee-Dexter
- School of Biological Sciences and Oceans Institute, University of Western Australia, Perth, Western Australia, Australia
- Institute of Marine Research, His, Norway
| | - Samuel Starko
- School of Biological Sciences and Oceans Institute, University of Western Australia, Perth, Western Australia, Australia
| | - Albert Pessarrodona
- School of Biological Sciences and Oceans Institute, University of Western Australia, Perth, Western Australia, Australia
| | - Georgina Wood
- School of Biological Sciences and Oceans Institute, University of Western Australia, Perth, Western Australia, Australia
| | | | - Cristina Piñeiro-Corbeira
- BioCost Research Group, Facultad de Ciencias, and CICA - Centro Interdisciplinar de Química e Bioloxía, Universidad de A Coruña, A Coruña, Spain
| | - Thomas Wernberg
- School of Biological Sciences and Oceans Institute, University of Western Australia, Perth, Western Australia, Australia
- Institute of Marine Research, His, Norway
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Krumhansl KA, Brooks CM, Lowen JB, O’Brien JM, Wong MC, DiBacco C. Loss, resilience and recovery of kelp forests in a region of rapid ocean warming. ANNALS OF BOTANY 2024; 133:73-92. [PMID: 37952103 PMCID: PMC10921841 DOI: 10.1093/aob/mcad170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Accepted: 11/08/2023] [Indexed: 11/14/2023]
Abstract
BACKGROUND AND AIMS Changes in kelp abundances on regional scales have been highly variable over the past half-century owing to strong effects of local and regional drivers. Here, we assess patterns and dominant environmental variables causing spatial and interspecific variability in kelp persistence and resilience to change in Nova Scotia over the past 40 years. METHODS We conducted a survey of macrophyte abundance at 251 sites spanning the Atlantic coast of Nova Scotia from 2019 to 2022. We use this dataset to describe spatial variability in kelp species abundances, compare species occurrences to surveys conducted in 1982 and assess changes in kelp abundance over the past 22 years. We then relate spatial and temporal patterns in abundance and resilience to environmental metrics. KEY RESULTS Our results show losses of sea urchins and the cold-tolerant kelp species Alaria esculenta, Saccorhiza dermatodea and Agarum clathratum in Nova Scotia since 1982 in favour of the more warm-tolerant kelps Saccharina latissima and Laminaria digitata. Kelp abundances have increased slightly since 2000, and Saccharina latissima and L. digitata are widely abundant in the region today. The highest kelp cover occurs on wave-exposed shores and at sites where temperatures have remained below thresholds for growth (21 °C) and mortality (23 °C). Moreover, kelp has recovered from turf dominance following losses at some sites during a warm period from 2010 to 2012. CONCLUSIONS Our results indicate that dramatic changes in kelp community composition and a loss of sea urchin herbivory as a dominant driver of change in the system have occurred in Nova Scotia over the past 40 years. However, a broad-scale shift to turf-dominance has not occurred, as predicted, and our results suggest that resilience and persistence are still a feature of kelp forests in the region despite rapid warming over the past several decades.
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Affiliation(s)
- K A Krumhansl
- Fisheries and Oceans Canada, Bedford Institute of Oceanography, Dartmouth, Nova Scotia, B2Y 4A2, Canada
| | - C M Brooks
- Fisheries and Oceans Canada, Bedford Institute of Oceanography, Dartmouth, Nova Scotia, B2Y 4A2, Canada
| | - J B Lowen
- Fisheries and Oceans Canada, Bedford Institute of Oceanography, Dartmouth, Nova Scotia, B2Y 4A2, Canada
| | - J M O’Brien
- Fisheries and Oceans Canada, Bedford Institute of Oceanography, Dartmouth, Nova Scotia, B2Y 4A2, Canada
| | - M C Wong
- Fisheries and Oceans Canada, Bedford Institute of Oceanography, Dartmouth, Nova Scotia, B2Y 4A2, Canada
| | - C DiBacco
- Fisheries and Oceans Canada, Bedford Institute of Oceanography, Dartmouth, Nova Scotia, B2Y 4A2, Canada
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Wernberg T, Thomsen MS, Baum JK, Bishop MJ, Bruno JF, Coleman MA, Filbee-Dexter K, Gagnon K, He Q, Murdiyarso D, Rogers K, Silliman BR, Smale DA, Starko S, Vanderklift MA. Impacts of Climate Change on Marine Foundation Species. ANNUAL REVIEW OF MARINE SCIENCE 2024; 16:247-282. [PMID: 37683273 DOI: 10.1146/annurev-marine-042023-093037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/10/2023]
Abstract
Marine foundation species are the biotic basis for many of the world's coastal ecosystems, providing structural habitat, food, and protection for myriad plants and animals as well as many ecosystem services. However, climate change poses a significant threat to foundation species and the ecosystems they support. We review the impacts of climate change on common marine foundation species, including corals, kelps, seagrasses, salt marsh plants, mangroves, and bivalves. It is evident that marine foundation species have already been severely impacted by several climate change drivers, often through interactive effects with other human stressors, such as pollution, overfishing, and coastal development. Despite considerable variation in geographical, environmental, and ecological contexts, direct and indirect effects of gradual warming and subsequent heatwaves have emerged as the most pervasive drivers of observed impact and potent threat across all marine foundation species, but effects from sea level rise, ocean acidification, and increased storminess are expected to increase. Documented impacts include changes in the genetic structures, physiology, abundance, and distribution of the foundation species themselves and changes to their interactions with other species, with flow-on effects to associated communities, biodiversity, and ecosystem functioning. We discuss strategies to support marine foundation species into the Anthropocene, in order to increase their resilience and ensure the persistence of the ecosystem services they provide.
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Affiliation(s)
- Thomas Wernberg
- Oceans Institute and School of Biological Sciences, University of Western Australia, Crawley, Western Australia, Australia;
- Flødevigen Research Station, Institute of Marine Research, His, Norway
| | - Mads S Thomsen
- Marine Ecology Research Group, School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
- Department of Ecoscience, Aarhus University, Roskilde, Denmark
| | - Julia K Baum
- Department of Biology, University of Victoria, Victoria, British Columbia, Canada
| | - Melanie J Bishop
- School of Natural Sciences, Macquarie University, Macquarie Park, New South Wales, Australia
| | - John F Bruno
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Melinda A Coleman
- National Marine Science Centre, New South Wales Department of Primary Industries, Coffs Harbour, New South Wales, Australia
| | - Karen Filbee-Dexter
- Oceans Institute and School of Biological Sciences, University of Western Australia, Crawley, Western Australia, Australia;
- Flødevigen Research Station, Institute of Marine Research, His, Norway
| | - Karine Gagnon
- Flødevigen Research Station, Institute of Marine Research, His, Norway
| | - Qiang He
- Coastal Ecology Lab, MOE Key Laboratory for Biodiversity Science and Ecological Engineering, School of Life Sciences, Fudan University, Shanghai, China
| | - Daniel Murdiyarso
- Center for International Forestry Research-World Agroforestry (CIFOR-ICRAF), Bogor, Indonesia
- Department of Geophysics and Meteorology, IPB University, Bogor, Indonesia
| | - Kerrylee Rogers
- School of Earth, Atmospheric, and Life Sciences, University of Wollongong, Wollongong, New South Wales, Australia
| | - Brian R Silliman
- Nicholas School of the Environment, Duke University, Durham, North Carolina, USA
| | - Dan A Smale
- Marine Biological Association of the United Kingdom, Plymouth, United Kingdom
| | - Samuel Starko
- Oceans Institute and School of Biological Sciences, University of Western Australia, Crawley, Western Australia, Australia;
| | - Mathew A Vanderklift
- Indian Ocean Marine Research Centre, Commonwealth Scientific and Industrial Research Organisation (CSIRO), Crawley, Western Australia, Australia
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Assis J, Alberto F, Macaya EC, Castilho Coelho N, Faugeron S, Pearson GA, Ladah L, Reed DC, Raimondi P, Mansilla A, Brickle P, Zuccarello GC, Serrão EA. Past climate-driven range shifts structuring intraspecific biodiversity levels of the giant kelp (Macrocystis pyrifera) at global scales. Sci Rep 2023; 13:12046. [PMID: 37491385 PMCID: PMC10368654 DOI: 10.1038/s41598-023-38944-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Accepted: 07/17/2023] [Indexed: 07/27/2023] Open
Abstract
The paradigm of past climate-driven range shifts structuring the distribution of marine intraspecific biodiversity lacks replication in biological models exposed to comparable limiting conditions in independent regions. This may lead to confounding effects unlinked to climate drivers. We aim to fill in this gap by asking whether the global distribution of intraspecific biodiversity of giant kelp (Macrocystis pyrifera) is explained by past climate changes occurring across the two hemispheres. We compared the species' population genetic diversity and structure inferred with microsatellite markers, with range shifts and long-term refugial regions predicted with species distribution modelling (SDM) from the last glacial maximum (LGM) to the present. The broad antitropical distribution of Macrocystis pyrifera is composed by six significantly differentiated genetic groups, for which current genetic diversity levels match the expectations of past climate changes. Range shifts from the LGM to the present structured low latitude refugial regions where genetic relics with higher and unique diversity were found (particularly in the Channel Islands of California and in Peru), while post-glacial expansions following ~ 40% range contraction explained extensive regions with homogenous reduced diversity. The estimated effect of past climate-driven range shifts was comparable between hemispheres, largely demonstrating that the distribution of intraspecific marine biodiversity can be structured by comparable evolutionary forces across the global ocean. Additionally, the differentiation and endemicity of regional genetic groups, confers high conservation value to these localized intraspecific biodiversity hotspots of giant kelp forests.
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Affiliation(s)
- Jorge Assis
- CCMAR, CIMAR, Universidade do Algarve, Gambelas, Faro, Portugal.
- Faculty of Bioscience and Aquaculture, Nord Universitet, Bodø, Norway.
| | - Filipe Alberto
- Department of Biological Sciences, University of Wisconsin, Milwaukee, USA
| | - Erasmo C Macaya
- Centro Fondap IDEAL and Departamento de Oceanografía, Universidad de Concepción, Concepción, Chile
| | - Nelson Castilho Coelho
- CCMAR, CIMAR, Universidade do Algarve, Gambelas, Faro, Portugal
- University of Pittsburgh School of Medicine, Pittsburgh, USA
| | - Sylvain Faugeron
- Núcleo Milenio MASH and IRL3614 Evolutionary Biology and Ecology of Algae, Facultad de Ciencias Biológicas, CNRS, Sorbonne Université, Universidad Austral de Chile, Pontificia Universidad Catolica de Chile, Santiago, Chile
| | | | - Lydia Ladah
- Departamento de Oceanografía Biológica, Centro de Investigación Científica y de Educación Superior de Ensenada, Ensenada, Baja California, Mexico
| | - Daniel C Reed
- Marine Science Institute, University of California Santa Barbara, Santa Barbara, USA
| | | | - Andrés Mansilla
- Cape Horn International Center (CHIC), Universidad de Magallanes, Punta Arenas, Chile
| | - Paul Brickle
- South Atlantic Environmental Research Institute, Stanley, Falkland Islands
| | - Giuseppe C Zuccarello
- School of Biological Sciences, Victoria University of Wellington, Wellington, New Zealand
| | - Ester A Serrão
- CCMAR, CIMAR, Universidade do Algarve, Gambelas, Faro, Portugal
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Nimbs MJ, Wernberg T, Davis TR, Champion C, Coleman MA. Climate change threatens unique evolutionary diversity in Australian kelp refugia. Sci Rep 2023; 13:1248. [PMID: 36690643 PMCID: PMC9870953 DOI: 10.1038/s41598-023-28301-z] [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: 03/28/2022] [Accepted: 01/17/2023] [Indexed: 01/24/2023] Open
Abstract
Climate change has driven contemporary decline and loss of kelp forests globally with an accompanying loss of their ecological and economic values. Kelp populations at equatorward-range edges are particularly vulnerable to climate change as these locations are undergoing warming at or beyond thermal tolerance thresholds. Concerningly, these range-edge populations may contain unique adaptive or evolutionary genetic diversity that is vulnerable to warming. We explore haplotype diversity by generating a Templeton-Crandall-Sing (TCS) network analysis of 119 Cytochrome C Oxidase (COI) sequences among four major population groupings for extant and putatively extinct populations only known from herbarium specimens of the dominant Laminarian kelp Ecklonia radiata in the south-western Pacific, a region warming at 2-4 times the global average. Six haplotypes occurred across the region with one being widespread across most populations. Three unique haplotypes were found in a deep-water range-edge population off Moreton Island, Queensland, which likely represents both a contemporary and historic refuge during periods of climatic change. Hindcasting E. radiata cover estimates using extant data, we reveal that this region likely supported the highest kelp cover in eastern Australia during the last glacial maximum. The equatorward range edge, deep-water kelp populations off Moreton Island represent a genetically diverse evolutionary refuge that is currently threatened by warming and requires prompt ex-situ conservation measures.
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Affiliation(s)
- Matt J Nimbs
- New South Wales Department of Primary Industries, National Marine Science Centre, Coffs Harbour, NSW, Australia.
- National Marine Science Centre, Southern Cross University, Coffs Harbour, NSW, Australia.
| | - Thomas Wernberg
- Oceans Institute and School of Biological Sciences, University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia
| | - Tom R Davis
- New South Wales Department of Primary Industries, National Marine Science Centre, Coffs Harbour, NSW, Australia
- National Marine Science Centre, Southern Cross University, Coffs Harbour, NSW, Australia
| | - Curtis Champion
- New South Wales Department of Primary Industries, National Marine Science Centre, Coffs Harbour, NSW, Australia
- National Marine Science Centre, Southern Cross University, Coffs Harbour, NSW, Australia
| | - Melinda A Coleman
- New South Wales Department of Primary Industries, National Marine Science Centre, Coffs Harbour, NSW, Australia
- National Marine Science Centre, Southern Cross University, Coffs Harbour, NSW, Australia
- Oceans Institute and School of Biological Sciences, University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia
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Species Diversity of Gelidium from Southern Madagascar Evaluated by an Integrative Taxonomic Approach. DIVERSITY 2022. [DOI: 10.3390/d14100826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The diversity of red algae is significantly increasing; in the recent interest of climate changes, taxonomic and biogeographic studies are needed in untouched regions such as ecological important islands. We examined a collection of Gelidium specimens gathered during the 2010 Atimo Vatae expedition based on the morphology and DNA sequencing of mitochondrial cox1 and plastid rbcL. Both morphological and molecular datasets demonstrated the presence of three species in Madagascar; G. leptum G.H.Boo, L.Le Gall and H.S.Yoon, sp. nov., described here, and G. sclerophyllum W.R.Taylor and G. usmanghanii Afaq-Husain and Shameel. Gelidium leptum is distinguished by thin, slender, flattened thalli with irregular branches, compactly arranged thick-walled cells in medulla, sparse rhizoidal filaments at both sides of branches, and elongate sori of tetrasporangia. Gelidium sclerophyllum, previously considered as endemic to the Tropical Eastern Pacific, is first reported in the Indian Ocean and Hawai’i; G. usmanghanii, previously reported to occur in Pakistan and Oman, also presents a first record in the Southern Hemisphere. Phylogenies inferred from cox1 and rbcL sequences suggests that each of the three species likely diverged from different ancestors. The Madagascan Gelidium comprises two geographical elements; Madagascan endemic (G. leptum) and widespread species (G. sclerophyllum and G. usmanghanii).
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