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Reem E, Douek J, Rinkevich B. Historical navigation routes in European waters leave their footprint on the contemporary seascape genetics of a colonial urochordate. Sci Rep 2023; 13:19076. [PMID: 37925572 PMCID: PMC10625628 DOI: 10.1038/s41598-023-46174-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2023] [Accepted: 10/28/2023] [Indexed: 11/06/2023] Open
Abstract
Humans have intensively sailed the Mediterranean and European Atlantic waters throughout history, from the upper Paleolithic until today and centuries of human seafaring have established complex coastal and cross-seas navigation networks. Historical literature revealed three major long-lasting maritime routes (eastern, western, northern) with four commencing locations (Alexandria, Venice, Genoa, Gibraltar) and a fourth route (circum-Italian) that connected between them. Due to oceangoing and technological constraints, most voyages were coastal, lasted weeks to months, with extended resting periods, allowing the development of fouling organisms on ship hulls. One of the abiding travellers in maritime routes is the colonial ascidian Botryllus schlosseri already known since the eighteenth century in European and Mediterranean ports. This species, was almost certainly one of the common hull fouling travellers in all trade routes for centuries. Employing COI haplotypes (1008 samples) and microsatellite alleles (995 samples) on colonies sampled from 64 pan-European sites, present-day Botryllus populations in the Mediterranean Sea/European Atlantic revealed significant segregation between all four maritime routes with a conspicuous partition of the northern route. These results reveal that past anthropogenic transports of sedentary marine species throughout millennia long seafaring have left their footprint on contemporary seascape genetics of marine organisms.
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Affiliation(s)
- Eitan Reem
- Israel Oceanography and Limnological Research, National Institute of Oceanography, Tel Shikmona, P.O. Box 9753, 3109701, Haifa, Israel.
| | - Jacob Douek
- Israel Oceanography and Limnological Research, National Institute of Oceanography, Tel Shikmona, P.O. Box 9753, 3109701, Haifa, Israel
| | - Baruch Rinkevich
- Israel Oceanography and Limnological Research, National Institute of Oceanography, Tel Shikmona, P.O. Box 9753, 3109701, Haifa, Israel
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2
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Harper KE, Scheinberg LA, Boyer KE, Sotka EE. Global distribution of cryptic native, introduced and hybrid lineages in the widespread estuarine amphipod Ampithoe valida. CONSERV GENET 2022. [DOI: 10.1007/s10592-022-01452-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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3
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An elongated COI fragment to discriminate botryllid species and as an improved ascidian DNA barcode. Sci Rep 2021; 11:4078. [PMID: 33603059 PMCID: PMC7892571 DOI: 10.1038/s41598-021-83127-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Accepted: 01/27/2021] [Indexed: 01/31/2023] Open
Abstract
Botryllids are colonial ascidians widely studied for their potential invasiveness and as model organisms, however the morphological description and discrimination of these species is very problematic, leading to frequent specimen misidentifications. To facilitate species discrimination and detection of cryptic/new species, we developed new barcoding primers for the amplification of a COI fragment of about 860 bp (860-COI), which is an extension of the common Folmer's barcode region. Our 860-COI was successfully amplified in 177 worldwide-sampled botryllid colonies. Combined with morphological analyses, 860-COI allowed not only discriminating known species, but also identifying undescribed and cryptic species, resurrecting old species currently in synonymy, and proposing the assignment of clade D of the model organism Botryllus schlosseri to Botryllus renierii. Importantly, within clade A of B. schlosseri, 860-COI recognized at least two candidate species against only one recognized by the Folmer's fragment, underlining the need of further genetic investigations on this clade. This result also suggests that the 860-COI could have a greater ability to diagnose cryptic/new species than the Folmer's fragment at very short evolutionary distances, such as those observed within clade A. Finally, our new primers simplify the amplification of 860-COI even in non-botryllid ascidians, suggesting their wider usefulness in ascidians.
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4
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Ruiz MB, Taverna A, Servetto N, Sahade R, Held C. Hidden diversity in Antarctica: Molecular and morphological evidence of two different species within one of the most conspicuous ascidian species. Ecol Evol 2020; 10:8127-8143. [PMID: 32788966 PMCID: PMC7417227 DOI: 10.1002/ece3.6504] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 05/27/2020] [Accepted: 06/03/2020] [Indexed: 12/16/2022] Open
Abstract
The Southern Ocean is one of the most isolated marine ecosystems, characterized by high levels of endemism, diversity, and biomass. Ascidians are among the dominant groups in Antarctic benthic assemblages; thus, recording the evolutionary patterns of this group is crucial to improve our current understanding of the assembly of this polar ocean. We studied the genetic variation within Cnemidocarpa verrucosa sensu lato, one of the most widely distributed abundant and studied ascidian species in Antarctica. Using a mitochondrial and a nuclear gene (COI and 18S), the phylogeography of fifteen populations distributed along the West Antarctic Peninsula and Burdwood Bank/MPA Namuncurá (South American shelf) was characterized, where the distribution of the genetic distance suggested the existence of, at least, two species within nominal C. verrucosa. When reevaluating morphological traits to distinguish between genetically defined species, the presence of a basal disk in one of the genotypes could be a diagnostic morphological trait to differentiate the species. These results are surprising due to the large research that has been carried out with the conspicuous C. verrucosa with no differentiation between species. Furthermore, it provides important tools to distinguish species in the field and laboratory. But also, these results give new insights into patterns of differentiation between closely related species that are distributed in sympatry, where the permeability of species boundaries still needs to be well understood.
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Affiliation(s)
- Micaela B. Ruiz
- Instituto de Diversidad y Ecología Animal (IDEA)Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)CórdobaArgentina
- Facultad de Ciencias Exactas Físicas y NaturalesDepartamento de Diversidad Biológica y Ecología, Ecología MarinaUniversidad Nacional de CórdobaCórdobaArgentina
| | - Anabela Taverna
- Instituto de Diversidad y Ecología Animal (IDEA)Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)CórdobaArgentina
- Facultad de Ciencias Exactas Físicas y NaturalesDepartamento de Diversidad Biológica y Ecología, Ecología MarinaUniversidad Nacional de CórdobaCórdobaArgentina
| | - Natalia Servetto
- Instituto de Diversidad y Ecología Animal (IDEA)Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)CórdobaArgentina
- Facultad de Ciencias Exactas Físicas y NaturalesDepartamento de Diversidad Biológica y Ecología, Ecología MarinaUniversidad Nacional de CórdobaCórdobaArgentina
| | - Ricardo Sahade
- Instituto de Diversidad y Ecología Animal (IDEA)Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)CórdobaArgentina
- Facultad de Ciencias Exactas Físicas y NaturalesDepartamento de Diversidad Biológica y Ecología, Ecología MarinaUniversidad Nacional de CórdobaCórdobaArgentina
| | - Christoph Held
- Section Functional Ecology, Evolutionary MacroecologyAlfred Wegener Institute Helmholtz‐Zentrum für Polar‐ und MeeresforschungBremerhavenGermany
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5
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Toward a resolution of the cosmopolitan Botryllus schlosseri species complex (Ascidiacea, Styelidae): mitogenomics and morphology of clade E (Botryllus gaiae). Zool J Linn Soc 2020. [DOI: 10.1093/zoolinnean/zlaa023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Abstract
Botryllus schlosseri is a model colonial ascidian and a marine invader. It is currently recognized as a species complex comprising five genetically divergent clades, with clade A globally distributed and clade E found only in Europe. This taxon has also been recently redescribed by designation of a clade A specimen as the neotype. To clarify the taxonomic status of clade E and its relationship to clade A, we examine the entire mitochondrial genome and study the morphology of clade E. The mitogenome of clade E has an identical gene order to clade A, but substantially differs in the size of several non-coding regions. Remarkably, the nucleotide divergence of clade A-clade E is incompatible with the intraspecies ascidian divergence, but similar to the congeneric one and almost identical to the divergence between species once considered morphologically indistinguishable (e.g. the pair Ciona intestinalis (Linnaeus, 1767)-Ciona robusta Hoshino & Tokioka, 1967, and the pair Botrylloides niger Herdman, 1886-Botrylloides leachii (Savigny, 1816)). Clade E differs morphologically from the Botryllusschlosseri neotype mainly in the number and appearance of the stomach folds, and the shape of the anal opening, the first intestinal loop and the typhlosole. Our integrative taxonomical approach clearly distinguishes clade E as a species separate from Botryllusschlosseri, with unique morphological and molecular characters. Therefore, we here describe clade E as the new species Botryllus gaiae sp. nov.
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6
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Sargent P, Hamel JF, Mercier A. The life history and feeding ecology of velvet shell, Velutina velutina (Gastropoda: Velutinidae), a specialist predator of ascidians. CAN J ZOOL 2019. [DOI: 10.1139/cjz-2018-0327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Velvet shell, Velutina velutina (Müller, 1776), is a specialist predator of ascidians, like other members of the gastropod family Velutinidae. Globally, invasive ascidians have become problematic, ecologically and economically, yet ecological knowledge of velutinids remains limited. This study outlines the life history and feeding ecology of V. velutina in eastern Canada based on laboratory work complemented by field observations. The life history of V. velutina is closely linked with ascidians, which serve as prey and protection for their egg capsules. Egg capsules were embedded within tunics of Aplidium glabrum (Verrill, 1871) and Ascidia callosa Stimpson, 1852, with a preference for the latter. Seasonal behavioural shifts were consistent annually and corresponded with seawater temperature cycles. Feeding dominated during the coldest months (January–May), growth occurred as water temperature increased to the annual maximum (June and July), transitioning to mating during the warmest period (July–August), and egg capsule deposition dominated as water temperature declined (November–January). Larvae hatched between January and July after 2–4 months of development. Velutina velutina preyed on all ascidian species presented during this study, including golden star tunicate, Botryllus schlosseri (Pallas, 1766), and vase tunicate, Ciona intestinalis (Linnaeus, 1767), two non-indigenous species, although solitary species were preferred.
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Affiliation(s)
- P.S. Sargent
- Department of Ocean Sciences, Memorial University, St. John’s, NL A1C 5S7, Canada
| | - J.-F. Hamel
- Society for the Exploration and Valuing of the Environment (SEVE), Portugal Cove–St. Philips, NL A1M 2B7, Canada
| | - A. Mercier
- Department of Ocean Sciences, Memorial University, St. John’s, NL A1C 5S7, Canada
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7
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Stronger predation in a subtropical community dampens an invasive species-induced trophic cascade. Biol Invasions 2018. [DOI: 10.1007/s10530-018-1819-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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8
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Darling JA, Carlton JT. A Framework for Understanding Marine Cosmopolitanism in the Anthropocene. FRONTIERS IN MARINE SCIENCE 2018; 5:293. [PMID: 31019910 PMCID: PMC6475922 DOI: 10.3389/fmars.2018.00293] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Recent years have witnessed growing appreciation for the ways in which human-mediated species introductions have reshaped marine biogeography. Despite this we have yet to grapple fully with the scale and impact of anthropogenic dispersal in both creating and determining contemporary distributions of marine taxa. In particular, the past several decades of research on marine biological invasions have revealed that broad geographic distributions of coastal marine organisms-historically referred to simply as "cosmopolitanism"-may belie complex interplay of both natural and anthropogenic processes. Here we describe a framework for understanding contemporary cosmopolitanism, informed by a synthesis of the marine bioinvasion literature. Our framework defines several novel categories in an attempt to provide a unified terminology for discussing cosmopolitan distributions in the world's oceans. We reserve the term eucosmopolitan to refer to those species for which data exist to support a true, natural, and prehistorically global (or extremely broad) distribution. While in the past this has been the default assumption for species observed to exhibit contemporary cosmopolitan distributions, we argue that given recent advances in marine invasion science this assignment should require positive evidence. In contrast, neocosmopolitan describes those species that have demonstrably achieved extensive geographic ranges only through historical anthropogenic dispersal, often facilitated over centuries of human maritime traffic. We discuss the history and human geography underpinning these neocosmopolitan distributions, and illustrate the extent to which these factors may have altered natural biogeographic patterns. We define the category pseudocosmopolitan to encompass taxa for which a broad distribution is determined (typically after molecular investigation) to reflect multiple, sometimes regionally endemic, lineages with uncertain taxonomic status; such species may remain cosmopolitan only so long as taxonomic uncertainty persists, after which they may splinter into multiple geographically restricted species. We discuss the methods employed to identify such species and to resolve both their taxonomic status and their biogeographic histories. We argue that recognizing these different types of cosmopolitanism, and the important role that invasion science has played in understanding them, is critically important for the future study of both historical and modern marine biogeography, ecology, and biodiversity.
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Affiliation(s)
- John A. Darling
- United States Environmental Protection Agency, National Exposure Research Laboratory, Research Triangle Park, NC, United States
| | - James T. Carlton
- Maritime Studies Program, Williams College-Mystic Seaport, Mystic, CT, United States
- Department of Biology, Williams College, Williamstown, MA, United States
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9
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Govindarajan AF, Carman MR, Khaidarov MR, Semenchenko A, Wares JP. Mitochondrial diversity in Gonionemus (Trachylina:Hydrozoa) and its implications for understanding the origins of clinging jellyfish in the Northwest Atlantic Ocean. PeerJ 2017; 5:e3205. [PMID: 28439470 PMCID: PMC5398274 DOI: 10.7717/peerj.3205] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 03/20/2017] [Indexed: 02/04/2023] Open
Abstract
Determining whether a population is introduced or native to a region can be challenging due to inadequate taxonomy, the presence of cryptic lineages, and poor historical documentation. For taxa with resting stages that bloom episodically, determining origin can be especially challenging as an environmentally-triggered abrupt appearance of the taxa may be confused with an anthropogenic introduction. Here, we assess diversity in mitochondrial cytochrome oxidase I sequences obtained from multiple Atlantic and Pacific locations, and discuss the implications of our findings for understanding the origin of clinging jellyfish Gonionemus in the Northwest Atlantic. Clinging jellyfish are known for clinging to seagrasses and seaweeds, and have complex life cycles that include resting stages. They are especially notorious as some, although not all, populations are associated with severe sting reactions. The worldwide distribution of Gonionemus has been aptly called a “zoogeographic puzzle” and our results refine rather than resolve the puzzle. We find a relatively deep divergence that may indicate cryptic speciation between Gonionemus from the Northeast Pacific and Northwest Pacific/Northwest Atlantic. Within the Northwest Pacific/Northwest Atlantic clade, we find haplotypes unique to each region. We also find one haplotype that is shared between highly toxic Vladivostok-area populations and some Northwest Atlantic populations. Our results are consistent with multiple scenarios that involve both native and anthropogenic processes. We evaluate each scenario and discuss critical directions for future research, including improving the resolution of population genetic structure, identifying possible lineage admixture, and better characterizing and quantifying the toxicity phenotype.
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Affiliation(s)
| | - Mary R Carman
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, United States
| | - Marat R Khaidarov
- A.V. Zhirmunsky Institute of Marine Biology, National Scientific Center of Marine Biology Far Eastern Branch, Russian Academy of Sciences, Vladivostok, Russia.,Far Eastern Federal University, Vladivostok, Russia
| | | | - John P Wares
- Department of Genetics, University of Georgia, Athens, United States.,Odum School of Ecology, University of Georgia, Athens, United States
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10
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Nydam ML, Stephenson EE, Waldman CE, De Tomaso AW. Balancing selection on allorecognition genes in the colonial ascidian Botryllus schlosseri. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2017; 69:60-74. [PMID: 28024871 DOI: 10.1016/j.dci.2016.12.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Revised: 12/22/2016] [Accepted: 12/22/2016] [Indexed: 06/06/2023]
Abstract
Allorecognition is the capability of an organism to recognize its own or related tissues. The colonial ascidian Botryllus schlosseri, which comprises five genetically distinct and divergent species (Clades A-E), contains two adjacent genes that control allorecognition: fuhcsec and fuhctm. These genes have been characterized extensively in Clade A and are highly polymorphic. Using alleles from 10 populations across the range of Clade A, we investigated the type and strength of selection maintaining this variation. Both fuhc genes exhibit higher within-population variation and lower population differentiation measures (FST) than neutral loci. The fuhc genes contain a substantial number of codons with >95% posterior probability of dN/dS > 1. fuhcsec and fuhctm also have polymorphisms shared between Clade A and Clade E that were present prior to speciation (trans-species polymorphisms). These results provide robust evidence that the fuhc genes are evolving under balancing selection.
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Affiliation(s)
- Marie L Nydam
- Division of Science and Mathematics, Centre College, 600 W. Walnut Street, Danville, KY 40422, United States.
| | - Emily E Stephenson
- Division of Science and Mathematics, Centre College, 600 W. Walnut Street, Danville, KY 40422, United States; Centre for Infectious Disease Research, P.O. Box 34681, Lusaka, 10101, Zambia.
| | - Claire E Waldman
- Division of Science and Mathematics, Centre College, 600 W. Walnut Street, Danville, KY 40422, United States.
| | - Anthony W De Tomaso
- Department of Molecular, Cellular, and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA 93106, United States.
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11
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Nydam ML, Giesbrecht KB, Stephenson EE. Origin and Dispersal History of Two Colonial Ascidian Clades in the Botryllus schlosseri Species Complex. PLoS One 2017; 12:e0169944. [PMID: 28107476 PMCID: PMC5249052 DOI: 10.1371/journal.pone.0169944] [Citation(s) in RCA: 19] [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: 11/04/2016] [Accepted: 12/27/2016] [Indexed: 11/28/2022] Open
Abstract
Human-induced global warming and species introductions are rapidly altering the composition and functioning of Earth’s marine ecosystems. Ascidians (Phylum Chordata, Subphylum Tunicata, Class Ascidiacea) are likely to play an increasingly greater role in marine communities. The colonial ascidian B. schlosseri is a cryptic species complex comprising five genetically divergent clades (A-E). Clade A is a global species, and Clade E has so far been identified in European waters only. Using the largest mitochondrial cytochrome oxidase I datasets yet assembled, we determine the origin and dispersal history of these species. Nucleotide diversity and Approximate Bayesian Computation analyses support a Pacific origin for Clade A, with two likely dispersal scenarios that both show the northwestern Atlantic populations establishing early in the history of the species. Both Discrete Phylogeographic Analysis and Approximate Bayesian Computation support an origin of Clade E on the French side of the English Channel. An unsampled lineage evolved from the French lineage, which reflects the conclusion from the median joining network that not all Clade E lineages have been sampled. This unsampled lineage gave rise to the haplotypes on the English side of the English Channel, which were the ancestors to the Mediterranean and Bay of Biscay populations. Clade E has a wider geographic range than previously thought, and shows evidence of recent range expansion. Both Clade A and Clade E should be considered widespread species: Clade A globally and Clade E within Europe.
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Affiliation(s)
- Marie L. Nydam
- Division of Science and Mathematics, Centre College, Danville, Kentucky, United States of America
- * E-mail:
| | - Kirsten B. Giesbrecht
- Division of Science and Mathematics, Centre College, Danville, Kentucky, United States of America
| | - Emily E. Stephenson
- Division of Science and Mathematics, Centre College, Danville, Kentucky, United States of America
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12
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Ma KC, Deibel D, Law KK, Aoki M, McKenzie CH, Palomares ML. Richness and zoogeography of ascidians (Tunicata: Ascidiacea) in eastern Canada. CAN J ZOOL 2017. [DOI: 10.1139/cjz-2016-0087] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Managers and policymakers in eastern Canada embrace science-based management of nonindigenous species and may benefit from having comprehensive regional species checklists at subnational jurisdictional levels. In this paper, regional checklists provide an account of the richness of ascidians in eastern Canada. Records of 58 ascidians resulted from reviewing 108 published sources, accessing data from two online databases, and collecting some common indigenous ascidian specimens. Analysis comparing the similarity of species among nine regions indicates that there is greater similarity in species composition between contiguous regions than between noncontiguous regions and suggests that there are four zoogeographic clusters in eastern Canada. Our checklists can inform managers and policymakers of the diversity of the ascidian taxa and can minimize taxonomic uncertainties of established nonindigenous and prospective invading species, for example, by identifying indigenous species that are congeners of nonindigenous species. The maintenance of checklists can be a valuable tool for the management of nonindigenous species as baselines to estimate changes in richness and to document the invasion status of nonindigenous species over time. For example, more importance can be placed on the spread of nonindigenous ascidians from one zoogeographic cluster to another than spread within the same cluster.
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Affiliation(s)
- Kevin C.K. Ma
- Québec-Océan, Département de biologie, Université Laval, Québec, QC G1V 0A6, Canada
- Department of Ocean Sciences, Memorial University of Newfoundland, St. John’s, NL A1C 5S7, Canada
| | - Don Deibel
- Department of Ocean Sciences, Memorial University of Newfoundland, St. John’s, NL A1C 5S7, Canada
| | - Kenneth K.M. Law
- Environmental Sciences Program, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Mai Aoki
- Biology Program, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Cynthia H. McKenzie
- Northwest Atlantic Fisheries Centre, Fisheries and Oceans Canada, St. John’s, NL A1C 5X1, Canada
| | - Maria L.D. Palomares
- Sea Around Us, Institute for the Oceans and Fisheries, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada
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13
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Phylogenetics, biogeography and population genetics of the ascidian Botryllus schlosseri in the Mediterranean Sea and beyond. Mol Phylogenet Evol 2016; 107:221-231. [PMID: 27825872 DOI: 10.1016/j.ympev.2016.10.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Revised: 09/27/2016] [Accepted: 10/08/2016] [Indexed: 11/23/2022]
Abstract
The wide distribution of the ascidian Botryllus schlosseri along the Mediterranean coasts has been documented since the eighteenth century. However, despite copious documentation, analyses of dispersal modes and genetic profiles were limited to local populations or restricted regions. In order to get a pan-Mediterranean overview, 288 specimens from 11 populations of B. schlosseri from the western and eastern Mediterranean basins were sampled and analyzed using five microsatellite loci and COI sequences. Both molecular markers revealed high polymorphisms, with 182 microsatellites alleles and 54 COI haplotypes. Overall, Fst, Dest, and COI Фpt values were 0.146, 0.635 and 0.322, respectively, reflecting a high genetic diversity and a significant genetic structure as compared to other B. schlosseri populations worldwide, reflected by substantially higher values for effective number of alleles (Ne) in the Mediterranean. A phylogenetic analysis of the COI sequences resulted in four distinct clades and two molecular operational taxonomic units (OTUs). We recorded a stronger genetic structure among the populations of the eastern basin compared to the western basin (microsatellites Fst=0.217 versus 0.082; COI Фpt=0.416 versus 0.171), suggesting either a restricted connectivity between the basins or a stronger genetic drift in each basin. The occurrence of two OTUs and different ecological conditions may also contribute to this finding. Mean Nei's genetic distance in the eastern Mediterranean populations was more than three times higher compared to the western basin. No correlation was observed between geographic and genetic distances (Mantel test), suggesting that maritime transport is the main dispersal vector of B. schlosseri colonies. The possibility that the Mediterranean is a center of diversity for B. schlosseri, and probably its site of origin, is further discussed.
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14
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Sheets EA, Cohen CS, Ruiz GM, da Rocha RM. Investigating the widespread introduction of a tropical marine fouling species. Ecol Evol 2016; 6:2453-71. [PMID: 27066231 PMCID: PMC4788974 DOI: 10.1002/ece3.2065] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Revised: 01/30/2016] [Accepted: 02/09/2016] [Indexed: 11/17/2022] Open
Abstract
Little is known about the number and rate of introductions into terrestrial and marine tropical regions, and if introduction patterns and processes differ from temperate latitudes. Botryllid ascidians (marine invertebrate chordates) are an interesting group to study such introduction differences because several congeners have established populations across latitudes. While temperate botryllid invasions have been repeatedly highlighted, the global spread of tropical Botrylloides nigrum (Herdman, 1886) has been largely ignored. We sampled B. nigrum from 16 worldwide warm water locations, including around the Panama Canal, one of the largest shipping hubs in the world and a possible introduction corridor. Using mitochondrial (COI) and nuclear (ANT) markers, we discovered a single species with low genetic divergence and diversity that has established in the Atlantic, Pacific, Indo‐Pacific, and Mediterranean Oceans. The Atlantic Ocean contained the highest diversity and multilocus theta estimates and may be a source for introductions to other regions. A high frequency of one mitochondrial haplotype was detected in Pacific populations that may represent a recent introduction in this region. In comparison to temperate relatives, B. nigrum displayed lower (but similar to temperate Botrylloides violaceus) genetic divergence and diversity at both loci that may represent a more recent global spread or differences in introduction pressures in tropical regions. Additionally, chimeras (genetically distinct individuals sharing a single body) were detected in three populations by the mitochondrial locus and validated using cloning, and these individuals contained new haplotype diversity not detected in any other colonies.
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Affiliation(s)
- Elizabeth A Sheets
- Romberg Tiburon Center for Environmental Studies Biology Department San Francisco State University 3150 Paradise Drive Tiburon California 94920
| | - C Sarah Cohen
- Romberg Tiburon Center for Environmental Studies Biology Department San Francisco State University 3150 Paradise Drive Tiburon California 94920
| | - Gregory M Ruiz
- Smithsonian Environmental Research Center 627 Contees Wharf Rd. Edgewater Maryland 21037
| | - Rosana M da Rocha
- Departamento de Zoologia Universidade Federal do Paraná CP 19020 81531-980 Curitiba Brazil
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15
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Freeman AS, Frischeisen A, Blakeslee AMH. Estuarine fouling communities are dominated by nonindigenous species in the presence of an invasive crab. Biol Invasions 2016. [DOI: 10.1007/s10530-016-1108-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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