Dataset Information

Oceanographic barriers to gene flow promote genetic subdivision of the tunicate Ciona intestinalis in a North Sea archipelago.

ABSTRACT: Pelagic larval development has the potential to connect populations over large geographic distances and prevent genetic structuring. The solitary tunicate Ciona intestinalis has pelagic eggs and a swimming larval stage lasting for maximum a few days, with the potential for a homogenizing gene flow over relatively large areas. In the eastern North Sea, it is found in a geomorphologically complex archipelago with a mix of fjords and open costal habitats. Here, the coastal waters are also stratified with a marked pycnocline driven by salinity and temperature differences between shallow and deep waters. We investigated the genetic structure of C. intestinalis in this area and compared it with oceanographic barriers to dispersal that would potentially reduce connectivity among local populations. Genetic data from 240 individuals, sampled in 2 shallow, and 4 deep-water sites, showed varying degrees of differentiation among samples (F_ST?=?0.0-0.11). We found no evidence for genetic isolation by distance, but two distant deep-water sites from the open coast were genetically very similar indicating a potential for long-distance gene flow. However, samples from different depths from the same areas were clearly differentiated, and fjord samples were different from open-coast sites. A biophysical model estimating multi-generation, stepping-stone larval connectivity, and empirical data on fjord water mass retention time showed the presence of oceanographic barriers that explained the genetic structure observed. We conclude that the local pattern of oceanographic connectivity will impact on the genetic structure of C. intestinalis in this region.

SUBMITTER: Johannesson K

PROVIDER: S-EPMC6061499 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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Oceanographic barriers to gene flow promote genetic subdivision of the tunicate <i>Ciona intestinalis</i> in a North Sea archipelago.

Johannesson Kerstin K Ring Anna-Karin AK Johannesson Klara B KB Renborg Elin E Jonsson Per R PR Havenhand Jon N JN

Marine biology 20180711 8

Pelagic larval development has the potential to connect populations over large geographic distances and prevent genetic structuring. The solitary tunicate <i>Ciona intestinalis</i> has pelagic eggs and a swimming larval stage lasting for maximum a few days, with the potential for a homogenizing gene flow over relatively large areas. In the eastern North Sea, it is found in a geomorphologically complex archipelago with a mix of fjords and open costal habitats. Here, the coastal waters are also st ...[more]

PMID: 30100627

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Project description:The tunicate Ciona intestinalis is an opportunistic invader with high potential for causing economic losses in aquaculture centers. Recent phylogenetic and population genetic analysis support the existence of a genetic complex described as C. intestinalis with two main dominant species (sp A and B) occurring worldwide. In Chile, the species has been observed around 30°S of latitude, but no official reports exist for the presence of C. intestinalis in southern regions (above 40°S), where most of the mollusk aquaculture centers are located. Here, we used occurrences from multiple invaded regions and extensive field sampling to model and validate the environmental conditions that allow the species to persist and to find the geographic areas with the most suitable environmental conditions for the spread of C. intestinalis in the Chilean coast. By studying the potential expansion of C. intestinalis southward in the Chilean Coast, we aimed to provide valuable information that might help the development of control plans before the species becomes a significant problem, especially above 40°S. Our results highlight that, by using portions of the habitat that are apparently distinguishable, the species seem to be not only genetically distinct, but ecologically distinct as well. The two regional models fitted for sp A and for sp B showed disagreement on which sections of Chilean coastline are considered more suitable for these species. While the model for sp A identifies moderately to highly suitable areas between 30° and 40°S, the model for sp B classifies the areas around 45°S as the most appropriate. Data from field sampling show a positive linear relationship between density of C. intestinalis and the index of suitability for sp A in aquaculture centers. Understanding the relation of the distinct species with the surrounding environment provided valuable insights about probable routes of dispersion in Chile, especially into those areas considered suitable for aquaculture activities but where the species has not yet been recorded. We discuss the implications of our findings as a useful tool to anticipate the invasion of such harmful invasive species with regard to the most relevant environmental variables.

Project description:Eight different types of sample (three samples each) were used in this study of cardiac cell migration in the tunicate Ciona intestinalis. The B7.5 lineage cells were isolated by Fluorescent Activated Cell Sorting (FACS) at the tailbud stage, when the cardiac precursors (anterior B7.5 lineage cells) are migrating into the trunk, while their sister cells (posterior 7.5 lineage cells) remain in the tail, where they form muscle cells. Cells were sorted at the late gastrula stage, prior to migration induction and after manipulation of the FGF-MAPK-Ets signaling pathway (targeted expression of dominant negative FGF receptor and Ets:VP16 fusion protein, targeted expression was achieved using the Mesp cis-regulatory DNA), FoxF function (a direct target of FGF-MAPK-Ets signaling, required primarily for cell migration) by targeted expression of FoxF:VP16 (constitutive activator) or FoxF:WRPW (constitutive repressor, dominant negative), Mesp function (over-expression of Mesp:VP16 inhibits primarily cell migration). Finally, the "whole embryo" samples were collected from dissociated whole tailbud embryos, without FACS. in summary the eight conditions are: "wt (files LC-wt-1,-2,-3)": wild_type B7.5 lineage cells, expressing GFP, sorted at the tailbud stage "Ets:VP16 (files LC-EV-1,-2,-3)": B7.5 lineage cells, expressing GFP and Ets:VP16, sorted at the tailbud stage "DnFGFR (files LC-dnFGFR-1,-2,-3)": B7.5 lineage cells, expressing GFP and dominant-negative FGF receptor, sorted at the tailbud stage. "FoxF:VP16 (files LC-FV-1,-2,-3)": B7.5 lineage cells, expressing GFP and FoxF:VP16, sorted at the tailbud stage. "FoxF:WRPW (files LC-FW-1,-2,-3)": B7.5 lineage cells, expressing GFP and FoxF:WRPW, sorted at the tailbud stage". "Mesp:VP16 (files LC-MV-1,-2,-3)": B7.5 lineage cells, expressing GFP and Mesp:VP16, sorted at the tailbud stage. "Late Gastrula (files LC-LG-1,-2,-3)": wild_type B7.5 lineage cells, expressing GFP, sorted at the late gastrula stage "whole embryo (files LC-whole-1,-2,-3": whole embryos, dissociated at the tailbud stage, not sorted.

Dataset Information

Oceanographic barriers to gene flow promote genetic subdivision of the tunicate Ciona intestinalis in a North Sea archipelago.

Publications

Oceanographic barriers to gene flow promote genetic subdivision of the tunicate <i>Ciona intestinalis</i> in a North Sea archipelago.

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