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Physical barriers and environmental gradients cause spatial and temporal genetic differentiation of an extensive algal bloom

Godhe, Anna; Sjöqvist, Conny; Sildever, Sirje; Sefbom, Josefin; Harardóttir, Sara; Bertos-Fortis, Mireia; Bunse, Carina; Gross, Susanna; Johansson, Emma and Jonsson, Per R., et al. (2016) In Journal of Biogeography 43(6). p.1130-1142
Abstract

Aim: To test if a phytoplankton bloom is panmictic, or whether geographical and environmental factors cause spatial and temporal genetic structure. Location: Baltic Sea. Method: During four cruises, we isolated clonal strains of the diatom Skeletonema marinoi from 9 to 10 stations along a 1132 km transect and analysed the genetic structure using eight microsatellites. Using F-statistics and Bayesian clustering analysis we determined if samples were significantly differentiated. A seascape approach was applied to examine correlations between gene flow and oceanographic connectivity, and combined partial Mantel test and RDA based variation partitioning to investigate associations with environmental gradients. Results: The bloom was... (More)

Aim: To test if a phytoplankton bloom is panmictic, or whether geographical and environmental factors cause spatial and temporal genetic structure. Location: Baltic Sea. Method: During four cruises, we isolated clonal strains of the diatom Skeletonema marinoi from 9 to 10 stations along a 1132 km transect and analysed the genetic structure using eight microsatellites. Using F-statistics and Bayesian clustering analysis we determined if samples were significantly differentiated. A seascape approach was applied to examine correlations between gene flow and oceanographic connectivity, and combined partial Mantel test and RDA based variation partitioning to investigate associations with environmental gradients. Results: The bloom was initiated during the second half of March in the southern and the northern- parts of the transect, and later propagated offshore. By mid-April the bloom declined in the south, whereas high phytoplankton biomass was recorded northward. We found two significantly differentiated populations along the transect. Genotypes were significantly isolated by distance and by the south-north salinity gradient, which illustrated that the effects of distance and environment were confounded. The gene flow among the sampled stations was significantly correlated with oceanographic connectivity. The depletion of silica during the progression of the bloom was related to a temporal population genetic shift. Main conclusions: A phytoplankton bloom may propagate as a continuous cascade and yet be genetically structured over both spatial and temporal scales. The Baltic Sea spring bloom displayed strong spatial structure driven by oceanographic connectivity and geographical distance, which was enhanced by the pronounced salinity gradient. Temporal transition of conditions important for growth may induce genetic shifts and different phenotypic strategies, which serve to maintain the bloom over longer periods.

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published
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keywords
Adaptation, Environmental gradient, Gene flow, Genetic structure, Isolation by distance, Population, Seascape, Skeletonema
in
Journal of Biogeography
volume
43
issue
6
pages
13 pages
publisher
Wiley-Blackwell
external identifiers
  • scopus:84957818454
  • wos:000378711000006
ISSN
0305-0270
DOI
10.1111/jbi.12722
language
English
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yes
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c29d439b-1816-4586-81b5-38cea28df940
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2017-01-27 12:02:14
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2017-09-18 11:34:31
@article{c29d439b-1816-4586-81b5-38cea28df940,
  abstract     = {<p>Aim: To test if a phytoplankton bloom is panmictic, or whether geographical and environmental factors cause spatial and temporal genetic structure. Location: Baltic Sea. Method: During four cruises, we isolated clonal strains of the diatom Skeletonema marinoi from 9 to 10 stations along a 1132 km transect and analysed the genetic structure using eight microsatellites. Using F-statistics and Bayesian clustering analysis we determined if samples were significantly differentiated. A seascape approach was applied to examine correlations between gene flow and oceanographic connectivity, and combined partial Mantel test and RDA based variation partitioning to investigate associations with environmental gradients. Results: The bloom was initiated during the second half of March in the southern and the northern- parts of the transect, and later propagated offshore. By mid-April the bloom declined in the south, whereas high phytoplankton biomass was recorded northward. We found two significantly differentiated populations along the transect. Genotypes were significantly isolated by distance and by the south-north salinity gradient, which illustrated that the effects of distance and environment were confounded. The gene flow among the sampled stations was significantly correlated with oceanographic connectivity. The depletion of silica during the progression of the bloom was related to a temporal population genetic shift. Main conclusions: A phytoplankton bloom may propagate as a continuous cascade and yet be genetically structured over both spatial and temporal scales. The Baltic Sea spring bloom displayed strong spatial structure driven by oceanographic connectivity and geographical distance, which was enhanced by the pronounced salinity gradient. Temporal transition of conditions important for growth may induce genetic shifts and different phenotypic strategies, which serve to maintain the bloom over longer periods.</p>},
  author       = {Godhe, Anna and Sjöqvist, Conny and Sildever, Sirje and Sefbom, Josefin and Harardóttir, Sara and Bertos-Fortis, Mireia and Bunse, Carina and Gross, Susanna and Johansson, Emma and Jonsson, Per R. and Khandan Jafarabadi, Saghar and Legrand, Catherine and Lips, Inga and Lundholm, Nina and Rengefors, Karin E. and Sassenhagen, Ingrid and Suikkanen, Sanna and Sundqvist, Lisa and Kremp, Anke},
  issn         = {0305-0270},
  keyword      = {Adaptation,Environmental gradient,Gene flow,Genetic structure,Isolation by distance,Population,Seascape,Skeletonema},
  language     = {eng},
  month        = {06},
  number       = {6},
  pages        = {1130--1142},
  publisher    = {Wiley-Blackwell},
  series       = {Journal of Biogeography},
  title        = {Physical barriers and environmental gradients cause spatial and temporal genetic differentiation of an extensive algal bloom},
  url          = {http://dx.doi.org/10.1111/jbi.12722},
  volume       = {43},
  year         = {2016},
}