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Phenotypically different microalgal morphospecies with identical ribosomal DNA: A case of rapid adaptive evolution?

Logares, Ramiro LU ; Rengefors, Karin LU ; Kremp, Anke; Shalchian-Tabrizi, Kamran; Boltovskoy, Andrés; Tengs, Torstein; Shurtleff, Aaron and Klaveness, Dag (2007) In Microbial Ecology 53(4). p.549-561
Abstract
The agents driving the divergence and speciation of free-living microbial populations are still largely unknown. We investigated the dinoflagellate morphospecies Scrippsiella hangoei and Peridinium aciculiferum, which abound in the Baltic Sea and in northern temperate lakes, respectively. Electron microscopy analyses showed significant interspecific differences in the external cellular morphology, but a similar plate pattern in the characteristic dinoflagellate armor. Experimentally, S. hangoei grew in a wide range of salinities (0–30), whereas P. aciculiferum only grew in low salinities (0–3). Despite these phenotypic differences and the habitat segregation, molecular analyses showed identical ribosomal DNA sequences (ITS1, ITS2, 5.8S,... (More)
The agents driving the divergence and speciation of free-living microbial populations are still largely unknown. We investigated the dinoflagellate morphospecies Scrippsiella hangoei and Peridinium aciculiferum, which abound in the Baltic Sea and in northern temperate lakes, respectively. Electron microscopy analyses showed significant interspecific differences in the external cellular morphology, but a similar plate pattern in the characteristic dinoflagellate armor. Experimentally, S. hangoei grew in a wide range of salinities (0–30), whereas P. aciculiferum only grew in low salinities (0–3). Despite these phenotypic differences and the habitat segregation, molecular analyses showed identical ribosomal DNA sequences (ITS1, ITS2, 5.8S, SSU, and partial LSU) for both morphospecies. Yet, a strong interspecific genetic isolation was indicated by amplified fragment length polymorphism (F ST = 0.76) and cytochrome b (cob) sequence divergence (∼1.90%). Phylogenetic reconstructions based on ribosomal (SSU, LSU) and mitochondrial (cob) DNA indicated a recent marine ancestor for P. aciculiferum. In conclusion, we suggest that the lacustrine P. aciculiferum and the marine-brackish S. hangoei diverged very recently, after a marine–freshwater transition that exposed the ancestral populations to different selective pressures. This hypothetical scenario agrees with mounting data indicating a significant role of natural selection in the divergence of free-living microbes, despite their virtually unrestricted dispersal capabilities. Finally, our results indicate that identical ITS rDNA sequences do not necessarily imply the same microbial species, as commonly assumed. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Microbial Ecology
volume
53
issue
4
pages
549 - 561
publisher
Springer
external identifiers
  • wos:000246565500004
  • scopus:34248551034
ISSN
1432-184X
DOI
10.1007/s00248-006-9088-y
language
English
LU publication?
yes
id
8479241e-f0f4-4b83-a7ef-9f9a9a809b9d (old id 628705)
date added to LUP
2007-11-27 14:59:49
date last changed
2017-11-19 03:32:12
@article{8479241e-f0f4-4b83-a7ef-9f9a9a809b9d,
  abstract     = {The agents driving the divergence and speciation of free-living microbial populations are still largely unknown. We investigated the dinoflagellate morphospecies Scrippsiella hangoei and Peridinium aciculiferum, which abound in the Baltic Sea and in northern temperate lakes, respectively. Electron microscopy analyses showed significant interspecific differences in the external cellular morphology, but a similar plate pattern in the characteristic dinoflagellate armor. Experimentally, S. hangoei grew in a wide range of salinities (0–30), whereas P. aciculiferum only grew in low salinities (0–3). Despite these phenotypic differences and the habitat segregation, molecular analyses showed identical ribosomal DNA sequences (ITS1, ITS2, 5.8S, SSU, and partial LSU) for both morphospecies. Yet, a strong interspecific genetic isolation was indicated by amplified fragment length polymorphism (F ST = 0.76) and cytochrome b (cob) sequence divergence (∼1.90%). Phylogenetic reconstructions based on ribosomal (SSU, LSU) and mitochondrial (cob) DNA indicated a recent marine ancestor for P. aciculiferum. In conclusion, we suggest that the lacustrine P. aciculiferum and the marine-brackish S. hangoei diverged very recently, after a marine–freshwater transition that exposed the ancestral populations to different selective pressures. This hypothetical scenario agrees with mounting data indicating a significant role of natural selection in the divergence of free-living microbes, despite their virtually unrestricted dispersal capabilities. Finally, our results indicate that identical ITS rDNA sequences do not necessarily imply the same microbial species, as commonly assumed.},
  author       = {Logares, Ramiro and Rengefors, Karin and Kremp, Anke and Shalchian-Tabrizi, Kamran and Boltovskoy, Andrés and Tengs, Torstein and Shurtleff, Aaron and Klaveness, Dag},
  issn         = {1432-184X},
  language     = {eng},
  number       = {4},
  pages        = {549--561},
  publisher    = {Springer},
  series       = {Microbial Ecology},
  title        = {Phenotypically different microalgal morphospecies with identical ribosomal DNA: A case of rapid adaptive evolution?},
  url          = {http://dx.doi.org/10.1007/s00248-006-9088-y},
  volume       = {53},
  year         = {2007},
}