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Recent evolutionary diversification of a protist lineage


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Logares, R, Daugbjerg, N, Boltovskoy, A, Kremp, A, Laybourn-Parry, J and Rengefors, K 2008 , 'Recent evolutionary diversification of a protist lineage' , Environmental Microbiology , pp. 1-13 , doi: 10.1111/j.1462-2920.2007.01538.x.

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Here, we have identified a protist (dinoflagellate)
lineage that has diversified recently in evolutionary
terms. The species members of this lineage inhabit
cold-water marine and lacustrine habitats, which are
distributed along a broad range of salinities (0–32)
and geographic distances (0–18 000 km). Moreover,
the species present different degrees of morphological
and sometimes physiological variability. Altogether,
we analysed 30 strains, generating 55 new
DNA sequences. The nuclear ribosomal DNA (nrDNA)
sequences (including rapidly evolving introns) were
very similar or identical among all the analysed isolates.
This very low nrDNA differentiation was contrasted
by a relatively high cytochrome b (COB)
mitochondrial DNA (mtDNA) polymorphism, even
though the COB evolves very slowly in dinoflagellates.
The 16 Maximum Likelihood and Bayesian phylogenies
constructed using nr/mtDNA indicated that
the studied cold-water dinoflagellates constitute a
monophyletic group (supported also by the morphological
analyses), which appears to be evolutionary
related to marine-brackish and sometimes toxic
Pfiesteria species. We conclude that the studied
dinoflagellates belong to a lineage which has diversified
recently and spread, sometimes over long
distances, across low-temperature environments
which differ markedly in ecology (marine versus
lacustrine communities) and salinity. Probably, this
evolutionary diversification was promoted by the
variety of natural selection regimes encountered in
the different environments.

Item Type: Article
Authors/Creators:Logares, R and Daugbjerg, N and Boltovskoy, A and Kremp, A and Laybourn-Parry, J and Rengefors, K
Journal or Publication Title: Environmental Microbiology
ISSN: 1462-2912
DOI / ID Number: 10.1111/j.1462-2920.2007.01538.x
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