15 research outputs found
Evidence of concurrent local adaptation and high phenotypic plasticity in a polar microeukaryote
10 pages, 3 figures, 2 tables, data accessibility http://datadryad.org doi:10.5061/dryad.07b2dEnvironmental Microbiology published by Society for Applied Microbiology and John Wiley & Sons Ltd. Here we investigated whether there is evidence of local adaptation in strains of an ancestrally marine dinoflagellate to the lacustrine environment they now inhabit (optimal genotypes) and/or if they have evolved phenotypic plasticity (a range of phenotypes). Eleven strains of Polarella glacialis were isolated and cultured from three different environments: the polar seas, a hyposaline and a hypersaline Antarctic lake. Local adaptation was tested by comparing growth rates of lacustrine and marine strains at their own and reciprocal site conditions. To determine phenotypic plasticity, we measured the reaction norm for salinity. We found evidence of both, limited local adaptation and higher phenotypic plasticity in lacustrine strains when compared with marine ancestors. At extreme high salinities, local lake strains outperformed other strains, and at extreme low salinities, strains from the hyposaline lake outperformed all other strains. The data suggest that lake populations may have evolved higher phenotypic plasticity in the lake habitats compared with the sea, presumably due to the high temporal variability in salinity in the lacustrine systems. Moreover, the interval of salinity tolerance differed between strains from the hyposaline and hypersaline lakes, indicating local adaptation promoted by different salinity. © 2014 The AuthorsThis work was supported by a grant from the Australian Antarctic Research Assessment Committee to J.L-P and KR and by The Swedish Research Council (621-2009-5324) to KR. RL has been financed by a Marie Curie Intra-European Fellowship (PIEF-GA-2009–235365, EU) and a Juan de la Cierva fellowship (JCI-2010–06594, Ministry of Science and Innovation, Spain)Peer Reviewe
Recent evolutionary diversification of a protist lineage
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