Biogeography in protists

Crossing the salinity barrier –
local adaptation, genetic divergence and speciation in microorganisms
(Swedish Research Council)


In this project we are investigating small-scale (< 10 km) genetic differentiation among lake populations of a marine/brackish dinoflagellates species Scrippsiella aff. hangoei. This species was previously considered endemic to the Baltic, but we have found a closely related species in saline Antarctic lakes located in the Vestfold Hills (Rengefors et al. 2008). In this same system we are studying salinity tolerance plasticity in the dinoflagellates species Polarella glacialis, which has a bi-polar distribution.

People involved: Karin Rengefors, Dr. Ramiro Logares (Spain) and Dr. Johanna Laybourn-Parry (UK).



Another part of this project is focused on the speciation event that has resulted in the formation of the two separate species Scrippsiella hangoei (marine) and Peridinium aciculiferum (freshwater) (Logares et al. 2008). We are investigating both genetic divergence and reproductive barriers between these two, and the sibling species S. aff. hangoei in the Antarctic lakes. Our previous studies indicate that salinity is a major barrier to speciation (Logares et al. 2008, 2009, 2010). Therefore, we are particularly interested in the response to salinity and differentiation at both the genetic and expression level. These studies are further pursued through the Marine Microbial Eukaryote Transcriptome Project funded by the Gordon and Betty Moore Foundation.

People involved: Karin Rengefors, Dr. Ramiro Logares (Spain) and Dr. Anke Kremp (Finland).


Invasion patterns, genetic divergence, and barriers to dispersal (Formas)


In two projects financed by the Swedish Research Council for Environment, Agricultural Sciences & Spatial Planning (Formas) we are investigating dispersal and population genetic structure in a potentially invasive freshwater phytoplankton species. The species, Gonyostomum semen, is known as a nuisance species that forms frequent and dense blooms in boreal lakes. We have approached the problem on how and if it has dispersed using molecular markers and population genetic analyses.

People involved: Karen Lebret, Emma Kritzberg, Karin Rengefors




In a second project the aim is to identify the barriers to dispersal in microalgal species that form blooms in freshwater lakes and the sea. This research has implications for the understanding of the spreading of microalgae and microorganisms in general, as well as for predicting the occurrence of new algal blooms. The approach is to determine the importance of physical versus biological dispersal barriers by analyzing the genetic diversity patterns.

People involved: Ingrid Sassenhagen, Karin Rengefors, Torbjörn Säll. At Gothenburg University: Josefin Sefbom , Dr. Anna Godhe, Dr. Kerstin Johanesson.

Community metagenomics of Antarctic Protists  – the importance of history versus environment


Dispersal and subsequent colonization of new habitats have important consequences for community composition. In order to study microbial communities it is imperative to know their taxonomic diversity. By the use of molecular techniques the diversity of protists has been shown to be much higher than what older methods indicated. A fundamental question is whether community composition of aquatic protists is a consequence of environmental filtering, mass effects, historical processes or a mix of the previous processes. In this project, marine and freshwater protist composition will be investigated in a lake metacommunity that includes marine-derived and glacial melt-water lakes (Vestfold Hills, Antarctica). These lakes operate very much as islands, imposing certain geographic limitations to populations, as well as dispersal among populations. The community composition is analyzed using 454-sequencing technology. This project and associated postdoctoral fellow is part of the CanMove center.

People involved: Sylvie Tesson, Karin Rengefors, Katarina Hedlund

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