Ecotype diversity in the marine picoeukaryote Ostreococcus (Chlorophyta, Prasinophyceae)
Article first published online: 21 MAR 2005
Volume 7, Issue 6, pages 853–859, June 2005
How to Cite
Rodríguez, F., Derelle, E., Guillou, L., Le Gall, F., Vaulot, D. and Moreau, H. (2005), Ecotype diversity in the marine picoeukaryote Ostreococcus (Chlorophyta, Prasinophyceae). Environmental Microbiology, 7: 853–859. doi: 10.1111/j.1462-2920.2005.00758.x
- Issue published online: 21 MAR 2005
- Article first published online: 21 MAR 2005
- Received 14 September, 2004; accepted 2 November, 2004.
The importance of the cyanobacteria Prochlorococcus and Synechococcus in marine ecosystems in terms of abundance and primary production can be partially explained by ecotypic differentiation. Despite the dominance of eukaryotes within photosynthetic picoplankton in many areas a similar differentiation has never been evidenced for these organisms. Here we report distinct genetic [rDNA 18S and internal transcribed spacer (ITS) sequencing], karyotypic (pulsed-field gel electrophoresis), phenotypic (pigment composition) and physiological (light-limited growth rates) traits in 12 Ostreococcus strains (Prasinophyceae) isolated from various marine environments and depths, which suggest that the concept of ecotype could also be valid for eukaryotes. Internal transcribed spacer phylogeny grouped together four deep strains isolated between 90 m and 120 m depth from different geographical origins. Three deep strains displayed larger chromosomal bands, different chromosome hybridization patterns, and an additional chlorophyll (chl) c-like pigment. Furthermore, growth rates of deep strains show severe photo-inhibition at high light intensities, while surface strains do not grow at the lowest light intensities. These features strongly suggest distinct adaptation to environmental conditions encountered at surface and the bottom of the oceanic euphotic zone, reminiscent of that described in prokaryotes.