Competition processes and population dynamics of phytoplankton
Elucidating the underpinnings of niche differentiation and competition is essential to understanding food webs. We published genome sequences from two pico algae isolates (Micromonas sp. RCC299 and Micromonas pusilla CCMP1545) sequenced in collaboration with the JGI, U.S. Department of Energy in Worden et al. Science 2009. These two isolates were once considered a single species (Micromonas pusilla), but are very clearly not the same species. They show massive genome divergence, share only ~90% of their protein-encoding genes and show other fundamental differences. The genome of RCC299 represents one of the few fully sequenced eukaryotic genomes (closed). These organisms also fall at the base of the green lineage and hence shed light on the evolution of higher plants, in addition to being important marine primary producers. We have been team members in the 2006 analysis of the genome of Ostreococcus tauri, a tiny, marine photosynthetic eukaryote discovered in 1994, and in the analyses of other important marine algae, including Emiliania huxleyi, Fragilariopsis cylindrus andBigelowiella natans. Lab field research has led to a better understanding of the distributions of various picoeukaryotes including ecotypes of Ostreococcus (see Demir et al. ISME J 2010) and Bathycoccus (see Monier et al. ISME J 2013). Much of this research highlights the overlap in resource utilization capabilities of heterotrophic and autotrophic microorganisms. We are now testing genome derived hypotheses on niche differentiation through large scale transcriptomics and proteomics. If you are interested in working with us on the ongoing Micromonas systems biology project please contact Alex.
An example of comparative physiology research in the lab is a project aimed to understand the photobiology of Micromonas and Ostreococcus. Specifically, their relative success in high-light/high-ultraviolet radiation environments is being investigated by a combination of genomic (in silico), micro-array, quantitative-PCR and biochemical approaches. Using gene and protein expression to detect real-time cell response to environmental changes (e.g. mitigating negative effects and capitalizing on favorable conditions) will help identify conditions of immediate relevance to survival or success. We are currently focusing on photoautotrophs but plan to apply similar approaches to predator populations. By avoiding the use of heavy-handed field manipulations that may be of little ecological relevance, this approach will help researchers define conditions contributing to the relative success of individual microbial populations. Click here to learn more about prasinophyte genomes.