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Project Progress

The marine environment comprises the largest contiguous “surface” habitat on Earth, but it is far from a continuous, homogenous environment. Spatial variation spans a continuous range from the micrometer (driven by “bottom up” molecular interactions) to the ocean and global scales (driven by “top down” global atmospheric, land, sea interactions) all of which can be highly temporally diverse. Biologically, prokaryotes dominate in terms of abundance, biomass, and biogeochemical processes, however only relatively recently have we begun to define the mechanisms of microbial community structuring and diversification in this environment. We have identified fine scale differentiation within the major microbial groups and our aim is to understand what the driving force of this diversification may be. Using the internal transcribed spacer (ITS) region of the ribosomal operon as a marker we have highlighted two interesting phenomena concerning marine microbial diversification. Firstly, the marine assemblage does not consist of organisms derived from a recent common lineage, but rather a vast array of closely related but discrete co-exiting populations. The mechanisms which maintain this “micro-diversity” are not understood. It may persists because the processes introducing genetic variation are more prevalent than those causing purging of genotypes from the population. However, this microdiversity may also be beneficial by contributing to a systems biological by confounding processes such as viral attack.

Secondly, we observed distinct clusters dominated by sequences retrieved from various depths and geographic regions, possibly indicating adaptation to subtle niche variation. Both these phenomena can be identified from Figure 1.

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We are collecting large datasets of ITS clusters from public databases, augmenting these with selected sampling, and aim to characterize the data in relation to physical and chemical oceanographic parameters to shed light on the mechanisms driving marine microbial diversification.