Publication Date:
2019-03-08
Description:
The Southern Ocean houses a diverse and productive community
of organisms. Unicellular eukaryotic diatoms are the main
primary producers in this environment, where photosynthesis is
limited by low concentrations of dissolved iron and large seasonal
fluctuations in light, temperature and the extent of sea ice.
How diatoms have adapted to this extreme environment is largely
unknown. Here we present insights into the genome evolution of
a cold-adapted diatom from the Southern Ocean, Fragilariopsis
cylindrus based on a comparison with temperate diatoms. We find
that approximately 24.7 per cent of the diploid F. cylindrus genome
consists of genetic loci with alleles that are highly divergent from
those of temperate diatoms (15.1 megabases of the total genome
size of 61.1 megabases). These divergent alleles were differentially
expressed across environmental conditions, including darkness,
low iron, freezing, elevated temperature and increased CO2. Alleles
with the largest ratio of non-synonymous to synonymous nucleotide
substitutions also show the most pronounced condition-dependent
expression, suggesting a correlation between diversifying selection
and allelic differentiation. Divergent alleles may be involved in
adaptation to environmental fluctuations in the Southern Ocean.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
,
isiRev
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