BlancMatthieuScienceAdvances17.pdf (1.35 MB)
Population genomics of picophytoplankton unveils novel chromosome hypervariability
journal contribution
posted on 2023-06-09, 07:27 authored by Romain Blanc-Mathieu, Marc Krasovec, Maxime Hebrard, Sheree Yau, Elodie Desgranges, Joel Martin, Wendy Schackwitz, Alan Kuo, Gerald Salin, Cecile Donnadieu, Yves Desdevises, Sophie Sanchez-Ferandin, Hervé Moreau, Eric Rivals, Igor V Grigoriev, Nigel Grimsley, Adam Eyre-WalkerAdam Eyre-Walker, Gwenael PiganeauTiny photosynthetic microorganisms that form the picoplankton (between 0.3 and 3 mm in diameter) are at the base of the food web in many marine ecosystems, and their adaptability to environmental change hinges on standing genetic variation. Although the genomic and phenotypic diversity of the bacterial component of the oceans has been intensively studied, little is known about the genomic and phenotypic diversity within each of the diverse eukaryotic species present. We report the level of genomic diversity in a natural population of Ostreococcus tauri (Chlorophyta, Mamiellophyceae), the smallest photosynthetic eukaryote. Contrary to the expec- tations of clonal evolution or cryptic species, the spectrum of genomic polymorphism observed suggests a large panmictic population (an effective population size of 1.2 × 107) with pervasive evidence of sexual reproduction. De novo assemblies of low-coverage chromosomes reveal two large candidate mating-type loci with suppressed recom- bination, whose origin may pre-date the speciation events in the class Mamiellophyceae. This high genetic diversity is associated with large phenotypic differences between strains. Strikingly, resistance of isolates to large double- stranded DNA viruses, which abound in their natural environment, is positively correlated with the size of a single hypervariable chromosome, which contains 44 to 156 kb of strain-specific sequences. Our findings highlight the role of viruses in shaping genome diversity in marine picoeukaryotes.
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Publication status
- Published
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- Published version
Journal
Science AdvancesISSN
2375-2548Publisher
American Association for the Advancement of ScienceExternal DOI
Issue
7Volume
3Article number
e1700239Department affiliated with
- Evolution, Behaviour and Environment Publications
Full text available
- Yes
Peer reviewed?
- Yes
Legacy Posted Date
2017-07-27First Open Access (FOA) Date
2017-07-27First Compliant Deposit (FCD) Date
2017-07-27Usage metrics
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