@article {bendif_rapid_2023,
	title = {Rapid diversification underlying the global dominance of a cosmopolitan phytoplankton},
	journal = {The ISME Journal},
	year = {2023},
	note = {Publisher: Nature Publishing Group},
	pages = {1{\textendash}11},
	abstract = {Marine phytoplankton play important roles in the global ecosystem, with a limited number of cosmopolitan keystone species driving their biomass. Recent studies have revealed that many of these phytoplankton are complexes composed of sibling species, but little is known about the evolutionary processes underlying their formation. Gephyrocapsa huxleyi, a widely distributed and abundant unicellular marine planktonic algae, produces calcified scales (coccoliths), thereby significantly affects global biogeochemical cycles via sequestration of inorganic carbon. This species is composed of morphotypes defined by differing degrees of coccolith calcification, the evolutionary ecology of which remains unclear. Here, we report an integrated morphological, ecological and genomic survey across globally distributed G. huxleyi strains to reconstruct evolutionary relationships between morphotypes in relation to their habitats. While G. huxleyi has been considered a single cosmopolitan species, our analyses demonstrate that it has evolved to comprise at least three distinct species, which led us to formally revise the taxonomy of the G. huxleyi complex. Moreover, the first speciation event occurred before the onset of the last interglacial period (\textasciitilde140 ka), while the second followed during this interglacial. Then, further rapid diversifications occurred during the most recent ice-sheet expansion of the last glacial period and established morphotypes as dominant populations across environmental clines. These results suggest that glacial-cycle dynamics contributed to the isolation of ocean basins and the segregations of oceans fronts as extrinsic drivers of micro-evolutionary radiations in extant marine phytoplankton.},
	keywords = {Microbial biooceanography, phylogenomics, population genetics, rcc1212, RCC1216, rcc1220, RCC1239, RCC1240, RCC1242, RCC1245, rcc1252, RCC1253, RCC1266, RCC1304, rcc1731, RCC1754, RCC1813, RCC1823, rcc1824, RCC1830, RCC1838, RCC1840, RCC1853, RCC1856, RCC3746, RCC4027, RCC4028, RCC4030, RCC5134, RCC5137, RCC5141, RCC6381, RCC6421, RCC6427, RCC6566, RCC6660, RCC6666, RCC911, RCC963},
	issn = {1751-7370},
	doi = {10.1038/s41396-023-01365-5},
	url = {https://www.nature.com/articles/s41396-023-01365-5},
	author = {Bendif, El Mahdi and Probert, Ian and Archontikis, Odysseas A. and Young, Jeremy R. and Beaufort, Luc and Rickaby, Rosalind E. and Filatov, Dmitry}
}
@article {sucheras-marx_coccolith_2022,
	title = {Coccolith size rules {\textendash} What controls the size of coccoliths during coccolithogenesis?},
	journal = {Marine Micropaleontology},
	volume = {170},
	year = {2022},
	pages = {102080},
	abstract = {Heterococcoliths are calcite platelets produced inside diploid coccolithophore cells and extruded to form a covering on the cell surface called a coccosphere. The size of coccoliths is an important parameter sometimes used to identify species, and it is observed to be influenced in extant species by abiotic parameters (e.g., CO2, light). However, the variable distribution of coccolith sizes occurring within a single coccosphere questions the mechanisms controlling coccolith size. A relationship between cell/coccosphere size and mean coccolith size was previously identified, called the {\textquotedblleft}coccolithophore size rules{\textquotedblright}. In this study, we query the mechanisms controlling the size of a coccolith during coccolithogenesis. A culture experiment on Gephyrocapsa huxleyi strain RCC1216 shows that coccolithogenesis occurs during the cell growth G1 interphase and newly produced coccoliths get bigger as the cell grows. These observations provide parameters for the development of two numerical models used to simulate the coccolith size distribution within a coccolithophore population. Neither model can accurately reproduce an empirical monoclonal coccolith size distribution, indicating that additional factors influence coccolith size. According to our results, coccolith size is only clearly related to cell size at the time of its formation. We confirm that application of the coccolithophore size rules model should be limited to inferring average cell dimensions from (fossil) coccolith biometry, and that comparisons are valid only in multipopulational studies. The coccolith size rule model {\textendash} the constraining effect of coccolith production during G1 interphase cell growth on coccolith size {\textendash} proposed here is applicable only for some placolith-forming species.},
	keywords = {Biometry, coccolith, coccolithophore, life cycle, RCC1216, Size variation},
	issn = {0377-8398},
	doi = {10.1016/j.marmicro.2021.102080},
	url = {https://www.sciencedirect.com/science/article/pii/S0377839821001213},
	author = {Such{\'e}ras-Marx, Baptiste and Viseur, Sophie and Walker, Charlotte E. and Beaufort, Luc and Probert, Ian and Bolton, Clara}
}
