%0 Journal Article %J The ISME Journal %D 2023 %T Rapid diversification underlying the global dominance of a cosmopolitan phytoplankton %A Bendif, El Mahdi %A Probert, Ian %A Archontikis, Odysseas A. %A Young, Jeremy R. %A Beaufort, Luc %A Rickaby, Rosalind E. %A Filatov, Dmitry %K Microbial biooceanography %K phylogenomics %K population genetics %K rcc1212 %K RCC1216 %K rcc1220 %K RCC1239 %K RCC1240 %K RCC1242 %K RCC1245 %K rcc1252 %K RCC1253 %K RCC1266 %K RCC1304 %K rcc1731 %K RCC1754 %K RCC1813 %K RCC1823 %K rcc1824 %K RCC1830 %K RCC1838 %K RCC1840 %K RCC1853 %K RCC1856 %K RCC3746 %K RCC4027 %K RCC4028 %K RCC4030 %K RCC5134 %K RCC5137 %K RCC5141 %K RCC6381 %K RCC6421 %K RCC6427 %K RCC6566 %K RCC6660 %K RCC6666 %K RCC911 %K RCC963 %X 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. %B The ISME Journal %P 1–11 %G eng %U https://www.nature.com/articles/s41396-023-01365-5 %R 10.1038/s41396-023-01365-5 %0 Journal Article %J Frontiers in Microbiology %D 2016 %T Recent reticulate evolution in the ecologically dominant lineage of coccolithophores %A Bendif, El Mahdi %A Probert, Ian %A Díaz-Rosas, Francisco %A Thomas, Daniela %A van den Engh, Ger %A Young, Jeremy R. %A von Dassow, Peter %K 2016 %K coccolithophores %K cyto-nuclear discordance %K diversity %K Emiliania %K evolution %K Gephyrocapsa %K introgressive hybridization %K rcc %K RCC4032 %K RCC4033 %K RCC4034 %K RCC4035 %K RCC4036 %K Reticulofenestra %K sbr?hyto %B Frontiers in Microbiology %V 7 %8 may %G eng %U http://journal.frontiersin.org/article/10.3389/fmicb.2016.00784 http://journal.frontiersin.org/Article/10.3389/fmicb.2016.00784/abstract %R 10.3389/fmicb.2016.00784 %0 Journal Article %J Protist %D 2015 %T Morphological and phylogenetic characterization of new gephyrocapsa isolates suggests introgressive hybridization in the Emiliania/Gephyrocapsa complex (haptophyta) %A Bendif, El Mahdi %A Probert, Ian %A Young, Jeremy R. %A von Dassow, Peter %K 2015 %K coccolithophores %K Emiliania huxleyi %K Gephyrocapsa muellerae %K Gephyrocapsa oceanica %K hybridization %K phylogeny. %K rcc %K RCC1281 %K RCC1282 %K RCC1284 %K RCC1286 %K RCC1292 %K RCC1300 %K RCC1305 %K RCC1307 %K RCC1316 %K RCC1317 %K RCC1318 %K RCC1319 %K RCC1320 %K RCC1562 %K RCC1839 %K RCC3370 %K RCC3862 %K RCC3898 %K species concept %X The coccolithophore genus Gephyrocapsa contains a cosmopolitan assemblage of pelagic species, including the bloom-forming Gephyrocapsa oceanica, and is closely related to the emblematic coccolithophore Emiliania huxleyi within the Noëlaerhabdaceae. These two species have been extensively studied and are well represented in culture collections, whereas cultures of other species of this family are lacking. We report on three new strains of Gephyrocapsa isolated into culture from samples from the Chilean coastal upwelling zone using a novel flow cytometric single-cell sorting technique. The strains were characterized by morphological analysis using scanning electron microscopy and phylogenetic analysis of 6 genes (nuclear 18S and 28S rDNA, plastidial 16S and tufA, and mitochondrial cox1 and cox3 genes). Morphometric features of the coccoliths indicate that these isolates are distinct from G. oceanica and best correspond to G. muellerae. Surprisingly, both plastidial and mitochondrial gene phylogenies placed these strains within the E. huxleyi clade and well separated from G. oceanica isolates, making Emiliania appear polyphyletic. The only nuclear sequence difference, 1bp in the 28S rDNA region, also grouped E. huxleyi with the new Gephyrocapsa isolates and apart from G. oceanica. Specifically, the G. muellerae morphotype strains clustered with the mitochondrial β clade of E. huxleyi, which, like G. muellerae, has been associated with cold (temperate and sub-polar) waters. Among putative evolutionary scenarios that could explain these results we discuss the possibility that E. huxleyi is not a valid taxonomic unit, or, alternatively the possibility of past hybridization and introgression between each E. huxleyi clade and older Gephyrocapsa clades. In either case, the results support the transfer of Emiliania to Gephyrocapsa. These results have important implications for relating morphological species concepts to ecological and evolutionary units of diversity. %B Protist %V 166 %P 323–336 %G eng %U http://www.sciencedirect.com/science/article/pii/S1434461015000243 %R 10.1016/j.protis.2015.05.003