title: Genetic delineation between and within the widespread coccolithophore morpho-species Emiliania huxleyi and Gephyrocapsa oceanica (Haptophyta).
abstract: Emiliania huxleyi and Gephyrocapsa oceanica are abundant coccolithophore morpho-species that play key roles in ocean carbon cycling due to their importance as both primary producers and cal-cifiers. Global change processes such as ocean acidification impact these key calcifying species. The physiology of E. huxleyi, a developing model species, has been widely studied, but its genetic delineation from G. oceanica remains unclear due to a lack of resolution in classical genetic markers. Using nuclear (18S rDNA and 28S rDNA), mitochondrial (cox1, cox2, cox3, rpl16, and dam), and plastidial (16S rDNA, rbcL, tufA, and petA) DNA markers from 99 E. huxleyi and 44 G. oceanica strains, we conducted a multigene/multistrain survey to compare the suitability of different markers for resolving phylogenetic patterns within and between these two morpho-species. The nuclear genes tested did not provide sufficient resolution to discriminate between the two morpho-species that diverged only 291Kya. Typical patterns of incomplete lineage sorting were generated in phylogenetic analyses using plastidial genes. In contrast, full morpho-species delineation was achieved with mitochondrial markers and common intra-morpho-species phylogenetic patterns were observed despite differing rates of DNA substitution. Mitochondrial genes are thus promising barcodes for distinguishing these coccolithophore morpho-species, in particular in the context of environmental monitoring.
authors.affiliation: CNRS UMR7144/UPMC, EPEP team, Station Biologique de Roscoff, Roscoff, 29682, France.|Marine Biological Association of the United Kingdom, Citadel Hill, Plymouth, Devon, PL1 2PB, UK.
authors.forename: El Mahdi
authors.initials: el M
authors.lastname: Bendif
authors.affiliation: CNRS/UPMC, FR2424, Station Biologique de Roscoff, Roscoff, 29682, France.
authors.forename: Ian
authors.initials: I
authors.lastname: Probert
authors.affiliation: CNRS UMR7144/UPMC, EPEP team, Station Biologique de Roscoff, Roscoff, 29682, France.
authors.forename: Margaux
authors.initials: M
authors.lastname: Carmichael
authors.affiliation: CNRS UMR7144/UPMC, EPEP team, Station Biologique de Roscoff, Roscoff, 29682, France.
authors.forename: Sarah
authors.initials: S
authors.lastname: Romac
authors.affiliation: Institute for Study of the Earth's Interior Okayama University, 827 Yamada, Misasa, Tottori, 682-0193, Japan.
authors.forename: Kyoko
authors.initials: K
authors.lastname: Hagino
authors.affiliation: CNRS UMR7144/UPMC, EPEP team, Station Biologique de Roscoff, Roscoff, 29682, France.
authors.forename: Colomban
authors.initials: C
authors.lastname: de Vargas
keywords: DNA barcoding; Emiliania huxleyi; Gephyrocapsa oceanica; coccolithophore; phylogeny; species complex