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  • Center for Marine Environmental Sciences; MARUM  (1)
  • LSU rRNA gene  (1)
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  • 1
    ISSN: 1432-1432
    Keywords: Foraminifera ; Sequence dissimilarity ; LSU rRNA gene ; Phylogeny
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An unusually high divergence was observed in the ribosomal RNA genes of a free-living population of foraminifera belonging to the genusAmmonia. The sequences of a large-subunit (LSU) rDNA expansion segment D1 and flanking regions were obtained from 20 specimens namedAmmonia sp. 1 andAmmonia sp. 2. The sequence divergence between the two species averages 14%. Within each species it ranges from 0.2% to 7.1% inAmmonia sp. 1 and from 0.7% to 2.3% inAmmonia sp. 2. We did not find two specimens having identical sequences. Moreover, in opposition to the generally acaepted view, rDNA sequence variations were also found within a single individual. The variations among several rDNA copies in a single specimen ofAmmonia may reach up to 4.9%. Most of the observed variations result from multiplication of CA or TA serial repeats occurring in two particularly variable regions. For single base changes, C-T transitions are most frequently observed. We discuss the evolution of expansion segments and their use for phylogenetic studies.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
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  • 2
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    PANGAEA
    In:  Supplement to: Kucera, Michal; Silye, Lóránd; Weiner, Agnes K M; Darling, Kate F; Lübben, Birgit; Holzmann, Maria; Pawlowski, Jan; Schönfeld, Joachim; Morard, Raphael (2017): Caught in the act: Anatomy of an ongoing benthic-planktonic transition in a marine protist. Journal of Plankton Research, 39 (3), 436-449, https://doi.org/10.1093/plankt/fbx018
    Publication Date: 2023-03-03
    Description: The transition from benthos to plankton requires multiple adaptations, yet so far it remains unclear how these are acquired in the course of the transition. To investigate this process, we analyzed the genetic diversity and distribution patterns of a group of foraminifera of the genus Bolivina with a tychopelagic mode of life (same species occurring both in benthos and plankton). We assembled a global sequence dataset for this group from single-cell DNA extractions and occurrences in metabarcodes from pelagic environmental samples. The pelagic sequences all cluster within a single monophyletic clade within Bolivina. This clade harbors three distinct genetic lineages, which are associated with incipient morphological differentiation. All lineages occur in plankton and benthos, but only one lineage shows no limit to offshore dispersal and has been shown to grow in the plankton. These observations indicate that the emergence of buoyancy regulation within the clade preceded the evolution of pelagic feeding and that the evolution of both traits was not channeled into a full transition into the plankton. We infer that in foraminifera, colonization of the planktonic niche may occur by sequential cooptation of independently acquired traits, with holoplanktonic species being recruited from tychopelagic ancestors.
    Keywords: Center for Marine Environmental Sciences; MARUM
    Type: Dataset
    Format: application/zip, 4 datasets
    Location Call Number Limitation Availability
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