Molecular phylogeny and symbiotic selectivity of the green algal genus Dictyochloropsis s.l. (Trebouxiophyceae): a polyphyletic and widespread group forming photobiont-mediated guilds in the lichen family Lobariaceae

Authors

  • Francesco Dal Grande,

    Corresponding author
    1. Biodiversity and Conservation Biology, Swiss Federal Research Institute WSL, Birmensdorf, Switzerland
    Current affiliation:
    1. Biodiversity and Climate Research Centre (BiK-F), Senckenberg Gesellschaft fuer Naturforschung, Frankfurt am Main, Germany
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  • Andreas Beck,

    1. Department of Lichenology and Bryology, Botanische Staatssammlung München, München, Germany
    2. GeoBio-Center, Ludwig-Maximilians Universität München, München, Germany
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  • Carolina Cornejo,

    1. Biodiversity and Conservation Biology, Swiss Federal Research Institute WSL, Birmensdorf, Switzerland
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  • Garima Singh,

    1. Biodiversity and Conservation Biology, Swiss Federal Research Institute WSL, Birmensdorf, Switzerland
    2. Department of Biological Sciences, Institute of Ecology, Evolution and Diversity, Goethe Universität, Frankfurt, Germany
    Current affiliation:
    1. Biodiversity and Climate Research Centre (BiK-F), Senckenberg Gesellschaft fuer Naturforschung, Frankfurt am Main, Germany
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  • Saran Cheenacharoen,

    1. Biodiversity and Conservation Biology, Swiss Federal Research Institute WSL, Birmensdorf, Switzerland
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  • Matthew P. Nelsen,

    1. Committee on Evolutionary Biology, University of Chicago, Chicago, IL, USA
    2. Department of Botany, The Field Museum, Chicago, IL, USA
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  • Christoph Scheidegger

    1. Biodiversity and Conservation Biology, Swiss Federal Research Institute WSL, Birmensdorf, Switzerland
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Summary

  • Dictyochloropsis s.l. is an ecologically important, common but little-studied genus of green algae. Here, we examined the diversity and host selectivity of algae attributed to this genus at both species-to-species and species-to-community levels.
  • We conducted a molecular investigation of 15 cultured strains and several lichen photobionts, using 18S rRNA, rbcL and ITS sequence data. We further used seven alga-specific microsatellite markers to study algal sharing among fungi of the family Lobariaceae in two populations in Madeira and Taiwan (454 lichens).
  • We found that the genus Dictyochloropsis s.l. is polyphyletic. Dictyochloropsis clade 1 comprises only free-living algae whereas Dictyochloropsis clade 2 includes lichenized algae as well as free-living algae. Fungal selectivity towards algae belonging to Dictyochloropsis clade 2 is high. Selectivity varies geographically, with photobionts being restricted to a single region. Finally, we showed that Dictyochloropsis clade 2 individuals are shared among different fungal hosts in communities of lichens of the Lobariaceae.
  • As for other green algal lineages, there is a high amount of cryptic diversity in Dictyochloropsis. Furthermore, co-evolution between Dictyochloropsis clade 2 algae and representatives of the Lobariaceae is manifested at the community level, with several unrelated fungal species being horizontally connected by shared photobiont clones.

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