title: Are heterotrophic and silica-rich eukaryotic microbes an important part of the lichen symbiosis?
abstract: We speculate that heterotrophic and/or silica-rich eukaryotic microorganisms maybe an important part of the lichen symbiosis. None of the very few studies of heterotrophic protists associated with lichens have considered the possibility that they may be of functional significance in the lichen symbiosis. Here we start to develop, currently speculative, theoretical ideas about their potential significance. For example, all the protist taxa identified in lichens we sampled in Ohio USA depend on silica for growth and construction of their cell walls, this could suggest that silica-rich lichen symbionts may be significant in the biogeochemistry of the lichen symbiosis. We also present arguments suggesting a role for protists in nitrogen cycling within lichen thalli and a potential role in controlling bacterial populations associated with lichens. In this necessarily speculative paper we highlight areas for future research and how newer technologies may be useful for understanding the full suite of organisms involved in the lichen symbiosis.
authors.affiliation: School of Natural Science and Psychology, Liverpool John Moores University , Byrom Street, Liverpool L3 3AF , UK.
authors.forename: David M
authors.initials: DM
authors.lastname: Wilkinson
authors.affiliation: School of Natural Science and Psychology, Liverpool John Moores University , Byrom Street, Liverpool L3 3AF , UK ; Environmental Research Institute, University of the Highlands and Islands , Ormlie Road, Thurso , Caithness , KW14 7EE , UK.
authors.forename: Angela L
authors.initials: AL
authors.lastname: Creevy
authors.affiliation: Department of Biology, Howard University , Washington , DC 20059 , USA.
authors.forename: Chiamaka L
authors.initials: CL
authors.lastname: Kalu
authors.affiliation: Department of Biology, Howard University , Washington , DC 20059 , USA.
authors.forename: David W
authors.initials: DW
authors.lastname: Schwartzman
keywords: chrysophyte; diatom; lichens; protists; symbiosis; testate amoebae