title: Closely related protist strains have different grazing impacts on natural bacterial communities.
abstract: Heterotrophic protists are abundant in most environments and exert a strong top-down control on bacterial communities. However, little is known about how selective most protists are with respect to their bacterial prey. We conducted feeding trials using cercomonad and glissomonad Cercozoa by assaying them on a standardized, diverse bacterial community washed from beech leaf litter. For each of the nine protist strains assayed here, we measured several phenotypic traits (cell volume, speed, plasticity and protist cell density) that we anticipated would be important for their feeding ecology. We also estimated the genetic relatedness of the strains based on the 18S rRNA gene. We found that the nine protist strains had significantly different impacts on both the abundance and the composition of the bacterial communities. Both the phylogenetic distance between protist strains and differences in protist strain traits were important in explaining variation in the bacterial communities. Of the morphological traits that we investigated, protist cell volume and morphological plasticity (the extent to which cells showed amoeboid cell shape flexibility) were most important in determining bacterial community composition. The results demonstrate that closely related and morphologically similar protist species can have different impacts on their prey base.
authors.affiliation: Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK.
authors.forename: Edvard
authors.initials: E
authors.lastname: Glücksman
authors.forename: Thomas
authors.initials: T
authors.lastname: Bell
authors.forename: Robert I
authors.initials: RI
authors.lastname: Griffiths
authors.forename: David
authors.initials: D
authors.lastname: Bass
mesh_terms: D001419:Bacteria / Q000254:growth & development*; D056907:Cercozoa / Q000235:genetics / Q000502:physiology*; D017753:Ecosystem; D020459:Genes, rRNA; D010641:Phenotype; D010802:Phylogeny; D011157:Population Dynamics; D012337:RNA, Ribosomal, 18S / Q000235:genetics
chemical_list: D012337:RNA, Ribosomal, 18S