title: Genotype × genotype interactions between the toxic cyanobacterium Microcystis and its grazer, the waterflea Daphnia.
abstract: Toxic algal blooms are an important problem worldwide. The literature on toxic cyanobacteria blooms in inland waters reports widely divergent results on whether zooplankton can control cyanobacteria blooms or cyanobacteria suppress zooplankton by their toxins. Here we test whether this may be due to genotype × genotype interactions, in which interactions between the large-bodied and efficient grazer Daphnia and the widespread cyanobacterium Microcystis are not only dependent on Microcystis strain or Daphnia genotype but are specific to genotype × genotype combinations. We show that genotype × genotype interactions are important in explaining mortality in short-time exposures of Daphnia to Microcystis. These genotype × genotype interactions may result in local coadaptation and a geographic mosaic of coevolution. Genotype × genotype interactions can explain why the literature on zooplankton-cyanobacteria interactions is seemingly inconsistent, and provide hope that zooplankton can contribute to the suppression of cyanobacteria blooms in restoration projects.
authors.affiliation: Laboratory of Aquatic Ecology and Evolutionary Biology K.U.Leuven, Leuven, Belgium.
authors.forename: Veerle
authors.initials: V
authors.lastname: Lemaire
authors.affiliation: Laboratory of Aquatic Ecology and Evolutionary Biology K.U.Leuven, Leuven, Belgium.
authors.forename: Silvia
authors.initials: S
authors.lastname: Brusciotti
authors.affiliation: Laboratory of Protistology and Aquatic Ecology, Ghent University Gent, Belgium.
authors.forename: Ineke
authors.initials: I
authors.lastname: van Gremberghe
authors.affiliation: Laboratory of Protistology and Aquatic Ecology, Ghent University Gent, Belgium.
authors.forename: Wim
authors.initials: W
authors.lastname: Vyverman
authors.affiliation: Laboratory of Aquatic Ecology and Evolutionary Biology K.U.Leuven, Leuven, Belgium.
authors.forename: Joost
authors.initials: J
authors.lastname: Vanoverbeke
authors.affiliation: Laboratory of Aquatic Ecology and Evolutionary Biology K.U.Leuven, Leuven, Belgium.
authors.forename: Luc
authors.initials: L
authors.lastname: De Meester
keywords: cyanobacteria toxins; eco-evolutionary dynamics; genotype × genotype interactions; geographic mosaic of coevolution; harmful algal blooms; top–down control