title: Rapid adaptation of harmful cyanobacteria to rising CO2.
abstract: Rising atmospheric CO2 concentrations are likely to affect many ecosystems worldwide. However, to what extent elevated CO2 will induce evolutionary changes in photosynthetic organisms is still a major open question. Here, we show rapid microevolutionary adaptation of a harmful cyanobacterium to changes in inorganic carbon (Ci) availability. We studied the cyanobacterium Microcystis, a notorious genus that can develop toxic cyanobacterial blooms in many eutrophic lakes and reservoirs worldwide. Microcystis displays genetic variation in the Ci uptake systems BicA and SbtA, where BicA has a low affinity for bicarbonate but high flux rate, and SbtA has a high affinity but low flux rate. Our laboratory competition experiments show that bicA + sbtA genotypes were favored by natural selection at low CO2 levels, but were partially replaced by the bicA genotype at elevated CO2 Similarly, in a eutrophic lake, bicA + sbtA strains were dominant when Ci concentrations were depleted during a dense cyanobacterial bloom, but were replaced by strains with only the high-flux bicA gene when Ci concentrations increased later in the season. Hence, our results provide both laboratory and field evidence that increasing carbon concentrations induce rapid adaptive changes in the genotype composition of harmful cyanobacterial blooms.
authors.affiliation: Department of Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, 1090 GE Amsterdam, The Netherlands;
authors.forename: Giovanni
authors.initials: G
authors.lastname: Sandrini
authors.affiliation: Department of Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, 1090 GE Amsterdam, The Netherlands;
authors.forename: Xing
authors.initials: X
authors.lastname: Ji
authors.affiliation: Department of Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, 1090 GE Amsterdam, The Netherlands;
authors.forename: Jolanda M H
authors.initials: JM
authors.lastname: Verspagen
authors.affiliation: Department of Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, 1090 GE Amsterdam, The Netherlands;
authors.forename: Robert P
authors.initials: RP
authors.lastname: Tann
authors.affiliation: Department of Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, 1090 GE Amsterdam, The Netherlands;
authors.forename: Pieter C
authors.initials: PC
authors.lastname: Slot
authors.affiliation: Department of Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, 1090 GE Amsterdam, The Netherlands; Wetsus, European Centre of Excellence for Sustainable Water Technology, 8900 CC Leeuwarden, The Netherlands;
authors.forename: Veerle M
authors.initials: VM
authors.lastname: Luimstra
authors.affiliation: Department of Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, 1090 GE Amsterdam, The Netherlands; Department of Aquatic Ecology, Netherlands Institute of Ecology, 6700 AB Wageningen, The Netherlands.
authors.forename: J Merijn
authors.initials: JM
authors.lastname: Schuurmans
authors.affiliation: Department of Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, 1090 GE Amsterdam, The Netherlands;
authors.forename: Hans C P
authors.initials: HC
authors.lastname: Matthijs
authors.affiliation: Department of Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, 1090 GE Amsterdam, The Netherlands; j.huisman@uva.nl.
authors.forename: Jef
authors.initials: J
authors.lastname: Huisman
mesh_terms: D000222:Adaptation, Physiological; D002244:Carbon / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism*; D046931:Microcystis / Q000235:genetics / Q000502:physiology*
chemical_list: D002245:Carbon Dioxide; D002244:Carbon
keywords: Microcystis aeruginosa; climate change; harmful algal blooms; microevolution; natural selection