title: GENOTYPE-BY-TEMPERATURE INTERACTIONS MAY HELP TO MAINTAIN CLONAL DIVERSITY IN ASTERIONELLA FORMOSA (BACILLARIOPHYCEAE).
abstract: Marine and freshwater phytoplankton populations often show large clonal diversity, which is in disagreement with clonal selection of the most vigorous genotype(s). Temporal fluctuation in selection pressures in variable environments is a leading explanation for maintenance of such genetic diversity. To test the influence of temperature as a selection force in continually (seasonally) changing aquatic systems we carried out reaction norms experiments on co-occurring clonal genotypes of a ubiquitous diatom species, Asterionella formosa Hassall, across an environmentally relevant range of temperatures. We report within population genetic diversity and extensive diversity in genotype-specific reaction norms in growth rates and cell size traits. Our results showed genotype by environment interactions, indicating that no genotype could outgrow all others across all temperature environments. Subsequently, we constructed a model to simulate the relative proportion of each genotype in a hypothetical population based on genotype and temperature-specific population growth rates. This model was run with different seasonal temperature patterns. Our modeling exercise showed a succession of two to several genotypes becoming numerically dominant depending on the underlying temperature pattern. The results suggest that (temperature) context dependent fitness may contribute to the maintenance of genetic diversity in isolated populations of clonally reproducing microorganisms in temporally variable environments.
authors.affiliation: Department of Aquatic Ecology, Netherlands Institute of Ecology (NIOO-KNAW), 6708 PB, Wageningen, The Netherlands.
authors.forename: Alena S
authors.initials: AS
authors.lastname: Gsell
authors.affiliation: Department of Aquatic Ecology, Netherlands Institute of Ecology (NIOO-KNAW), 6708 PB, Wageningen, The Netherlands.
authors.forename: Lisette N
authors.initials: LN
authors.lastname: de Senerpont Domis
authors.affiliation: Département de Biologie and Centre d'études nordiques (CEN), Université Laval, Québec, QC GIV 0A6, Canada.
authors.forename: Anna
authors.initials: A
authors.lastname: Przytulska-Bartosiewicz
authors.affiliation: Department of Aquatic Ecology, Netherlands Institute of Ecology (NIOO-KNAW), 6708 PB, Wageningen, The Netherlands.|Department of Aquatic Ecology and Water Quality Management, Wageningen University, 6700 AA, Wageningen, The Netherlands.
authors.forename: Wolf M
authors.initials: WM
authors.lastname: Mooij
authors.affiliation: Department of Aquatic Ecology, Netherlands Institute of Ecology (NIOO-KNAW), 6708 PB, Wageningen, The Netherlands.|Department of Biology, University of Utrecht, 3584 CH, Utrecht, The Netherlands.
authors.forename: Ellen
authors.initials: E
authors.lastname: van Donk
authors.affiliation: Department of Aquatic Ecology, Netherlands Institute of Ecology (NIOO-KNAW), 6708 PB, Wageningen, The Netherlands.|Department of Aquatic Ecology, Eawag, 8600, Dübendorf, Switzerland.
authors.forename: Bas W
authors.initials: BW
authors.lastname: Ibelings
keywords: coexistence; environmental variability; fluctuating selection; similarity; thermal reaction norms