title: Phenotypic variability in unicellular organisms: from calcium signalling to social behaviour.
abstract: Historically, research has focused on the mean and often neglected the variance. However, variability in nature is observable at all scales: among cells within an individual, among individuals within a population and among populations within a species. A fundamental quest in biology now is to find the mechanisms that underlie variability. Here, we investigated behavioural variability in a unique unicellular organism, Physarum polycephalum. We combined experiments and models to show that variability in cell signalling contributes to major differences in behaviour underpinning some aspects of social interactions. First, following thousands of cells under various contexts, we identified distinct behavioural phenotypes: 'slow-regular-social', 'fast-regular-social' and 'fast-irregular-asocial'. Second, coupling chemical analysis and behavioural assays we found that calcium signalling is responsible for these behavioural phenotypes. Finally, we show that differences in signalling and behaviour led to alternative social strategies. Our results have considerable implications for our understanding of the emergence of variability in living organisms.
authors.affiliation: CRCA, Université de Toulouse, CNRS, Toulouse, France.
authors.forename: David
authors.initials: D
authors.lastname: Vogel
authors.affiliation: Mathematics Department, Uppsala University, Uppsala, Sweden.
authors.forename: Stamatios C
authors.initials: SC
authors.lastname: Nicolis
authors.affiliation: LAPLACE, Université de Toulouse, CNRS, Toulouse, France Cajal Institute-Consejo Superior de Investigaciones Científicas, Madrid, Spain.
authors.forename: Alfonso
authors.initials: A
authors.lastname: Perez-Escudero
authors.affiliation: Centre for Human Genetics, Electronic City Phase I, Bangalore 560100, India.
authors.forename: Vidyanand
authors.initials: V
authors.lastname: Nanjundiah
authors.affiliation: Mathematics Department, Uppsala University, Uppsala, Sweden.
authors.forename: David J T
authors.initials: DJ
authors.lastname: Sumpter
authors.affiliation: CRCA, Université de Toulouse, CNRS, Toulouse, France audrey.dussutour@univ-tlse3.fr.
authors.forename: Audrey
authors.initials: A
authors.lastname: Dussutour
mesh_terms: D020013:Calcium Signaling; D014644:Genetic Variation; D008954:Models, Biological; D010641:Phenotype; D016839:Physarum polycephalum / Q000235:genetics / Q000502:physiology*; D012919:Social Behavior
keywords: behavioural phenotype; calcium; slime mould; social behaviour; variability