title: Trade-offs limiting the evolution of coloniality: ecological displacement rates used to measure small costs.
abstract: Multicellular organisms that benefit from division of labour are presumably descended from colonial species that initially derived benefits from larger colony size, before the evolution of specialization. Life in a colony can have costs as well as benefits, but these can be hard to measure. We measured physiological costs to life in a colony using a novel method based on population dynamics, comparing growth rates of unicells and kairomone-induced colonies of a green alga Desmodesmus subspicatus against a reference co-occurring species. Coloniality negatively affected growth during the initial log growth phase, while no adverse effect was detected under nutrient-limited competitive conditions. The results point to costs associated with traits involved in rapid growth rather than those associated with efficient growth under resource scarcity. Some benefits of coloniality (e.g. defence from herbivory) may be different from when this trait evolved, but our approach shows how costs would have depended on conditions.
authors.affiliation: Department of Ecology, Evolution and Behavior, University of Minnesota, 1987 Upper Buford Circle, Saint Paul, MN 55108, USA.
authors.forename: Kiyoko
authors.initials: K
authors.lastname: Yokota
authors.forename: Robert W
authors.initials: RW
authors.lastname: Sterner
mesh_terms: D005075:Biological Evolution; D002452:Cell Count; D000460:Chlorophyta / Q000254:growth & development* / Q000378:metabolism / Q000648:ultrastructure; D004463:Ecology; D007301:Insect Hormones / Q000378:metabolism; D016014:Linear Models
chemical_list: D007301:Insect Hormones; C013078:kairmones