title: Development and evolution of caste dimorphism in honeybees - a modeling approach.
abstract: The difference in phenotypes of queens and workers is a hallmark of the highly eusocial insects. The caste dimorphism is often described as a switch-controlled polyphenism, in which environmental conditions decide an individual's caste. Using theoretical modeling and empirical data from honeybees, we show that there is no discrete larval developmental switch. Instead, a combination of larval developmental plasticity and nurse worker feeding behavior make up a colony-level social and physiological system that regulates development and produces the caste dimorphism. Discrete queen and worker phenotypes are the result of discrete feeding regimes imposed by nurses, whereas a range of experimental feeding regimes produces a continuous range of phenotypes. Worker ovariole numbers are reduced through feeding-regime-mediated reduction in juvenile hormone titers, involving reduced sugar in the larval food. Based on the mechanisms identified in our analysis, we propose a scenario of the evolutionary history of honeybee development and feeding regimes.
authors.affiliation: Department of Zoology, Stockholm University Stockholm, Sweden ; Wissenschaftskolleg zu Berlin Wallotstrasse 19, Berlin, Germany.
authors.forename: Olof
authors.initials: O
authors.lastname: Leimar
authors.forename: Klaus
authors.initials: K
authors.lastname: Hartfelder
authors.forename: Manfred D
authors.initials: MD
authors.lastname: Laubichler
authors.forename: Robert E
authors.initials: RE
authors.lastname: Page
keywords: Caste determination; developmental evolution; plasticity; polyphenism; social insects