Meeting Abstract

1.4  Wednesday, Jan. 4  Phenotypic plasticity of feeding performance as a response to diet in cichlids: suction versus biting. TKINT, T*; DE MEYER, J; HELSEN, P; VAN HOOREBEKE, L; VERHEYEN, E; ADRIAENS , D; Ghent University, Belgium; Ghent University, Belgium; Antwerp University, Belgium; Ghent University, Belgium; RBINS, Brussels, Belgium; Ghent University, Belgium Tim.tkint@ugent.be

The explosive radiation of cichlids in the East-African Lakes is considered an important model system for evolutionary research. To explain their very high rates of speciation several hypotheses have been suggested. The decoupling of the oral and pharyngeal jaws is considered their most important key innovation, but recently it has been found that several other factors may also play a role in their adaptive radiation. Local adaptive responses, resulting from phenotypic plasticity allow species to adapt to immediate environmental changes during their lifetime, which has the potential of becoming a heritable trait through processes like genetic assimilation. We investigated phenotypic plasticity in response to different feeding modes in two cichlid species from Lake Victoria: Haplochromis piceatus, a suction feeder and H. fischeri, a biter. We raised groups of both species on food with the same nutritional quality, but different physical characteristics, simulating different feeding modes: suction feeding from the water column, scraping food and biting on hard pellets. To visualize the plastic response we performed a geometric morphometric analysis and we also compared feeding performance based on morphological proxies (theoretical bite force, KT,…). Ossification patterns of the lower jaw were compared using µ-CT data. To some degree, the observed morphological variation between treatments seemed to be related to improving the imposed mode of feeding.