Meeting Abstract
142.3 Monday, Jan. 7 Phenotypic plasticity of jaw morphology as a response to diet in two cichlid species and their hybrid TKINT, T*; DE MEYER , J; HELSEN, P; BOONE, M; VERHEYEN, E; ADRIAENS, D; Ghent University, Belgium; Ghent University, Belgium; Antwerp University, Belgium; UG-CT, Ghent, Belgium; Royal Belgian Institute of Natural Sciences, Brussels, Belgium; Ghent University, Belgium Tim.tkint@ugent.be
To explain the very high rates of speciation of cichlids in the East-African Lakes several hypotheses have been suggested. The decoupling of the oral and pharyngeal jaws is considered their most important key innovation, but it has been found that several other factors may also play a role in their adaptive radiation. Local adaptive responses, resulting from phenotypic plasticity, may allow cichlids to rapidly adapt to environmental changes during their lifetime and through processes like genetic assimilation such a response has the potential of becoming a heritable trait. Genetic studies have also confirmed that hybridization has occurred in the wild and that this potentially leads to novel phenotypes through transgressive segregation. 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 and their hybrid on food with the same nutritional quality, but different physical characteristics, simulating different feeding modes: (1) suction feeding from the water column, (2) scraping food and (3) biting on hard pellets. To visualize the plastic response we performed a geometric morphometric analysis of head morphology and we also compared feeding performance based on morphological proxies (theoretical bite force, KT,…). Furthermore we focused on the lower jaw, one of the most important elements in the oral apparatus. Based on micro-CT scans we compared ossification patterns and analyzed shape differences using 3D morphometrics. To some degree, the observed morphological variation between treatments seemed to be related to improving the imposed mode of feeding.
