Meeting Abstract
P3.184 Tuesday, Jan. 6 The developmental basis for craniofacial morphology of cichlid fishes FUJIMURA, Koji*; OKADA, Norihiro; Tokyo Inst. of Tech, Yokohama, JAPAN; Tokyo Inst. of Tech, Yokohama, JAPAN kojifujiyb@yahoo.co.jp
Cichlid fishes of Great African Lakes are excellent examples of explosive adaptive radiation. One of the most important traits by which we can distinguish each species is the shape of feeding apparatus, which has been adapted to the wide variety of trophic habitats present in the lake. To study the molecular mechanism underlying the diversification of cichlids jaw shape, we need to understand the developmental basis of craniofacial morphology in the cichlids. First, we described the developmental stages for the embryonic, larval and early juvenile periods of Nile tilapia Oreochromis niloticus. We newly defined 32 stages using a numbered staging system. For embryonic development, we defined 18 stages (St.1-18), which were grouped into seven periods. For larval development, we defined seven stages (St.19-25), which were grouped into two periods. For juvenile development until 30 dpf, we defined seven stages (St.26-32) in the early juvenile period. Second, we described the identification, the timing and the sequence of the skeletal elements of Nile tilapia, categorized by the developmental stages. The chondrogenesis started in St.17. The deposition of osteoid for the dermal bones started in Stage 18. The uptake of calcium dramatically shifted from the surface of the larvae to the gills in St.20. The bone mineralization of the skeleton started in St.25. Third, we assessed the shape changes of the lower jaw bone during development of Nile tilapia and a Lake Victoria cichlid Haplochromis chilotes using geometric morphometrics. Principal component analysis showed both commonalities and differences in the morphological changes between the cichlids. These data provide basic information as a starting point for understanding the molecular mechanisms underlying this adaptive trait of East African cichlids.
