The Developmental Basis for Vertebral Number Variation in Teleost Fishes

I propose a project to address how cell movements and segmentation clock dynamics may have contributed to vertebral number variability in teleost fishes. To achieve this, I will use three species of teleost fish: Zebrafish (Danio rerio) and the Lake Malawi cichlids, Rhamphochromis sp. 'chillingali' and Astatotilapia calliptera. These species will be used as they show distinct differences in their number of vertebrae (32, 30, and 36 respectively), and because they show both close interrelatedness (R. 'chillingali' and A. calliptera share 99.75% of their genome4) and large phylogenetic divergence (cichlids vs. Zebrafish) (Figure 1A), allowing us insight into the plasticity of developmental processes across phylogeny. Furthermore, the geometry of the posterior axis in R. 'chillingali' and A. calliptera embryo is different to that of Zebrafish,
suggesting that the axial elongation dynamics of these species may differ, making these species an excellent model system for exploring the effects of cell movements and GRNs on vertebral number.
To answer this question, I will divide my work into two avenues of research. One will take a live-modelling22 approach to explore the effects of differing cell movements and tissue shape changes on the patterning potential of the segmentation clock (Part I), and the other will characterize the components and dynamics of the GRN controlling the segmentation clock in the two cichlid species (Part II).