Combining experimental embryology and geometric morphometrics to uncover the evolution of vertebral variability in Lake Malawi cichlids

The axial skeleton is of great functional importance for locomotion in vertebrates. Vertebrae are critical skeletal bones and have modified multiple times during the evolution of vertebrate animals. The evolutionary change of number, proportion (the ratio of one vertebrae type over another) and shape of vertebrae has been modified during vertebrate diversification to permit the emergence of varied body forms. For example, large numbers of thoracic (chest) vertebrae support the elongated body axis of snakes. In contrast, giraffes increase the growth-rate of their cervical (neck) vertebrae, relative to their other vertebrae, to support their extraordinarily long necks. Diverse vertebral counts and proportions are found in Lake Malawi cichlids, a morphologically, ecologically, and behaviourally diverse ray-finned fish family that have radiated from a single common ancestor over the last one million years. This is particularly remarkable given that Lake Malawi cichlids are extremely closely related, differing genetically by an average of just 0.19-0.27%, lower than genetic difference between human populations. Understanding how developmental mechanisms underpinning vertebral morphology have been modified, in a background with limited genetic variation and in short evolutionary time, is important in determining how vertebrates have evolved remarkable body plan diversity.

The research falls into the following BBSRC priority areas:
Data driven biology
Systems approaches to the biosciences