Dr. Francesca Raffini

Genetic and environmental basis underlying the bilateral asymmetry in scale-eating cichlids
One of the most interesting questions in evolutionary biology is to explain the unusual evolution of left-right asymmetry in some species. This diversion from the “norm” of symmetrical animals is an extreme case of adaptive evolution. The scale-eating cichlid fish Perissodus microlepis from Lake Tanganiyka (Africa) is a remarkable example of asymmetric mouths that are either left-bending or right-bending. This morphological asymmetry results in its lateralized foraging behaviour, where a left-bending morph preferentially feeds on the scales of the right side of its victim fish and a right-bending morph bites the scales of the left side. This striking dimorphism made this fish a textbook example of the astonishing degree of ecological specialization and negative frequency-dependent selection. Nevertheless, the genomic basis and developmental mechanisms that determine this notable morphological and behavioural laterality remain entirely unclear. During my PhD, I will investigate the genetic and environmental (such as plasticity or individual feeding behaviour) basis underlying the bilateral asymmetry observed in this fish. This PhD project will result in relevant contributions in understanding the bases and the long-term maintenance of left-right asymmetry in animals.