The adaptive response of lineages to various environmental conditions relies on the ability of such systems to achieve and maintain functions. Myogenic organs are known for their extreme plasticity and functional diversity. In addition to morphological variation, new functions are probably related to changes in the neural pathways. To date, anatomical, physiological, and neural modifications underlying the establishment and evolution of new muscle functions are virtually unknown. Catfish from the genus Synodontis (Mochokidae) were recently shown to be ideal subjects to study macro-evolutionary processes. Depending on the species, they produce sounds, electric discharges (EODs), or both (though not simultaneously) using the same protractor muscle.
Accordingly, I have formulated two hypotheses that are not mutually exclusive and are the foundations of the present proposal.
1) Having mochokid species able to emit both EODs and sounds using the same myogenic tissue (i.e. protactor ‘muscle’) implies the development of two distinct neural pathways.
2) Electric communication (at least) in this taxon evolved as an exaptation of acoustic communication. Therefore, my research project aims to provide insights into the anatomical, physiological, and neural adaptations that underlie function changes in a vertebrate myogenic organ (work package 1), and to explore the evolutionary history of acoustic and electric communication in mochokids (work package 2). Work package 1 consists in a comparison of three species that differ in their functional phenotype (sounds, EODs, or both). Work package 2 investigates the evolutionary history of the protractor muscle with comparative phylogenetic methods. This study will improve our understanding of the evolution of myogenic organs and central nervous system