Investigation of Individualistic Behavior in Astyanax mexicanus Reveals Evolutionary Divergent Patterns Among Surface and Cave Conspecifics

A conserved and important form of variability within and across species is behavioral individuality or the inter-individual variation in behavioral responses to similar stimuli. Although there is extensive research on the neurobiological basis of individuality, little is known about how individualistic behaviors are imposed on the brain and the mechanisms by which they change through evolution. A considerable impediment to addressing this question has been the lack of a suitable model organism with naturally occurring differences in behavior and physiology which can be manipulated experientially. Astyanax mexicanus is an emerging vertebrate model in evolutionary biology comprising two same-species morphological types. This system shares neuronal and molecular homology with zebrafish in which turning bias, an individualistic behavior, has been established. Accordingly, A. mexicanus can be used to determine how individuality is imposed on the brain and how the evolution of distinct brain loci alters individuality at the behavioral and neurological levels.