On April 24 there will be a talk by Øyvind Øverli on "Melanin-based skin spots reflect stress coping style in salmonid fish: Practical and evolutionary implications"
Time: Thursday 24th April, 13.00
Place: Meeting room, 2nd floor (283), IHA
Salmonid fish are known for extensive genetic and life-history variation, which arise through homing after oceanic migration, with sub-populations localized and adapted to different sites and environments within water systems. Within populations, genetic and epigenetic factors interact to shape individual neuroendocrine and behavioral profiles, conferring variable vulnerability to stress and disease. It is however debated how alternative behavioral syndromes and stress coping styles evolve and are maintained by natural selection. I will present evidence that individual variation in stress responsiveness is reflected in the visual appearance of two species of teleost fish, rainbow trout (Oncorhynchus mykiss) and Atlantic salmon (Salmo salar). Salmon and trout skin vary from immaculate to densely spotted, with black spots formed by eumelanin-containing chromatophores. In both species, more spotted individuals show a reduced cortisol response to stress along with increased pro-active behavior. Corticosteroid suppression of immune function provides a novel link between melanin based coloration and disease resistance. Furthermore, this explicit visual manifestation of alternative coping styles can elucidate the evolution of animal personalities, conveniently revealing frequencies of occurrence in different environments and response to selective pressures.
