The effects of carotenoid and food intake on caudal fin regeneration in male guppies

The trade-offs involved in allocating carotenoid pigments and food to healing and regrowing damaged caudal fin tissue v. other functions were examined in guppies Poecilia reticulata, a species in which females prefer males that display larger amounts of carotenoids in their skin. The guppies were derived from four natural populations in Trinidad that differed in resource availability but not predation intensity. Carotenoids, food and site of origin did not affect either absolute or relative fin regrowth, which suggested that fin regeneration in guppies was not constrained by carotenoid availability. It is possible that carotenoid intake influences fin regeneration in the presence of natural stressors such as predators. There was a significant negative interaction between food level in the laboratory and resource availability in the field: males from low-resource-availability sites regrew more fin tissue when raised on the high food level, and males from high-resource-availability sites regrew more fin tissue when raised on the low food level. The direction of this interaction runs counter to theoretical expectations.