Meeting Abstract

20.4  Saturday, Jan. 4 14:15  Genetic and plastic variation in metabolic rates of locally adapted extremophile fish PASSOW, CN*; GREENWAY, RS; JEYASINGH, P; TOBLER, M; Oklahoma State University, Stillwater Courtney.passow@okstate.edu

Extreme environments profoundly affect energy budgets of organisms, as the maintenance of homeostasis under stressful conditions requires costly morphological, physiological, or behavioural adaptations. Whether long-term exposure to extreme environmental conditions drives adaptive shifts in energy metabolism remains an open question. Here, we studied variation in routine metabolic rate in genetically distinct and locally adapted populations of extremophile fishes (Poecilia mexicana) living in toxic, hydrogen sulfidic-rich springs and caves. Routine metabolism was measured in field and laboratory trials to isolate genetic and plastic sources of variation. Specifically, we quantified routine metabolic rate in wild-caught individuals from four habitats (non-sulfidic surface, sulfidic surface, non-sulfidic cave, and sulfidic cave) and laboratory-raised individuals from the same populations exposed to experimental manipulations of resource availability. Results showed that both laboratory and field experiments indicated elevated routine metabolic rates in populations from cave compared to surface habitats, which may be linked to previously established behavioural differences. Fish from non-sulfidic and sulfidic habitats did not differ in routine metabolic rates in the field, but common garden experiments revealed that sulfidic populations exhibited higher routine metabolism when energy availability was abundant and reduced routine metabolism when resources were scarce. The results of this study indicate that adaptation to extreme environments directly impacts energy metabolism. Different abiotic stressors have unique effects on the evolution of energy metabolism in extremophile fish; cave environments are associated with genetically based changes in routine metabolic rates, while sulfidic environments favour metabolic rate plasticity.