Reduction of energetic demands through modification of body size and routine metabolic rates in extremophile fish

Courtney N. Passow, Ryan Greenway, Lenin Arias-Rodriguez, Punidan D. Jeyasingh, Michael Tobler

Research output: Contribution to journalArticlepeer-review

30 Scopus citations


Variation in energy availability or maintenance costs in extreme environments can exert selection for efficient energy use, and reductions in organismal energy demand can be achieved in two ways: reducing body mass or metabolic suppression. Whether long-term exposure to extreme environmental conditions drives adaptive shifts in body mass or metabolic rates remains an open question. We studied body size variation and variation in routine metabolic rates in locally adapted populations of extremophile fish (Poecilia mexicana) living in toxic, hydrogen sulfide–rich springs and caves. We quantified size distributions and routine metabolic rates in wild-caught individuals from four habitat types. Compared with ancestral populations in nonsulfidic surface habitats, extremophile populations were characterized by significant reductions in body size. Despite elevated metabolic rates in cave fish, the body size reduction precipitated in significantly reduced energy demands in all extremophile populations. Laboratory experiments on common garden–raised fish indicated that elevated routine metabolic rates in cave fish likely have a genetic basis. The results of this study indicate that adaptation to extreme environments directly impacts energy metabolism, with fish living in cave and sulfide spring environments expending less energy overall during routine metabolism.

Original languageEnglish (US)
Pages (from-to)371-383
Number of pages13
JournalPhysiological and Biochemical Zoology
Issue number4
StatePublished - Jun 27 2015

Bibliographical note

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  • Adaptation
  • Cave environments
  • Energy consumption
  • Extreme environments
  • Hydrogen sulfide springs
  • Poecilia mexicana
  • Resource availability


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