Osmoregulatory Physiology of Pupfish (Cyprinodon spp.) in Freshwater

摘要: of a dissertation at the University Miami. Dissertation supervised by Professor Martin Grosell. No. pages in text. (148) Active uptake Na + gill fish is fundamental to their osmoregulation and thus survival freshwater environments. Studies date have demonstrated several different mechanisms which can accomplish this important physiological function. This provides comparative characterization coastal pupfish, Cyprinodon variegatus (Cvv), closely related Lake Eustis C. v. hubbsi (Cvh), endangered desert macularius (Cm). When acclimated slightly saline (7 mM ) all three use low affinity /H exchanger (NHE) for apical uptake. Cvv also uses :K :2Cl cotransporter under these conditions, first time has been functionally fish. 2 , strictly rely on NHE Only Cvh, naturally occurs eight dilute lakes central Florida, was able acclimate 0.1 conditions switches high In other studied that freshwater, operates metabolon with an Rh glycoprotein (ammonia transporter) H operation thermodynamically constrained environment. confirmed Cvh does not NHE-Rh metabolon, but instead acquires from carbonic anhydrase mediated hydration CO2 allow freshwater. exposed water. Finally, because only are suffering habitat loss water quality degradation through urban development, evaluated whether should be designated separate species Cvv, allowing greater environmental protection. While there no clear consensus definition species, within regulatory framework Endangered Species Act, heritable differences between partial preand post-zygotic isolation two subspecies, likely monophyletic origin support designation as evolutionarily significant unit, species.