THE FUNCTIONAL INTEGRITY OF NORTHERN LEOPARD-FROG (RANA-PIPIENS) AND GREEN-FROG (RANA-CLAMITANS) POPULATIONS IN ORCHARD WETLANDS - 1 - GENETICS, PHYSIOLOGY, AND BIOCHEMISTRY OF BREEDING ADULTS AND YOUNG-OF-THE-YEAR

Northern leopard frogs (Rana pipiens) and green frogs (Rana clamitans) were evaluated at eight wetland sites, four of which were within appl e orchards, to determine if environmental changes associated with orch ard management affected measured biological parameters. Size, age, gen etic variation, condition indices, levels of circulating steroid hormo nes, 7-ethoxyresorufin-O-deethylase activity (EROD), and organochlorin e and organophosphorus residues in breeding males sampled at pond site s in orchards were compared to the same parameters measured in breedin g males from reference sites. Also, the size and physiological conditi on of young-of-the-year captured in orchard and reference ponds were c ompared. No evidence of a reduction in genetic variation was found in populations of either species at any sites, but unexpectedly high aver age heterozygosity values (0.191-0.28) in concert with low overall fix ation indices (0.012-0.059) in adults of both species did suggest that pond populations were interacting with neighboring populations in non orchard habitats, Few significant differences in levels of circulating steroid hormones or condition indices of breeding males were found am ong sites. Significant EROD induction in male green frogs collected fr om one orchard site during one sampling event was the only indication that a metabolic challenge due to presence of cytochrome P450-inducing toxicants may have existed, whereas elevated concentrations of organo chlorines (dichlorodiphenyltrichloroethane [DDT]- or endosulfan-relate d) in green frog tissues suggested that frogs at three orchard sites w ere taking up pesticides. Significant differences in size of equivalen t-age male and juvenile leopard frogs and green frogs occupying differ ent study sites suggested that suboptimal habitat characteristics exis ted at one or two of the four orchard sites. However, site-specific ha bitat deficiencies could not be related to orchard study sites in gene ral, and, thus, wetlands in apple orchards appeared to provide viable breeding habitat for both northern leopard frogs and green frogs.