Leopard frog

Abstract: Mechanistic models of the H2O and energy dynamic interrelationships between a terrestrial amphibian and its environments were developed and applied in a study of the temperature and water relations of the northern leopard frog Rana pipiens Schreber. The models illustrate the relative importance of air temperature, relative humidity, wind speed, absorbed solar and thermal radiation, substrate temperature, and soil H2O potential on the core temperatures, hydration levels, and rates of hydration level change during desiccation and rehydration for leopard frogs of different size. Leopard frogs' core temperatures are influenced most by ambient air and substrate temperatures, whereas absorbed radiation has a subordinant effect. Evaporative H2O loss rates are strongly influenced by absorbed radiation and virtually not influenced at all by substrate temperature (relative humidity, air temperature, and wind speed were also shown to be strongly influential on evaporative H2O loss). Water uptake from wet soils (ψsoil > —150 mb) is determined primarily by the properties of the frog, whereas H2O uptake from relatively drier soils (ψsoil < —300 mb) is determined by the conductive properties of the soil. Results of computer simulations suggest that leopard frogs in southern Wisconsin environments should not be found at great distances from standing H2O or soils with H2O potentials < —150 mb. Data taken from the literature and viewed in context of the theory of H2O exchange between an amphibian and soil, suggests that leopard frogs may rarely venture from saturated soils (ψ soil = 0). Results of simulations also imply that leopard frogs in most natural environmental circumstances will not generally have core temperatures greatly different from ambient air temperatures; thus, implying that any behavioral thermoregulatory ability would likely be crude. The modeling approach provides an extremely practical technique to study mechanistic interactions of the many environmental variables involved in the temperature and water relations of terrestrial amphibians.

Abstract: Vehicular traffic can be a major source of mortality for some species. Highly uagile organisms may be at a disadvantage in landscapes with roads because they are more likely to encounter roads and incur traffic mortality. To test this prediction, we assessed the population abundance of two anuran species of differing vagility, the leopard frog (Rana pipiens more vaglie) and the green frog (Rana clamitans, less vagile), at30 breeding ponds. Traffic density, an index of the amount of potential traffic mortality, was measured in concentric circles radiating from the ponds out to 5 km. We conducted multiple linear regressions relating population abundance to traffic density, pond variables, and landscape habitat variables and found that leopard frog population density was negatively affected by traffic density within a radius of 1.5km. There was no evidence that the presence of vehicular traffic affected green frog populations, these results suggest that traffic mortality can cause population declines and that more vagile species may be more vulnerable to road mortality than less vagile species.

Abstract: Increasing nitrate levels in surface and ground waters are of global concern. Effects of nitrates on human health are well documented, but effects on amphibians have received little attention. I exposed Bufo americanus (American toad), Pseudacris triseriata (chorus frog), Rana pipiens (leopard frog), and Rana clamitans (green frog) tadpoles to ammonium nitrate fertilizer in water. In acute tests, mortality varied among species (96-h LC50; 13.6-39.3 mg/L NO3-N) and significant weight loss occurred. In chronic tests (100 d; 0, 2.5, 5, 10 mg/L NO3-N) chorus frog and leopard frog tadpoles had significantly lower survivorship in the 10-mg/L treatments, but green frog survivorship was not affected. Number of chorus frogs metamorphosing was significantly lower in the 10-mg/L treatment, but development time was not affected. In acute exposures, reduced activity, weight loss, and physical abnormalities were observed. Toxic effects of ammonium nitrate occurred in all four species at concentrations that are commonly exceeded in agricultural areas globally. Nitrate fertilizers may play a role in the apparent global amphibian decline.

Abstract: THE male specific (H-Y) antigen of mice was discovered with the observation that within certain inbred strains, females reject male skin grafts, whereas skin grafts exchanged between all other sex combinations are accepted1 (reviewed in ref. 2). It is now established that females sensitised with male skin grafts (or immunised with male spleen cells) produce antibody which is cytotoxic for sperm3 and dissociated male epidermal cells4. Using the sperm cytotoxicity test and the mixed haemadsorption-hybrid antibody (MHA˙HA) test, we demonstrated earlier5 that the H-Y antigen of mice is cross reactive or identical with antigen found in male rats, guinea pigs, rabbits and humans. Since then we have extended our survey to classes other than mammals, and we give evidence here for the occurrence of murine H-Y (or a cross reactive) antigen in the white leghorn chicken (Gallus domesticus) and in two amphibian species, the leopard frog (Rana pipiens) and the South African clawed frog (Xenopus laevis).