RESUMO
Thermal biology, and therefore energy acquisition and survival, of ectotherms can be affected by diel and seasonal patterns of environmental temperatures. Galápagos Lava Lizards live in seasonal environments that are characterized by a warm and wet period when reproductive activity is maximal, and cooler and drier period. With the use of radiotelemetric techniques to record lizard surface temperatures (Ts), we studied the thermal ecology of the San Cristóbal Lava Lizard (Microlophus bivittatus) during both the warm and cool seasons over two years. During the diel activity period and when operative temperatures exceeded Tset-min, at least on rock faces without canopy, 52% or less of the Ts observations fell within the laboratory-determined Tset range (36-40 °C). Therefore, lizards may have avoided very warm midday temperatures in shaded microhabitats and the lag times in changes in Ts values occurred as operative temperatures rose rapidly during late morning warming phase. Lizards effectively thermoregulated during a year with moderate warm season temperatures and during a cool season that was unseasonably warm. In contrast, lizards less effectively thermoregulated during the warmest and coolest years of the study. We did not detect intersexual differences in thermoregulation although males may thermoregulate less effectively than do females during the cool season although we were unable to detect significant differences using our nonparametric statistical techniques.
Assuntos
Regulação da Temperatura Corporal , Lagartos/fisiologia , Animais , Ecossistema , Equador , Feminino , Masculino , Estações do Ano , TemperaturaRESUMO
Experimental L(III) X-ray absorption near edge structure (XANES) spectra of the distorted octahedral neptunium oxo ions NpO(2)(OH)(4)(2-), NpO(4)(OH)(2)(3-), and NpO(6)(6-) are interpreted using relativistic full multiple scattering calculations of the X-ray absorption process. In this series of compounds, the neptunium cation exhibits two different oxidation states, VI and VII, with coordination spheres from di- to tetra oxo for the first two compounds. The comparison between calculated XANES spectra using the feff code and experimental ones shows that the main features in the spectra are determined by the local coordination around the actinide metal center. Furthermore, the projected density of electronic states (DOS) calculated from the XANES simulations using the feff code are compared to calculations using ADF code. They are both discussed in terms of molecular orbitals and qualitative evolution of bonding within this series of compounds.