Seasonal effects on intestinal enzyme activity in the Australian agamid lizard, Lophognathus temporalis.

The tropical agamid lizard, Lophognathus temporalis, has higher metabolic and feeding rates during the wet season compared to the dry season. Also, lizards from urban sites tend to be larger than those from natural sites, partly due to site differences in food availability. Therefore, we hypothesized that activity of membrane-bound intestinal enzymes and masses of organs related to digestion would differ both seasonally and between urban and natural sites.

Physiological ecology of frillneck lizards in a seasonal tropical environment.

The frillneck lizard, Chlamydosaurus kingii, is a conspicuous component of the fauna of the wetdry tropics of northern Australia during the wet season, but it is rarely seen in the dry season. Previous studies have demonstrated that during the dry season the field metabolic rate (FMR) is only about one-quarter of the wet-season rate, and one factor involved in this seasonal drop is a change in the behavioural thermoregulation of the species such that lower body temperatures (T s) are selected during dry-season days. Here we examine other factors that could be responsible for the seasonal change in FMR: standard metabolic rates (SMR) and activity.