                      Figure 2 - Geographic range of the Eastern Fence Lizard (Sceloporus undulatus). Diamonds indicate approximate locations of published field studies. The STAR is the Pine Barrens site in New Jersey.

Figure 4A - As an observer viewed the tape, s/he tracked the lizard’s movements by moving a commercially available plan scanner (Scale-Link TM ) exactly over the image of the lizard as it moved back and forth in the chamber (Figure 4). We wrote a LINUX driver for this device and a C program to log the scaler output into a computer file.

Figure 4A - Time lapse video image of lizards in their metabolic chambers. Observers used these images to track a lizard’s movements as it moved back and forth in the chamber.

Figure 4B - Observers tracked the lizard’s movements by moving a plan scanner (Scale-Link TM, over the video image of the lizard as it moved back and forth in the chamber. Bob Neveln wrote a LINUX driver for this device and a C program to log the scaler output - the full documentation to this software is available in Neveln, B Linux: Assembly Language Programming. Prentice Hall. (example 11.4, pages ). {software available from the author, {75% actual size}

Metabolic Rate digesting time Metabolic Rate ( oxygen consumption/ time fed Metabolic Rate fasting Specific Dynamic Effect defecated Figure 1 - The Specific Dynamic Effect (SDE) is the integrated difference between an animal’s fed and fasting metabolic rates.

A B C total distance (cm) metabolic rate (ml O 2 /h) Figure 7 – Representative data showing the relationship between the total distance of movements in the chamber and metabolic rate (for lizard #4, unfed runs, 35 o C, on 6/17/98). Each datum stems from a 24 minute O 2 consumption run and analysis of the corresponding segment of the video tape movement record. The actual movement traces for points marked A, B, and C appear in Figure 8.

metabolic rate (ml O 2 /h) 16:0020:000:0004:0008:0012:00 time of day feddefecated unfed fed Figure 10 – “Adjusted” metabolic rates for the fed and unfed runs versus time over the time from feeding to defecation for lizard #4 (6/17-19/98, 35 o C).

using adjusted metabolic rates: using unadjusted metabolic rates: Lizard ID Table 2 - Estimates of Specific Dynamic Effect (  SDE), the % of ingested food energy spent on digestion, and the % rise in metabolism due to digestion using the adjusted metabolic rates (after removing the effects of activity) and using the raw metabolic rate measurements. Lizard ID

adjusted unfed unadjusted unfed adjusted fed unadjusted fed Figure 11 - Average adjusted and unadjusted metabolic rates for four lizards in fed and unfed states at 30 0 C. There was a significant difference between the means of adjusted fed and unfed metabolic rates (t-test, t = 3.38, P<0.03), but no difference between the means of unadjusted fed and unfed metabolic rates of these four lizards.