Interhabitat differences in energy acquisition and expenditure in a lizard
Cnemidophorus hyperythrus, a small (approx. =4-g) teiid lizard, occurs along an elevational thorn scrub-thorn woodland-thorn forest habitat gradient in the cape region of Baja California. The authors compared body size, daily energy expenditure (DEE, measured with double labeled water), relative feeding rate (as reflected by H/sub 2/O influx rate), behavior, and abundance of this species at two sites along the gradient. At the inland thorn woodland site C. hyperythrus were more abundant (approx. =50 lizards/ha.). Mean body mass of woodland site lizards was 13% greater than that of scrub lizards. The DEE of the thorn woodland lizards, 330 site J x g/sup -1/ x d/sup -1/, and their H/sub 2/O influx, 99 mm/sup 3/ x g/sup -1/ x d/sup -1/, were also higher than the thorn scrub lizards', 219 J x g/sup -1/ x d/sup -1/ and 52 mm/sup 3/ x g/sup -1/ x d/sup -1/. Diets at the two sites were similar. There were no differences between sexes in diet, DEE, or H/sub 2/ influx. Daily maintenance energy costs were calculated based upon laboratory measures of O/sub 2/ consumption of resting lizards at a series of temperatures that represented the daily range of body temperatures experienced by lizards in the field. Activity costs (=DEE minus maintenance) were three times higher in the woodland lizards. Behavioral observations showed that woodland lizards were active most of the day (approx. =9 h/d) whereas scrub lizards were active primarily in the morning (approx. =3.5 h/d). Thus, the higher activity cost, DEE, and feeding rate of woodland lizards can be explained by their longer daily activity period. We suggest causal factors for the difference in daily activity period, and discuss implications of length of daily forging period for adult body size, population density, and various life history parameters of lizards.
- Research Organization:
- Univ. of California, Los Angeles
- DOE Contract Number:
- AC03-76SF00012
- OSTI ID:
- 6605923
- Journal Information:
- Ecology; (United States), Vol. 65:1
- Country of Publication:
- United States
- Language:
- English
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