T. Mathies et Rm. Andrews, INFLUENCE OF PREGNANCY ON THE THERMAL BIOLOGY OF THE LIZARD, SCELOPORUS-JARROVI - WHY DO PREGNANT FEMALES EXHIBIT LOW BODY TEMPERATURES, Functional ecology, 11(4), 1997, pp. 498-507
1. Selected body temperatures of female lizards, Sceloporus jarrovi, w
ere measured on a photothermal gradient during late pregnancy and agai
n when postpartum, and pregnant females were subjected to one of three
fluctuating temperature regimes that simulated body temperatures of (
1) pregnant females, (2) postpartum females or (3) allowed normal ther
moregulation. 2. Overall, females selected lower body temperatures whe
n pregnant (mean = 32.0 degrees C) than when postpartum (mean = 33.5 d
egrees C). 3. Females regulated body temperature more precisely when p
regnant than when postpartum as judged by their smaller variances in b
ody temperature throughout the day. 4. When pregnant, females selected
a lower mean maximum body temperature (mean: pregnant = 32.8 degrees
C; postpartum = 34.5 degrees C) than when postpartum, but selected mea
n minimum body temperatures did not differ. 5. None of the experimenta
l temperature treatments was detrimental to pregnant females. Female b
ody length increased during pregnancy but the rate of increase did not
differ among treatments. Moreover, length-adjusted body mass of postp
artum females did not differ among treatments. 6. Pregnant females tha
t experienced postpartum body temperatures produced neonates that were
smaller in body mass and length than pregnant females that experience
d pregnant body temperatures and females that were allowed to thermore
gulate. 7. For neonates resulting from the postpartum body temperature
treatment, the disparity in the body length, but not mass, was still
observed at 9 days of age, although survival and growth of neonates wa
s high and did not differ among treatments. 8. The results demonstrate
that pregnant females could maintain higher postpartum body temperatu
res without compromising their physical condition, but select relative
ly low body temperatures, presumably to avoid decrements in offspring
fitness.