Timing of locomotor impairment and shift in thermal preferences during gravidity in a viviparous lizard

Abstract

Summary Locomotor impairment and shift in thermal preferences during gestation have been documented in some lizards, but few studies have investigated their timing. Here, endurance capacity, sprint speed and selected body temperature of gravid females of the viviparous lizard Lacerta vivipara (Jacquin) were measured weekly before and after parturition. Significant temporal variation of endurance and sprint speed was detected. A marked decrease in locomotor abilities occurred 2 weeks before parturition ( c. 35% for endurance and 25% for sprint speed). A rapid recovery was observed a few days after parturition for endurance, while sprint speed recovered more slowly. A physical impairment due to body mass was detected for endurance capacity, but not for sprint speed. The recovery of locomotor abilities after parturition was independent of the intensity of reproductive investment. Mass‐independent variation in locomotor performances might be explained by physiological consequences of reproduction independent of the physical burden. Females basking under laboratory conditions selected low body temperatures during the final month of gestation (29·8 °C ± 0·12 SE) and a drastic increase occurred in the few days following parturition (33·4 °C ± 0·13 SE). These results call for a more detailed investigation of the mechanisms underlying trade‐offs between reproduction, locomotion and thermoregulation in lizards.