Energy reserve utilization and energy budgets were compared in tailed and tailless adult female Coleonyx brevis. Carcass, fat body and caudal energy reserves were used for vitellogenesis; mass and energy content (cal/mg and/or cal/reserve) of each were significantly lower at oviposition than at the initiation of vitellogenesis. Total energy reserves accounted for 53% of the reproductive energy investment in tailed females compared to 29% in tailless females. Tailed females had over twice as many reserve calories for egg production than tailless females. Caudal energy reserves represented 60% of the total reserves of tailed females and were one-third greater than the total energy reserves of tailless females. To produce a clutch of eggs both tailed and tailless females supplemented energy reserves with net metabolizable energy that was available after metabolic costs were paid. Tailless females had a significantly greater rate of food ingestion and more net metabolizable energy available for reproduction than tailed females, yet allocated significantly fewer calories/day to reproduction than tailed females, primarily because of the loss of caudal reserves. Reproductive efforts of tailed and tailless females were equivalent. However, the loss of caudal reserves resulted in the production of eggs that were significantly lower in mass and energy content (cal/mg and cal/egg) than when caudal reserves were used. Results empirically support the hypothesis that reproduction has energetic priority over tail regeneration in short-lived, iteroparous species with a low probability of future reproductive success.

Handling of autotomized, thrashing and autotomized, exhausted tails of the lizard Scincella lateralis by mammals and snakes was tested to examine the function of postautotomy tail movement. Tail movement attracted a mammal's attack to the tail, permitting the lizard to escape and increased the time required for a snake to subdue a tail before swallowing it, increasing the lizard's escape time by 40 percent. Lactate concentrations of autotomized tails after movement were compared to those of intact tails after rest in S. lateralis, a species with a high rate of autotomized tail thrashing, and Anolis carolinensis, a species with a low rate of thrashing. Postautotomy movement increased tail lactate concentration in both species, but mean tail lactate concentration in S. lateralis was 60 percent higher than that in A. carolinensis, and a third higher than that reportedfor whole-body lactate content of the very mobile lizard Dipsosaurus dorsalis.

No abstract

Squamate reptiles rely heavily on two nasal chemical senses in directing most of their behavior: nasal olfaction and vomeronasal function. For most behaviors in most species, the vomeronasal system is the predominant sense. It has been suggested, however, that geckos are unusual in the extent to which they rely on nasal olfaction rather than vomeronasal function. In this study, we use defensive tail display as a behavioral bioassay to examine the context and relative use of olfaction vs. vomeronasal function in a eublepharid gecko, Coleonyx brevis. When presented with appropriate snake‐predator skin chemicals in the absence of relevant visual stimuli, C. brevis exhibits a defensive tail display that has been shown to be adaptive in defending against snake predators. We demonstrate that olfactory cues alone are sufficient to provoke the behavior and that geckos precede the display in many cases with “buccal pulsing,” a behavior that we suggest is an olfactory sampling mechanism analogous to mammalian sniffing. Our results support the gecko‐olfaction hypothesis and demonstrate that geckos use nasal olfaction to discriminate among potential predator species. We discuss alternative hypotheses for the origin of species‐specific, chemosensory predator identification in Coleonyx. © 1996 Wiley‐Liss, Inc.