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When locomotor activity is brief, physiological steady state conditions are not attained. It is therefore difficult to model the energetic costs of intermittent activity using standard methods. This difficulty is addressed by considering as reflective of the metabolic costs of activity not only the oxygen consumed during the activity itself, but also the excess post-exercise oxygen consumption (EPOC) and any excess metabolites persisting at the end of EPOC. This paper briefly reviews the metabolic events associated with EPOC, and then examines how this approach can be applied to address questions of how behavioral variables associated with locomotion (activity duration, intensity, frequency) can influence the energetic costs to the animal per unit distance. Using data for lizards, mice, and others, EPOC can be shown to be the major component of energetic costs when durations are short, regardless of exercise intensity. Brief activity is much more expensive by this measure than is steady state locomotion, regardless of phylogeny or body mass. Three studies of intermittent locomotion provide evidence that brief behaviors can be undertaken at lower metabolic costs than predicted from single bouts of activity when repeated in a frequent, repeated pattern. Metabolic savings appear greatest when the pause period between behaviors is short relative to EPOC duration, the time for organismal metabolic rate to return to pre-exercise levels, although longer pause periods may increase endurance.

One of the primary goals of functional morphology is the quantification of behavior in relation to morphological variation. The two major clades of lizards, scleroglossa and autarchoglossa, show substantial variation in cranial morphology, hyoid apparatus, tongue musculature, and the functional morphology of lizard feeding. However, our understanding of the behavioral variation present in lizard feeding is limited and no work to date has adequately described the range of behaviors lizards use to ingest and process prey. The goal of this study is to describe and quantify the behavioral repertoire lizards use while feeding. Feeding bouts were videotaped in a phylogenetically diverse sample of lizard taxa and behavioral categories were delineated. Five distinct types of prey processing behavior were described (transport, inertial transport, side-to side movement, puncture crushing, and 'palatal crushing'). All taxa engaged in prey transport behaviors. However, the frequencies of the five behaviors differed between scleroglossan and autarchoglossan lizards. Per feeding bout, autarchoglossans consistently engaged in more puncture crushing, transport, and total number of feeding behaviors. Also, autarchoglossans showed an increased tendency to intersperse behaviors during a feeding bout. Interestingly, all lizards exhibited a previously undescribed behavior that we are calling 'palatal crushing'. Here, the prey item was held and compressed between the dorsal surface of the tongue and the hard palate. Several hypotheses will be put forth to explain this behavior as well as the behavioral variation observed between scleroglossan and autarchoglossan lizards.

This study addressed the role of testosterone (T) in the development of sexually dimorphic behavior in the green anole lizard, Anolis carolinensis. We described the developmental pattern of endogenous T concentrations, and determined the behavioral effects of experimentally elevated T, in both juvenile males and females. T concentrations in the plasma of hatchlings from laboratory-incubated eggs and field-sampled juveniles of all sizes, as well as in the yolks of freshly laid eggs in the laboratory, were compared to plasma T concentrations in adult males and females. There were no sex-specific differences in plasma T in hatchlings and small juveniles ([is less than] 26 mm snout-vent length, SVL; [is less than] 14 d old). However, plasma T sharply increased in juvenile males, but not females, after approximately 14 d post-hatching, and it became significantly higher after approximately 38 d post-hatching ([is greater than] 30 mm SVL). Plasma T for juvenile males was within the range detected in breeding adult females, but it was 20- to 45-fold lower than that of adult males, breeding or post-breeding. Furthermore, eggs that gave rise to males contained nearly twice as much yolk T on the day of oviposition as those that gave rise to females (0.9 vs. 0.5 pg/mg, respectively). Behavior trials revealed that, in comparison to juveniles given empty implants, juvenile males and females given T-implants had increased rates of nearly every behavior monitored, approaching those found in breeding adult males. These results demonstrate that in spite of sex differences in endogenous T exposure during ontogeny, juveniles of both sexes exhibit an equivalent behavioral response to elevated T.

Real or perceived changes in the environment of a lizard can evoke adaptive behavioral responses that are coordinated by the neural and endocrine mechanisms of the stress response. Acute responses, involving catecholamines released in varying proportion at different sites along their sympathetic pathways may interact with and be complemented by chronic responses involving the hypothalamic-adrenocortical system. The central and systemic consequences of these actions include apparent changes in affect and motivation. These changes result in altered responses to environmental stimuli including the social stimuli that male and female conspecifics may provide. This review will collate and summarize the results of a program of research into the neural and endocrine causes and consequences of specific behavioral patterns seen in the small diurnal lizard, Anolis carolinensis. I will then attempt a synthesis that will hopefully illuminate the manner in which autonomic reflexes come under the influence of environmental stimuli and attain significance as social signals.

We have shown previously that relatively long-term aggressive interaction with conspecifics increased aggression in anoles. In this study, we investigated short-term priming effects of different stimuli on aggressive behaviors. Male Anolis carnolinensis were randomly assigned into one of the following priming conditions: an aggressive encounter with a conspecific, a threatening heterospecific lizard, physical stress and exertion, or control. After a ten-minute priming session, animals were tested with a live conspecific. Dewlap (D), push-up (P) and lateral compression (L) displays were measured. Anoles primed with the heterospecific encounter showed increased aggressive behavior (D: p=0.047; P: p=0.03; L: p=0.034 in one-tailed Wilcoxon Matched-Pairs Signed-Ranks Test). Anoles primed with a conspecific aggressive encounter showed an intermediate increase in aggressive behavior, whereas controls and animals receiving physical exertion showed no increase. Thus, while situations other than conspecific aggressive interactions can prime later aggressive responses, stress and physical exertion alone are not sufficient.

During ontogeny in Anolis carolinensis, males eat more, grow faster and display more than females. Also, male dewlap area increases faster than body size but female dewlap area increases linearly. The expression o these sexual dimorphisms is expected based on the intrasexual selection experienced by polygynous males. However, the relationship of sexual dimorphism to androgen levels during ontogeny has not been explored. We collected blood from 35 males and 35 females across all juvenile size classes and on the day of hatching. We will analyze these samples for testosterone and dihydrotestosterone levels by a radioimmunoassay that we have validated for use with lizard plasma. We expect that males of all size classes will have higher androgen levels than size-matched females. We do not expect to find androgen level peaks in hatchlings of either sex, which would suggest that no discrete critical period exists for the organizing actions of androgens and that, for some species, critical periods are greatly prolonged or nonexistent.