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Several observational and experimental studies have shown that perch diameter has an impact on the development of hind-limb length (HL) in Anolis species. This “phenotypic plasticity” in relative hind-limb growth (RHG) has implications for short-term and long-term adaptation to different structural habitats. Our study is the first to replicate research in which hatchling/juvenile Anolis sagrei were reared on narrow-diameter or broad-diameter dowels in a laboratory setting. Although subjects reared on different dowel diameters did not differ significantly in RHG at 5 weeks into the experiment, results at 15 weeks revealed a significant effect of treatment but not of sex: subjects in the broad (N = 69) treatment group exhibited significantly greater RHG than did subjects in the narrow (N = 61) treatment group. We extended this research with a novel follow-up study: we placed our lab-reared subjects into outdoor enclosures where they had a choice of narrow- or broad-diameter dowels on which to perch...

The coloration of animal integuments evolves in response to numerous and often competing selective pressures. Although male-male competition and female mate choice characteristically select for increased color conspicuousness, visibility to predators and to prey often select for decreased conspicuous- ness. We examined three populations of Common Collared Lizards, Crotaphytus collaris, in Oklahoma (Arcadia Lake, Glass Mountains, Wichita Mountains) that have been argued to differ in the intensity of natural and sexual selection acting on their color patterns. Our study had two main objectives. First, reflectance spectra were obtained from the lizards to replicate and extend previous work on differences in sexual dichromatism among these populations. Second, spectra were gathered on components of visual backgrounds at our study sites to explore the possibility that each population may be relatively cryptic within its own habitat. Results showed that most body regions differed significantly in sexual dichromatism among populations, but in contrast to prior work, no one population was more sexually dichromatic than another for all body regions examined. Males exhibited less overlap in coloration with their visual backgrounds than did females (i.e., males were more conspicuous), and females overlapped more in coloration with rocks than with other visual backgrounds. The population estimated previously to experience the strongest predation pressure (Arcadia Lake) was shown in the present study to be the least conspicuous. Some support also was found for the proposition that even the most ''colorful'' population (Wichita Mountains) may not always be conspicuous when viewed against its typical visual background.

A hallmark trait of the lizard genus Anolis is the presence of remarkable interspecific variation in dewlap color patterns. Yet, considerable intraspecific variation also occurs in many Anolis species. In Florida different populations of the Green Anole (Anolis carolinensis) exhibit red, pink, magenta, and even greenish-gray dewlaps. To date, comparisons of color variation in this species have used subjective techniques based on human color perception. Instead, we used an objective method—reflectance spectrometry—to quantify A. carolinensis dewlap and body color variation along a transect from northeastern to southwestern Florida. Reflectance readings of local vegetation allowed us to calculate contrast of the lizards with their visual backgrounds. By incorporating local ambient light and A. carolinensis spectral sensitivity into additional calculations, we were able to estimate lizard-background contrast from the perspective of the lizards. Results revealed dewlap and dorsum spectra to differ si...

Many members of the Iguania group of lizards engage in stereotyped and species-specific ''pushup'' or ''headbob'' displays. Temporal attributes of displays have been quantified for a number of species in the genus Anolis, but few of these studies have examined effects on display structure of signaler sex, display context, and population. With this goal in mind we conducted a comparative study of three Anolis species permanently established (''naturalized'') on the island of Bermuda: Anolis grahami from Ja- maica, Anolis extremus from Barbados, and Anolis leachi from Antigua and Barbuda. These anoles are dis- tantly related to each other and to Anolis carolinensis—the only Anolis species for which all of the above influences on display structure have been examined in detail. Adults were field-captured and transported to the laboratory where paired interactions were videotaped and headbob displays analyzed. Results re- vealed one or more variables to exhibit sexual dimorphism in each species, and display context had little influence on signal structure. We then compared results from our founder populations on Bermuda with those published for two of our study species' source populations. No significant differences in headbob display units were found between A. grahami on Bermuda and on Jamaica. In contrast, male A. extremus on Bermuda produced fewer units per display than did males from Barbados, although the nature of the published data prevented statistical comparison.

Headbob displays from 22 adult male Anolis conspersus of three "color morphs" (green, brown, and blue) were videotaped in the laboratory. Frame-by-frame coordinates of the vertical head mo- tions were used to generate display-action-pattern (DAP) graphs. Field observations had revealed that only one type of headbob display ("Type A") was performed when males displayed to nonspecific audiences while moving around their territories ("male-alone context"). During staged male encounters in the lab ("male-male context"), Type A displays and a second type of display ("Type B") were produced. The two types of displays were partitioned into units that were compared among the color morphs. We then trans- formed the display units with principle components analysis and used one-way ANOVAs to test statistically for differences among the color morphs at the "unit" level. Finally, we used discriminant function analysis to test for color morph differences at the "display" level. Graphical visualization and statistical analyses showed that, like body coloration, the green and the brown morph are more distinctive from each other than either is from the blue morph, although the differences in display units among the color forms are subtle. Given that A. conspersus is a member of the seven-species Anolis radiation on Jamaica, we compare the structure of one of its displays (Type A) with that of its closest relative, Anolis grahami. Last, we speculate on the possible origin of the unusual display structure observed in the A. conspersus Type B display.