Subdigital and subcaudal microornamentation in chamaeleonidae—A comparative study

Locomotion on horizontal and vertical substrates requires effective attachment systems. In three clades of arboreal and rupicolous Iguanidae, Gekkota and Scincidae adhesive systems consisting of microscopic hair‐like structures (setae) have been evolved independently. Also the substrate contacting sites on toes and tails of chameleons (Chamaeleonidae) are covered with setae. In the present comparative scanning electron microscopy study, we show that representatives from the chamaeleonid genera Calumma, Chamaeleo, Furcifer, and Trioceros feature highly developed setae that are species‐specific and similar on their feet and tail. These 10 μm long, unbranched setae rather resemble those in anoline and scincid lizards than the larger and branched setae of certain gecko species. In contrast to the thin triangular tips of other lizards, all examined species of the genera Furcifer and Calumma and one of the five examined species of the genus Trioceros have spatulate tips. All other examined species of genera Trioceros and Chamaeleo bear setae with narrowed, fibrous tips. Unlike the setae of other lizards, chamaeleonid setal tips do not show any orientation along the axis of the toes, but they are flexible to bend in any direction. With these differences, the chameleon's unique microstructures on the zygodactylous feet and prehensile tail rather increase friction for arboreal locomotion than being a shear‐induced adhesive system as setal pads of other lizards. J. Morphol., 2013. © 2013 Wiley Periodicals, Inc.     

Molecular phylogenetics of squamata: the position of snakes, amphisbaenians, and dibamids, and the root of the squamate tree

Squamate reptiles (snakes, lizards, and amphisbaenians) serve as model systems for evolutionary studies of a variety of morphological and behavioral traits, and phylogeny is crucial to many generalizations derived from such studies. Specifically, the traditional dichotomy between Iguania (anoles, iguanas, chameleons, etc.) and Scleroglossa (skinks, geckos, snakes, etc.) has been correlated with major evolutionary shifts within Squamata. We present a molecular phylogenetic study of 69 squamate species using approximately 4600 (2876 parsimony-informative) base pairs (bp) of DNA sequence data from the nuclear genes RAG-1(approximately 2750 bp) and c-mos(approximately 360 bp) and the mitochondrial ND2 region (approximately 1500 bp), sampling all major clades and most major subclades. Under our hypothesis, species previously placed in Iguania, Anguimorpha, and almost all recognized squamate families form strongly supported monophyletic groups. However, species previously placed in Scleroglossa, Varanoidea, and several other higher taxa do not form monophyletic groups. Iguania, the traditional sister group of Scleroglossa, is actually highly nested within Scleroglossa. This unconventional rooting does not seem to be due to long-branch attraction, base composition biases among taxa, or convergence caused by similar selective forces acting on nonsister taxa. Studies of functional tongue morphology and feeding mode have contrasted the similar states found in Sphenodon(the nearest outgroup to squamates) and Iguania with those of Scleroglossa, but our findings suggest that similar states in Sphenodonand Iguania result from homoplasy. Snakes, amphisbaenians, and dibamid lizards, limbless forms whose phylogenetic positions historically have been impossible to place with confidence, are not grouped together and appear to have evolved this condition independently. Amphisbaenians are the sister group of lacertids, and dibamid lizards diverged early in squamate evolutionary history. Snakes are grouped with iguanians, lacertiforms, and anguimorphs, but are not nested within anguimorphs.     

Sampling skinks and geckos in artificial cover objects in a dry mixed grassland-shrubland with mammalian predator control

Introduced mammalian predators threaten populations of endemic New Zealand lizards but their effects on lizard populations have not been quantified on the mainland. We trialled the use of artificial cover objects (ACOs) for sampling small terrestrial lizards (the skinks Oligosoma maccanni, O. nigriplantare polychroma and O. inconspicuum, and gecko Hoplodactylus maculatus) in three experimental mammal-management treatments: a mammal-proof fence, two sites in an intensive mammal-removal area, and an experimental control site with no mammal removal. These predator control regimes were established in 2005-2006 to protect endangered grand skinks (O. grande) and Otago skinks (O. otagense) at Macraes Flat, North Otago. We (1) counted skinks and geckos found under ACOs on a single day and compared these counts between treatments, and (2) estimated lizard population sizes (N) based on capture-mark-recapture (CMR) of lizards under ACOs in daily and weekly sampling sessions. Our results provide baseline data of the abundance of the small lizard species shortly after implementation of predator management. Single-day counts of skinks were significantly higher inside the mammal fence compared with the experimental control. No consistent differences were found between the other treatments. Significantly more skinks were counted in gully habitats than in ridge habitats. N?, counts of skinks from the first day of CMR, and the total number of individuals caught were correlated, but these relationships must be validated with independent data. Few geckos were caught unless ACOs were placed near rock outcrops. Only two skinks but 25% of geckos moved between adjacent ACOs (5-m spacing). The recapture rate of skinks was low; captures declined when ACOs were checked daily but not when they were checked weekly. Because of potential biases of these methods, we propose to compare counts in ACOs and N? based on CMR in ACOs with N? based on CMR in pitfall traps with 3-m spacing.     

Whole-organism studies of adhesion in pad-bearing lizards: creative evolutionary solutions to functional problems

Understanding the evolution of complex functional traits is a challenge for evolutionary physiology. Here we investigate the evolution of subdigital toepads in lizards, which have arisen independently at least three times, although with subtle anatomical differences. Some designs (anole, gecko) appear functionally equivalent, whereas other designs (skink) are inferior. The functional equivalence of geckos and anoles highlights the creative aspect of the evolutionary process in that these two groups have arrived at the same functional endpoint along very different trajectories. However, this functional equivalence does not result in equivalence for performance at whole-organism tasks (e.g., running uphill), as the evolution of behavior (e.g., toe-furling) has enabled geckos to be superior climbers than anoles. We also show that adaptive increases in the toepad size within a closely related lizard genus (Anolis) has resulted in concomitant evolution of enhanced clinging ability and increased perch heights. A third insight is that pad-bearing geckos are capable of carrying tremendous loads (up to 250% of body weight) up smooth surfaces, and that the toepad itself does not appear limiting. This comparative and whole-organism approach to lizard toepads underscores how organisms can evolve multiple solutions to evolutionary problems.     

Extant Lizard Tracks: Variation and Implications for Paleoichnology

In this study, I collected tracks and trackways from nine species of extant lizards representing all five major lizard clades. Previously, tracks from species of only two of these clades were described. Lizard tracks conventionally are regarded as having curved digit imprints that progressively increase in length from digit I to IV, with a smaller digit V directing antero-laterally. However, the zygodactylous feet of chameleons (Calumma parsonii and Furcifer pardalis), the posteriorly directed digit V in the pes of ground-dwelling geckos (Eublepharis macularius) and the rounded feet of blue-tongued skinks (Tiliqua scincoides) did not make “typical” lizard tracks, and demonstrate that even within a limited taxonomic sample there can be considerable variation in the morphologies of lizard tracks. Among the lizards examined, mode of locomotion and how the feet function have more influence on the morphology of tracks than does the phylogenetic affinities of the trackmaker. This preliminary neoichnological study increases the known variation in lizard tracks and aids in interpreting the fossil trackway record by providing comparative information that can be used to identify fossil tracks made by lizards.     

Mechanisms of adhesion in geckos

The extraordinary adhesive capabilities of geckos have challengedexplanation for millennia, since Aristotle first recorded hisobservations. We have discovered many of the secrets of geckoadhesion, yet the millions of dry, adhesive setae on the toesof geckos continue to generate puzzling new questions and valuableanswers. Each epidermally-derived, keratinous seta ends in hundredsof 200 nm spatular tips, permitting intimate contact with roughand smooth surfaces alike. Prior studies suggested that adhesiveforce in gecko setae was directly proportional to the waterdroplet contact angle (     

The herpetofauna of Timor-Leste: a first report

Fieldwork conducted throughout Timor-Leste in September 2004 and July 2009 resulted in a collection or recording of 263 herpetological specimens (100 amphibians, 163 reptiles), comprising at least seven species of frogs and toads, 20 species of lizards, seven species of snakes, two species of turtles, and one species of crocodile. Among the amphibians, the most frequently encountered species were toads (Duttaphrynus melanostictus), rice paddy frogs (genus Fejervarya), and rhacophorid treefrogs (Polypedates cf. leucomystax). All three variants of rice paddy frogs encountered represent undescribed species similar to Fejervarya verruculosa from neighboring Wetar Island. Records of Fejervarya cancrivora and Fejervarya limnocharis for Timor Island are apparently errors based on misidentification. We obtained voucher specimens for a total of 147 lizards and voucher photographs only for four specimens of Varanus timorensis. Aside from geckos frequently associated with human habitations (e.g., Gehyra mutilata, Gekko gecko, Hemidactylus frenatus, Hemidactylus platyurus), we discovered an as yet undescribed species of bent-toed gecko, genus Cyrtodactylus, in the Same valley. Our specimens of Hemidactylus platyurus are the first record of this species from Timor-Leste. Commonly encountered skinks included four-fingered skinks (genus Carlia), wedge skinks (genus Sphenomorphus), and night skinks (genus Eremiascincus). Notable among the 15 snakes collected was the frequency of pitvipers (Cryptelytrops insularis), which amounted to over 25% of all snakes. Our specimen of the wolfsnake Lycodon subcinctus is the first record of this species for Timor-Leste. Based on these findings, it appears that the biodiversity of amphibians and reptiles in this remote corner of Wallacea is much greater than previously thought, particularly with respect to scincid lizards. The detail we provide in the species accounts is designed to allow the use of this report as a preliminary field guide to the amphibians and reptiles of Timor-Leste. However, survey work is ongoing.     

Microornamentation of leaf chameleons (Chamaeleonidae: Brookesia,Rhampholeon, and Rieppeleon)—with comments on the evolution of microstructures in the chamaeleonidae

Chameleons (Chamaeleonidae) feature many adaptations to their arboreal lifestyle, including zygodactylous feet, a prehensile tail, and epidermal microstructures. In arboreal tree chameleons, the substrate‐contacting site of the feet and tail is covered by microscopic hair‐like structures (setae) of 6–20 µm length. Their friction enhancing function has been shown in recent studies. Leaf chameleons and one representative of the tree chameleons (Chamaeleo namaquensis) secondarily have become ground‐dwelling. Because leaf chameleons are paraphyletic, one could expect that in the three leaf chameleon genera Brookesia, Rhampholeon, and Rieppeleon and the tree chameleon Ch. namaquensis, epidermis has adapted independently to terrestrial locomotion. Using scanning electron microscopy, we investigated the substrate‐contacting surfaces of the feet (subdigital) of 17 leaf chameleon species and five tree chameleon species that have not yet been examined. Additionally, surfaces not involved in locomotion, the flanks (dorsolateral), and scale interstices, were examined. Although the subdigital microstructures in leaf chameleons are more diverse than in tree chameleons, we found some features across the genera. The subdigital microornamentation of Rhampholeon spinosus consists of long thin setae and spines, comparable to those of tree chameleons. All other Rhampholeon species have spines or short but broad setae. Rh. spectrum had tooth‐like structures instead of setae. Subdigital scales of Brookesia have either thorns or conical scale‐tops in the center and feature honeycomb microstructures. In Rieppeleon, subdigital scales have a thorn. Scale surfaces are covered by honeycombs and short hair‐like structures (spines). As subdigital scales with a thorn in the center and honeycomb microstructures were also found in the terrestrial tree chameleon Ch. namaquensis, one can assume that this geometry is a convergent adaptation to terrestrial locomotion. Despite the great number of genus‐specific traits, the convergent evolution of honey‐comb structures in Brookesia, Rieppeleon, and Ch. namaquensis and the high variability of spines and setae in Rhampholeon suggests a rapid adaptation of subdigital microornamentation in Chamaeleonidae. J. Morphol. 276:167–184, 2015. © 2014 Wiley Periodicals, Inc.     

Total lactate dehydrogenase activity of tail muscle is not cold-adapted in nocturnal lizards from cool-temperate habitats

The dependence of metabolic processes on temperature constrains the behavior, physiology and ecology of many ectothermic animals. The evolution of nocturnality in lizards, especially in temperate regions, requires adaptations for activity at low temperatures when optimal body temperatures are unlikely to be obtained. We examined whether nocturnal lizards have cold-adapted lactate dehydrogenase (LDH). LDH was chosen as a representative metabolic enzyme. We measured LDH activity of tail muscle in six lizard species (n = 123: three nocturnal, two diurnal and one crepuscular) between 5 and 35 °C and found no differences in LDH-specific activity or thermal sensitivity among the species. Similarly, the specific activity and thermal sensitivity of LDH were similar between skinks and geckos. Similar enzyme activities among nocturnal and diurnal lizards indicate that there is no selection of temperature specific LDH enzyme activity at any temperature. As many nocturnal lizards actively thermoregulate during the day, LDH may be adapted for a broad range of temperatures rather than adapted specifically for the low temperatures encountered when the animals are active. The total activity of LDH in tropical and temperate lizards is not cold-adapted. More data are required on biochemical adaptations and whole animal thermal preferences before trends can be established.     

Arachnids secrete a fluid over their adhesive pads

Background

Many arachnids possess adhesive pads on their feet that help them climb smooth surfaces and capture prey. Spider and gecko adhesives have converged on a branched, hairy structure, which theoretically allows them to adhere solely by dry (solid-solid) intermolecular interactions. Indeed, the consensus in the literature is that spiders and their smooth-padded relatives, the solifugids, adhere without the aid of a secretion.

Methodology and Principal Findings

We investigated the adhesive contact zone of living spiders, solifugids and mites using interference reflection microscopy, which allows the detection of thin liquid films. Like insects, all the arachnids we studied left behind hydrophobic fluid footprints on glass (mean refractive index: 1.48–1.50; contact angle: 3.7–11.2°). Fluid was not always secreted continuously, suggesting that pads can function in both wet and dry modes. We measured the attachment forces of single adhesive setae from tarantulas (Grammostola rosea) by attaching them to a bending beam with a known spring constant and filming the resulting deflection. Individual spider setae showed a lower static friction at rest (26%±2.8 SE of the peak friction) than single gecko setae (Thecadactylus rapicauda; 96%±1.7 SE). This may be explained by the fact that spider setae continued to release fluid after isolation from the animal, lubricating the contact zone.

Significance

This finding implies that tarsal secretions occur within all major groups of terrestrial arthropods with adhesive pads. The presence of liquid in an adhesive contact zone has important consequences for attachment performance, improving adhesion to rough surfaces and introducing rate-dependent effects. Our results leave geckos and anoles as the only known representatives of truly dry adhesive pads in nature. Engineers seeking biological inspiration for synthetic adhesives should consider whether model species with fluid secretions are appropriate to their design goals.     

The structure and development of the digital lamellae of lizards

The epidermal setae and the spinules of the digital lamellae of anoline and gekkonid lizards are shed periodically along with the rest of the outer layer of the skin. These structures are developed within the lamellae prior to ecdysis. The setae are larger and more complicated than the spinules and begin their development first. The setae of Anolis start as aggregations of tonofibrils beneath the plasma membrane of the presumptive Oberhautchen cells. These cells are arranged in rows parallel to the surface, several cell layers beneath the alpha layer of the skin. The developing setae protrude into the clear layer cells as finger-like projections, with the tonofibrils longitudinally oriented in the direction of growth. About 100 setae are formed by each Oberhautchen cells in Anolis. In late development, the clear layer cells lose their cellular contents and when shed along with all distal cells, retain a template of the new setae or spinules. The spinules and setae are formed before the fibrous and alpha layers of the new skin. The fibrous layer, which occurs only on the ventral (outer) layer of the lamellae, and the Oberhautchen with its setae and spinules, is considered the beta layer. The alpha layer, which occurs adjacent to the fibrous layer on the ventral surface and adjacent to the Oberhautchen on the dorsal (inner) surface, is morphologically identical to that of mammalian α keratin. The shed lizard skin consists of the alpha and beta layers as well as the degenerating cells of the outer epidermal generation, and the clear layer. The clear layer that is shed shows the template of the new setae and spinules developed in the new skin layer. The separation of the new from the old skin occurs along the intercellular space between the clear layer cells and the new Oberhautchen. The alpha layer of the skin is not fully keratinized at shedding. The setae of the digital lamellae of lizards represent unique epidermal structures — intracellular keratinized microstructures.     

Effects of substrate structure on speed and acceleration capacity in climbing geckos

We studied the effects of substrate structure on locomotor performance in a climbing gecko, Hemidactylus garnoti . We quantified three performance traits (acceleration capacity, instantaneous speed, and final speed) on three substrates: (i) smooth wood, (ii) a cloth surface, and (iii) a wire mesh. While acceleration capacity and instantaneous speed were highest on the wooden surface, final speed did not differ significantly among substrates. Using scanning electron microscopy (SEM) pictures, we estimated that 98% of the wooden surface is available for adhesion by the setae on the toepads, while this percentage is much lower for the mesh and cloth (41 and 37%, respectively). We suggest that when a gecko climbs up a gap-filled substrate, such as the wire mesh or cloth, adhesion will only happen between part of the toepad and the substrate, resulting in a diminished acceleration capacity. The higher acceleration capacity on the wooden substrate and the fact that the geckos tend to slip less often on this particular surface, may explain the difference in instantaneous speed. As for final speed, geckos might achieve similar final speeds on all three substrates by employing different locomotor strategies. Our results suggest that microhabitat use in nature might have a profound effect on locomotor performance and survival for climbing lizards such as geckos.  © 2005 The Linnean Society of London, Biological Journal of the Linnean Society , 2005, 85 , 385–393.     

Tempo and mode of performance evolution across multiple independent origins of adhesive toe pads in lizards

Understanding macroevolutionary dynamics of trait evolution is an important endeavor in evolutionary biology. Ecological opportunity can liberate a trait as it diversifies through trait space, while genetic and selective constraints can limit diversification. While many studies have examined the dynamics of morphological traits, diverse morphological traits may yield the same or similar performance and as performance is often more proximately the target of selection, examining only morphology may give an incomplete understanding of evolutionary dynamics. Here, we ask whether convergent evolution of pad‐bearing lizards has followed similar evolutionary dynamics, or whether independent origins are accompanied by unique constraints and selective pressures over macroevolutionary time. We hypothesized that geckos and anoles each have unique evolutionary tempos and modes. Using performance data from 59 species, we modified Brownian motion (BM) and Ornstein–Uhlenbeck (OU) models to account for repeated origins estimated using Bayesian ancestral state reconstructions. We discovered that adhesive performance in geckos evolved in a fashion consistent with Brownian motion with a trend, whereas anoles evolved in bounded performance space consistent with more constrained evolution (an Ornstein–Uhlenbeck model). Our results suggest that convergent phenotypes can have quite distinctive evolutionary patterns, likely as a result of idiosyncratic constraints or ecological opportunities.     

Experiments on dispersal: Short-term floatation of insular anoles,with a review of similar abilities in other terrestrial animals

Summary The floatation ability of a common Carribean insular lizard, Anolis sagrei, was tested under controlled conditions in a laboratory seawater wave tank. Short-term passive floatation abilities are extensive: all 39 animals survived 1 h, and 30% of those tested were still afloat by 24 h.The survival times for anoles in seawater are much greater than those reported in the literature for the 19 species of small mammals tested in freshwater; only mediumsized mammals have comparable abilities. Floatation, unaided by rafts, is a likely means of dispersal for anoles and perhaps other lizards between nearby islands such as in the Bahamas. The literature on observed overwater dispersal distances in non-volant animals is tabulated; data are rather scarce.     

A trophic cascade initiated by an invasive vertebrate alters the structure of native reptile communities

Invasive vertebrates are frequently reported to have catastrophic effects on the populations of species which they directly impact. It follows then, that if invaders exert strong suppressive effects on some species then other species will indirectly benefit due to ecological release from interactions with directly impacted species. However, evidence that invasive vertebrates trigger such trophic cascades and alter community structure in terrestrial ecosystems remains rare. Here, we ask how the cane toad, a vertebrate invader that is toxic to many of Australia's vertebrate predators, influences lizard assemblages in a semi‐arid rangeland. In our study area, the density of cane toads is influenced by the availability of water accessible to toads. We compared an index of the abundance of sand goannas, a large predatory lizard that is susceptible to poisoning by cane toads and the abundances of four lizard families preyed upon by goannas (skinks, pygopods, agamid lizards and geckos) in areas where cane toads were common or rare. Consistent with the idea that suppression of sand goannas by cane toads initiates a trophic cascade, goanna activity was lower and small lizards were more abundant where toads were common. The hypothesis that suppression of sand goannas by cane toads triggers a trophic cascade was further supported by our findings that small terrestrial lizards that are frequently preyed upon by goannas were more affected by toad abundance than arboreal geckos, which are rarely consumed by goannas. Furthermore, the abundance of at least one genus of terrestrial skinks benefitted from allogenic ecosystem engineering by goannas where toads were rare. Overall, our study provides evidence that the invasion of ecosystems by non‐native species can have important effects on the structure and integrity of native communities extending beyond their often most obvious and frequently documented direct ecological effects.     

Diet and conservation implications of an invasive chameleon, <Emphasis Type="Italic">Chamaeleo jacksonii</Emphasis> (Squamata: Chamaeleonidae) in Hawaii

We summarize information on current distribution of the invasive lizard Chamaeleo jacksonii and predict its potential distribution in the Hawaiian Islands. Potential distribution maps are based on climate models developed from known localities in its native range and its Hawaiian range. We also present results of analysis of stomach contents of a sample of 34 chameleons collected from native, predominantly dryland, forest on Maui. These data are the first summarizing prey range of this non-native species in an invaded native-forest setting. Potential distribution models predict that the species can occur throughout most of Hawaii from sea level to >2,100 m elevation. Important features of this data set are that approximately one-third of the diet of these lizards is native insects, and the lizards are consuming large numbers of arthropods each day. Prey sizes span virtually the entire gamut of native Hawaiian arthropod diversity, thereby placing a large number of native species at risk of predation. Our dietary results contrast with expectations for most iguanian lizards and support suggestions that chameleons comprise a third distinct foraging-mode category among saurians. The combination of expanding distribution, large potential range size, broad diet, high predation rates, and high densities of these chameleons imply that they may well become a serious threat to some of the Hawaiian fauna.     

Phylogeography and dispersal in the velvet gecko (Oedura lesueurii), and potential implications for conservation of an endangered snake (Hoplocephalus bungaroides)

ABSTRACT: BACKGROUND: To conserve critically endangered predators, we also need to conserve the prey species upon which they depend. Velvet geckos (Oedura lesueurii) are a primary prey for the endangered broad-headed snake (Hoplocephalus bungaroides), which is restricted to sandstone habitats in southeastern Australia. We sequenced the ND2 gene from 179 velvet geckos, to clarify the lizards' phylogeographic history and landscape genetics. We also analysed 260 records from a longterm (3-year) capture-mark-recapture program at three sites, to evaluate dispersal rates of geckos as a function of locality, sex and body size. RESULTS: The genetic analyses revealed three ancient lineages in the north, south and centre of the species' current range. Estimates of gene flow suggest low dispersal rates, constrained by the availability of contiguous rocky habitat. Mark-recapture records confirm that these lizards are highly sedentary, with most animals moving < 30 m from their original capture site even over multi-year periods. CONCLUSION: The low vagility of these lizards suggests that they will be slow to colonise vacant habitat patches; and hence, efforts to restore degraded habitats for broad-headed snakes may need to include translocation of lizards.     

Friction and adhesion in the tarsal and metatarsal scopulae of spiders

Friction and adhesion forces of the ventral surface of tarsi and metatarsi were measured in the bird spider Aphonopelma seemanni (Theraphosidae) and the hunting spider Cupiennius salei (Ctenidae). Adhesion measurements revealed no detectable attractive forces when the ventral surfaces of the leg segments were loaded and unloaded against the flat smooth glass surface. Strong friction anisotropy was observed: friction was considerably higher during sliding in the distal direction. Such anisotropy is explained by an anisotropic arrangement of microtrichia on setae: only the setal surface facing in the distal direction of the leg is covered by the microtrichia with spatula-like tips. When the leg is pushed, the spatula-shaped tips of microtrichia contact the substrate, whereas, when the leg is pulled over a surface, setae bend in the opposite direction and contact the substrate with their spatulae-lacking sides. In an additional series of experiments, it was shown that desiccation has an effect on the friction force. Presumably, drying of the legs results in reduction of the flexibility of the setae, microtrichia, spatulae, and underlying cuticle; this diminishes the ability to establish proper contact with the substrate and thus reduces the contact forces.     

An Analysis of Inter-Population Divergence in Visual Display Behavior of the Green Anole Lizard (Anolis carolinensis)

Variation in habitat structure can profoundly affect the evolution of visual displays in animals. We compared the field display behavior of two populations of the green anole lizard (Anolis carolinensis) in Southern Louisiana. These two populations occupy habitats varying markedly in structure (clumped vs. continuous), ecological setting (urban vs. natural) and the degree of male competition and predation. We filmed 56 large adult male lizards during the active spring reproductive period and detected substantial divergence in display behavior between populations. We found that (1) relative dewlap areas did not differ significantly between populations, (2) Tulane anoles spent about twice as much time displaying compared with Good Hope field anoles, although the average display duration did not differ significantly between populations, and (3) the two populations differed significantly in the relative frequency of display types: lizards from the Tulane population used a higher proportion of A and B display types, whereas Good Hope Field anoles used C displays more often. Finally, we detected differences in other aspects of display behavior (use of display modifiers, volley length distributions). We suggest that these display differences may result from differences in green anole male density (three times higher at Tulane), combined with habitat differences (clumped vs. continuous).