Ernest E. Williams

The Origin of Faunas. Evolution of Lizard Congeners in a Complex Island Fauna: A Trial Analysis

The history of faunas, whether studied by paleontologists and zoogeographers or by systematists, has customarily been described in terms of phylogeny or colonization—in terms, therefore, of the origin or arrival of species. However, a major element permitting the build-up of faunas has been the coadaptation of their species-the fact that they are ecologically fitted together. Study of this coadaptation among living species is, in fact, a major part of modern ecology. Yet ecologista have, on their part, avoided history; they have avoided any attempt to look closely, theoretically or empirically, at the historical sequence of events in the build-up of a complex coadapted fauna.

Convergent and Alternative Designs in the Digital Adhesive Pads of Scincid Lizards

Prasinohaema virens, an arboreal scincid lizard, differs from its closest relatives in that it exhibits subdigital adhesive setae resembling those of anoles in shape and those of geckos in some aspects of size. The other scincid species in this genus as well as those in a presumed ancestral genus exhibit pad scales with surface folds and ruffles but no setae; at least one of these species uses an adhesive grip similar to that of anoles and geckos. Thus, there appear to be two strikingly different epidermal specializations for adhesive grip within this small radiation.

Phylogenetic relationships of the lizard families : essays commemorating Charles L. Camp

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An Estimation of Redundancy and Information Content of Anole Dewlaps

Redundancy is a common feature of message systems and is known to occur in animal communications on a qualitative basis. The following is an attempt to estimate quantitatively the amount of information and redundancy in the dewlap displays of certain sympatric lizards. By redundancy we mean those elements in the display beyond the minimum necessary for a particular message. This analysis of eight species of Anolis known or expected to occur sympatrically at a mountain locality, La Palma, in Hispaniola, grew from observations made during a survey of the ecological relations among these small arboreal iguanid lizards (Rand and Williams 1969). As is usual with sympatric anoles, each species at La Palma has a distinctive dewlap. This dewlap is a large, usually brightly colored and variously patterned sheet of skin which is folded against the throat when at rest and extended by a flexible cartilage during display. The dewlap, which may occur in both sexes or, more frequently, in males only, is highly specialized for signal functions. Its use has been described in advertisement, in courtship, and in aggressive displays (Rand 1967; Ruibal 1967; Carpenter 1965; Kastle 1963; Greenberg and Noble 1944; Evans 1938). Though experimental evidence is lacking, it seems likely that the dewlap is a major display, perhaps the major display, involved in species recognition. Differences between species in dewlaps may serve as premating isolating mechanisms. We have assumed that anoles could distinguish any simple colors, patterns, or shapes which we ourselves could distinguish easily. This assumption is unproven at present, but color vTision has been demonstrated in iguanid lizards (Forbes et al. 1964), and the work on the reactions of Anolis carolinensis to aposematic insects (Sexton 1964) shows that anoles can make fairly sophisticated visual discriminations. We have also assumed that species recognition among anoles may be more complex than simple releasers. Table 1 compares the dewlaps of six of the seven species known from La Palma and two additional species that may occur there. One species from La Palma, A. aliniger which lacks a dewlap in both sexes, is omitted in the following discussion. (A. aliniger possesses a striking orange and black mark in the axilla which may be used in display in situations where other

Scanning electron microscopy of changes in epidermal structure occurring during the shedding cycle in squamate reptiles

Previous studies of squamate epidermal structure have focused on either histology and ultrastructure or oberhautchen surface texture as revealed by scanning electron microscopy (SEM). Using SEM data drawn from a variety of lizard taxa (primarily iguanids, but also agamids, chamaeleonids, and scincids), as well as amphisbaenians and colubrid snakes, we relate the surfaces encountered in gross dissection of squamate skin to histologically identifiable layers, and characterize their surface structure. Only the oberhautchen bears the repeating pattern of ornamentation noted by previous authors. Because the clear layer is a perfect template of the oberhautchen surface, it is the only layer with which the oberhautchen might be confused. However, the clear layer can be identified by its tendency to curl and crack during preparation. All other surfaces encountered were relatively featureless, except for impressions left by dermal “papillae” associated with mechanoreceptors. Using a method for examining preserved specimens to determine the stage in the shedding cycle, we assess two sources of variation in epidermal surface structure: stage in the shedding cycle and wear. Examination of immature renewal‐phase epidermis suggests that the oberhautchen does not mature synchronously across a single scale or across body regions. Comparing inner‐ and outer‐generation oberhautchen in sheddingphase epidermis, we conclude that changes in surface appearance caused by natural wear fall into two categories: discrete scratches and accumulation of debris. We see no evidence of overall “buffing” on a microscopic level, though surface structure may be obscured by scratches and gouges. Many squamate taxa show a gradient from low relief surface structure on elevated regions such as keels to high relief patterns at scale edges. This gradient is not due to wear; its significance is unknown.

Ontogenetic variation in the molariform teeth of lizards

ABSTRACT The presence of enlarged molariform teeth in some groups of lizards has been known since the early nineteenth century. Few papers, however, have documented ontogenetic variation in the development of such teeth. This paper discusses and evaluates both new and previously described examples of molariform teeth in fossil and Recent squamates of the families Iguanidae, Teiidae, Lacertidae, Scincidae, Xantusiidae, Anguidae, Varanidae, Mosasauridae, and Amphisbaenidae. New data on ontogenetic change in Iguanidae (Chamaeleolis, Diplolaemus), Teiidae (Ameiva), Scincidae (Tiliqua), and Anguidae (Diploglossus) are given. Most species with enlarged teeth as adults have unmodified teeth in hatchling or young individuals, but in a few species (Dracaena guianensis, Teiidae; Tiliqua scincoides, Scincidae; Amphisbaena ridleyi, Amphisbaenidae) the dental modification is already present in early ontogenetic stages. Lack of information on the diet of lizards in general and young animals in particular prevents formu...

Fission in the Evolution of a Lizard Karyotype

The lizard Anolis monticola has a diploid chromosome number of 48 (24 macrochromosomes and 24 micrcchromosomes). More primitive members of the genus, as determined by bone morphology, have 12 macrochromosomes and 24 microchromosomes. Since the higher chromosome number is the derived condition, this is a case of karyotypic change by centric fission.

Interactions Among Members of the Anolis distichus Complex in and near the Sierra de Baoruco, Dominican Republic

Examination of contact areas between sibling species of the Anolis distichus complex at several montane sites in the Sierra de Baoruco, Dominican Republic, and at those nearby lowland localities reported by T. P. Webster, indicates a multiplicity of interactions between species in this complex. Anolis distichus and A. brevirostris exhibit diverse interactions at the montane localities, including parapatry with dewlap similarity, syntopy with dewlap similarity, and sympatry with marked dewlap difference. No evidence of hybridization between the two species was found at any montane site. At the two lowland localities, where interspecific difference in dewlap coloration was either variable or minimal, hybridization between Anolis distichus and A. brevirostris was common, with hybrids representing 18 and 31% of the two samples. A difference in dewlap color- ation appears to be only one of several factors required for proper species recognition. Habitat and behavioral differences, as well as historical factors, also influence the present interactions between the two species.

Over 300 Years of Collecting in the Caribbean

This chapter discusses the collection of herpetofauna from the West Indies from over 300 years. It gives a comparison of the known herpetofauna in the West Indies as listed by Thomas Barbour and Albert Schwartz and Henderson. Thomas Barbour in his 1914 published work titled “A Contribution to the Zoogeography of the West Indies, With Special Reference to the Amphibians and Reptiles” had listed 158 species of which seven were Mabuya and 73 were Anoles . In nonanoline lizards, he reported 29 Sphaerodactylus , 15 Ameiva , 11 Leiocephalus , nine Celestus , six Cyclura , three Aristelliger and a Gymnodactylus . Schwartz and Henderson listed a total of 152 species of frogs, 125 of them Eleutherodactylus and 294 species of lizards and 128 of these are Anolis and a new endemic anoline genus, Chamaelinorops was recorded. There are 99 snakes recognized: 21 Typhlops , eight leptotyphlops , nine Epicrates and 13 Tropidophis . The chapter also mentions Hans Sloane (1660–1753), who is considered as the real founder of the British Museum; his collections provided the base for the museum.