Analysis of the locomotor activity of a nocturnal desert lizard (Reptilia: Gekkonidae: Teratoscincus scincus) under varying moonlight

1. This project seeks to identify determinants of the variation observed in the foraging behavior of predatory animals, especially in moonlight, using a lizard as a model. 2. Moonlight generally enhances the foraging efficiency of nocturnal visual predators and often depresses the locomotor activity of prey animals. Previous evidence has indicated for three different nocturnal species of smallish gecko lizards that they respond to moonlight by increasing their activity. 3. In this study some aspects of the foraging activity of the somewhat larger nocturnal psammophilous Teratoscincus scincus, observed near Repetek and Ashgabat, Turkmenistan, were significantly depressed by moonlight, while several confounding factors (sex, maturity, size, sand temperature, hour, prior handling and observer effect) were taken into account. 4. This behavioral difference may relate to the eye size of the various species. 5. Additionally, a novel method of analyzing foraging behavior shows that in this species the duration of moves increases the duration of subsequent stationary pauses. Measurement of locomotor speed, yielding an average speed of 220% of the maximum aerobic speed, indicates a need for these pauses. Secondarily, pause duration decreases the duration of subsequent moves, precluding escalation of move duration. 6. The results of this and related projects advocate the taking into account of physiological and environmental factors that may affect an animal's foraging behavior.     

Ultrastructural differentiation of spermiogenesis in Scincus scincus (Scincidae,Reptilia)

BackgroundKnowledge of spermiogenesis in reptiles, especially in lizards, is very limited. Lizards found in Arabian deserts have not been considered for detailed studies due to many reasons and the paucity of these animals. Therefore, we designed a study on the differentiation and morphogenesis of spermiogenesis, at an ultrastructural level, in a rare lizard species, Scincus scincus.ResultsThe spermiogenesis process includes the development of an acrosomal vesicle, aggregation of acrosomal granules, formation of subacrosomal nuclear space, and nuclear elongation. A role for manchette microtubules was described in nuclear shaping and organelle movement. During head differentiation, the fine granular chromatin of the early spermatid is gradually replaced by highly condensed contents in a process called chromatin condensation. Furthermore, ultrastructural features of sperm tail differentiation in S. scincus were described in detail. The commencement was with caudal migration toward centrioles, insertion of the proximal centriole in the nuclear fossa, and extension of the distal centrioles to form the microtubular axoneme. Subsequently, tail differentiation consists of the enlargement of neck portion, middle piece, the main and end pieces.ConclusionsThis study aids in the understanding of different aspects of spermiogenesis in the lizard family and unfurls evolutionary links within and outside reptiles.     

The origin of parachuting locomotion in gekkonid lizards (Reptilia: Gekkonidae)

Several recent studies have focused on the ability of the gekkonid Ptychozoon lionatum to parachute, utilizing its enlarged lateral body folds. Little attention has been paid, however, to the evolution of such behavious and here several aspects pertaining to the origin of parachuting are integrated. Behavioural shifts and morphological modifications are considered together and evaluated in the light of ecological information. It is apparent that certain behavioural shifts were the precursors of subsequent morphological changes. The structural design of the body folds is also considered in relation to parachuting behaviour and both the gross morphology and histology are shown to be significantly modified to permit effective parachuting. The absene of musculature in the lateral body flaps of geckos is confirmed and a model for the integration of the various factors involved in effective parachuting is presented. Here the importance of the structure-function and habitat-behaviour sets are emphasized together with their new interrelationships when a protoadaptation becomes functional.     

Burrow Characteristics and Microhabitat Use of the Turpan Wonder Gecko Teratoscincus roborowskii(Squamata,Gekkonidae)

Burrow structural charactersitcs and microhabitat use of the Turpan wonder gecko Teratoscincus roborowskii(Gekkonidae) were studied between April and September of 2013 in the Turpan Eremophytes Botanic Garden,in the Turpan Depression of Western China.Burrow depth,entrance orientation,entrance height and width were observed.We assessed microhabitat selection and noted differences in microhabitat use among males,females,and juveniles.The magnitude of selection was measured using Jacobs' index of selectivity.Entrance height and width of the burrows of adults were significantly larger than those of juveniles,but the difference in burrow depth was not significant.The directional orientation of the burrow entrance showed a preference for the north-northeast and south-southeast,which were likely influenced by local prevailing winds and sunlight.Both the adult and juvenile geckos prefer to construct their burrows in sandy soil within a layer of loose soil whose thickness is greater than 30 cm.A majority of the burrows were located within 20 m of the nearest plant.Nearly half(48%) of the entrances of juveniles were located within 5 m of the nearest vegetation,significantly different from those of the adults.Results showed that the Turpan wonder gecko did not utilize microhabitats according to their availability,but rather that it preferred microhabitats which contained dead wood or the caper bush.Our results suggested that burrow characteristics and microhabitat selection were important factors in T.roborowskii adaptation to harsh and arid desert habitats.     

The genus Paragehyra (Reptilia: Sauria: Gekkonidae) in southern Madagascar

Paragehyra Angel is a gekkonine genus endemic to Madagascar. From 1929 until the present, the genus was represented only by the holotype of the single known species. Paragehyra petiti. The type locality of P. petiti is in the driest part of Madagascar (south-west) where rainless periods may exceed 11 months and the original vegetation consists of thorn scrub or dry deciduous forest. No new individuals of P. petiti were observed. However, a second, undescribed species of the genus was discovered in October 1990 on the opposite side of the island (south-east) in primary-low montane rainforest. The new form was observed at four localities at the southernmost extremity of rainforest in Madagascar.     

Development of the subdigital adhesive pads of Ptyodactylus guttatus (Reptilia: Gekkonidae)

Subdigital adhesive pads play an important role in the locomotion of many species of gekkonid lizards. These pads consist of integrated components derived from the epidermis, dermis, vascular system, subcuticular tendons, and phalanges. These components become intimately associated with each other during the developmental differentiation of the digits and the sequence of this integration is outlined herein in Ptyodactylus guttatus. The pads initially appear as paired swellings at the distal tips of the digits. Subsequently, a fan-like array of naked scansors develops on the ventral surface of each digit, at about the same time that scales differentiate over the surface of the foot as a whole. At the time of appearance of the naked scansors, the vascular sinus system of the pad also differentiates, along with subcuticular connective tissue specializations. At this stage the digits, along with the rest of the body, are clad in an embryonic periderm. Only after hatching and as the periderm is shed, do the epidermal setae and spines appear. The developmental sequence described here is consistent with predictions previously advanced about the evolutionary origin and elaboration of subdigital pads in gekkonid lizards. The paucity of available staged embryonic material leaves many questions unresolved.     

The phylogeography of the gecko Cyrtopodion kotschyi (Reptilia: Gekkonidae) in the Aegean archipelago

Cyrtopodion kotschyi is a small gecko, widely distributed on the islands of the Aegean archipelago and the adjacent mainland. We unveiled the phylogeography of the species by using a portion of the cytochrome oxidase I mitochondrial DNA gene from 35 insular and mainland populations. The distinct geographic distribution of the major clades of the phylogenetic tree and its topology suggest a spatial and temporal sequence of phylogenetic separations that coincide with some major paleogeographical separations during the geological history of the Aegean and support a mainly vicariant pattern of differentiation. The separation times and 95% confidence limits among the different clades were estimated according to two different paleogeographical scenarios. The very high interpopulation genetic divergence (up to 20% uncorrected pairwise distances) and the better concordance between paleogeographical and phylogenetic separations for one of the scenarios suggest that species differentiation started during Miocene (about 10 Mya) due to the fragmentation of the united landmass of "Agais" that was Aegean at that time.     

The Ultrastructure of the Spermatozoa of Squamata—I. Scincidae,Gekkonidae and Pygopodidae (Reptilia)

Abstract Squamate autapomorphies seen in sperm of the Scincidae (e.g. Ctenotus robustus, Carlia pectoralis, Cryptoblepharus virgatus, and Lampropholis delicata) are penetration of the fibrous sheath of the axoneme into the midpiece, and the paracrystalline subacrosomal cone. Sphenomorphus group spermatozoa (e.g. Ctenotus) and the Egernia group (Tiliqua) differ from the more derived Eugongylus group (C. virgatus, L. delicata and C. pectoralis) in that the acrosome is elongate and apically depressed; the perforatorium is strongly oblique; the midpiece is relatively short, with four dense ring structures in longitudinal succession; mitochondria are columnar; and enlarged peripheral fibres 3 and 8 do not show the gross anterior enlargement seen in Carlia and Lampropholis. Heteronotia binoei (Gekkonidae) sperm have no epinuclear electron-lucent region; nuclear shoulders are smooth, as in sphenomorph but not Eugongylus group skinks; mitochondria are columnar; unlike skinks, the median surfaces of the mitochondria are indented by triangular, sometimes longitudinally, interconnected dense bodies. In Lialis burtonis (Pygopodidae) sperm, the perforatorium extends virtually to the tip of the fore-shortened apically domed acrosome; nuclear shoulders are absent; the mitochondria alternate singly or in groups with one or more dense bodies which also form an interrupted collar around the distal centriole. Spermatozoal ultrastructure suggests that a common ancestry of snakes and pygopods deserves consideration.     

Epidermal fine structure of the toe tips of Sphaerodactylus cinereus (Reptilia, Gekkonidae)

This paper deals with epidermal structures of the sphaerodactyline gecko Sphaerodactylus cinereus : adhesive pads, cutaneous sensilla and intraepidermal axon terminals.
The adhesive pad is restricted to a single terminal scale and bears approximately 6,000 setae. The setae are complex, hair-like structures which branch and sub-branch up to five times. The terminal ends are shaped like inverted cones. They provide the friction which enables the gecko to walk even on vertical glass-plates.
Cutaneous sensilla of supposed mechanoreceptive function are found in groups of three or four at the anterior free edge of all dorsal and distal scales of the digit. The sensillum consists of a circular platelet in an epidermal depression bordered by an annular furrow and two or three bristles in a central position.
Discoid axon terminals in the digital scales are located between relatively stiff structures: the corneous layers of the epidermis and a layer of tonofibrillar bundles. The axon terminals are hypothesized to be sensitive to the internal pressure depending on hyperextension of the toe.     

Karyotypic evolution in Gehyra (Gekkonidae: Reptilia) IV. Chromosome change and speciation

Karyotypic data are presented for six additional species from the genus Gehyra collected in Australia, New Guinea and Fiji. C and G-banding of three of the very diverse species which all share the ancestral 2n=44 karyotype, further strengthens the phylogenetic model for the evolution of this complex. With 19 Australian species and chromosome races of Gehyra now karyotyped, it has been possible to evaluate the mode of chromosomal evolution and the role that chromosome change has played in speciation in this genus. It is clear that speciation in certain karyomorph groups has occurred allopatrically, without any gross chromosomal changes. However, in the numerous chromosome races and species which have been involved in colonizing radiations, chromosomal rearrangements have been intricately associated with the speciation process.     

Sexual characteristics and spermatogenesis in males of the parthenogenetic gecko Lepidodactylus lugubris (Reptilia, Gekkonidae)

Obligately parthenogenetic lizards usually are all-female populations of hybrids producing diploid oocytes by premeiotic endomitosis and quasi-normal meiosis. In an all-female strain of the gekkonid lizard Lepidodactylus lugubris several phenotypic males arose spontaneously. The sexual characteristics of these males were studied using light and electron microscopy and compared with normal males of the bisexual genus Lygodactylus. Emphasis was layed on morphology of seminiferous tubules, occurrence of spermatogenic stages and ultrastructure of spermatozoa. The phenotypic males possessed preanal pores filled with secretions and a sexual nephric segment which were exactly the same as in normal, reproductively active males. In the testes, density and morphology of non-spermatogenic cell types, the Leydig and Sertoli cells, indicate a normal production of testicular testosterone and a normal function of the blood-testis barrier, respectively. Both in the normal and the phenotypic males, all meiotic cell types of spermatogenesis can be recognised in the seminiferous tubules and are apparently identical, indicating a normal meiosis without impairment in the phenotypic males. In contrast, the differentiation process of spermatids is markedly disturbed in the phenotypic males of L. lugubris. In the normal male, spermiogenesis results in mature spermatids and spermatozoa with small elongated nuclei, an acrosomal complex, and a flagellar tail possessing one axoneme. Spermatozoa fill both the lumen of most seminiferous tubules and the lumina of ductus epididymidis and ductus deferens. In the phenotypic male, spermiogenesis results in seemingly normal spermatids and in spermatozoa with large, non-elongated, deformed nuclei and/or irregular tails possessing more than one axoneme. Both the lumen of most seminiferous tubules and the lumina of the ductus epididymidis and the ductus deferens contain relatively few spermatozoa. We suggest that the phenotypic males inherited the ability for a premeiotic endomitosis from their all-female ancestral lineage. While in females this leads to quasi-normal meiosis and diploid oocytes capable of development, the small nuclei of the spermatozoa are unable to contain a diploid set of chromosomes. Because of the high amount of deformed spermatozoa and possibly uncontrolled loss of genetic material in structurally normal, but aneuploid spermatozoa we conclude that these otherwise perfect males are infertile, thus constituting another example of gametic sterility.     

Discovery of a diploid population of theHemidactylus garnotii-vietnamensis complex (Reptilia: Gekkonidae)

A diploid member of the parthenogenetic gekkonid species complexHemidactylus garnotii-vietnamensis was discovered for the first time from Thailand. This gecko, seemingly unisexual and parthenogenetic, possesses 2n=2x=38 chromosomes, showing distinct heteromorphisms. The absence of bisexual congeneric species with a combination of karyomorphs to produce this karyotype indicates the occurrence of chromosomal rearrangements after the initial estabilishment of a diploid clonal lineage of hybrid origin. Results of karyotypic comparisons of the present sample and the three known triploid species belonging to theH. garnotii-vietnamensis complex suggest that a triploid karyomorph similar to that ofH. vietnamensis has first emerged through an insemination of the diploid parthenogen's egg by the sperm from a bisexual species having 44 chromosomes (all telocentric), and that the karyomorph subsequently experienced some minor chromosomal aberrations to produce the karyomorphs ofH. vietnamensis andH. garnotii. The origin of theH. stejnegeri karyotype still remains an open question for future studies.     

Conditioning reduces metabolic rate and time to steady-state in the lizard Naultinus manukanus (Reptilia: Gekkonidae)

The rate of oxygen consumption (VO2) is commonly used as a measure of whole organism metabolic rate, but requires the animal to be motionless and at rest. Few studies have measured whether animals that appear motionless are truly at rest, or whether being in a novel environment elevates metabolic rate. We investigated whether conditioning of the gecko Naultinus manukanus to experimental procedures influenced the VO2 and probability of achieving a constant rate of oxygen consumption. Metabolic rate was measured at 24 degrees C in 22 individuals until a steady-state was achieved, or for 80 min if no steady-state was reached, once a day on 5 consecutive days (five trials). Geckos in the first trial, when compared with subsequent trials, had a significantly higher mass-adjusted VO2 (0.89+/-0.06 vs. 0.67+/-0.05 ml O2 h(-1), respectively), and time to reach a steady-state VO2 (66+/-8 vs. 47+/-3 min, respectively), as well as a significantly lower probability of reaching a steady-state VO2 (24% vs. 74%, respectively). We conclude that there may be hidden inaccuracies in studies that do not condition animals and that at least one conditioning trial should be used to obtain a metabolic rate at rest for small lizards.     

Formal taxa, species groups, and perception of the genus Diplodactylus (Reptilia: Gekkonidae)

Genera with large numbers of species present particular difficulties; the analysis of relationships, of included taxa may be roblematic. One attempt to aproach this problem involves the reco of clusters of species tIat may be informally assembgd into species groups. The problems tE:g the recognition of such assemblages may induce are exlored. It is not that the species groups, as originail formulated, are problematic as they are initiafy erected to demarcate clusters withm an imperfectly known phylogeny of a supposedly monophyletic group. These species groups, however, tend to become recognized as “taxa” rather than operationaf clusters and as such tend to influence the approach to the inclusive taxon taken by subsequent workers. Rather than testing the concept of the species grous, there is a tendency to retain them and to insert other groups between them that do not exactly fit the original scheme. The establishment of species groups, first used to clarify a complex situation, has teen a source of problems for subseuent workers. The history of this aproach is traced for the gekkonid genus Diplodactylus and the problems that have arisen are outlined.     

Gradient of reduced glutathione in the tail of Hemidactylus leschenaultii (Sauria: Gekkonidae)

A proximo-distal gradient of reduced glutathione (GSH), a non enzymatic antioxidant was observed in the original tails of the lizard, H. leschenaultii. In the regenerating tails, a gradual increase in the level of GSH was noted with tail elongation. In the newly regenerated tails also the level of GSH remained higher in the proximal part than the corresponding distal parts.     

The systematics of the Phelsuma madagascariensis species group of day geckos (Reptilia: Gekkonidae) in the Seychelles

Conventional taxonomy of the Seychelles populations of the Phelsuma madagascariensis species group has failed to illustrate the principal patterns of phenetic variation between island populations. The taxonomic history of the populations is discussed critically, and a revised nomenclature is suggested from the results of a recent comprehensive study of the forms using multivariate morphometrics. Three phenetic groups from the granitic islands are referred to as Phelsuma sundbergi sundbergi from the north western islands; P. s. ladiguensis from the north eastern islands; and P. s. longinsulae from the southern islands. Phelsuma abbotti populations from Aldabra and Assumption are considered subspecifically distinct, and not conspecific with the granitic island forms. The other coralline island populations are closely allied to the races from the granitic islands and probably represent recent colonization or introductions by man.     

Complex estimates of evolutionary relationships in Tarentola mauritanica (Reptilia: Gekkonidae) derived from mitochondrial DNA sequences

Mitochondrial DNA (12S rRNA, 16S rRNA) sequences were analysed within Tarentola mauritanica and other selected species of Tarentola. Several highly genetically distinct lineages occur in North Africa, revealing phylogroups in southern and central Morocco, northern Morocco, Algeria, Tunisia, and Libya. A single haplotype characterizes populations across Spain, Portugal, Italy, Menorca, Crete, and Tunisia raising the possibility of an anthropogenic introduction followed by rapid population expansion throughout southern Europe. T. mauritanica is paraphyletic with respect to T. angustimentalis, a Canary islands endemic. The high genetic diversity observed across North Africa suggests T. mauritanica may represent a species complex.     

Ungual asymmetry in the context of pedal symmetry in Ailuronyx (Reptilia Gekkonidae): modification for an opposable grip

The claws of the gekkonine gecko genus Ailuronyx are unique in being asymmetrically disposed. Those of digits I-III are curved towards the body, whereas those of digits IV and V curve away from the body. This ungual asymmetry is imposed upon the essentially symmetrical pedal morphology that typifies pad-bearing geckos. The resultant functional organization of manus and pes parallels that seen in chameleons. The pedal configuration of Ailuronyx seychellensis appears to provide a mechanical advantage for locomotion on at least some of the animal's natural substrata.