Step on it: can footprints from tracking tunnels be used to identify lizard species?

There are few effective or efficient established methods for monitoring cryptic herpetofauna. Footprint tracking tunnels are routinely used to index small mammal populations, but also have potential for monitoring herpetofauna. We evaluated the utility of tracking tunnels for identification of New Zealand lizards using captive- and wild-sourced animals (four skink and eight gecko species). All skink prints that we obtained were indistinct or obscure, but we obtained relatively clear, measurable prints for all gecko species. We found that identification to species level was possible for the two gecko species for which we had a large sample—Naultinus gemmeus and Woodworthia ‘Otago large’—using linear discriminant analysis (the best model correctly assigned 96.1% of individuals). Our findings suggest that footprints from tracking tunnels may be used to distinguish between species of geckos. Additional research is needed to assess the ability to further discriminate intra- and inter-genera lizard footprints from tracking tunnels, and the utility of the technique for surveying and monitoring lizard populations.     

Paralogous origin of the rhodopsinlike opsin genes in lizards

Rhodopsinlike opsins constitute a distinct phylogenetic group (Yokoyama 1994, Mol. Biol. Evol. 11:32–39). This RH2 group includes the green-sensitive opsins in chicken and goldfish and the blue-sensitive opsin in a nocturnal lizard gecko. In the present study, we isolated and sequenced the genomic DNA clones for the RH2 opsin gene, rh2 _Ac , of the diurnal lizard Anolis carolinensis. This single-copy gene spans 18.3 kb from start to stop codons, making it the longest opsin gene known in vertebrates. Phylogenetic analysis strongly suggests that rh2 _Ac is more closely related to the chicken green opsin gene than to the gecko blue opsin gene. This gene tree differs from the organismal tree, where the two lizard species should be most closely related, implying that rh2 _Ac and the gecko blue-sensitive opsin genes have been derived from duplicate ancestral genes.Correspondence to: S. Yukiyama     

Morphological and biochemical analyses of original and regenerated lizard tails reveal variation in protein and lipid composition

Caudal autotomy, or voluntary self-amputation of the tail, is a common and effective predator evasion mechanism used by most lizard species. The tail contributes to a multitude of biological functions such as locomotion, energetics, and social interactions, and thus there are often costs associated with autotomy. Notably, relatively little is known regarding bioenergetic costs of caudal autotomy in lizards, though key morphological differences exist between the original and regenerated tail that could alter the biochemistry and energetics. Therefore, we investigated lizard caudal biochemical content before and after regeneration in three gecko and one skink species. Specifically, we integrated biochemical and morphological analyses to quantify protein and lipid content in original and regenerated tails. All lizards lost significant body mass, mostly protein, due to autotomy and biochemical results indicated that original tails of all species contained a greater proportion of protein than lipid. Morphological analyses of two gecko species revealed interspecific differences in protein and lipid content of regenerated lizard tails. Results of this study contribute to our understanding of the biochemical consequences of a widespread predator evasion mechanism.     

Patterns of coccidial prevalence in lizards of Mauritius

This paper reports prevalence of coccidial oocysts in fecal samples from 6 endemic and 2 introduced lizard species on Mauritius, an island nation in the Indian Ocean. Total coccidian prevalence was 54% (n = 341) for the endemic 'ornate day gecko,' Phelsuma ornata; 48% (n = 159) for the endemic 'Durrell's night gecko,' Nactus durrelli; 53% (n = 15) for the endemic 'Serpent Island night gecko,' N. serpensinsula; and 78% (n = 248) for the introduced gecko, Hemidactylus frenatus. These high prevalences may reflect lack of long-lasting immune response to coccidial infection. There were few significant differences in prevalence among age, island, sex, or body condition within species, suggesting that these coccidia are relatively nonpathogenic and have little effect on host fitness. Prevalence was higher in the dry season than the wet season. These data suggest other factors, such as low host immune response to reinfection, affect overall prevalence more significantly than the effect of humidity on oocyst survival on Mauritius. No coccidia were found in samples from the endemic 'Gunner's Quoin night gecko,' N. coindemirensis (n = 155), probably reflecting parasite extinction due to a host population bottleneck following historical introduction of rats. There was no evidence of competitive or facilitative interactions between Eimeria sp. and Isospora sp., but evidence of competition between 2 Eimeria species in the 'ornate day gecko,' Phelsuma ornata. No evidence was found of cross-species infection, suggesting that reptile coccidia have high host specificity and are, therefore, poor subjects for studies of parasite-mediated competition and the evolution of sex.     

Molecular cloning of P450 aromatase from the leopard gecko and its expression in the ovary

In this study, we identified the cDNA of P450 aromatase in the leopard gecko, a lizard with temperature-dependent sex determination. The cDNA encodes a putative protein of 505 amino acids. The deduced amino acid sequence of leopard gecko aromatase cDNA showed 80% identity with that of turtles, 70% with humans and 77% with chickens. This is the first report of the identification of P450 aromatase cDNA in squamata species. It has been reported that this gene is expressed in different layers of cells in the ovary of mammalian species and avian species. Thus, we also investigated cells expressing the mRNA of this gene in the ovary of the leopard gecko by RT-PCR and in situ hybridization. The mRNA expression of leopard gecko P450 aromatase was localized in both the thecal and granulosa cell layers in the ovary. The expression in thecal and granulosa cell layers was examined in the largest follicle, second largest follicle and third largest follicle by RT-PCR. A higher level of mRNA expression was observed in the granulosa cell layer of the second largest follicle than in other cell layers. This result may reflect the characteristics of follicles in species with automonochronic ovulation.     

Ratios between number of neuroglial cells and number and volume of nerve cells in the spinal ganglia of two species of reptiles and three species of mammals

We studied the ratios between number of neuroglial (=satellite) cells and number and volume of neurons with which they are associated in the spinal ganglia of two species of reptiles (lizard and gecko) and three species of mammals (mouse, rat, and rabbit). In all five species, we found that the number of satellite cells associated with a nerve cell body increased with increasing volume of the latter. This result shows that there is a quantitative balance between neuroglia and nerve tissue in spinal ganglia. This balance seems to be maintained by a tight regulation of the number of satellite cells. We also found that the mean volume of nerve cell body corresponding to a satellite cell was lower for small neurons than for large ones. Since satellite cells metabolically support spinal ganglion neurons, the metabolic needs of small neurons are better satisfied than those of large ones. For a nerve cell body of a given size, the number of associated satellite cells did not differ between the lizard and gecko, nor between the mouse, rat, and rabbit. However, this number was significantly smaller in the reptiles than in the mammals. This result could be explained by the lower metabolic rate in the nervous system of poikilotherms than mammals, or could have a phylogenetic significance. These two interpretations are not mutually exclusive.     

Comparative fine structure of the axial skeleton inside the regenerated tail of some lizard species and the tuatara (Sphenodon punctatus)

The regenerated tail of the New Zealand gecko Hoplodactylus maculatus is equipped with an elastic cartilaginous tube as skeletal axis. Other lizard species and Sphenodon punctatus possess variably developed hyaline cartilaginous tubes. Moreover, H. maculatus enhances the functional performance of its tail by long elastic fibres, which are arranged all around the central regenerated spinal cord. The different characteristics of the regenerated skeleton could be related to the different environments that the species studied occupy in nature.     

Into the light: diurnality has evolved multiple times in geckos

Geckos are the only major lizard group consisting mostly of nocturnal species. Nocturnality is presumed to have evolved early in gecko evolution and geckos possess numerous adaptations to functioning in low light and at low temperatures. However, not all gecko species are nocturnal and most diurnal geckos have their own distinct adaptations to living in warmer, sunlit environments. We reconstructed the evolution of gecko activity patterns using a newly generated time‐calibrated phylogeny. Our results provide the first phylogenetic analysis of temporal activity patterns in geckos and confirm an ancient origin of nocturnality at the root of the gecko tree. We identify multiple transitions to diurnality at a variety of evolutionary time scales and transitions back to nocturnality occur in several predominantly diurnal clades. The scenario presented here will be useful in reinterpreting existing hypotheses of how geckos have adapted to varying thermal and light environments. These results can also inform future research of gecko ecology, physiology, morphology and vision as it relates to changes in temporal activity patterns. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, ●●, ●●–●●.     

The status of Leishmania tarentolae/Trypanosoma platydactyli

Taxonomic studies and classification of Leishmania species have developed rapidly in recent years, but controversy still surrounds the relationships between those species infecting lizards and those infecting mammals. Some authorities maintain that the leishmanias o f lizards form a sufficiently distinct group to be ranked as a separate genus - Sauroleishmania(1,2) - while Wallbanks et al. have gone further to suggest that such species might be classified within the genus Trypanosoma(3). This suggestion followed from work showing that promostigote forms of Trypanosoma platydactyli from a gecko, had similar isoenzyme profiles to Leishmania tarentolae, a well-known species from lizards. In this article however, Larry Simpson and George Holz Jr discuss conflicting evidence, concluding from recent studies of DNA and lipid composition that the lizard leishmanias are more closely related to mammalian leishmanias than to trypanosomes.0.     

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.     

Molecular phylogenetic relationships among species of the Malagasy-Comoran gecko genus Paroedura (Squamata: Gekkonidae)

We use approximately 3100bp of mitochondrial (ND2, ND4) and nuclear (RAG1, phosducin) DNA sequence data to recover phylogenetic relationships among 14 of the 16 recognized taxa of the lizard genus Paroedura as well as two undescribed forms. These geckos are endemic to Madagascar and the Comores and are popularly kept and bred by herpetoculturalists. The closest relative of Paroedura is another Indian Ocean leaf-toed gecko, Ebenavia. Both Bayesian inference and maximum parsimony strongly support the monophyly of two major clades within Paroedura that conflict with existing species group assignments based on scale characteristics. Our well-resolved tree elucidates a biogeographic pattern in which eastern Paroedura are most basal and western and south-western species form a monophyletic group. Our data demonstrate the phylogenetic utility of phosducin, a novel marker in squamate phylogenetics, at the intrageneric level.     

Auditory nerve fibre activity in the Tokay gecko

Journal of Comparative Physiology A - We have recorded from single auditory nerve fibres in the lizard,Gekko gecko, while changing the animal's temperature within the range 19–30 °C....     

Establishment and characterization of rough-tailed gecko original tail cells

Some of lizard species have the ability to lose their tail in order to defend against predators and regenerate the new tail. Lizard’s regenerated tail has attracted scientists’ attention for unraveling the regeneration process, but less information is known about the cellular characterization and cell growth properties of original tail. This research aimed to report cell culture and banking process of rough-tailed gecko or Cyrtopodion scabrum’s original tail cell sample from inner tissue without skin using tissue explant technique. For banking reports, it is essential to analyze this cells’ potential to proliferate, to investigate biological aspects such as cell culture features, differentiation and chromosome number and to report its species identification and quality control. To achieve optimal growth conditions, three different temperatures for incubation including 18, 23 and 37 °C and two different media including DMEM and L-15 were applied. The expanded cells were studied for their potential to adipose and osteoblast differentiation. Results indicated that lizard’s original tail cells could be successfully obtained by explant technique. The cells demonstrated fibroblast like morphology with population doubling times of approximately 24?±?0.5 h. Karyotyping analysis showed a distribution of 2n?=?40 chromosome number for this cell line. The comparison of different incubation media and temperatures showed that cell growth is equally optimal in all mentioned conditions according to growth curves. Adipose and osteoblast differentiation was obviously observed in these cells which confirms the hint of stem-ness in the produced mixed cells. According to cell banking policies, produced cells were also checked for bacterial, fungal, yeast and mycoplasma contaminations and no contamination was observed. Multiplex PCR for identification of species confirmed the species of lizard with no cross-contamination with other cells in the cell bank. Establishment of authenticated and well-characterized lizard’s original tail cell line will provide a valuable source for subsequent in vitro regenerative research and molecular studies which are not feasible in in vivo methods. This finding will allow us to get an opportunity to create and preserve a new collection of lizard cell lines in the future.     

Helminths of the exotic lizard Hemidactylus mabouia from a rock outcrop area in southeastern Brazil

The helminth fauna of 291 Hemidactylus mabouia (Lacertilia: Gekkonidae) from a rock outcrop area in the state of S?o Paulo, Southeastern Brazil, was studied. Five species were recovered, namely one unidentified species of centrorhynchid acanthocephalan (present only as cystacanths) and the nematodes Parapharyngodon sceleratus, P. largitor (Oxyuroidea: Pharingodonidae), Physaloptera sp. (Spiruroidea: Physalopteridae) and one indeterminate species of Acuariidae (Acuaroidea), with the latter two forms present only as larvae. Infection rates tended to increase with host size, but appeared to be unaffected by season. Hemidactylus mabouia shared most of its helminth fauna with two other sympatric lizard hosts, Mabuya frenata and Tropidurus itambere. The helminth assemblage of the H. mabouia population appears to have been entirely acquired by this exotic gecko from the local helminth species pool, rather than possessing any species from the parasite faunas of the original African populations.     

Interactions between native and invasive gecko lizards in tropical Australia

Invasive geckos of the genus Hemidactylus (Gekkonidae) are spreading rapidly through urban environments in many tropical and subtropical parts of the world. The invaders have caused rapid declines in native gecko abundance in some areas, but their interactions with Australian native species remain unknown. In a small rural village near Darwin, we found that Hemidactylus frenatus is abundant around both lighted and unlighted buildings, but rarely found in surrounding bushland. It is sympatric with the larger Gehyra australis (Gekkonidae) in this disturbed site, and often forages on the same buildings, but is active mostly during the dry‐season (vs. wet‐season for G. australis) and is competitively subordinate to the larger native species. In laboratory encounters, H. frenatus fled from G. australis, and modified its refuge‐site use in the presence of the native lizard. In those same trials, the native gecko often attacked and rarely fled; and did not shift its refuge‐site selection. In field surveys, the two taxa frequently co‐occurred. However, substrate use of the invasive H. frenatus was modified by the presence of the native G. australis, consistent with competitive displacement. Our counts of H. frenatus were highest during the dry‐season, when G. australis (like most other small native reptiles) is relatively inactive. The invasive gecko thus appears to be exploiting a ‘vacant niche’ around buildings, rather than displacing the native gecko taxon. This outcome may reflect the size disparity between the native species and the invader; Hemidactylus frenatus may well have significant ecological impacts on smaller native lizards.     

Salmonella in gut and droppings of three pest lizards in Nigeria

The carriage rate of Salmonella in the gut of three lizard species, namely the Agama lizard (Agama agama) (64), the wall gecko (Geckonidae) (60), the snake lizard (Ameiva ameiva) (52), and 60 samples of lizard dropping; and their survival under various environmental conditions was investigated. A gastrointestinal Salmonella carriage rate of 32, 39 and 48% were observed for the wall gecko, the Agama and snake lizards respectively. An isolation rate of 35% was also recorded for pooled lizard droppings. Salmonella survived in the droppings for 4 weeks in tap water and wet sand, 6 weeks in direct contact with air and up to 8 weeks when mixed with dry sand. An inoculum of 10⁶ c.f.u./g of a pure Salmonella isolate obtained from the lizard droppings proliferated extensively in sterile wet and dry soil samples, but decreased rapidly in the other environments. Salmonella was still detectable after 3 weeks in non-sterile wet and dry soil samples, up to 2 weeks in tap water, and approximately 8 days in powdered milk and gari. The potential public health significance of the observations is discussed.     

Using testis size to predict the mating systems of New Zealand geckos

Abstract

The mating system is unknown for the majority of New Zealand geckos (Family Gekkonidae). I investigated interspecific variation in relative testis volume across 19 New Zealand gecko taxa and 63 additional species of squamate reptiles from other countries to make predictions about the social mating system of the New Zealand geckos. Relative testis size varied greatly between species of New Zealand gecko, with testes ranging from 119% larger than expected to 75% smaller than expected. This variation was even greater across other squamates, with testes ranging from 55 to 152% of expected size. This variation could not be explained by seasonality of breeding, clutch size or the sex ratio of populations. As species subject to more intense sperm competition sport relatively larger testes in other vertebrate groups, it is likely that similar variation in gecko testis size is due to differences in mating systems between species. Based on testis volume, it is predicted that at least half of the New Zealand gecko taxa studied are likely to have polygynandrous mating systems.     

Overlap of Female Reproductive Cycles Explains Shortened Interclutch Interval in a Lizard with Invariant Clutch Size (Squamata: Gekkonidae: Paroedura picta)

Abstract Variable clutch size is unambiguously an ancestral state in reptiles. Only several lizard lineages have evolved so-called invariant clutch size, where all females lay just one or two eggs per clutch. This mode of reproduction is characteristic for geckos. In some gecko lineages, decreased fecundity in a single clutch is compensated by conspicuous shortening of interclutch intervals. The proximate mechanism of high clutch frequency in these geckos is not known. Here, we document that three subsequently laid clutches develop simultaneously in females of the Madagascar ground gecko (Paroedura picta). The extremely short interclutch intervals in this species-even as short as a week-thus could be attributed to the overlap of female reproductive cycles. Such overlap should be associated with altered female hormonal cycles. Based on measurements of hormonal levels, we suggest that cycles of estradiol and progesterone during reproductive cycles of females in P. picta are largely independent. Thus, in contrast to the presumable ancestral reptile state, higher levels of progesterone do not seem to interfere with vitellogenesis in this species. We discuss potential consequences of this derived mode of reproduction, such as possible simultaneous maternal transfer of nutrients and other yolk components to several subsequent clutches.     

Potential impacts of intraguild predation by invasive Asian house geckos

The introduction of the Asian house gecko, Hemidactylus frenatus, to mainland Australia has sparked considerable debate in regard to its potential impacts on native lizard species. Their historically patchy distribution across Australia has gained attention as populations have spread into peri‐urban and native bushland. Hemidactylus frenatus potentially pose a threat to native species through competition and predation. I documented some activity of H. frenatus during the day, including foraging, which may broaden the potential impacts to diurnal species. Here, I highlight (i) the potential impact of predation by H. frenatus on native lizards and (ii) the need for empirical studies directly quantifying competitive encounters, with special interest in intraguild predation.