Special Issue: 100 years of scientific excavations at UNESCO World Heritage Site Monte San Giorgio and global research on Triassic marine Lagerstätten.

Only a few Swiss fossil localities are known globally and of which, the UNESCO World Heritage Site Monte San Giorgio, which extends from Switzerland into Italy, is the most important one. Following the discovery of the occurrence of articulated skeletons of marine reptiles in the local mines, large excavations were organized by Bernhard Peyer from the University of Zurich starting 1924. With this collection of articles, we commemorate the successful excavations and research, which initiated the publication of a series of monographies, mostly on the vertebrates but also on the invertebrates of this locality. Especially with the discovery of several remarkably similar Konservat-Lagerstätten in China, the discoveries from Monte San Giorgio gained global relevance. New methodologies such as computed tomography produced a wealth of new data, particularly on endocranial anatomy of several tetrapods.

Cocaine- and Amphetamine-Regulated Transcript Peptide in the Central Nervous System of the Gecko, Hemidactylus leschenaultii: Molecular Characterization, Neuroanatomical Organization, and Regulation by Neuropeptide Y.

Neuropeptide cocaine- and amphetamine-regulated transcript (CART) is widely expressed in the brains of teleosts, amphibians, birds, and mammals and has emerged as a conserved regulator of energy balance across these vertebrate phyla. However, as yet, there is no information on CART in the reptilian brain. We characterized the cDNA encoding CART and mapped CART-containing elements in the brain of gecko, Hemidactylus leschenaultii (hl) using a specific anti-CART antiserum. We report a 683-bp hlcart transcript containing a 336-bp open reading frame, which encodes a putative 111-amino acid hl-preproCART. The 89-amino acid hl-proCART generated from hl-preproCART produced two putative bioactive hl-CART-peptides. These bioactive CART-peptides were > 93% similar with those in rats/humans. Although reverse transcription-polymerase chain reaction (RT-PCR) detected hlcart-transcript in the brain, CART-containing neurons/fibers were widely distributed in the telencephalon, diencephalon, mesencephalon, rhombencephalon, spinal cord, and retina. The mitral cells in olfactory bulb, neurons in the paraventricular, periventricular, arcuate (Arc), Edinger-Westphal, and brainstem nuclei were intensely CART-positive. In view of antagonistic roles of neuropeptide Y (NPY) and CART in energy balance in the framework of mammalian hypothalamus, we probed CART-NPY interaction in the hypothalamus of H. leschenaultii. Double immunofluorescence showed a dense NPY-innervation of Arc CART neurons. Ex vivo hypothalamic slices treated with NPY/NPY-Y1-receptor agonist significantly reduced hlcart-mRNA levels in the Arc-containing tissues and CART-ir in the dorsal-Arc. However, CART-ir in ventral-Arc was unaffected. NPY via Y1-receptors may regulate energy balance by inhibiting dArc CART neurons. This study on CART in a reptilian brain fills the current void in literature and underscores the conserved feature of the neuropeptide across the entire vertebrate phyla.

Palaeognaths reveal evolutionary ancestry of the avian Major Histocompatibility Complex class II.

The multigene family of the Major Histocompatibility Complex (MHC) codes for the key antigen-presenting molecules of the vertebrate immune system. In birds, duplicated MHC class II (MHC-II) genes are highly homogenized by concerted evolution and, thus, identification of their orthologous relationships across long evolutionary timescales remains challenging. Relatively low evolutionary rate of avian MHC class IIA genes has been expected to provide a promising avenue to allow such inferences, but availability of MHC-IIA sequences in non-model bird species has been limited until recently. Here, taking advantage from accumulating genomic resources, we identified and analysed MHC-IIA sequences from the most basal lineage of extant birds (Palaeognathae). Conserved region of the MHC-IIA membrane-proximal domain was used to search for orthologous relationships between palaeognath birds and non-avian reptiles. First, analyses of palaeognath sequences revealed the presence of a separate MHC-IIA gene lineage (DAA3) in kiwis, which did not cluster with previously described avian MHC-IIA lineages (DAA1 and DAA2). Next, phylogenetic reconstruction showed that kiwi DAA3 sequences form a single well supported cluster with turtle MHC-IIA. High similarity of these sequences most likely reflects their remarkable evolutionary conservation and retention of ancient orthologous relationships, which can be traced back to basal archosauromorphs ca. 250 million years ago. Our analyses offer novel insights into macroevolutionary history of the MHC and reinforce the view that rapid accumulation of high-quality genome assemblies across divergent non-model species can substantially advance our understanding of gene evolution.

Smaller islands, bigger appetites: evolutionary strategies of insular endemic skinks.

Competitive dietary and morphological divergence among co-occurring species are fundamental aspects of ecological communities, particularly on islands. Cabo Verde (~570 km west of continental Africa) hosts several endemic reptiles descended from common ancestors, with sympatric species exhibiting wide morphological variation and competing for limited resources. To explore the mechanisms of resource partitioning between coexisting species, DNA metabarcoding was used to compare the diets of large and small skinks, Chioninia vaillantii and Chioninia delalandii, in sympatric and allopatric contexts on Fogo Island and in a more competitive context on the small and resource-poor Cima Islet. The morphological variation of all populations was also examined to test the character displacement hypothesis and to compare the effect of different competitive scenarios. Results showed significant differences in diet and linear measurements between species and populations. The two sympatric populations of C. delalandii on Fogo and Cima showed similar changes in head morphology compared to the allopatric population, supporting character displacement. The effect of higher competitive pressure on Cima was evidenced by the increased morphological and dietary variation observed. This study demonstrates how sister species develop dietary adaptations/morphologies to maintain stable coexistence, especially in highly competitive scenarios, providing useful insights for effective conservation strategies.

Are toe fringes important for lizard burying in highly mobile sand?

Toe fringes are a key innovation for sand dwelling lizards, and the relationship between toe fringe function and substrate properties is helpful in understanding the adaptation of lizards to sand dune environments. We tested the sand burial performance of Phrynocephalus mystaceus on different sand substrates with toe fringe manipulation, with the aim of assessing whether the function of the toe fringes shifts under different substrate properties, especially in highly mobile substrates. The sand burial performance of P. mystaceus was influenced by substrate properties in relation to the toe fringe states of the lizard. After removal of the bilateral toe fringes, the sand burial ability score of P. mystaceus was significantly higher on sand substrates below 100 mesh than on native sand substrates. As the angle of stability of the substrate properties decreased, the sand burial performance of the lizard was even better after the bilateral toe fringes were removed. The results of the LASSO model and the path analysis model showed that the stability angle provided the opposite effect on sand burial performance in different toe fringe states. These results further suggest that the sand burial function of toe fringes may not be suitable for highly mobile sand substrates. It remains to be tested further whether the function of toe fringes is more important for running on sand.

Opportunity begets opportunity to drive macroevolutionary dynamics of a diverse lizard radiation.

Evolution proceeds unevenly across the tree of life, with some lineages accumulating diversity more rapidly than others. Explaining this disparity is challenging as similar evolutionary triggers often do not result in analogous shifts across the tree, and similar shifts may reflect different evolutionary triggers. We used a combination of approaches to directly consider such context-dependency and untangle the complex network of processes that shape macroevolutionary dynamics, focusing on Pleurodonta, a diverse radiation of lizards. Our approach shows that some lineage-wide signatures are lost when conditioned on sublineages: while viviparity appears to accelerate diversification, its effect size is overestimated by its association with the Andean mountains. Conversely, some signals that erode at broader phylogenetic scales emerge at shallower ones. Mountains, in general, do not affect speciation rates; rather, the occurrence in the Andean mountains specifically promotes diversification. Likewise, the evolution of larger sizes catalyzes diversification rates, but only within certain ecological and geographical settings. We caution that conventional methods of fitting models to entire trees may mistakenly assign diversification heterogeneity to specific factors despite evidence against their plausibility. Our study takes a significant stride toward disentangling confounding factors and identifying plausible sources of ecological opportunities in the diversification of large evolutionary radiations.

Epidermal Differentiation Genes of the Common Wall Lizard Encode Proteins with Extremely Biased Amino Acid Contents.

The epidermal differentiation complex (EDC) is a cluster of genes that code for protein components of cornified cells on the skin surface of amniotes. Squamates are the most species-rich clade of reptiles with skin adaptations to many different environments. As the genetic regulation of the skin epidermis and its evolution has been characterized for only a few species so far, we aimed to determine the organization of the EDC in a model species of squamates, the common wall lizard (Podarcis muralis). By comparative genomics, we identified EDC genes of the wall lizard and compared them with homologs in other amniotes. We found that the EDC of the wall lizard has undergone a major rearrangement leading to a unique order of three ancestral EDC segments. Several subfamilies of EDC genes, such as those encoding epidermal differentiation proteins containing PCCC motifs (EDPCCC) and loricrins, have expanded by gene duplications. Most of the EDPCCC proteins have cysteine contents higher than 50%, whereas glycine constitutes more than 50% of the amino acid residues of loricrin 1. The extremely biased amino acid compositions indicate unique structural properties of these EDC proteins. This study demonstrates that cornification proteins of the common wall lizard differ from homologous proteins of other reptiles, illustrating the evolutionary dynamics of diversifying evolution in squamates.

Thalattosauria in time and space: a review of thalattosaur spatiotemporal occurrences, presumed evolutionary relationships and current ecological hypotheses.

In the wake of the greatest mass extinction in Earth's history, the End-Permian Mass Extinction, the Triassic was a time of recovery and innovation. Aided by warm climatic conditions and favorable ecological circumstances, many reptilian clades originated and rapidly diversified during this time. This set the stage for numerous independent invasions of the marine realm by several reptilian clades, such as Ichthyosauriformes and Sauropterygia, shaping the oceanic ecosystems for the entire Mesozoic. Although comparatively less speciose, and temporally and latitudinally more restricted, another marine reptile clade, the Thalattosauriformes, stands out because of their unusual and highly disparate cranial, dental and skeletal morphology. Research on Thalattosauriformes has been hampered by a historic dearth of material, with the exception of rare material from Lagerstätten and highly fossiliferous localities, such as that from the UNESCO world heritage site of Monte San Giorgio. Consequently, their evolutionary origins and paleobiology remain poorly understood. The recent influx of new material from southwestern China and North America has renewed interest in this enigmatic group prompting the need for a detailed review of historic work and current views. The earliest representatives of the group may have been present from the late Early Triassic onwards in British Columbia. By the Ladinian the group had achieved a wide distribution across the northern hemisphere, spanning the eastern Panthalassic as well as the eastern and western Tethyan provinces. Distinct morphological and likely ecological differences exist between the two major clades of Thalattosauriformes, the Askeptosauroidea and the Thalattosauroidea, with the latter showing a higher degree of cranial and skeletal morphological disparity. In-group relationships remain poorly resolved beyond this bipartition. Overall, thalattosaurs may be closely related to other marine reptile groups such as ichthyopterygians and sauropterygians. However, their exact position within Diapsida remains elusive. Future focal points should utilize modern digital paleontological approaches to explore the many fragmentary specimens of otherwise poorly sampled localities.

First record of Isospora amphiboluri in the thorny devil, Moloch horridus.

Poor long-term survival (Mean = 2.16 y; 95% CI 1.68-2.65) was identified in a captive population of thorny devils (Moloch horridus) held at the Alice Springs Desert Park in the Northern Territory, Australia, over a period of 27 years. There was no significant difference in survival time (after acquisition) of wild-caught individuals compared captive born animals, or males compared to females. Limited information was available regarding the cause(s) of death for animals found dead or euthanased. Health of the live population at the time of the study (n = 14) was assessed by clinical history review, physical examination, and faecal examination. Large numbers of coccidian oocysts measuring 20-24 µm in diameter were identified upon faecal examination. Molecular investigation of genomic DNA from these samples identified Isospora amphiboluri based on the sequences of partial regions of the mitochondrial cytochrome c oxidase subunit 1 gene (cox1) and the nuclear small subunit of ribosomal RNA gene (SSU). Isospora amphiboluri was originally described from the bearded dragon (Pogona barbata) and has since been recorded in the inland bearded dragon (Pogona vitticeps) and the central netted dragon (Ctenophorus nuchalis). The present case expands the host range for I. amphiboluri. Histological examination of tissues was not available, and therefore the potential role of I. amphiboluri in morbidity and mortality of M. horridus is not clear. Further research is required to understand if colonization with I. amphiboluri is pathogenic in this species.

Parasites of reptiles in Iran (1922-2023): A literature review.

Reptiles are among the most diverse groups of animals, inhabiting nearly all continents and environments. Understanding their parasite biodiversity has garnered significant interest, particularly from a One Health perspective. Although the highly diverse reptile fauna of Iran, comprising 272 species i.e. 89 snakes (Serpentes), 171 lizards (Sauria), 8 turtles, 2 tortoises (Testudines), 1 crocodile (Crocodilia), and 1 worm-lizard (Amphisbaenia), there is a shortage of information about parasites. The present review is a compilation of 62 studies published from 1922 to August 2024. We present information on 56 species of reptiles from five groups (amphisbaenians, crocodiles, testudines, snakes, and lizards) and 98 parasitic taxa belonging to different protozoa and metazoa i.e. nematodes, cestodes, trematodes, acanthocephala, leeches, ticks, mites, and myiasis -producing flies. Although 63 taxa were diagnosed at the species level, 35 parasite taxa were only reported at the genus or family levels. Reviewing the literature, we found a paucity of information about endemic reptiles several of which are vulnerable species. Considering that some of the detected parasites e.g. Cryptosporidium and amoebae have serious clinical and/or public health threats molecular diagnostic techniques are needed for precise identification and understanding of the epidemiology and the potential zoonotic implications associated with parasites of reptiles. There is also a need to understand the exact distribution and host-parasite associations in different reptilian species present in Iran including the role of the reptiles as intermediate and reservoir hosts.

Premeiotic endoreplication is the mechanism of obligate parthenogenesis in rock lizards of the genus Darevskia.

Among vertebrates, obligate parthenogenesis occurs exclusively in squamate reptiles. Premeiotic endoreplication in a small subset of developing oocytes has been documented as the mechanism of production of unreduced eggs in minutely explored obligate parthenogenetic lineages, namely in teiids and geckos. The situation in the lacertid genus Darevskia has been discussed for decades. Certain observations suggested that the ploidy level is restored during egg formation through a fusion of egg and polar body nuclei in Darevskia unisexualis and D. armeniaca. In this study, we re-evaluated the fusion hypothesis by studying diplotene chromosomes in adult females of sexual species D. raddei nairensis and obligate parthenogens D. armeniaca, D. dahli and D. unisexualis. We revealed 19 bivalents in the sexual species and 38 bivalents in the diploid obligate parthenogens, which uncovers premeiotic endoreplication as the mechanism of the production of non-reduced eggs in parthenogenetic females. The earlier contradicting reports can likely be attributed to the difficulty in identifying mispairing of chromosomes in pachytene, and the fact that in parthenogenetic reptiles relying on premeiotic endoreplication only a small subset of developing oocytes undergo genome doubling and overcome the pachytene checkpoint. This study highlights co-option of premeiotic endoreplication for escape from sexual reproduction in all independent hybrid origins of obligate parthenogenesis in vertebrates studied to date.

Comparison of four different protocols using levobupivacaine for spinal anaesthesia in red-footed tortoises (Chelonoidis carbonarius).

Background: The popularity of tortoises kept in captivity is increasing and has caused concern regarding the necessity to establish safe and straightforward anaesthesia for those reptiles. Aim: This study aimed to compare four protocols using levobupivacaine in spinal anaesthesia for the blockade of the caudal neuraxis of red-footed tortoises (Chelonoidis carbonarius). Methods: Twenty-four tortoises were randomly assigned into four groups: G1, levobupivacaine 0.75% (1.15 mg kg-1); G2, levobupivacaine 0.37% (1.15 mg kg-1); G3, levobupivacaine 0.75% (2.3 mg kg-1); and G4, levobupivacaine 0.75% (0.1 ml 5 cm-1 of straight carapace length). Tortoises were evaluated for respiratory rate, muscle relaxation, response to hindlimb or tail pinch, and cloacal reflex. Results: A 1.15 mg kg-1 dose of levobupivacaine 0.37% appears adequate for shorter procedures, whereas a 1.15 mg kg-1 dose of levobupivacaine 0.75% should be appropriate for longer procedures in red-footed tortoises. Conclusion: Our results are the first to show the effects of levobupivacaine on spinal anaesthesia in reptiles. Weight-based doses presented more intense and more homogeneous effects than carapace length-based doses in red-footed tortoises. Spinal anaesthesia of red-footed tortoises was safe and effective with any of the weight-based protocols.

Biological pest regulation can benefit from diverse predation modes.

Increases in agricultural intensity due to anthropogenic demands alongside the need to reduce the reliance on pesticides have resulted in an urgent need for sustainable options for pest control. Biological pest regulation is an alternative strategy that relies on natural predators and is essentially a by-product of successful foraging. Therefore, knowledge of the predator's specific foraging behaviour can significantly improve bioregulation. In this article, we discuss the implications of predators' diverse foraging modes on their efficiency as bioregulators of crop pests using amphibians and reptiles as models. Amphibians and reptiles are promising bioregulators as they are insectivorous, and the diversity in their foraging styles-ambush and active foraging, differing in energy expenditure, movement, cognitive abilities, reliance on cues, response to predatory risk, competition and prey salience-can have specific impacts on pest regulation. We propose the uptake of this concept into strategizing pest management actions. We are now moving towards an era of biological pest regulation, which is the most targeted, economically profitable method with zero negative impact on the ecosystem. Utilizing diverse traits associated with the different foraging modes in vertebrate predators can be a crucial tool in allowing pest management to adapt to the extreme challenges it is facing.

Postcranial anatomy of Besanosaurus leptorhynchus (Reptilia: Ichthyosauria) from the Middle Triassic Besano Formation of Monte San Giorgio (Italy/Switzerland), with implications for reconstructing the swimming styles of Triassic ichthyosaurs.

Besanosaurus leptorhynchus Dal Sasso & Pinna, 1996 was originally described on the basis of a single complete fossil specimen excavated near Besano (Italy). However, a recent taxonomic revision and re-examination of the cranial osteology allowed for the assignment of five additional specimens to the taxon. Here, we analyse, describe and discuss the postcranial anatomy of Besanosaurus leptorhynchus in detail. The size of the specimens examined herein ranged from slightly more than one meter to eight meters. Overall, several diagnostic character states for this taxon are proposed, demonstrating a mosaic of plesiomorphic and derived features. This is best exemplified by the limbs, which show very rounded elements in the forelimbs, and pedal phalanges with retained rudimentary shafts. We suggest that the widely spaced phalanges in the forefins of Besanosaurus leptorhynchus were embedded in a fibrocartilage-rich connective tissue, like in modern cetaceans. We also review the similarities of Besanosaurus with Pessopteryx and Pessosaurus, allowing us to conclude that Besanosaurus is not a junior synonym of either of the two taxa. Lastly, to test the swimming capabilities of Besanosaurus leptorhynchus, we expanded on a previously published study focussing on reconstructing the swimming styles of ichthyosaurs. Besanosaurus leptorhynchus was found to possess a peculiar locomotory mode, somewhat intermediate between anguilliform swimmers, such as Cymbospondylus and Utatsusaurus, and some shastasaur-grade (e.g., Guizhouichthyosaurus) and early-diverging euichthyosaurian (e.g., Californosaurus) ichthyosaurs. Based on our results, we furthermore suggest that mixosaurids acquired their characteristic body profile (dorsal fin and forefins that are distinctly enlarged compared to the hindfins) independently and convergently to the one that later appeared in Parvipelvia. Moreover, the different swimming styles inferred for Cymbospondylus, Mixosauridae, and Besanosaurus strengthen the earlier hypothesis of niche partitioning among these three distinct ichthyosaur taxa from the Besano Formation. Supplementary Information: The online version contains supplementary material available at 10.1186/s13358-024-00330-9.

Swiss ichthyosaurs: a review.

Switzerland is an ichthyosaur country: it has a rich record of marine reptile fossils, particularly the fish-shaped ichthyosaurs, and the according research. Here, we provide an overview over the 12 or more genera and at least 13 species plus numerous fragmentary remains of ichthyosaurs from the Triassic to the Cretaceous that have been discovered in twelve cantons thus far, of which four species are based on Swiss holotypes. This wealth of ichthyosaur species can be explained by their abundance in the Middle Triassic conservation deposits (Konservat Lagerstätte) of Monte San Giorgio, as well as occasional discoveries in strata of Middle Triassic to Early Cretaceous age. The moderate abundance of outcrops in reasonable conditions in combination with the long history of palaeontological research in Switzerland explains this good fossil record. In addition to this unique overview, we provide more data for further studies and update the knowledge of these taxa.

Transient Cooling Resets Circadian Rhythms of Locomotor Activity in Lizards.

Animals frequently experience temperature fluctuations in their natural life cycle, including periods of low temperatures below their activity range. For example, poikilothermic animals are known to enter a hibernation-like state called brumation during transient cooling. However, the knowledge regarding the physiological responses of brumation is limited. Specifically, the impact of exposure to low-temperature conditions outside the range of temperature compensation on the subsequent circadian behavioral rhythms remains unclear. In this study, we investigated the effects of transient cooling on the behavioral circadian rhythm in the non-avian reptile, the bearded dragon (Pogona vitticeps). Under constant light (LL) conditions at 30 °C, the animals exhibited a free-running rhythm, and exposure to low temperatures (4 °C) caused a complete cessation of locomotion. Furthermore, we revealed that the behavioral rhythm after rewarming is determined not by the circadian phase at the onset or the duration of cooling, but by the timing of cooling cessation.

Morphological evolution and niche conservatism across a continental radiation of Australian blindsnakes.

Understanding how continental radiations are assembled across space and time is a major question in macroevolutionary biology. Here, we use a phylogenomic-scale phylogeny, a comprehensive morphological dataset and environmental niche models to evaluate the relationship between trait and environment, and assess the role of geography and niche conservatism in the continental radiation of Australian blindsnakes. This fossorial snake group comprises 47 described species and is widespread across various biomes on continental Australia. Although we expected blindsnakes to be morphologically conserved, we found considerable interspecific variation in all morphological traits we measured. Absolute body length is negatively correlated with mean annual temperature and body shape ratios are negatively correlated with soil compactness. We found that morphologically similar species are likely not a result of ecological convergence. Age-overlap correlation tests revealed niche similarity decreased with relative age of speciation events. We also found low geographical overlap across the phylogeny suggesting speciation is largely allopatric with low rates of secondary range overlap. Our study offers insights into the eco-morphological evolution of blindsnakes, and the potential for phylogenetic niche conservatism to influence continental scale radiations.

Clinical features, surgical management and outcome of squamous and basal cell carcinoma in squamates and chelonians.

BACKGROUND: Squamous cell carcinoma (SCC) is one of the most commonly diagnosed neoplastic disorders in reptiles. Recently, however, it has been demonstrated that basal cell carcinomas (BCCs) are frequently misclassified as SCCs. Several histological SCC and BCC variants have been characterised and their classification may allow the establishment of appropriate prognosis estimation and treatment approaches. HYPOTHESIS/OBJECTIVES: To describe the clinical features and surgical outcomes of SCCs and BCCs diagnosed between 2010 and 2022 in reptiles. ANIMALS: Thirty-three captive reptiles (21 squamates and 12 chelonians). MATERIALS AND METHODS: Detailed clinical history, including staging and surgical outcomes, were performed. Statistical analysis assessed significant factors using Prism (v8.2.1). RESULTS: While SCC was predominantly diagnosed in lizards, BCC was most commonly diagnosed in chelonians, and both neoplasms mainly occurred in adult to aged, male individuals. Although the gross pathological findings were highly comparable between SCC and BCC, considerable variation could be seen according to the primary location (oral, cutaneous or epidermis of the shell). Humane euthanasia or noncurative intent surgeries were performed in a minority of the cases. Curative intent surgeries were successful in 19 of 27 cases during a 1- to 7-year follow-up period, yet recurrence was seen in 8 cases. The results of this study allowed the identification of significant high-risk prognostic factors for SCC and BCC in reptiles. CONCLUSIONS AND CLINICAL RELEVANCE: This study contributes to predicting the clinical behaviour and prognosis of distinct SCC and BCC histological variants, and selecting the most appropriate treatment protocol.

Microhabitat and adhesive toepads shape gecko limb morphology.

Different substrates pose varied biomechanical challenges that select specific morphologies, such as long limbs for faster running and short limbs for balanced posture while climbing narrow substrates. We tested how gecko locomotion is affected by the microhabitat they occupy and by a key adaptation-adhesive toepads-through analyzing how those are related to limb morphology. We collected microhabitat and toepads data for over 90% of limbed gecko species, and limb measurements for 403 species from 83 of the 121 limbed gecko genera, which we then used in phylogenetic comparative analyses. Our data highlight the association of adhesive toepads with arboreality, but a phylogenetic analysis shows that this relationship is not significant, suggesting that these traits are phylogenetically constrained. Comparative analyses reveal that pad-bearing species possess shorter hindlimbs and feet, more even limb lengths, and lower crus: thigh ratios, than padless geckos, across microhabitats. Saxicolous geckos have the longest limbs and limb segments. This is probably influenced by selection for long strides, increased takeoff velocity, and static stability on inclined surfaces. Terrestrial geckos have more even hind- and forelimbs than arboreal geckos, unlike patterns found in other lizards. Our findings underline the difficulty to infer on microhabitat-morphology relationships from one taxon to another, given their differing ecologies and evolutionary pathways. We emphasize the importance of key innovation traits, such as adhesive toepads, in shaping limb morphology in geckos and, accordingly, their locomotion within their immediate environment.

Arsenic and metal levels in snake tissues from Lagoa Santa Karst, Brazil.

Concentrations of one metalloid (As) and eight metals (Cd, Cr, Cu, Hg, Mn, Ni, Pb, and Zn) were determined in tissues (muscle, liver, and kidney) of eight snake species (Bothrops neuwiedi, Crotalus durissus, Dipsas mikanii, Epicrates crassus, Helicops modestus, Micrurus carvalhoi, Oxyrhopus guibei, and Oxyrhopus trigeminus) from Lagoa Santa Karst. Except for Cu and Zn, all other analyzed elements were detected in concentrations within the ranges previously reported for snakes inhabiting polluted areas, emphasizing Hg (specific Hg mean concentrations varied from 0.87 to 9.76 µg g-1 d.w). The highest mean concentrations of all elements except Zn were found in muscle samples of the false corals O. guibei (means ranged from 2.01 [Pb] to 9.76 [Hg]). The highest Zn mean concentration (13.77 µg g-1 d.w) was detected in the kidney of the water snake H. modestus. No significant correlation was found between element concentrations and body size for all species. Significant interorgan differences were observed for As, Cr, Cu, Hg, Mn, Pb, and Zn concentrations in the three tissues in H. modestus. Significant interspecific differences were found in at least one organ for all elements. Significant pairwise differences were found between diet specialist species and between these species and broader diet species, while no significant difference was found between the broader diet species. The bioaccumulation of As and metals in snakes from Lagoa Santa Karst could be associated with natural rock dissolution and erosion processes but also with the wide-scale mining in the region and the increased agriculture and urbanization.