Reptile Taxa Research Articles

Temperature-Dependent Sex Determination in Crocodilians and Climate Challenges.

The sex of crocodilians is determined by the temperature to which the eggs, and hence the developing embryo are exposed during critical periods of development. Temperature-dependent sex determination is a process that occurs in all crocodilians and numerous other reptile taxa. The study of artificial incubation temperatures in different species of crocodiles and alligators has determined the specific temperature ranges that result in altered sex ratios. It has also revealed the precise temperature thresholds at which an equal number of males and females are generated, as well as the specific developmental period during which the sex of the hatchlings may be shifted. This review will examine the molecular basis of the sex-determination mechanism in crocodilians elucidated during recent decades. It will focus on the many patterns and theories associated with this process. Additionally, we will examine the consequences that arise after hatching due to changes in incubation temperatures, as well as the potential benefits and dangers of a changing climate for crocodilians who display sex determination based on temperature.

Report of abnormal tail regeneration of Eremias yarkandensis (Sauria: Lacertidae) and its locomotor performance.

Caudal autotomy is a phenomenon observed in many reptile taxa, and tail loss is a pivotal functional trait for reptiles, with potentially negative implications for organism fitness due to its influence on locomotion. Some lizard species can regenerate a lost tail, which sometimes can lead to the development of more than one tail (i.e., abnormal tail regeneration) in the process. However, little is currently known about the impact of abnormal tail regeneration on locomotor performance. In this study, we document abnormal tail regeneration in Eremias yarkandensis, a reptile species native to northwestern China. Additionally, we investigated the sprint speed and endurance performance of these lizards. This study provides the first report on abnormal tail regeneration and its locomotor performance on a Chinese reptile. We suggest that the abnormal regeneration of tails may contribute to the accumulation of food reserves in the species. In light of our findings, we propose that herpetologists continue to share their sporadic observations and assess the locomotor performance of species experiencing abnormal tail regeneration, further expanding our understanding of this intriguing phenomenon.

A combined palaeomodelling approach reveals the role as selective refugia of the Mediterranean peninsulas

The northern Mediterranean reptiles and amphibians show contrasting biogeographic histories during the Plio-Pleistocene. The influence of European climate changes on the evolution of the biogeographic ranges of taxa with a rich fossil record is determined herein combining different proxies to obtain well-supported palaeoclimatic scenarios. Ecological Niche Modelling through the ensemble modelling approach was used to reconstruct the climatic niche of selected reptile and amphibian genera, combining modern occurrences with seven independent bioclimatic variables. The obtained model was then projected on past scenarios using fossil data to crosscheck the validity of the climatic explanation for the selective extirpations. Palaeobotanical proxies and the hypsodonty of mammals were used to reconstruct the humidity pattern of the last million years in the studied area. The climate of the Italian Peninsula during the Last Glacial Maximum was proved herein to be unsuitable for many reptile taxa, which persisted in this area until the Early or Late Pleistocene, whereas they survived till the present day in the Iberian and/or Balkans peninsulas. On the contrary, all the proxies agree that Italy was comparably more humid than the other peninsulas during the Pliocene and Pleistocene, therefore allowing the prolonged survival of amphibian taxa (including the still living Salamandrina and Speleomantes), which became extinct or extirpated elsewhere in Europe. An intensification of the conservation efforts concerning amphibians, particularly sensitive to the global climate change, is recommended in the Italian Peninsula, which acted as an amphibian refugium for Europe due to its peculiar climatic history.

Holocene vertebrate fauna in Fergana Valley, Kyrgyzstan, based on fossils from the Obishir-5 rock shelter

Central Asia is a region that, owing to its geographical position, has always been at the intersection of cultures. In the Fergana Valley, located in the very heart of Central Asia, the Late Pleistocene–Early Holocene is characterized by the expansion and intensification of human settlements. This cultural event has previously been linked to global climate changes that took place during the Pleistocene–Holocene transition. In order to reconstruct local climatic conditions in the area during this period, it is worth studying the fossil vertebrate faunas from late Quaternary sites in the Fergana Valley. The Obishir-5 rock shelter, dating to the Late Pleistocene–Early Holocene period, discovered in the middle of the 20th century, is a key archeological site in the valley. To date no thorough zooarcheological research has been done on the excavated faunal remains. Here we present the results of the first faunal analysis of the small vertebrates found at this site. We studied the taxonomic composition of remains, which was then used to make paleoenvironmental reconstructions. In total, we identified 13 small mammal species and three bird species. In addition, the assemblage contained one amphibian and two reptile taxa. The faunal composition suggests that during the final Pleistocene and Early Holocene the study area enjoyed a stable climate with vegetation dominated by open biotopes (alpine meadows, steppes, semi-deserts). Its location makes the Fergana Valley an example of a geographically isolated area for a terrestrial fauna which can exist for a long time without being influenced by biotic factors from neighbouring territories.

Skinks of Oceania, New Guinea, and Eastern Wallacea: an underexplored biodiversity hotspot

Context Skinks comprise the dominant component of the terrestrial vertebrate fauna in Oceania, New Guinea, and Eastern Wallacea (ONGEW). However, knowledge of their diversity is incomplete, and their conservation needs are poorly understood. Aims To explore the diversity and threat status of the skinks of ONGEW and identify knowledge gaps and conservation needs. Methods We compiled a list of all skink species occurring in the region and their threat categories designated by the International Union for Conservation of Nature. We used available genetic sequences deposited in the National Center for Biotechnology Information’s GenBank to generate a phylogeny of the region’s skinks. We then assessed their diversity within geographical sub-divisions and compared to other reptile taxa in the region. Key results Approximately 300 species of skinks occur in ONGEW, making it the second largest global hotspot of skink diversity following Australia. Many phylogenetic relationships remain unresolved, and many species and genera are in need of taxonomic revision. One in five species are threatened with extinction, a higher proportion than almost all reptile families in the region. Conclusions ONGEW contain a large proportion of global skink diversity on <1% of the Earth’s landmass. Many are endemic and face risks such as habitat loss and invasive predators. Yet, little is known about them, and many species require taxonomic revision and threat level re-assessment. Implications The skinks of ONGEW are a diverse yet underexplored group of terrestrial vertebrates, with many species likely facing extreme risks in the near future. Further research is needed to understand the threats they face and how to protect them.

Comparative cytogenetics on Zamenis lineatus and Elaphe quatuorlineata (Serpentes: Colubridae)

Because of their peculiar genomic and chromosomal characteristics, reptiles are extraordinary model organisms to study karyotype and sex chromosome evolution, but despite the growing interest in their evolutionary cytogenetics, only a small fraction of species have a known karyotype. We performed a comparative cytogenetic analysis on Elaphe quatuorlineata and Zamenis lineatus, using classic and molecular techniques. We provide the karyotype of these two species and an assessment of their chromosomal features. Chromosome analysis was performed with standard karyotyping, C-banding, sequential C-banding + CMA3 + DAPI and Ag-NOR staining. On E. quatuorlineata, we also performed CMA3-methyl green staining and Fluorescence in situ Hybridization mapping NOR loci (NOR-FISH). Elaphe quatuorlineata and Z. lineatus show a very similar karyotype of 2n = 36, with 8 macro- and 10 microchromosome pairs, but differ in the morphology of the pair 8, which resulted submetacentric in the former and metacentric in the latter species. By comparing our data to those available from the literature on congeneric species, we analysed the occurrence of primitive and derivate chromosomal characters and provide cytotaxonomic insights, which further support the species status of Z. lineatus. In both species, the 4th pair was identified as the sex chromosome pair (ZZ/ZW) and NORs were localized on a microchromosome pair. We finally highlight in both genera Elaphe and Zamenis different stages of heterochromatinization of the W chromosome, in agreement with the progressive diversification model of sex chromosome as already shown in different reptile taxa.

Impact of COVID‐19 on wild meat trade in Nigerian markets

Impact of <scp>COVID</scp>‐19 on wild meat trade in Nigerian markets

Late Miocene amphibians and reptiles: new insight into the pre-Messinian herpetofaunas in Turkey

ABSTRACT The herpetofauna of the late Miocene age in Turkey is nearly unknown, as it is represented by a single known anguine assemblage from the latest Miocene of Süleymanli locality. The amphibians and reptiles from the three early late Miocene (MN 9) localities of Bayraktepe 2, Kütahya, and Altıntaş in Anatolia are described here. One amphibian (Latonia spp.) and five squamate (Pseudopus sp., Varanus sp., Colubrinae indet. 1 and 2, and Naja sp.) taxa are revealed. The Bayraktepe 2 and Kütahya localities are dominated by anuran remains, and exclusively Latonia, whereas the Altıntaş locality is represented by reptilian taxa. Although the material is relatively poor, it provides the first information about the late Miocene assemblage of amphibians and reptiles in Turkey. The records of Naja and Varanus from Altıntaş are currently the oldest records of these taxa in Anatolia.

Heightened among-individual variation in life history but not morphology is related to developmental temperature in reptiles.

Increases in phenotypic variation under extreme (e.g. novel or stressful) environmental conditions are emerging as a crucial process through which evolutionary adaptation can occur. Lack of prior stabilizing selection, as well as potential instability of developmental processes in these environments, may lead to a release of phenotypic variation that can have important evolutionary consequences. Although such patterns have been shown in model study organisms, we know little about the generality of trait variance across environments for non-model organisms. Here, we test whether extreme developmental temperatures increase the phenotypic variation across diverse reptile taxa. We find that the among-individual variation in a key life-history trait (post-hatching growth) increases at extreme cold and hot temperatures. However, variations in two measures of hatchling morphology and in hatchling performance were not related to developmental temperature. Although extreme developmental temperatures may increase the variation in growth, our results suggest that plastic responses to stressful incubation conditions do not generally make more extreme phenotypes available to selection. We discuss the reasons for the general lack of increased variability at extreme incubation temperatures and the implications this has for local adaptation in hatchling morphology and physiology.

Aggregation Propensity of Serum Amyloid A1 in Captive Zoo and Free‐living Wild Animals

AA Amyloidosis is the most common form of amyloid disease, occurring in humans, domestic animals, wildlife and captive zoo animals and is defined by the misfolding of serum amyloid A (SAA), an apolipoprotein of high-density lipoprotein (HDL). SAA is a positive acute phase protein that is synthesized by the liver during chronic states of inflammation or stress, depositing mainly in the liver, spleen and kidneys. AA amyloidosis poses the highest risk to zoo species within captivity given the diverse number of species susceptible to the disease, transmissibility of the disease, pre-disposing factors, and close housing conditions in zoo facilities. Susceptibility to AA amyloidosis may be dependent upon the propensity of SAA to aggregate in different species. Variation in the 104 amino acid sequence of the SAA protein may contribute to the likelihood that SAA will misfold under chronic conditions. While the proteolytic cleavage or removal of the C-terminal tail of SAA is known to result in formation of fibrils, the molecular mechanism of SAA aggregation is not completely understood. This study proposes to investigate areas of the SAA1 peptide that are likely to misfold and how mutation has led to evolutionary divergence and species-specific susceptibility to the disease. A bioinformatic analysis was performed to predict the aggregation score (Tango program). Homology and variance in each SAA1 peptide were demonstrated via sequence alignment prepared in BioEdit. A phylogenetic analysis prompted us to identify potential mutations for the design of a peptide library. Using bioinformatic (tango program) and thioflavin-T fluorescence assays, we studied the aggregation propensity of SAA1 fragments derived from amyloidogenic species and non-amyloidogenic species. Aggregation propensity in the first 1-25 amino acids was assessed via Tango to which SAA1 in humans, felids, mice and equids were predicted to be most susceptible to aggregation, while SAA1 in avian and reptile taxa were least likely to aggregate. A ThT experiment performed on fragments belonging to 8 different species demonstrated that fragments from felids, mice and humans are highly prone to aggregate and supportive of bioinformatic results. SAA1 fragment peptides derived from the rainbow trout and Chinese soft-shelled turtles exhibited a low propensity of aggregation. Mutation in the SAA1 peptide may contribute to the amyloidogenicity of the protein, which may help identify high-risk species and establish an evolutionary basis for the disease. Evaluation and identification of peptide residues that have a higher propensity to aggregate, in addition to the evaluation of conditions that may contribute to misfolding, will help direct the development of small molecule therapeutics that prevent AA amyloidosis.

A high mountain lizard from Peru: The world’s highest-altitude reptile

Life at high altitudes is particularly challenging for ectothermic animals like reptiles and involves the evolution of specialised adaptations to deal with low temperatures, hypoxia and intense UV radiation. As a result, only very few reptile taxa are able to survive above 5,000 m elevation and herpetological observations from these altitudes are exceedingly rare. We report here an exceptional observation of a lizard population (Liolaemus aff. tacnae; Reptilia, Squamata) from the high Andes of Peru. During an ascent of Chachani mountain (6,054 m, 16°11'S, 71°32'W), we observed and documented photographically this species living between 5,000 and 5,400 m above sea level. Following a review of literature, we show that this is the highest known record of a reptile species.

Development of a 16S metabarcoding assay for the environmental DNA (eDNA) detection of aquatic reptiles across northern Australia

A severe lack of distribution data for aquatic reptiles in northern Australia leaves many taxa vulnerable to extirpation and extinction. Environmental DNA (eDNA) technologies offer sensitive and non-invasive genetic alternatives to trapping and visual surveys and are increasingly employed for the detection of aquatic and semi-aquatic reptiles. However, these eDNA approaches have largely applied species-specific primers that do not provide a cost-effective avenue for the simultaneous detection of multiple reptilian taxa. Here, we present a mitochondrial 16S rRNA metabarcoding assay for the broad detection of aquatic and semi-aquatic reptile species. This assay is tested on water samples collected at multiple sampling sites at two tropical locations, including 12 marine and estuarine sites in Roebuck Bay, Western Australia, and four estuarine sites in Cooktown, Queensland, Australia. In total, nine reptile taxa were detected from 10 of the 16 sampled sites, including marine and freshwater turtles, aquatic, semi-aquatic and terrestrial snakes, and terrestrial skinks. However, inconsistencies in the detection of previously observed aquatic reptiles at our sampled sites, such as saltwater crocodile and sea snakes, indicated that further research is required to assess the reliability, strengths and limitations of eDNA methods for aquatic reptile detection before it can be integrated as a broad-scale bioassessment tool.

Pequeños vertebrados del relleno kárstico del Pleistoceno Superior de Avetrana (Apulia, Sur de Italia)

El depósito (cavidad kárstica) de La Grave, localidad cercana a la pequeña ciudad de Avetrana (Tarento, Italia meridional), ha dado lugar a numerosos fósiles de vertebrados. Los restos de grandes mamíferos han sido objeto de varios estudios. En este trabajo se examinan los restos de pequeños vertebrados y se identifican cuatro taxones de anfibios (Bufo bufo, Bufotes gr. B. viridis, Hyla gr. H. Arborea and Rana (s.l.) sp.), cuatro de reptiles (Testudo hermanni, Podarcis sp., Zamenis gr. Z. longissimus, Natrix natrix), y nueve de pequeños mamíferos (Erinaceus europaeus, Crocidura suaveolens, Arvicola italicus, Microtus (Terricola) savii, Microtus (Microtus) arva­lis, Apodemus gr. A. sylvaticus - A. flavicollis, Hystrix (Acanthion) vinogradovi, Oryctolagus cuniculus and Lepus corsicanus). Desde un punto de vista biocronológico, los datos sobre los vertebrados pequeños y grandes indican una edad entre el comienzo del Pleistoceno tardío (MIS 5e) y la parte central del MIS 3. Es probable que el estrato fosilífero más reciente (nivel 8) se haya depositado durante un período más frío en comparación con las capas anteriores. Los datos de pequeños vertebrados fósiles combinados con los que proceden de los grandes mamífe­ros y aves evidencian la presencia, cerca de la cavidad kárstica, de espacios abiertos (praderas) con charcos de agua, bordeados por zonas boscosas y, no muy lejos, la presencia de una costa rocosa.

Annotated list of amphibian and reptile taxa described by Ilya Sergeevich Darevsky (1924–2009)

Ilya S. Darevsky co-described 70 taxa (three genera, 46 species, 21 subspecies) in 44 publications belonging to five orders, eight families of amphibians and reptiles during his career in herpetology. Of this number, three taxa are fossil and 57 taxa are currently considered as valid. By the regions where new taxa were discovered Southeast Asia and Western Asia (includes Caucasus and Asia Minor) dominates. The largest number of descriptions was published in the Russian Journal of Herpetology.

A contribution to the herpetofauna from the late Miocene of Gritsev (Ukraine)

Excavations in the locality Gritsev (karstic fillings of the upper Miocene age in a limestone quarry in Shepetovsky District, Khmelnitsky Region, Ukraine) revealed, since 1983 when excavations started, a rich vertebrate fauna that includes also amphibians and lizards. The material is rich enough to assess individual and developmental variation within some taxa (e.g., Pseudopus pannonicus). Although the fragmentary nature of the disarticulated bones does not sometimes allow precise taxonomic assignment, morphological differences in, e.g., dental characteristics suggest the presence of some other ones, not formally named forms. Thus, the list of the amphibian and reptilian taxa from Gritsev is by far not complete, but their osteological characteristics are representative to such a degree that they can provide information for comparisons with other European Miocene herpetofaunas.

Variable reptile responses to introduced predator control in southern Australia

Context Australia harbours an immense diversity of reptiles, which are generally expected to have frequent and diverse trophic interactions with introduced mammalian carnivores. Nevertheless, the potential for predatory or competitive interactions is likely to be contingent on multiple processes, including the importance of reptiles in the diet of introduced predators, alongside overlaps in their body sizes and ecological niches that would influence the strength of their interactions. In Australia’s temperate and relatively productive mesic environments there is little understanding of how introduced mammalian predators affect reptile assemblages. Aims The aim was to investigate the effects that a European red fox (Vulpes vulpes; 5–7kg) suppression program had on the abundance and species richness of a reptile community, with species ranging in size from the largest local ectothermic predator, the lace monitor (Varanus varius; 4–7kg), to small terrestrial reptiles (mostly 10–150g). Methods We utilised two sampling designs (baited camera monitoring stations and pitfall trapping) to evaluate the effects of fox suppression and other site-level ecological covariates (fire regime and habitat vegetation characteristics) on the lace monitor and small terrestrial reptiles. Reptile abundance and richness at site level were estimated from count-related abundance models. Key results For lace monitors, significantly higher abundances occurred in poison-baited areas relative to control areas. This suggests that fox suppression can affect the populations of the lace monitor via mesopredator release arising from reduced competition and, possibly, predation. For small terrestrial reptiles, neither abundance nor species richness were influenced by fox suppression. Individual abundances of the three most common small reptile species matched the overall pattern, as only responses to structural parameters of the habitat were detected. Conclusions Fox suppression can have different impacts for different reptile taxa, pending their ecological niche, as only the largest species was affected. Implications Increase in lace monitor abundance may change food web dynamics in fox-suppressed sites, such as by increasing predation pressure on arboreal marsupials.

Town and Country Reptiles: A Review of Reptilian Responses to Urbanization.

The majority of the world population is now inhabiting urban areas, and with staggering population growth, urbanization is also increasing. While the work studying the effects of changing landscapes and specific urban pressures on wildlife is beginning to amass, the majority of this work focuses on avian or mammalian species. However, the effects of urbanization likely vary substantially across taxonomic groups due to differences in habitat requirements and life history. The current article aims first to broaden the review of urban effects across reptilian species; second, to summarize the responses of reptilian fauna to specific urban features; and third, to assess the directionality of individual and population level responses to urbanization in reptile species. Based on our findings, urban research in reptilian taxa is lacking in the following areas: (1) investigating interactive or additive urban factors, (2) measuring multiple morphological, behavioral, and physiological endpoints within an animal, (3) linking individual to population-level responses, and (4) testing genetic/genomic differences across an urban environment as evidence for selective pressures.

All is Not Lost: Herpetofaunal “Extinctions” in the Fiji Islands

Abstract: Invasive mammals are implicated in the decline or extinction of numerous insular vertebrate species worldwide, yet rediscoveries of supposedly extinct vertebrates occur regularly. In particular, recent records of secretive amphibian and reptile taxa in the Fiji Islands show that earlier claimed extirpations of Fijian wildlife were erroneous. We add to this growing body of evidence by documenting the Fiji barred treeskink Emoia trossula (Squamata: Scincidae) from Vanua Levu island, Fiji, where it was widely considered extirpated. Regional literature, coupled with this new record, emphasizes the conservation importance of remote forest blocks in Fiji as refugia against nonnative predatory mammals. Moreover, a clear need exists for additional survey work in Fiji to document the contemporary distribution of endemic and endangered herpetofaunal species across the archipelago.

Integrating "Evo" and "Devo": The Limb as Model Structure.

Reconciling the origins of morphological diversity with the deep homology of underlying mechanisms is a question fundamental to the goals of evolutionary developmental biology ("evo-devo" or EDB). In this paper I argue that differing research agendas in evolutionary and developmental biology have hindered how we address this question, but that the limb provides ideal "common ground" for their fuller integration. To support this idea, I review two previous analyses of limb variation in mammal, bird, and reptile taxa that offer complementary approaches to explaining diversity. Specifically, I present evidence suggesting that: (1) a shared genetic architecture affects the pattern of between limb developmental integration, while their functional dissociation is linked to both increased phenotypic evolvability and diversity of interlimb proportions, and (2) within limb proportional diversity is biased such that proximal and distal segments function as tradeoffs while the middle segment is more conservative, a signal that is both evident from early in morphogenesis and suggestive of an "inhibitory cascade" model of limb proximo-distal axis development. In the first case, shared genetic mechanisms predict both observed developmental integration between limbs and patterns of clade-specific diversity. In the second case, underappreciated patterns of phenotypic diversity suggest novel insights into the underlying developmental mechanisms by which variation is generated. These studies show how insights from both evolutionary and developmental biology of the limb may be used to generate novel testable hypotheses into the origins of diversity that are broadly applicable to the integration of EDB.

Early twentieth-century paleontological research of Freidrich von Huene: contributions to the knowledge of Late Cretaceous vertebrates of Central Brazil

Friedrich von Huene’s important scientific research on tetrapod fossils from Central Brazil has received little attention, even though it represents a significant contribution to early studies of vertebrate paleontology in the country including the first discoveries of dinosaur fossils in Brazil. von Huene described five reptile taxa in two papers published in important German scientific journals and used these specimens to make paleogeographic inferences regarding the Cretaceous of the Southern Hemisphere. von Huene warrants recognition as the first specialist to describe in detail the fossil reptile fauna of Central Brazil, which was made possible only by his network of contacts with important and influential naturalists of the cities of Rio de Janeiro and São Paulo.