Search Results (6)

Caudal autotomy, the ability to shed a portion of the tail, is a widespread defence strategy among lizards. Following caudal autotomy, and during regeneration, lizards face both short- and long-term costs associated with the physical loss of the tail and the energy required for regeneration. As such, the speed at which the individual regenerates its tail (regeneration rate) should reflect the fitness priorities of the individual. However, multiple factors influence the regeneration rate in lizards, making inter-specific comparisons difficult and hindering broader scale investigations. We review regeneration rates for lizards and tuatara from the published literature, discuss how species’ fitness priorities and regeneration rates are influenced by specific, life history and environmental factors, and provide recommendations for future research. Regeneration rates varied extensively (0–4.3 mm/day) across the 56 species from 14 family groups. Species-specific factors, influencing regeneration rates, varied based on the type of fracture plane, age, sex, reproductive season, and longevity. Environmental factors including temperature, photoperiod, nutrition, and stress also affected regeneration rates, as did the method of autotomy induction, and the position of the tail also influenced regeneration rates for lizards. Additionally, regeneration could alter an individual’s behaviour, growth, and reproductive output, but this varied depending on the species. Full article

The ability to repair injuries among reptiles, i.e., ectothermic amniotes, is similar to that of mammals with some noteworthy exceptions. While large wounds in turtles and crocodilians are repaired through scarring, the reparative capacity involving the tail derives from a combined process of wound healing and somatic growth, the latter being continuous in reptiles. When the tail is injured in juvenile crocodilians, turtles and tortoises as well as the tuatara (Rhynchocephalia: Sphenodon punctatus, Gray 1842), the wound is repaired in these reptiles and some muscle and connective tissue and large amounts of cartilage are regenerated during normal growth. This process, here indicated as “regengrow”, can take years to produce tails with similar lengths of the originals and results in only apparently regenerated replacements. These new tails contain a cartilaginous axis and very small (turtle and crocodilians) to substantial (e.g., in tuatara) muscle mass, while most of the tail is formed by an irregular dense connective tissue containing numerous fat cells and sparse nerves. Tail regengrow in the tuatara is a long process that initially resembles that of lizards (the latter being part of the sister group Squamata within the Lepidosauria) with the formation of an axial ependymal tube isolated within a cartilaginous cylinder and surrounded by an irregular fat-rich connective tissue, some muscle bundles, and neogenic scales. Cell proliferation is active in the apical regenerative blastema, but much reduced cell proliferation continues in older regenerated tails, where it occurs mostly in the axial cartilage and scale epidermis of the new tail, but less commonly in the regenerated spinal cord, muscles, and connective tissues. The higher tissue regeneration of Sphenodon and other lepidosaurians provides useful information for attempts to improve organ regeneration in endothermic amniotes. Full article

The tuatara or New Zealand “spiny-backed lizard” (Sphenodon punctatus) is the sole surviving member of an order of reptiles that pre-dates the dinosaurs. Among its characteristics and peculiarities, the tuatara is renowned for being slow-breathing and long-lived; it possesses a third eye on the top of its skull for sensing ultraviolet light; and the sex of its progeny is determined by soil temperatures. This article unravels a tuatara’s-eye view of climate change, considering this creature’s survival across geological epochs, its indigenous lineage and its sensitivities to the fast-shifting conditions of the Anthropocene. This article examines the tuatara’s evolving role as an icon of biodiversity-under-threat and the evolving role of zoos and sanctuaries as explicators of climate change, forestallers of extinction, and implementers of the reproductive interventions that are increasingly required to secure the future of climate-vulnerable species. It is also interested in the tuatara as a witness to the rapid and ongoing human-wrought climate change which has secured the lifeworld reconstruction that is foundational to the settler colonial enterprise in Aotearoa/New Zealand. Linking this to the Waitangi Tribunal’s Wai 262 report (Ko Aotearoa Tēnei, 2011), the article considers what the tuatara teaches about kaitiakitanga (guardianship) and climates of change. Full article

Because biological invasions can cause many negative impacts, accurate predictions are necessary for implementing effective restrictions aimed at specific high-risk taxa. The pet trade in recent years became the most important pathway for the introduction of non-indigenous species of reptiles worldwide. Therefore, we decided to determine the most common species of lizards, snakes, and crocodiles traded as pets on the basis of market surveys in the Czech Republic, which is an export hub for ornamental animals in the European Union (EU). Subsequently, the establishment and invasion potential for the entire EU was determined for 308 species using proven risk assessment models (RAM, AS-ISK). Species with high establishment potential (determined by RAM) and at the same time with high potential to significantly harm native ecosystems (determined by AS-ISK) included the snakes Thamnophis sirtalis (Colubridae), Morelia spilota (Pythonidae) and also the lizards Tiliqua scincoides (Scincidae) and Intellagama lesueurii (Agamidae). Full article

A recent study reported the discovery of an endogenous reptilian foamy virus (FV), termed ERV-Spuma-Spu, found in the genome of tuatara. Here, we report two novel reptilian foamy viruses also identified as endogenous FVs (EFVs) in the genomes of panther gecko (ERV-Spuma-Ppi) and Schlegel’s Japanese gecko (ERV-Spuma-Gja). Their presence indicates that FVs are capable of infecting reptiles in addition to mammals, amphibians, and fish. Numerous copies of full length ERV-Spuma-Spu elements were found in the tuatara genome littered with in-frame stop codons and transposable elements, suggesting that they are indeed endogenous and are not functional. ERV-Spuma-Ppi and ERV-Spuma-Gja, on the other hand, consist solely of a foamy virus-like env gene. Examination of host flanking sequences revealed that they are orthologous, and despite being more than 96 million years old, their env reading frames are fully coding competent with evidence for strong purifying selection to maintain expression and for them likely being transcriptionally active. These make them the oldest EFVs discovered thus far and the first documented EFVs that may have been co-opted for potential cellular functions. Phylogenetic analyses revealed a complex virus–host co-evolutionary history and cross-species transmission routes of ancient FVs. Full article

Reptiles are among the oldest known amniotes and are highly diverse in their morphology and ecological niches. These animals have an evolutionarily ancient innate-immune system that is of great interest to scientists trying to identify new and useful antimicrobial peptides. Significant work in the last decade in the fields of biochemistry, proteomics and genomics has begun to reveal the complexity of reptilian antimicrobial peptides. Here, the current knowledge about antimicrobial peptides in reptiles is reviewed, with specific examples in each of the four orders: Testudines (turtles and tortosises), Sphenodontia (tuataras), Squamata (snakes and lizards), and Crocodilia (crocodilans). Examples are presented of the major classes of antimicrobial peptides expressed by reptiles including defensins, cathelicidins, liver-expressed peptides (hepcidin and LEAP-2), lysozyme, crotamine, and others. Some of these peptides have been identified and tested for their antibacterial or antiviral activity; others are only predicted as possible genes from genomic sequencing. Bioinformatic analysis of the reptile genomes is presented, revealing many predicted candidate antimicrobial peptides genes across this diverse class. The study of how these ancient creatures use antimicrobial peptides within their innate immune systems may reveal new understandings of our mammalian innate immune system and may also provide new and powerful antimicrobial peptides as scaffolds for potential therapeutic development. Full article