First evidence towards chemical self-recognition in a gecko

Self-recognition is the ability to recognise stimuli originating from oneself. Humans and most great apes show evidence of true self-recognition in the mirror test. They use their reflection to remove a mark that is only visible in the mirror. Not all animals, however, rely primarily on vision. In lizards, chemical cues are important in social interactions. A number of lizard species show chemical self-recognition but it has never been investigated in a gecko species. Here, we test the tokay gecko (Gekko gecko) a territorial species with parental care on their ability to discriminate their own skin and faecal chemicals from those of same-sex, unfamiliar conspecifics. Geckos show a higher response rate towards chemicals from unfamiliar individuals compared to self-produced chemicals and a water control. Lizards showed self-directed behaviour, responded stronger to skin chemicals and females responded more than males. Our study provides first evidence towards self-recognition and for a social function of chemical present on faeces in tokay geckos but further tests are needed to confirm true self-recognition. Tokay geckos are an excellent model species to investigate individual recognition to demonstrate more sophisticated social cognitive abilities than have previously been attributed to reptiles.

Evaluation on the Legal Trade of Tokay gecko (Lacertidae; Gekkonidae; Gekko gecko Linnaeus, 1758) in Indonesia

Tokay gecko (Gekko gecko) is a large-sized gecko from the genus of Gekko, which is most commonly found from South Asia, southern China, and Southeast Asia. In Indonesia, these species are common to inhabit human-modified habitat in Sumatera, Borneo, Java, Bali, Lesser Sundas, Sulawesi, and Moluccas. In recent years, the demand for Tokay gekko with high use-value in both national and international markets has increased, one of which is used for traditional medicine. This situation raised the concern on the decreasing of the wild population and the validity of captive breeding programs that produced a large number of individuals. Several reports had estimated millions of individuals have been exported from Indonesia either legally or illegally, however, the exact number never been reported. The purpose of this study is to evaluate the trend on the harvested Tokay gecko and its origin based on the source code information. The data were collected from government records, including specimens harvested from the wild and specimens produced from captivity during 2013 - 2018 (six years). The results showed that the legally exported specimens were sourced from wild (W) and captive breeding (C or F). The total numbers of individuals exported from the wild harvest are 97.146, and all export realization is below the wild harvest quota. However, there are the large numbers of individuals exported and declared as specimens produced from the captive breeding facilities (6.965.000 with source code F, and 1.236.000 with source code C). More importantly, the high level of specimens produced from captive breeding facilities is unlikely to match with the biological capacity of this species. Therefore, we predict that specimens labeled captive breeding were likely sourced from the wild.

Strongly directional responses to tones and conspecific calls in the auditory nerve of the Tokay gecko, Gekko gecko.

The configuration of lizard ears, where sound can reach both surfaces of the eardrums, produces a strongly directional ear, but the subsequent processing of sound direction by the auditory pathway is unknown. We report here on directional responses from the first stage, the auditory nerve. We used laser vibrometry to measure eardrum responses in Tokay geckos, and in the same animals recorded 117 auditory nerve single fiber responses to free-field sound from radially distributed speakers. Responses from all fibers showed strongly lateralized activity at all frequencies, with an ovoidal directivity that resembled the eardrum directivity. Geckos are vocal and showed pronounced nerve fiber directionality to components of the call. To estimate the accuracy with which a gecko could discriminate between sound sources, we computed the Fisher information (FI) for each neuron. FI was highest just contralateral to the midline, front and back. Thus, the auditory nerve could provide a population code for sound source direction, and geckos should have a high capacity to differentiate between midline sound sources. In brain, binaural comparisons, for example by IE neurons, should sharpen the lateralized responses and extend the dynamic range of directionality.

Setal Field Transects, Evolutionary Transitions and Gecko–Anole Convergence Provide Insights Into the Fundamentals of Form and Function of the Digital Adhesive System of Lizards

Recent years have witnessed a multitude of studies focusing on gekkotan adhesion. Intense interest in this phenomenon was triggered by the discovery of the manner and magnitude of the forces generated by the hair-like filaments (setae) on the toe pads and inspired the development of the next generation of smart, reversible synthetic adhesives. Most studies pursuing these goals have concentrated on the generalized form and properties of gekkotan setae outlined in those key early studies, resulting in the fabrication of synthetic filaments of uniform dimensions. Although there are over 1,800 species of extant geckos, and hundreds of species of anoles (a separate lizard lineage that has convergently evolved adhesive toe pads), most investigations have used relatively few species as the source of basic information, the Tokay gecko (Gekko gecko) being the most prominent among these. Such exemplar taxa generally exhibit structurally intricate setae and morphologically complex configurations of the adhesive apparatus. Setal structure taken to be characteristic of these taxa is generally reported by singular statements of maximal length, diameter, density and branching pattern. Contemporaneous work focusing on the configuration of setae at locations across the toe pads and upon the evolutionary origin of adhesively competent digits in anoles and specific lineages of geckos, however, has revealed extensive variation of setal structure within individuals, information about how setae may have arisen from non-adhesive filamentous precursors, and how newly adhesively competent digits have been integrated into pre-existing patterns of locomotor mechanics and kinematics. Such observations provide insights into what is minimally necessary for adhesively competent digits to function and reveal the simplest configuration of components that make this possible. We contend that information gleaned from such studies will assist those seeking to employ the principles of fibrillar-based adhesion, as exemplified by lizards, for bio-inspired applications.

Specific DNA mini-barcoding for identification of Gekko gecko and its products

Background The dry body of the Tokay Gecko (Gekko gecko) is the source of a valuable traditional Chinese medicine, it is therefore listed as a Class II protected animal species in China. Due to increasing market demand and a declining supply of the species, a considerable number of adulterants have emerged in the market. Thus, it is necessary to establish an accurate and rapid method of identification for distinguishing G. gecko from its adulterants and for separating it from highly processed products. Methods A total of 274 COI sequences were analyzed by using MEGA 5.0 software. Several specific primers were designed to amplify mini-barcode regions and identify G. gecko from its counterfeits and products. Results 274 COI sequences of G. gecko and 15 adulterants species were analyzed. G. gecko could be distinguished from its adulterants through BLAST analysis, intra- and inter-specific distance analyses, and an NJ tree based on COI sequences. Two pairs of specific primers designed for this study, COISF2/COISR2 and COISF3/COISR3, amplified 200- and 133-bp fragments of the COI region, respectively, both of which were suitable for the identification of G. gecko and its adulterants. Furthermore, COISF3/COISR3 detected G. gecko in 15 batches of products. Conclusion Therefore, the specific DNA mini-barcoding method developed here may be a powerful tool for the identification of G. gecko and counterfeits, and may also be used to distinguish G. gecko from its highly processed by-products.