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Hsu, Ping Yuan, Liehui Ge, Xiaopeng Li, Alyssa Y. Stark, Chrys Wesdemiotis, Peter H. Niewiarowski i Ali Dhinojwala. "Direct evidence of phospholipids in gecko footprints and spatula–substrate contact interface detected using surface-sensitive spectroscopy". Journal of The Royal Society Interface 9, nr 69 (24.08.2011): 657–64. http://dx.doi.org/10.1098/rsif.2011.0370.
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Observers ranging from Aristotle to young children have long marvelled at the ability of geckos to cling to walls and ceilings. Detailed studies have revealed that geckos are ‘sticky’ without the use of glue or suction devices. Instead, a gecko's stickiness derives from van der Waals interactions between proteinaceous hairs called setae and substrate. Here, we present surprising evidence that although geckos do not use glue, a residue is transferred on surfaces as they walk—geckos leave footprints . Using matrix-free nano-assisted laser desorption-ionization mass spectrometry, we identified the residue as phospholipids with phosphocholine head groups. Moreover, interface-sensitive sum-frequency generation spectroscopy revealed predominantly hydrophobic methyl and methylene groups and the complete absence of water at the contact interface between a gecko toe pad and the substrate. The presence of lipids has never been considered in current models of gecko adhesion. Our analysis of gecko footprints and the toe pad–substrate interface has significant consequences for models of gecko adhesion and by extension, the design of synthetic mimics.
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Barton, Diane P., Paolo Martelli, William Luk, Xiaocheng Zhu i Shokoofeh Shamsi. "Infection of Hexametra angusticaecoides Chabaud & Brygoo, 1960 (Nematoda: Ascarididae) in a population of captive crested geckoes, Correlophus ciliatus Guichenot (Reptilia: Diplodactylidae)". Parasitology 147, nr 6 (12.02.2020): 673–80. http://dx.doi.org/10.1017/s0031182020000219.
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AbstractHere we report on the infection of captive crested geckos Correlophus ciliatus Guichenot (Reptilia: Diplodactylidae), with adults of the ascaridoid nematode, Hexametra angusticaecoides Chabaud & Brygoo, 1960 (Ascarididae). A population of captive crested geckoes became ill and died within a short period of time. Nematodes were recovered from the crested geckoes examined from within the coelomic cavity, penetrating various organs and migrating through subcutaneous tissues, as well as emerging through the geckos' skin. One gecko was treated with levamisole following surgical excision of nematodes from under the skin; this gecko survived. The potential source of the nematode infection in the captive geckoes is discussed. It is most likely that wild-caught Madagascan mossy geckoes, Uroplatus sikorae Boettger (Reptilia: Gekkonidae), introduced the infection to the colony. Molecular sequences of the nematodes are the first produced for the members of this genus. A redescription of the species and its genetic characterization based on the internal transcribed spacer sequence data is provided, suggesting some of the morphological criteria that have been used in the past to distinguish between Hexametra spp. may have been intraspecific morphological variations.
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Stark, Alyssa Y., i Christopher T. Mitchell. "Stick or Slip: Adhesive Performance of Geckos and Gecko-Inspired Synthetics in Wet Environments". Integrative and Comparative Biology 59, nr 1 (27.04.2019): 214–26. http://dx.doi.org/10.1093/icb/icz008.
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Abstract The gecko adhesive system has inspired hundreds of synthetic mimics principally focused on replicating the strong, reversible, and versatile properties of the natural system. For geckos native to the tropics, versatility includes the need to remain attached to substrates that become wet from high humidity and frequent rain. Paradoxically, van der Waals forces, the principal mechanism responsible for gecko adhesion, reduce to zero when two contacting surfaces separate even slightly by entrapped water layers. A series of laboratory studies show that instead of slipping, geckos maintain and even improve their adhesive performance in many wet conditions (i.e., on wet hydrophobic substrates, on humid substrates held at low temperatures). The mechanism for this is not fully clarified, and likely ranges in scale from the chemical and material properties of the gecko’s contact structures called setae (e.g., setae soften and change surface confirmation when exposed to water), to their locomotor biomechanics and decision-making behavior when encountering water on a substrate in their natural environment (e.g., some geckos tend to run faster and stop more frequently on misted substrates than dry). Current work has also focused on applying results from the natural system to gecko-inspired synthetic adhesives, improving their performance in wet conditions. Gecko-inspired synthetic adhesives have also provided a unique opportunity to test hypotheses about the natural system in semi-natural conditions replicated in the laboratory. Despite many detailed studies focused on the role of water and humidity on gecko and gecko-inspired synthetic adhesion, there remains several outstanding questions: (1) what, if any, role does capillary or capillary-like adhesion play on overall adhesive performance of geckos and gecko-inspired synthetics, (2) how do chemical and material changes at the surface and in the bulk of gecko setae and synthetic fibrils change when exposed to water, and what does this mean for adhesive performance, and (3) how much water do geckos encounter in their native environment, and what is their corresponding behavioral response? This review will detail what we know about gecko adhesion in wet environments, and outline the necessary next steps in biological and synthetic system investigations.
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Gao, Xue Shan, Jie Shao, Fu Quan Dai, Cheng Guo Zong i Wen Zeng Guo. "A Gecko-Inspired Robot for Wind Power Tower Inspection". Applied Mechanics and Materials 461 (listopad 2013): 831–37. http://dx.doi.org/10.4028/www.scientific.net/amm.461.831.
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In order to accomplish the task of wind power tower inspection, a heavy-loaded climbing robot inspired by geckos is presented in this paper. The robot not only imitates body’s functions of geckos but also shows a design method. Wind power tower is a conical wall surface and its smallest radius is less than 2m. There will be a great gap when a robot climbing on such wall with small radius. The extraordinary climbing ability of geckos is considered as a remarkable design of nature that is attributed to its soft body, its multi-degree-of-freedom legs, and its strong-adsorbed toes. Focus on the feature of working on such wall surface, gecko’s body, toes and legs are simplified as free joints, magnetic units and redundant tracks respectively, based on the functions of gecko’s limbs and body. The adaptability of the robot is tested by the experiments in laboratory. With the gecko-inspired structure, the robot can climb on the wall surface with minimum 2m in diameter in any direction.
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Uetz, Peter, Alex Slavenko, Shai Meiri i Matthew Heinicke. "Gecko diversity: a history of global discovery". Israel Journal of Ecology and Evolution 66, nr 3-4 (6.11.2020): 117–25. http://dx.doi.org/10.1163/22244662-bja10003.
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1935 gecko species (and 224 subspecies) were known in December 2019 in seven families and 124 genera. These nearly 2000 species were described by ~950 individuals of whom more than 100 described more than 10 gecko species each. Most gecko species were discovered during the past 40 years. The primary type specimens of all currently recognized geckos (including subspecies) are distributed over 161 collections worldwide, with 20 collections having about two thirds of all primary types. The primary type specimens of about 40 gecko taxa have been lost or unknown. The phylogeny of geckos is well studied, with DNA sequences being available for ~76% of all geckos (compared to ~63% in other reptiles) and morphological characters now being collected in databases. Geographically, geckos occur on five continents and many islands but are most species-rich in Australasia (which also houses the greatest diversity of family-level taxa), Southeast Asia, Africa, Madagascar, and the West Indies. Among countries, Australia has the highest number of geckos (241 species), with India, Madagascar, and Malaysia being the only other countries with more than 100 described species each. As expected, when correcting for land area, countries outside the tropics have fewer geckos.
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Suwatik, Suwatik, Nenden Sri Wahyuni, Santi Mulyawati, Mulik Siti Nur Rohmah, Rr Indira Dewi Anggraeni, Raflen Ari Gerungan i Diki Diki. "Preliminary Study of Common House Gecko (Cosymbotus platyurus) Density in Java Island". International Journal of Research in Community Services 2, nr 4 (5.10.2021): 142–49. http://dx.doi.org/10.46336/ijrcs.v2i4.226.
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Common house gecko (Cosymbotus platyurus) is the most abundant house gecko species in Indonesia. The geckos live in home yard, garden, and in homes. It is part of food chain in its habitat, as its preys include cockroaches, flies, and termites. Previous studies found that this gecko are not found in mountainous area in West Java. In this study, the researchers observe population density of common house geckos in various types of habitats (houses and parks) with their home territory. The methods used were direct survey methods followed by literature study. The study is conducted in Java island (Jakarta, Tangerang, Bandung, Bogor, Sleman). Preliminary result of this study is house geckos are very active at night, because of the effect of light produced by lights that attract the attention of insects, gecko food.
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Song, Yi, Zhendong Dai, Zhouyi Wang i Robert J. Full. "Role of multiple, adjustable toes in distributed control shown by sideways wall-running in geckos". Proceedings of the Royal Society B: Biological Sciences 287, nr 1926 (6.05.2020): 20200123. http://dx.doi.org/10.1098/rspb.2020.0123.
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Remarkable progress has been made characterizing one of nature's most integrated, hierarchical structures––the fibrillar adhesive system of geckos. Nonetheless, we lack an understanding of how multiple toes coordinate to facilitate geckos' acrobatic locomotion. Here, we tested the control function of gecko toes by running them on vertical substrates varying in orientation, friction and roughness. Sideways wall-running geckos realigned the toes of their top feet upward to resist gravity. Toe contact area was not compromised, but redistributed. Geckos aligned all toes upward to resist slipping when encountering low-friction patches during sideways wall-running. Negotiation of intermittent slippery strips showed an increased contribution of particular toes to compensate for toes that lost adhesion. Increasing substrate roughness using discrete rods perpendicular to sideways locomotion resulted in geckos bending and/or rotating toes to conform to and even grasp the rods, with potential forces more than five times body weight. Geckos increase their effectiveness of manoeuvrability in demanding environments by taking advantage of the distributed control afforded by multiple toes. Our findings provide insight on biological attachment and offer inspiration to advance gecko-inspired robotics and other biomimetic applications.
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Hu, Shihao, Stephanie Lopez, Peter H. Niewiarowski i Zhenhai Xia. "Dynamic self-cleaning in gecko setae via digital hyperextension". Journal of The Royal Society Interface 9, nr 76 (13.06.2012): 2781–90. http://dx.doi.org/10.1098/rsif.2012.0108.
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Gecko toe pads show strong adhesion on various surfaces yet remain remarkably clean around everyday contaminants. An understanding of how geckos clean their toe pads while being in motion is essential for the elucidation of animal behaviours as well as the design of biomimetic devices with optimal performance. Here, we test the self-cleaning of geckos during locomotion. We provide, to our knowledge, the first evidence that geckos clean their feet through a unique dynamic self-cleaning mechanism via digital hyperextension. When walking naturally with hyperextension, geckos shed dirt from their toes twice as fast as they would if walking without hyperextension, returning their feet to nearly 80 per cent of their original stickiness in only four steps. Our dynamic model predicts that when setae suddenly release from the attached substrate, they generate enough inertial force to dislodge dirt particles from the attached spatulae. The predicted cleaning force on dirt particles significantly increases when the dynamic effect is included. The extraordinary design of gecko toe pads perfectly combines dynamic self-cleaning with repeated attachment/detachment, making gecko feet sticky yet clean. This work thus provides a new mechanism to be considered for biomimetic design of highly reuseable and reliable dry adhesives and devices.
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Gumbs, Rikki, Rachel C. Williams, Anthony M. Lowney i Darrell Smith. "Spatial and species-level metrics reveal global patterns of irreplaceable and imperiled gecko phylogenetic diversity". Israel Journal of Ecology and Evolution 66, nr 3-4 (6.11.2020): 239–52. http://dx.doi.org/10.1163/22244662-bja10020.
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Abstract Phylogenetic Diversity (PD) is increasingly recognised as a useful tool for prioritising species and regions for conservation effort. Increased availability of spatial and phylogenetic data for reptiles now facilitates their inclusion in phylogenetically-informed conservation prioritisation efforts. Geckos are a highly divergent and diverse clade that comprises almost 20% of global reptile diversity. Their global distribution is coincident with numerous anthropogenic threats, making them worthy of conservation prioritisation. Here, we combine phylogenetic, spatial distribution and extinction risk data for geckos with global human encroachment data to identify both regions and species representing irreplaceable gecko diversity at risk from human pressure. We show that high levels of irreplaceable gecko diversity are restricted to regions under intense human pressure, such as India, Sri Lanka and the Caribbean. There is a lack of extinction risk data for the western regions of Angola and Namibia, and yet these regions harbour high levels of irreplaceable diversity. At the species level, geckos display more unique PD than other lizards and snakes and are of greater conservation concern under our metric. The PD represented by Data Deficient geckos is at comparable risk to that of Endangered species. Finally, estimates of potential gecko diversity loss increase by up to 300% when species lacking extinction risk data are included. Our analyses show that many evolutionarily unique gecko species are poorly known and are at an increased risk of extinction. Targeted research is needed to elucidate the conservation status of these species and identify conservation priorities.
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Meiri, Shai. "What geckos are – an ecological-biogeographic perspective". Israel Journal of Ecology and Evolution 66, nr 3-4 (6.11.2019): 253–63. http://dx.doi.org/10.1163/22244662-20191075.
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Geckos are a hyper-diverse, ancient, and globally distributed group. They have diverged early from other squamates and thus can be expected to differ from them along multiple ecological, life history, and biogeographic axes. I review a wide range of gecko traits, comparing them to those of other lizard taxa, to identify the unique, and unifying, attributes of geckos among lizards, based on comprehensive databases of lizard distributions and biological attributes. Few traits completely separate geckos from other lizard taxa, yet they differ to a large degree along many axes: they are more restricted to low latitudes and altitudes, are especially diverse on islands, but relatively scarce in America. They are small lizards, that lay small, fixed clutch sizes, for which they compensate only partially by laying frequently. Because they mature at relatively similar ages and have similar lifespans to other lizards, geckos produce fewer offspring over a year, and over their lifetimes, perhaps implying that they enjoy higher survival rates. While being the only large lizard clade of predominantly nocturnal lizards a large proportion of species is active by day. Gecko body temperatures and preferred temperatures are lower than those of other lizards –even when they are compared to lizards with similar activity times. Worryingly, most geckos have small ranges that often reside completely outside of protected areas – much more frequently than in other reptile and vertebrate taxa.
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Stewart, William J., i Timothy E. Higham. "Passively stuck: death does not affect gecko adhesion strength". Biology Letters 10, nr 12 (grudzień 2014): 20140701. http://dx.doi.org/10.1098/rsbl.2014.0701.
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Many geckos use adhesive toe pads on the bottom of their digits to attach to surfaces with remarkable strength. Although gecko adhesion has been studied for hundreds of years, gaps exist in our understanding at the whole-animal level. It remains unclear whether the strength and maintenance of adhesion are determined by the animal or are passively intrinsic to the system. Here we show, for the first time, that strong adhesion is produced passively at the whole-animal level. Experiments on both live and recently euthanized tokay geckos ( Gekko gecko ) revealed that death does not affect the dynamic adhesive force or motion of a gecko foot when pulled along a vertical surface. Using a novel device that applied repeatable and steady-increasing pulling forces to the foot in shear, we found that the adhesive force was similarly high and variable when the animal was alive (mean ± s.d. = 5.4 ± 1.7 N) and within 30 min after death (5.4 ± 2.1 N). However, kinematic analyses showed that live geckos are able to control the degree of toe pad engagement and can rapidly stop strong adhesion by hyperextending the toes. This study offers the first assessment of whole-animal adhesive force under extremely controlled conditions. Our findings reveal that dead geckos maintain the ability to adhere with the same force as living animals, disproving that strong adhesion requires active control.
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Shang, Lei, Wen Bo Wang, Ting Ting Liu, Lei Cai, Hao Wang i Zhen Dong Dai. "An Equipment Used for Studying the Vestibular Perception of Gekko gecko". Applied Mechanics and Materials 461 (listopad 2013): 570–76. http://dx.doi.org/10.4028/www.scientific.net/amm.461.570.
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The study of vestibule neurons specific firing mode of Gekko gecko under stimulus of different angles and rotating speeds has an important theoretical significance to reveal the control mechanism of Gekko geckos vestibular position as well as to the development of gecko-robots. A vari-angle rotating equipment was made to give different stimulus in study of Gekko geckos vestibular electrophysiology. The equipment mainly consisted of four parts as follows: fastening panel for stereotaxic instrument, shaft locking device, counterweight, driving system. The shaft locking device and counterweight realized tight fixation and torque equilibrium at different angles respectively. Fastening panel matched the general stereotaxic instrument. A stepper motor driver controlled the velocity and acceleration of rotation. Initial experiment verified that the equipment had superiority of easy operation, reliable positioning and accurate control of angle and speed, which indicated that it could meet the demand of the Gekko geckos vestibule research.
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Cermakova, E., M. Oliveri, Z. Knotkova i Z. Knotek. "Effect of a GnRH agonist (deslorelin) on ovarian activity in leopard geckos (Eublepharis macularius)". Veterinární Medicína 64, No. 5 (28.05.2019): 228–30. http://dx.doi.org/10.17221/167/2018-vetmed.
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The aim of this study was to evaluate the effectiveness of deslorelin acetate in the regulation of reproductive activity in captive leopard geckos (Eublepharis macularius). Fourteen healthy adult females were separated into two groups. Under general anaesthesia, deslorelin acetate implants (4.7 mg) or placebo implants were administered into the coelom of ten female geckos and four female geckos, respectively. One healthy adult male Leopard gecko was added to each group of females (five females with GnRH implants and two females with placebo implants). The geckos were regularly monitored over two breeding seasons (visual examination, weight control). Nesting sites were checked daily. There were no postoperative complications or any other health problems during the study. Implant administration did not result in long-term suppression of reproductive function. No significant differences were found in the number of clutches between the female groups (deslorelin implants versus placebo implants) or in the number of clutches between the two breeding seasons. Deslorelin acetate implants did not interfere with ovarian activity in captive female leopard geckos. The use of GnRH agonist implants is not an appropriate method for control of reproductive function in female leopard geckos.
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Higham, Timothy E., Anthony P. Russell i Karl J. Niklas. "Leaping lizards landing on leaves: escape-induced jumps in the rainforest canopy challenge the adhesive limits of geckos". Journal of The Royal Society Interface 14, nr 131 (czerwiec 2017): 20170156. http://dx.doi.org/10.1098/rsif.2017.0156.
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The remarkable adhesive capabilities of geckos have garnered attention from scientists and the public for centuries. Geckos are known to have an adhesive load-bearing capacity far in excess (by 100-fold or more) of that required to support their body mass or accommodate the loading imparted during maximal locomotor acceleration. Few studies, however, have investigated the ecological contexts in which geckos use their adhesive system and how this may influence its properties. Here we develop a modelling framework to assess whether their prodigious adhesive capacity ever comes under selective challenge. Our investigation is based upon observations of escape-induced aerial descents of canopy-dwelling arboreal geckos that are rapidly arrested by clinging to leaf surfaces in mid-fall. We integrate ecological observations, adhesive force measurements, and body size and shape measurements of museum specimens to conduct simulations. Using predicted bending mechanics of petioles and leaf midribs, we find that the drag coefficient of the gecko, the size of the gecko and the size of the leaf determine impact forces. Regardless of the landing surface, safety factors for geckos range from a maximum of just over 10 to a minimum of well under one, which would be the point at which the adhesive system fails. In contrast to previous research that intimates that gecko frictional adhesive capacity is excessive relative to body mass, we demonstrate that realistic conditions in nature may result in frictional capacity being pushed to its limit. The rapid arrest of the lizard from its falling velocity likely results in the maximal loading to which the adhesive system is exposed during normal activities. We suggest that such activities might be primary determinants in driving their high frictional adhesive capacity.
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Izadi, Hadi, Katherine M. E. Stewart i Alexander Penlidis. "Role of contact electrification and electrostatic interactions in gecko adhesion". Journal of The Royal Society Interface 11, nr 98 (6.09.2014): 20140371. http://dx.doi.org/10.1098/rsif.2014.0371.
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Geckos, which are capable of walking on walls and hanging from ceilings with the help of micro-/nano-scale hierarchical fibrils (setae) on their toe pads, have become the main prototype in the design and fabrication of fibrillar dry adhesives. As the unique fibrillar feature of the toe pads of geckos allows them to develop an intimate contact with the substrate the animal is walking on or clinging to, it is expected that the toe setae exchange significant numbers of electric charges with the contacted substrate via the contact electrification (CE) phenomenon. Even so, the possibility of the occurrence of CE and the contribution of the resulting electrostatic interactions to the dry adhesion of geckos have been overlooked for several decades. In this study, by measuring the magnitude of the electric charges, together with the adhesion forces, that gecko foot pads develop in contact with different materials, we have clarified for the first time that CE does contribute effectively to gecko adhesion. More importantly, we have demonstrated that it is the CE-driven electrostatic interactions which dictate the strength of gecko adhesion, and not the van der Waals or capillary forces which are conventionally considered as the main source of gecko adhesion.
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Gulimova, Victoria, Alexandra Proshchina, Anastasia Kharlamova, Yuliya Krivova, Valery Barabanov, Rustam Berdiev, Victor Asadchikov, Alexey Buzmakov, Denis Zolotov i Sergey Saveliev. "Reptiles in Space Missions: Results and Perspectives". International Journal of Molecular Sciences 20, nr 12 (20.06.2019): 3019. http://dx.doi.org/10.3390/ijms20123019.
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Reptiles are a rare model object for space research. However, some reptile species demonstrate effective adaptation to spaceflight conditions. The main scope of this review is a comparative analysis of reptile experimental exposure in weightlessness, demonstrating the advantages and shortcomings of this model. The description of the known reptile experiments using turtles and geckos in the space and parabolic flight experiments is provided. Behavior, skeletal bones (morphology, histology, and X-ray microtomography), internal organs, and the nervous system (morphology, histology, and immunohistochemistry) are studied in the spaceflight experiments to date, while molecular and physiological results are restricted. Therefore, the results are discussed in the scope of molecular data collected from mammalian (mainly rodents) specimens and cell cultures in the parabolic and orbital flights and simulated microgravity. The published data are compared with the results of the gecko model studies after the 12–44.5-day spaceflights with special reference to the unique peculiarities of the gecko model for the orbital experiments. The complex study of thick-toed geckos after three spaceflights, in which all geckos survived and demonstrated effective adaptation to spaceflight conditions, was performed. However, future investigations are needed to study molecular mechanisms of gecko adaptation in space.
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Wang, Hao, Wenbo Wang, Yi Song, Lei Cai i Zhendong Dai. "Passive Cushiony Biomechanics of Head Protection in Falling Geckos". Applied Bionics and Biomechanics 2018 (2018): 1–7. http://dx.doi.org/10.1155/2018/9857894.
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Gekko geckos are capable to crawl on the steep even on upside-down surfaces. Such movement, especially at great altitude, puts them at high risks of incidentally dropping down and inevitable body or head impactions, though they may trigger air-righting reaction (ARR) to attenuate the landing shocks. However, the air-righting ability (ARA) in Gekko geckos is not fully developed. The implementation of ARR in some geckos is quite slow; and for those without tails, the ARR is even unobservable. Since ARA is compromised in Gekko geckos, there must be some other mechanisms responsible for protecting them from head injuries during falls. In this study, we looked into a Gekko gecko’s brain to study its internal environment and structure, using the magnetic resonance imaging (MRI) technique. The results showed that the brain parenchyma was fully surrounded by the cerebrospinal fluid (CSF) in the skull. A succulent characteristic was presented, which meant the intracalvarium was significantly occupied by the CSF, up to 45% in volume. Then a simplified three-dimensional finite element model was built, and a dynamic simulation was conducted to evaluate the mechanical property of this succulent characteristic during the head impactions. These implied the succulent characteristic may play certain roles on the self-protection in case of head impaction, which is adaptable to the Gekko gecko’s locomotion and behavior.
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Shao, Donghao, Zhouyi Wang, Aihong Ji, Zhendong Dai i Poramate Manoonpong. "A gecko-inspired robot with CPG-based neural control for locomotion and body height adaptation". Bioinspiration & Biomimetics 17, nr 3 (18.04.2022): 036008. http://dx.doi.org/10.1088/1748-3190/ac5a3c.
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Abstract Today’s gecko-inspired robots have shown the ability of omnidirectional climbing on slopes with a low centre of mass. However, such an ability cannot efficiently cope with bumpy terrains or terrains with obstacles. In this study, we developed a gecko-inspired robot (Nyxbot) with an adaptable body height to overcome this limitation. Based on an analysis of the skeletal system and kinematics of real geckos, the adhesive mechanism and leg structure design of the robot were designed to endow it with adhesion and adjustable body height capabilities. Neural control with exteroceptive sensory feedback is utilised to realise body height adaptability while climbing on a slope. The locomotion performance and body adaptability of the robot were tested by conducting slope climbing and obstacle crossing experiments. The gecko robot can climb a 30° slope with spontaneous obstacle crossing (maximum obstacle height of 38% of the body height) and can climb even steeper slopes (up to 60°) without an obstacle or bump. Using 3D force measuring platforms for ground reaction force analysis of geckos and the robot, we show that the motions of the developed robot driven by neural control and the motions of geckos are dynamically comparable. To this end, this study provides a basis for developing climbing robots with adaptive bump/obstacle crossing on slopes towards more agile and versatile gecko-like locomotion.
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Shine, Richard, Jonathan K. Webb, Mark Fitzgerald i Joanna Sumner. "The impact of bush-rock removal on an endangered snake species, Hoplocephalus bungaroides (Serpentes : Elapidae)". Wildlife Research 25, nr 3 (1998): 285. http://dx.doi.org/10.1071/wr97022.
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We examined the impact of habitat degradation (removal of surface rocks) on an endangered snake species (Hoplocephalus bungaroides, Elapidae) at 23 sites in south-eastern Australia, by quantifying the impact of rock removal on (i) the availability of suitable shelter-sites for the snakes and their major prey species (the velvet gecko, Oedura lesueurii), and (ii) the numbers of snakes and geckos. Our survey showed that both the snakes and the geckos prefer rocks lying on other rocks, rather than on soil, and select rocks of particular sizes. The rocks removed by bush-rock collectors overlap considerably in size (diameter and thickness) and substrate (rock on rock) with those used by broad-headed snakes and velvet geckos. Multivariate path analysis suggests that population densities of broad-headed snakes (as measured by capture rates) may be determined primarily by gecko numbers, which in turn depend upon availability of suitable rocks. In some sites, rock numbers were substantially reduced by anthropogenic disturbance. Thus, our survey data suggest that bush-rock removal has contributed to the endangerment of H. bungaroides.
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Gamble, Tony. "Duplications in Corneous Beta Protein Genes and the Evolution of Gecko Adhesion". Integrative and Comparative Biology 59, nr 1 (27.04.2019): 193–202. http://dx.doi.org/10.1093/icb/icz010.
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Abstract Corneous proteins are an important component of the tetrapod integument. Duplication and diversification of keratins and associated proteins are linked with the origin of most novel integumentary structures like mammalian hair, avian feathers, and scutes covering turtle shells. Accordingly, the loss of integumentary structures often coincides with the loss of genes encoding keratin and associated proteins. For example, many hair keratins in dolphins and whales have become pseudogenes. The adhesive setae of geckos and anoles are composed of both intermediate filament keratins (IF-keratins, formerly known as alpha-keratins) and corneous beta-proteins (CBPs, formerly known as beta-keratins) and recent whole genome assemblies of two gecko species and an anole uncovered duplications in seta-specific CBPs in each of these lineages. While anoles evolved adhesive toepads just once, there are two competing hypotheses about the origin(s) of digital adhesion in geckos involving either a single origin or multiple origins. Using data from three published gecko genomes, I examine CBP gene evolution in geckos and find support for a hypothesis where CBP gene duplications are associated with the repeated evolution of digital adhesion. Although these results are preliminary, I discuss how additional gecko genome assemblies, combined with phylogenies of keratin and associated protein genes and gene duplication models, can provide rigorous tests of several hypotheses related to gecko CBP evolution. This includes a taxon sampling strategy for sequencing and assembly of gecko genomes that could help resolve competing hypotheses surrounding the origin(s) of digital adhesion.
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Powell, Robert, Robert Henderson, Cory Lindsay i Saul Nava. "Microhabitat, activity, and density of a dwarf gecko (Sphaerodactylus parvus) on Anguilla, West Indies". Amphibia-Reptilia 22, nr 4 (2001): 455–64. http://dx.doi.org/10.1163/15685380152770417.
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AbstractSphaerodactylus parvus is a dwarf gecko endemic to the Anguilla Bank in the Lesser Antilles, West Indies. Aspects of S. parvus ecology were studied at six sites on Anguilla. Geckos were encountered most frequently in association with rock spills, and gecko population densities (0-5.2/m2) were correlated positively with rock densities. A disproportionate number of rocks which harbored S. parvus were on complex substrates of smaller rocks, leaf litter, and small sticks. Geckos became active in the late afternoon and early evening (after air temperature dropped below under-rock temperature). Activity peaked between 1900 h and 2100 h, but S. parvus was active in leaf litter until at least shortly past midnight. Potential problems associated with field studies of these diminutive gekkonids are discussed.
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Birn-Jeffery, Aleksandra V., i Timothy E. Higham. "Geckos significantly alter foot orientation to facilitate adhesion during downhill locomotion". Biology Letters 10, nr 10 (październik 2014): 20140456. http://dx.doi.org/10.1098/rsbl.2014.0456.
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Geckos employ their adhesive system when moving up an incline, but the directionality of the system may limit function on downhill surfaces. Here, we use a generalist gecko to test whether limb modulation occurs on downhill slopes to allow geckos to take advantage of their adhesive system. We examined three-dimensional limb kinematics for geckos moving up and down a 45° slope. Remarkably, the hind limbs were rotated posteriorly on declines, resulting in digit III of the pes facing a more posterior direction (opposite to the direction of travel). No significant changes in limb orientation were found in any other condition. This pes rotation leads to a dramatic shift in foot function that facilitates the use of the adhesive system as a brake/stabilizer during downhill locomotion and, although this rotation is not unique to geckos, it is significant for the deployment of adhesion. Adhesion is not just advantageous for uphill locomotion but can be employed to help deal with the effects of gravity during downhill locomotion, highlighting the incredible multi-functionality of this key innovation.
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Webb, Jonathan K., Weiguo Du, David Pike i Richard Shine. "Generalization of predator recognition: Velvet geckos display anti-predator behaviours in response to chemicals from non-dangerous elapid snakes". Current Zoology 56, nr 3 (1.06.2010): 337–42. http://dx.doi.org/10.1093/czoolo/56.3.337.
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Abstract Many prey species detect chemical cues from predators and modify their behaviours in ways that reduce their risk of predation. Theory predicts that prey should modify their anti-predator responses according to the degree of threat posed by the predator. That is, prey should show the strongest responses to chemicals of highly dangerous prey, but should ignore or respond weakly to chemicals from non-dangerous predators. However, if anti-predator behaviours are not costly, and predators are rarely encountered, prey may exhibit generalised antipredator behaviours to dangerous and non-dangerous predators. In Australia, most elapid snakes eat lizards, and are therefore potentially dangerous to lizard prey. Recently, we found that the nocturnal velvet gecko Oedura lesueurii responds to chemicals from dangerous and non-dangerous elapid snakes, suggesting that it displays generalised anti-predator behaviours to chemicals from elapid snakes. To explore the generality of this result, we videotaped the behaviour of velvet geckos in the presence of chemical cues from two small elapid snakes that rarely consume geckos: the nocturnal golden-crowned snake Cacophis squamulosus and the diurnal marsh snake Hemiaspis signata. We also videotaped geckos in trials involving unscented cards (controls) and cologne-scented cards (pungency controls). In trials involving Cacophis and Hemiaspis chemicals, 50% and 63% of geckos spent long time periods (> 3 min) freezing whilst pressed flat against the substrate, respectively. Over half the geckos tested exhibited anti-predator behaviours (tail waving, tail vibration, running) in response to Cacophis (67%) or Hemiaspis (63%) chemicals. These behaviours were not observed in control or pungency control trials. Our results support the idea that the velvet gecko displays generalised anti-predator responses to chemical cues from elapid snakes. Generalised responses to predator chemicals may be common in prey species that co-occur with multiple, ecologically similar, dangerous predators.
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Niewiarowski, Peter H., Ali Dhinojwala i Austin M. Garner. "A Physical Model Approach to Gecko Adhesion Opportunity and Constraint: How Rough Could It Be?" Integrative and Comparative Biology 59, nr 1 (7.05.2019): 203–13. http://dx.doi.org/10.1093/icb/icz029.
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AbstractIt has been nearly 20 years since Autumn and colleagues established the central role of van der Waals intermolecular forces in how geckos stick. Much has been discovered about the structure and function of fibrillar adhesives in geckos and other taxa, and substantial success has been achieved in translating natural models into bioinspired synthetic adhesives. Nevertheless, synthetics still cannot match the multidimensional performance observed in the natural gecko system that is simultaneously robust to dirt and water, resilient over thousands of cycles, and purportedly competent on surfaces that are rough at drastically different length scales. Apparent insensitivity of adhesion to variability in roughness is particularly interesting from both a theoretical and applied perspective. Progress on understanding the extent to which and the basis of how the gecko adhesive system is robust to variation in roughness is impeded by the complexity of quantifying roughness of natural surfaces and a dearth of data on free-ranging gecko substrate use. Here we review the main challenges in characterizing rough surfaces as they relate to collecting relevant estimates of variation in gecko adhesive performance across different substrates in their natural habitats. In response to these challenges, we propose a practical protocol (borrowing from thermal biophysical ecological methods) that will enable researchers to design detailed studies of structure–function relationships of the gecko fibrillar system. Employing such an approach will help provide specific hypotheses about how adhesive pad structure translates into a capacity for robust gecko adhesion across large variation in substrate roughness. Preliminary data we present on this approach suggest its promise in advancing the study of how geckos deal with roughness variation. We argue and outline how such data can help advance development of design parameters to improve bioinspired adhesives based on the gecko fibrillar system.
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Whitford, Malachi D., Grace A. Freymiller, Timothy E. Higham i Rulon W. Clark. "Shaking things up: the unique feeding behaviour of western banded geckos when consuming scorpions". Biological Journal of the Linnean Society 135, nr 3 (5.01.2022): 533–40. http://dx.doi.org/10.1093/biolinnean/blab167.
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Abstract Predators that feed on dangerous prey species must evolve mechanisms to reduce the likelihood of injury or death during a predation attempt. Scorpions are prime examples of dangerous prey items for insectivores, because they can inflict a venomous and potentially fatal sting when attacked. Despite this risk, the western banded gecko (Coleonyx variegatus), a generalist insectivore, occasionally preys on dune scorpions (Smeringurus mesaensis). We use high-speed videography to examine the modulation of prey capture biomechanics in relationship to prey type. The capture of undefended evasive (cricket) and non-evasive (worms) prey follows previous studies of lizard attack kinematics. However, we have discovered a unique shake-feeding behaviour used by western banded geckos when feeding on scorpions, whereby the gecko bites the scorpion, then performs very rapid side-to-side shaking with its head and body. Given the speed and violence of shake-feeding, we suggest that geckos shake the scorpion to cause mass trauma and subsequent immobility or, potentially, to break the stinger and render the scorpion harmless. This behaviour might be widespread among geckos that feed on these dangerous prey species.
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MOCKETT, SARAH, TRENT BELL, ROBERT POULIN i FÁTIMA JORGE. "The diversity and evolution of nematodes (Pharyngodonidae) infecting New Zealand lizards". Parasitology 144, nr 5 (15.12.2016): 680–91. http://dx.doi.org/10.1017/s0031182016002365.
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SUMMARYHost–parasite co-evolutionary studies can shed light on diversity and the processes that shape it. Molecular methods have proven to be an indispensable tool in this task, often uncovering unseen diversity. This study used two nuclear markers (18S rRNA and 28S rRNA) and one mitochondrial (cytochrome oxidase subunit I) marker to investigate the diversity of nematodes of the family Pharyngodonidae parasitizing New Zealand (NZ) lizards (lygosomine skinks and diplodactylid geckos) and to explore their co-evolutionary history. A Bayesian approach was used to infer phylogenetic relationships of the parasitic nematodes. Analyses revealed that nematodes parasitizing skinks, currently classified asSkrjabinodon, are more closely related toSpauligodonthan toSkrjabinodoninfecting NZ geckos. Genetic analyses also uncovered previously undetected diversity within NZ gecko nematodes and provided evidence for several provisionally cryptic species. We also examined the level of host–parasite phylogenetic congruence using a global-fit approach. Significant congruence was detected between gecko-Skrjabinodonphylogenies, but our results indicated that strict co-speciation is not the main co-evolutionary process shaping the associations between NZ skinks and geckos and their parasitic nematodes. However, further sampling is required to fully resolve co-phylogenetic patterns of diversification in this host–parasite system.
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Higham, Timothy E., Anthony P. Russell, Peter H. Niewiarowski, Amber Wright i Thomas Speck. "The Ecomechanics of Gecko Adhesion: Natural Surface Topography, Evolution, and Biomimetics". Integrative and Comparative Biology 59, nr 1 (27.04.2019): 148–67. http://dx.doi.org/10.1093/icb/icz013.
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Abstract The study of gecko adhesion is necessarily interdisciplinary due to the hierarchical nature of the adhesive system and the complexity of interactions between the animals and their habitats. In nature, geckos move on a wide range of surfaces including soft sand dunes, trees, and rocks, but much of the research over the past two decades has focused on their adhesive performance on artificial surfaces. Exploring the complex interactions between geckos and their natural habitats will reveal aspects of the adhesive system that can be applied to biomimetic research, such as the factors that facilitate movement on dirty and rough surfaces with varying microtopography. Additionally, contrasting suites of constraints and topographies are found on rocks and plants, likely driving differences in locomotion and morphology. Our overarching goals are to bring to light several aspects of ecology that are important for gecko–habitat interactions, and to propose a framework for how they can inspire material scientists and functional ecologists. We also present new data on surface roughness and topography of a variety of surfaces, and adhesive performance of Phelsuma geckos on surfaces of varying roughness. We address the following key questions: (1) why and how should ecology be incorporated into the study of gecko adhesion? (2) What topographical features of rocks and plants likely drive adhesive performance? (3) How can ecological studies inform material science research? Recent advances in surface replication techniques that eliminate confounding factors among surface types facilitate the ability to address some of these questions. We pinpoint gaps in our understanding and identify key initiatives that should be adopted as we move forward. Most importantly, fine details of locomotor microhabitat use of both diurnal and nocturnal geckos are needed.
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Keating, Shannon E., Madison Blumer, L. Lee Grismer, Aung Lin, Stuart V. Nielsen, Myint Kyaw Thura, Perry L. Wood, Evan S. H. Quah i Tony Gamble. "Sex Chromosome Turnover in Bent-Toed Geckos (Cyrtodactylus)". Genes 12, nr 1 (19.01.2021): 116. http://dx.doi.org/10.3390/genes12010116.
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Lizards and snakes (squamates) are known for their varied sex determining systems, and gecko lizards are especially diverse, having evolved sex chromosomes independently multiple times. While sex chromosomes frequently turnover among gecko genera, intrageneric turnovers are known only from Gekko and Hemidactylus. Here, we used RADseq to identify sex-specific markers in two species of Burmese bent-toed geckos. We uncovered XX/XY sex chromosomes in Cyrtodactylus chaunghanakwaensis and ZZ/ZW sex chromosomes in Cyrtodactylus pharbaungensis. This is the third instance of intrageneric turnover of sex chromosomes in geckos. Additionally, Cyrtodactylus are closely related to another genus with intrageneric turnover, Hemidactylus. Together, these data suggest that sex chromosome turnover may be common in this clade, setting them apart as exceptionally diverse in a group already known for diverse sex determination systems.
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Amadi, Nioking, Golden Chizi Gladstone, Chimela Wala, Leonardo Vignoli, Adaobi Ugbomeh i Luca Luiselli. "Habitat use and food habitats of a gecko population in a west African suburban area". European Journal of Ecology 6, nr 1 (16.03.2020): 1–12. http://dx.doi.org/10.17161/eurojecol.v6i1.13316.
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1.The spatial and trophic ecology of Afrotropical gecko populations are poorly known. Here, we report ecological observations on Brook’s House Gecko (Hemidactylus angulatus), a widespread gekkonid species, in the Rivers State University of Science and Technology campus, Port Harcourt, Nigeria.2. A total of 488 gecko individuals were recorded during the present study, in two surveyed habitat types: (i) plantationm trees (PTH) and (ii) buildings (BDH). In PTH, they were observed in 13 out of 15 species of trees present in the study area, with their (log) frequency of sightings being positively correlated to the (log) frequency of surveyed trees per species.3. The geckos used substantially the non-native ornamental trees of the PTH habitat. Pinus ponderosa and Elaeis guineensis were significantly preferred by geckos over all the other tree species.4. Geckos also used frequently the buildings (BDH habitat) at the university campus. There was no correlationbetween (log) area of each building and (log) number of observed lizards.5. We collected faeces from 51 gecko individuals in dry season and 66 in wet season. There were no significantdietary differences between seasons, with Diptera and adult Lepidoptera dominating in the diet.6. Dietary habits of geckos differed significantly between habitat types, with Araneae and Lepidoptera (larvae)being eaten much more frequently in BDH, and in Coleoptera and Isopoda that were eaten much more frequently in PTH The diversity dietary metrics (Shannon and Dominance indices) were very similar either between seasons or between habitats.7. Our independent set of analyses (diet diversity metrics; contingency tables on taxonomic dietary compositionand rank-abundance diagrams) showed that lizards exhibited a same feeding strategy in both wet and dry seasons as well as in the two habitat types, although the diet composition differed significantly between habitats.8. A “mixed” foraging strategy was apparently used by Hemidactylus angulatus at the study area, as also observed in other gekkonid species from elsewhere.
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ARNOLD, E. NICHOLAS, i GEORGE POINAR. "A 100 million year old gecko with sophisticated adhesive toe pads, preserved in amber from Myanmar". Zootaxa 1847, nr 1 (11.08.2008): 62. http://dx.doi.org/10.11646/zootaxa.1847.1.5.
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A new genus and species of gecko is described from a posterior lower limb and foot, and a partial tail, preserved in Lower Cretaceous amber from Myanmar that is 97–110My old. It appears to be the oldest unequivocal fossil gecko, predating fragmentary skeletal remains from the Upper Cretaceous and being 43–56 My older than Yanatarogecko from the Lower Eocene, previously the oldest known gecko preserved in amber. It also provides firm evidence that gekkotans and possibly gekkonids were in Asia at this time. The Myanmar specimen shows, that the distinctive foot proportions and sophisticated adhesive mechanism, involving pads on the toes with transverse lamellae probably bearing numerous hairlike setae found in many modern geckos, had already evolved around 100My ago. The specimen is very small, even compared with juveniles of the smallest living geckos. However, the high numbers of lamellae on its toe pads suggest it is from a juvenile of a species with relatively large adult body size.
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Wang, Xiaoqing, Wenbo Wang i Zhendong Dai. "The Neural Control Mechanisms of Gekkonid Adhesion Locomotion: The Effect of Spinal Cord Lesions". Biomimetics 7, nr 3 (22.07.2022): 98. http://dx.doi.org/10.3390/biomimetics7030098.
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Objective: the role of the supraspinal system in the neural control mechanisms of adhesion locomotor pattern formation was studied in lizard Gekko gecko. Methods: the locomotor performance and adaptation of the chronically lesioned Gekko gecko was documented before and after either partial or complete spinal lesions. They were filmed moving on a flat and smooth platform that was inclined at 0°, ±45°, and ±90°, as well as the horizontal mats and the vertical oak background board in the terraria, to evaluate locomotor functional recovery. The geckos were also tested on the platform by two half and nose-up or -down rotations in steps of 15° throughout 180° to investigate the recovery of the ability to respond dynamically to external perturbations. Results: after relatively small lesions of a hemisection, the locomotor performance was largely indistinguishable from that before and after a sham operation. During the initial period of recovery after the largest lesions of a dorsal or a ventral hemisection within 1 wk, the geckos behaved essentially as the complete spinal geckos, while permanent deficits in locomotor performance remained and did not decrease afterwards for ≥6 mth. Conclusions: by analyzing the correlation among locomotor performances, and between locomotor performances and spinal cord lesions, we suggest that the dorsal spinal pathways and ventral spinal pathways participate, respectively, in the control of the limb coupling, and in the deployment and the detachment of the adhesive apparatus. The present study will provide certain neurobiological guidance for the design of bio-robots, as well as sprawling robots inspired by the geckos.
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Withers, P. C., K. P. Aplin i Y. L. Werner. "Metabolism and evaporative water loss of Western Australian geckos (Reptilia : Sauria : Gekkonomorpha)". Australian Journal of Zoology 48, nr 2 (2000): 111. http://dx.doi.org/10.1071/zo99007.
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Resting metabolic rate (RMR) and evaporative water loss (EWL) were measured, and resistance (R) to evaporative water loss and water use index (WUI = EWL/RMR) were calculated, for 22 species of Western Australian gecko. For all available gecko data, body mass and temperature explained 85% of the variability in RMR (=14.5 mass0.833 100.0398 Ta µL h–1), and 70% of the variability in EWL (=0.126 mass0.539 100.049 Ta mg h–1 ). For Western Australian geckos, RMR and EWL were significantly influenced by body mass, using conventional regression and phylogenetic analyses. Resistance to evaporative water loss (R) was not significantly affected by body mass. Water use index was inversely related to body mass: WUI = 21.9 M–0.344 mg mL O2–1. There were significant differences between species for R and for standardised residuals of RMR, EWL and WUI. R was not correlated with phylogeny, and was significantly higher (P = 0.020) for saxicolous geckos (1467 s cm-1) than terrestrial geckos (797 s cm–1); arboreal geckos had an intermediate R (977 s cm–1). Species that ate termites had lower standardised linear regression residuals (P = 0.003) for RMR than did species that ate more general diets. Standardised residuals for EWL were almost significantly related to microhabitat (P = 0.053). Standardised residuals for WUI were significantly related to microhabitat (P = 0.016); saxicolous species had lower WUI than terrestrial species. Standardised linear regression residuals of the residuals from autoregression (which should be independent of both mass and phylogeny effects) still significantly correlated RMR and diet, but not EWL or WUI with microhabitat.
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Peattie, Anne M., Carmel Majidi, Andrew Corder i Robert J. Full. "Ancestrally high elastic modulus of gecko setal β-keratin". Journal of The Royal Society Interface 4, nr 17 (20.03.2007): 1071–76. http://dx.doi.org/10.1098/rsif.2007.0226.
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Typical bulk adhesives are characterized by soft, tacky materials with elastic moduli well below 1 MPa. Geckos possess subdigital adhesives composed mostly of β-keratin, a relatively stiff material. Biological adhesives like those of geckos have inspired empirical and modelling research which predicts that even stiff materials can be effective adhesives if they take on a fibrillar form. The molecular structure of β-keratin is highly conserved across birds and reptiles, suggesting that material properties of gecko setae should be similar to that of β-keratin previously measured in birds, but this has yet to be established. We used a resonance technique to measure elastic bending modulus in two species of gecko from disparate habitats. We found no significant difference in elastic modulus between Gekko gecko (1.6 GPa±0.15 s.e.; n =24 setae) and Ptyodactylus hasselquistii (1.4 GPa±0.15 s.e.; n =24 setae). If the elastic modulus of setal keratin is conserved across species, it would suggest a design constraint that must be compensated for structurally, and possibly explain the remarkable variation in gecko adhesive morphology.
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Schwarz, Rachel, Gavin Stark, Antonis Antonopolous, Yuval Itescu, Panayiotis Pafilis, David G. Chapple i Shai Meiri. "Specialist versus Generalist at the Intraspecific Level: Functional Morphology and Substrate Preference of Mediodactylus kotschyi Geckos". Integrative and Comparative Biology 61, nr 1 (28.06.2021): 62–75. http://dx.doi.org/10.1093/icb/icab066.
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Synopsis Populations of the same species occupying different microhabitats can either exhibit generalized traits across them or display intraspecific variability, adapting to each microhabitat in order to maximize performance. Intraspecific variability contributes to the generation of diversity, following selection and adaptation, and understanding such variability is important for comprehending how individuals choose their microhabitats. Compared with interspecific variability, however, intraspecific variability in functional morphology and its relationship with microhabitat preference and use have been relatively little studied. Here we examined whether populations of the gecko Mediodactylus kotschyi that differ in the substrates they occupy display habitat-specific behaviors and differing morphologies associated with functional adaptation to their microhabitats. We collected 207 geckos from under or on rocks or on trees from seven populations in Greece. On large islands individuals occupy both substrates; whereas small islets are devoid of trees and the geckos are restricted to rocks, while on the mainland they are only found on trees. We determined gecko substrate preferences in the laboratory, together with their clinging abilities to the different substrates. We measured their limbs, digits, and claws and assessed how these measurements relate to clinging ability. Geckos from all populations preferred the tree made available to them, but this preference was not statistically significant. Geckos from both large and small islands clung better to the tree than to the rock in the laboratory, while those from the mainland clung similarly to both substrates. Geckos collected from trees had longer manual digits and hind limbs. Geckos collected from large and small islands had taller (longer on the dorso-ventral axis; henceforth “deeper”) claws. Longer digits and deeper but shorter claws were associated with a better ability to cling to rocks. Our findings suggest that while M. kotschyi is potentially preferentially arboreal, due to the great variation and plasticity it possesses, it can successfully also exploit the habitats available on the smallest, treeless islets in the Aegean Sea. Our study suggests that the dichotomous use of generalist versus specialist in describing species’ habitat use is oversimplified, and we suggest the use of a generalist–specialist gradient instead.
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Stark, Gavin, Rachel Schwarz i Shai Meiri. "Does nocturnal activity prolong gecko longevity?" Israel Journal of Ecology and Evolution 66, nr 3-4 (6.11.2020): 231–38. http://dx.doi.org/10.1163/22244662-20191074.
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The majority of lizard clades are ancestrally and predominantly diurnal. The only major taxon in which most species are nocturnal is the Gekkota (geckos and pygopodids). As ectothermic thermoregulators, lizard metabolic rates are highly temperature dependent, and diurnal lizards therefore demonstrate higher metabolic rates than nocturnal ones. Furthermore, exposure to solar radiation is thought to reduce ectothermic longevity by increasing both metabolic costs and the rate of accumulating harmful mutations through UV radiation (UVC specifically). In being nocturnal, ectothermic species may reduce their intrinsic mortality rates and thus live longer. To test this hypothesis, we collected literature data on the maximum longevities of 740 lizard species, of which 185 are geckos. We examined whether geckos live longer than other lizards, and whether activity time affects gecko longevity. While geckos live relatively long for lizards of their size, their activity time was found to be unrelated to longevity, contradicting our predictions. We suggest that diurnal species may have evolved higher resistance to UV radiation via thicker, more keratinized skin. Elevated metabolic rates do not automatically equate with faster aging. Mortality through extrinsic causes (e.g., predation) may impose much stronger selective pressures than intrinsic causes.
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Pensabene, Eleonora, Lukáš Kratochvíl i Michail Rovatsos. "Independent Evolution of Sex Chromosomes in Eublepharid Geckos, A Lineage with Environmental and Genotypic Sex Determination". Life 10, nr 12 (10.12.2020): 342. http://dx.doi.org/10.3390/life10120342.
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Geckos demonstrate a remarkable variability in sex determination systems, but our limited knowledge prohibits accurate conclusions on the evolution of sex determination in this group. Eyelid geckos (Eublepharidae) are of particular interest, as they encompass species with both environmental and genotypic sex determination. We identified for the first time the X-specific gene content in the Yucatán banded gecko, Coleonyx elegans, possessing X1X1X2X2/X1X2Y multiple sex chromosomes by comparative genome coverage analysis between sexes. The X-specific gene content of Coleonyx elegans was revealed to be partially homologous to genomic regions linked to the chicken autosomes 1, 6 and 11. A qPCR-based test was applied to validate a subset of X-specific genes by comparing the difference in gene copy numbers between sexes, and to explore the homology of sex chromosomes across eleven eublepharid, two phyllodactylid and one sphaerodactylid species. Homologous sex chromosomes are shared between Coleonyx elegans and Coleonyx mitratus, two species diverged approximately 34 million years ago, but not with other tested species. As far as we know, the X-specific gene content of Coleonyx elegans / Coleonyx mitratus was never involved in the sex chromosomes of other gecko lineages, indicating that the sex chromosomes in this clade of eublepharid geckos evolved independently.
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Russell, Anthony P., i Aaron M. Bauer. "The morphology of the digits of the golden gecko, Calodactylodes aureus and its implications for the occupation of rupicolous habitats". Amphibia-Reptilia 10, nr 2 (1989): 125–40. http://dx.doi.org/10.1163/156853889x00160.
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AbstractThe recent rediscovery of the golden gecko, Calodactylodes aureus, after more than 100 years, has given occasion to reconsider both its phylogenetic position amongst the gekkonine geckos and the functional aspects of its subdigital pads. The morphology of these pads and the anatomical basis of their control suggests that Afroedura among a grouping of gekkonine geckos with phenetically similar digits, shows the greatest structural similarity to Calodactylodes. Available data do not support a robust hypothesis of actual relationship between these two genera, but if relationship is not the underlying dictator of the similarity seen, the degree of convergence is remarkable. The general similarity in digital form of those genera possessing terminal, leaf-like scansors, both in the Gekkoninae and Diplodactylinae, appears to be associated with rupicolous habitats and indicates an evolutionary pathway by which more extensive climbing pads may have arisen. It is likely that this morphotypic pathway has been followed independently by several lineages of gekkonine and diplodactyline geckos.
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Fakhri Fauzan, Muhammad, Quraisy Zakky, Ibnu Hibban Hartono, Awal Riyanto i Amir Hamidy. "Habitat Preference and Population Study of House Gecko (Gekko gecko) in Seribu Islands, Special Capital Region of Jakarta". Jurnal Biologi Indonesia 18, nr 2 (2022): 205–12. http://dx.doi.org/10.47349/jbi/18022022/205.
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The house gecko (Gekko gecko) or tokek is a reptile species known widely used as an export commodity. Overexploitation can threaten wild populations of tokek in the wild. The research was conducted through a Visual Encounter Survey on the islands of Tidung, Pari, and Untung Jawa from 27 November to 02 December 2021. We also distributed questionnaires about the insight and presence of geckos in residents' homes or buildings. The number of respondents have been interviewed are 117 people, while for direct observation the results obtained are 273 individuals. The highest number of geckos was found on Pari Island and the least was on Untung Jawa Island. The house gecko is distributed throughout on these islands and is relatively more abundant in residential areas. The house gecko is most found on power poles and building walls and in breadfruit trees (Artocarpus altilis). Area of The Kepulauan Seribu is about 474562 hectares with a land area of 877 hectares. The population density of tokek based on direct observation was 13.60 individuals/ha. Therefore, the estimated population of tokek; in the Seribu Islands based on direct observations is around 11930.12 individuals.
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Russell, Anthony P., Alyssa Y. Stark i Timothy E. Higham. "The Integrative Biology of Gecko Adhesion: Historical Review, Current Understanding, and Grand Challenges". Integrative and Comparative Biology 59, nr 1 (7.05.2019): 101–16. http://dx.doi.org/10.1093/icb/icz032.
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Abstract Geckos are remarkable in their ability to reversibly adhere to smooth vertical, and even inverted surfaces. However, unraveling the precise mechanisms by which geckos do this has been a long process, involving various approaches over the last two centuries. Our understanding of the principles by which gecko adhesion operates has advanced rapidly over the past 20 years and, with this knowledge, material scientists have attempted to mimic the system to create artificial adhesives. From a biological perspective, recent studies have examined the diversity in morphology, performance, and real-world use of the adhesive apparatus. However, the lack of multidisciplinarity is likely a key roadblock to gaining new insights. Our goals in this paper are to 1) present a historical review of gecko adhesion research, 2) discuss the mechanisms and morphology of the adhesive apparatus, 3) discuss the origin and performance of the system in real-world contexts, 4) discuss advancement in bio-inspired design, and 5) present grand challenges in gecko adhesion research. To continue to improve our understanding, and to more effectively employ the principles of gecko adhesion for human applications, greater intensity and scope of interdisciplinary research are necessary.
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Griffing, Aaron H., Thomas J. Sanger, Lilian Epperlein, Aaron M. Bauer, Anthony Cobos, Timothy E. Higham, Emily Naylor i Tony Gamble. "And thereby hangs a tail: morphology, developmental patterns and biomechanics of the adhesive tails of crested geckos ( Correlophus ciliatus )". Proceedings of the Royal Society B: Biological Sciences 288, nr 1953 (16.06.2021): 20210650. http://dx.doi.org/10.1098/rspb.2021.0650.
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Among the most specialized integumentary outgrowths in amniotes are the adhesive, scale-like scansors and lamellae on the digits of anoles and geckos. Less well-known are adhesive tail pads exhibited by 21 gecko genera. While described over 120 years ago, no studies have quantified their possible adhesive function or described their embryonic development. Here, we characterize adult and embryonic morphology and adhesive performance of crested gecko ( Correlophus ciliatus ) tail pads. Additionally, we use embryonic data to test whether tail pads are serial homologues to toe pads. External morphology and histology of C . ciliatus tail pads are largely similar to tail pads of closely related geckos. Functionally, C . ciliatus tail pads exhibit impressive adhesive ability, hypothetically capable of holding up to five times their own mass. Tail pads develop at approximately the same time during embryogenesis as toe pads. Further, tail pads exhibit similar developmental patterns to toe pads, which are markedly different from non-adhesive gecko toes and tails. Our data provide support for the serial homology of adhesive tail pads with toe pads.
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Liu, Shuang Yi, Min Min Tang, Ai Kah Soh i Liang Hong. "In Situ Characterization of the Mechanical Behavior of Gecko's Spatulae by Atomic Force Microscopy". Journal of Nano Research 22 (maj 2013): 85–93. http://dx.doi.org/10.4028/www.scientific.net/jnanor.22.85.
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In-situ characterization of the mechanical behavior of geckos spatula has been carried out in detail using multi-mode AFM system. Combining successful application of a novel AFM mode, i.e. Harmonix microscopy, the more detail elastic properties of spatula is brought to light. The results obtained show the variation of the mechanical properties on the hierarchical level of a seta, even for the different locations, pad and stalk of the spatula. A model, which has been validated using the existing experimental data and phenomena as well as theoretical predictions for geckos adhesion, crawling and self-cleaning of spatulae, is proposed in this paper. Through contrast of adhesive and craw ability of the gecko on the surfaces with different surface roughness, and measurement of the surface adhesive behaviors of Teflon, the most effective adhesion of the gecko is more dependent on the intrinsic properties of the surface which is adhered.
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Liu, Shuang Yi, Min Min Tang, Ai Kah Soh i Liang Hong. "In Situ Characterization of the Mechanical Behavior of Gecko’s Spatulae by Atomic Force Microscopy". Journal of Nano Research 25 (październik 2013): 101–9. http://dx.doi.org/10.4028/www.scientific.net/jnanor.25.101.
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In-situ characterization of the mechanical behavior of geckos spatula has been carried out in detail using multi-mode AFM system. Combining successful application of a novel AFM mode, i.e. Harmonix microscopy, the more detail elastic properties of spatula is brought to light. The results obtained show the variation of the mechanical properties on the hierarchical level of a seta, even for the different locations, pad and stalk of the spatula. A model, which has been validated using the existing experimental data and phenomena as well as theoretical predictions for geckos adhesion, crawling and self-cleaning of spatulae, is proposed in this paper. Through contrast of adhesive and craw ability of the gecko on the surfaces with different surface roughness, and measurement of the surface adhesive behaviors of Teflon, the most effective adhesion of the gecko is more dependent on the intrinsic properties of the surface which is adhered.
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Hawkes, Elliot W., Eric V. Eason, David L. Christensen i Mark R. Cutkosky. "Human climbing with efficiently scaled gecko-inspired dry adhesives". Journal of The Royal Society Interface 12, nr 102 (styczeń 2015): 20140675. http://dx.doi.org/10.1098/rsif.2014.0675.
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Since the discovery of the mechanism of adhesion in geckos, many synthetic dry adhesives have been developed with desirable gecko-like properties such as reusability, directionality, self-cleaning ability, rough surface adhesion and high adhesive stress. However, fully exploiting these adhesives in practical applications at different length scales requires efficient scaling (i.e. with little loss in adhesion as area grows). Just as natural gecko adhesives have been used as a benchmark for synthetic materials, so can gecko adhesion systems provide a baseline for scaling efficiency. In the tokay gecko ( Gekko gecko ), a scaling power law has been reported relating the maximum shear stress σ max to the area A : σ max ∝ A −1/4 . We present a mechanical concept which improves upon the gecko's non-uniform load-sharing and results in a nearly even load distribution over multiple patches of gecko-inspired adhesive. We created a synthetic adhesion system incorporating this concept which shows efficient scaling across four orders of magnitude of area, yielding an improved scaling power law: σ max ∝ A −1/50 . Furthermore, we found that the synthetic adhesion system does not fail catastrophically when a simulated failure is induced on a portion of the adhesive. In a practical demonstration, the synthetic adhesion system enabled a 70 kg human to climb vertical glass with 140 cm 2 of adhesive per hand.
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Reese, David J., JM Kinsella, Jacqueline M. Zdziarski, Qi-Yun Zeng i Ellis C. Greiner. "Parasites in 30 Captive Tokay Geckos, Gekko gecko". Journal of Herpetological Medicine and Surgery 14, nr 2 (styczeń 2004): 21–25. http://dx.doi.org/10.5818/1529-9651.14.2.21.
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Barry, Manuela, John F. Cockrem i Dianne H. Brunton. "Seasonal variation in plasma corticosterone concentrations in wild and captive adult Duvaucel's geckos (Hoplodactylus duvaucelii) in New Zealand". Australian Journal of Zoology 58, nr 4 (2010): 234. http://dx.doi.org/10.1071/zo10023.
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Most of New Zealand’s herpetofauna species are threatened and in decline. Yet, little is known about their basic physiology and endocrinology. This study examined plasma corticosterone (CORT) concentrations in a threatened endemic New Zealand reptile, the Duvaucel’s gecko, in relation to season, sex, body temperature, body condition and female reproductive condition (pregnant versus non-pregnant). In addition, seasonal plasma CORT concentrations were compared between captive geckos from a breeding facility and a wild population to determine whether concentrations of CORT were chronically elevated in captive lizards. Plasma CORT concentrations showed significant seasonal variation, but were not related to sex, body temperature, body condition or female reproductive condition. Geckos, which successfully bred in captivity each year, did not exhibit chronically elevated plasma CORT levels but showed an elevation of plasma CORT concentrations in summer compared with wild geckos. Information on basal CORT concentrations in species of conservation concern can be beneficial for improving their management and can aid in identifying and evaluating stress-related changes in hormone patterns of individuals and chronic stress, which is particularly relevant for threatened species breeding programs.
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Bauer, A. M. "Gecko Adhesion in Space and Time: A Phylogenetic Perspective on the Scansorial Success Story". Integrative and Comparative Biology 59, nr 1 (30.04.2019): 117–30. http://dx.doi.org/10.1093/icb/icz020.
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Abstract An evolutionary perspective on gecko adhesion was previously hampered by a lack of an explicit phylogeny for the group and of robust comparative methods to study trait evolution, an underappreciation for the taxonomic and structural diversity of geckos, and a dearth of fossil evidence bearing directly on the origin of the scansorial apparatus. With a multigene dataset as the basis for a comprehensive gekkotan phylogeny, model-based methods have recently been employed to estimate the number of unique derivations of the adhesive system and its role in lineage diversification. Evidence points to a single basal origin of the spinulate oberhautchen layer of the epidermis, which is a necessary precursor for the subsequent elaboration of a functional adhesive mechanism in geckos. However, multiple gains and losses are implicated for the elaborated setae that are necessary for adhesion via van der Waals forces. The well-supported phylogeny of gekkotans has demonstrated that convergence and parallelism in digital design are even more prevalent than previously believed. It also permits the reexamination of previously collected morphological data in an explicitly evolutionary context. Both time-calibrated trees and recently discovered amber fossils that preserve gecko toepads suggest that a fully-functional adhesive apparatus was not only present, but also represented by diverse architectures, by the mid-Cretaceous. Further characterization and phylogenetically-informed analyses of the other components of the adhesive system (muscles, tendons, blood sinuses, etc.) will permit a more comprehensive reconstruction of the evolutionary pathway(s) by which geckos have achieved their structural and taxonomic diversity. A phylogenetic perspective can meaningfully inform functional and performance studies of gecko adhesion and locomotion and can contribute to advances in bioinspired materials.
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Autumn, Kellar, i Nick Gravish. "Gecko adhesion: evolutionary nanotechnology". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 366, nr 1870 (11.01.2008): 1575–90. http://dx.doi.org/10.1098/rsta.2007.2173.
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If geckos had not evolved, it is possible that humans would never have invented adhesive nanostructures. Geckos use millions of adhesive setae on their toes to climb vertical surfaces at speeds of over 1 m s −1 . Climbing presents a significant challenge for an adhesive in requiring both strong attachment and easy rapid removal. Conventional pressure-sensitive adhesives (PSAs) are either strong and difficult to remove (e.g. duct tape) or weak and easy to remove (e.g. sticky notes). The gecko adhesive differs dramatically from conventional adhesives. Conventional PSAs are soft viscoelastic polymers that degrade, foul, self-adhere and attach accidentally to inappropriate surfaces. In contrast, gecko toes bear angled arrays of branched, hair-like setae formed from stiff, hydrophobic keratin that act as a bed of angled springs with similar effective elastic modulus to that of PSAs. Setae are self-cleaning and maintain function for months during repeated use in dirty conditions. Setae are an anisotropic ‘frictional adhesive’ in that adhesion requires maintenance of a proximally directed shear load, enabling either a tough bond or spontaneous detachment. Gecko-like synthetic adhesives may become the glue of the future—and perhaps the screw of the future as well.
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Mason, Alexandra K., Jeongha Lee, Sean M. Perry, Kimberly L. Boykin, Fabio Del Piero, Michael Lierz i Mark A. Mitchell. "Determining the Effects of Serial Injections of Pregnant Mare Serum Gonadotropin on Plasma Testosterone Concentrations, Testicular Dynamics, and Semen Production in Leopard Geckos (Eublepharis macularius)". Animals 11, nr 9 (24.08.2021): 2477. http://dx.doi.org/10.3390/ani11092477.
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Reptiles are highly susceptible to anthropogenic activities as a result of their narrow geographical ranges and habitat specialization, making them a conservation concern. Geckos represent one of the mega-diverse reptile lineages under pressure; however, limited assisted reproductive technologies currently exist for these animals. Exogenous pregnant mare serum gonadotropin (PMSG) has been found to exhibit follicle stimulating hormone-like action and has been routinely used to alter reproductive hormones of vertebrates in assisted reproductive protocols. The purpose of this study was to determine the effects of serial injections of 20 IU and 50 IU PMSG on circulating testosterone concentrations, testicular dynamics, and semen production in a model species of gecko. Twenty-four captive-bred, adult, male leopard geckos (Eublepharis macularius) were divided into three treatment groups and administered a once-weekly injection of either PMSG or saline for a total of nine weeks. Ultrasonographic testicular measurements, electrostimulation for semen collection, and venipuncture were performed on days 0, 21, 42, and 63. Right unilateral orchidectomies and epididymectomies were performed in all animals on day 63; tissues were submitted for histopathology. PMSG treated geckos had significantly higher testicular volumes and weights, spermatozoa motility, and spermatozoa concentrations compared with controls. However, there were no significant differences in testosterone concentrations by treatment or time. Under the conditions outlined, PMSG is effective at stimulating spermatogenesis and increasing testicular size, but not effective at increasing testosterone concentrations in the leopard gecko between October–December in the Northern hemisphere.
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Kun, Marcelo E., Carla Piantoni, John D. Krenz i Nora R. Ibargüengoytía. "Dietary analysis of Homonota darwini (Squamata: Gekkonidae) in Northern Patagonia". Current Zoology 56, nr 4 (1.08.2010): 406–10. http://dx.doi.org/10.1093/czoolo/56.4.406.
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Abstract Our study investigated the diet of the southernmost gecko in the world, Homonota darwini. Fifty-three specimens were captured during spring and summer in four locations in Patagonia, Argentina. The stomach contents of the specimens were identified, and we found that prey consisted of six main groups: Coleoptera, Hymenoptera, Homoptera and Araneae, and the adults and larvae of moth Lepidoptera. Lepidoptera was the major dietary component. The presence of ants and moths as common prey suggests an ambush feeding strategy. In spring, females consumed more ants than males although no other dietary differences between males and females were evident. We found nine geckos with empty stomachs and six parasitized by nematodes. Presence of empty stomachs corroborates previous observations of other nocturnal geckos and non-gecko lizards. Reduced foraging success of nocturnal lizards could be due to difficulty in prey detection due to dim light, reduced or erratic activity of insect prey at night, or shorter activity times of geckos relative to diurnal success. Sex and season were not associated with the incidence of empty stomachs. Principal component analysis showed that four food alternatives correlated with season. The constraint of nocturnality, coupled with low night-time temperatures restricting feeding to only a few hours after sunset, appear to have caused a generality of diet which may limit energy acquisition. We conclude that H. darwini is an arthropod generalist and likely an ambush forager, as are many other nocturnal gekkonids.
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Atmaja, Vesti Yunisya, Deni Parlindungan, Sipriyadi Sipriyadi, Fery Fernando Sinaga, Ika Saputri, Reti Novianti, Untung Priadi i Widia Gusti. "Population Estimation of Double–Spotted Gecko, Gekko monarchus (Sclegel, 1836) at 5 Regency in Bengkulu Province". JURNAL PEMBELAJARAN DAN BIOLOGI NUKLEUS 8, nr 3 (25.11.2022): 593–607. http://dx.doi.org/10.36987/jpbn.v8i3.3242.
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The Double–Spotted Gecko (Gekko monarchus) is one of the reptiles on the list of wild animals given an annual utilization quota for their capture in the wild. Bengkulu Province, as one of the distribution place of G. monarchus does not yet have data on its population. The research was conducted on 13 November to 2 December 2021, using two methods: interviews with the community and a Visual Encountered Survey at night. The research area in the five districts is 61.49 ha, the number of houses visited is 433, and the number of people interviewed is 386. The number of geckos counted in the interviews was 315, while from direct observation, there were 275. Geckos were most found at house and dominated (41.2%) by hiding between wooden walls. Based on the results of extrapolation calculations, the population estimates for the Double–Spotted Gecko are North Bengkulu 43,720–54,427 individuals; Mukomuko 32,997–51,810 tails; Central Bengkulu 6,248–9,187 individuals; Total 39,883–72,720 individuals; and South Bengkulu 11,469–11,592 individuals.