The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
Piotr Tryjanowski - One of the best experts on this subject based on the ideXlab platform.
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Do males pay more? A male-biased predation of common lizard (Zootoca vivipara) by great grey shrike (Lanius excubitor)
acta ethologica, 2019Co-Authors: Marcin Antczak, Viktória Majláthová, Igor Majláth, Martin Hromada, Anna Ekner-grzyb, Martin Bona, Piotr TryjanowskiAbstract:Predation is one of the most important factors affecting biology, ecology and behaviour of the prey. We have studied predation of the common lizard ( Zootoca vivipara ) by the great grey shrike ( Lanius excubitor ) in farmland habitats in western Poland. Shrike caches were used as a source of information about preyed Lizards. Shrikes hunt significantly more adult males than females, juveniles and sub-adults; the pattern was similar over all three study years. Male lizard had longer activity time than female; therefore, they seem to be under predation pressure for a longer time during breeding season. Capture and count transect data of common lizard populations living within and outside shrike territories showed significant seasonal differences: within shrike territories, there was lower proportion of males than females; moreover, in some territories, the number of males in the lizard population was negatively correlated with the number of males impaled by shrikes. Our findings suggest that in this particular predator-prey system, shrikes may be a strong selective force for Lizards’ population dynamics. Male-biased predation could be caused by differences in the behaviour of adult male and female Lizards, namely longer activity of males and differences in space and refuge use.
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Blood parasites in two co-existing species of Lizards (Zootoca vivipara and Lacerta agilis)
Parasitology Research, 2010Co-Authors: Viktória Majláthová, Igor Majláth, Božena Haklová, Martin Hromada, Anna Ekner, Marcin Antczak, Piotr TryjanowskiAbstract:We investigated the occurrence of blood parasites of two lizard species: the common or viviparous lizard ( Zootoca vivipara ) and the sand lizard ( Lacerta agilis ) in western Poland. Selected traits of lizard body morphology were studied with respect to the presence and intensity of haematozoan infection in blood samples collected from 218 adult Lizards; 88 of the common lizard and 130 of the sand lizard. Haemogregarinid blood parasites were found to be the common parasite of both lizard species in studied locality with prevalence 39.8 (95% CL, 29.5–50.8) for Z. vivipara and 22.3 (95% CL, 15.5–30.4) for L. agilis . Incidence of parasitemia did not differ between sexes and was not correlated with morphological traits or presence of ectoparasites— Ixodes ricinus ticks. However, a significant difference between the two species of Lizards was a greater frequency of haemogregarinid parasitism in Z. vivipara .
C. Michael Bull - One of the best experts on this subject based on the ideXlab platform.
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A nose for Lizards; can a detection dog locate the endangered pygmy bluetongue lizard (Tiliqua adelaidensis)?
Transactions of The Royal Society of South Australia, 2016Co-Authors: Torben P. Nielsen, Gary Jackson, C. Michael BullAbstract:ABSTRACTEnvironmental detection dogs have been used in various research and conservation projects. By detecting scent, dogs are capable of finding animals or scats that are virtually undetectable to humans. The endangered pygmy bluetongue lizard (Tiliqua adelaidensis) is endemic to heavily fragmented patches of native grassland in the mid-north region of South Australia. The Lizards live in spider burrows with entrance diameters of 10–20 mm, which makes them difficult to find. This study presents the first data showing that a dog can detect pygmy bluetongue Lizards. The dog showed the ability to distinguish between pygmy bluetongue lizard scent and the scent of sleepy lizard (Tiliqua rugosa) and bearded dragon (Pogona barbata). The dog also found more than 30 occupied lizard burrows in the field. Up until now surveys of this endangered lizard have relied on human visual detection of burrows, which is a very labour-intensive process. Although the climate and the ecology of the Lizards pose a challenge to d...
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A thirsty little lizard: drinking by the pygmy bluetongue lizard
Transactions of The Royal Society of South Australia, 2015Co-Authors: Torben P. Nielsen, Mehregan Ebrahimi, C. Michael BullAbstract:ABSTRACTThe pygmy bluetongue lizard (Tiliqua adelaidensis) is an endangered scincid lizard, endemic to the Mid North region of South Australia, where it occupies heavily fragmented patches of native grassland. Pygmy bluetongue Lizards live in spider burrows and rarely venture far from their burrows. This limits their access to free standing water, and it was previously unknown whether Lizards acquired all the water they needed from their food, or whether they could access an alternative source of water. This paper presents 27 observations of Lizards drinking either from drops of morning dew or from rain drops accumulated on vegetation close to their burrow entrances. These observations suggest that pygmy bluetongue Lizards can supplement their water requirements independent of free standing water sources, like streams or ponds, if there is vegetation that can collect dew and rain close to burrow entrances. Vegetation that can hold water droplets for a short time provides flexibility for the Lizards in mai...
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Responses of the endangered pygmy bluetongue lizard to conspecific scats
Journal of Ethology, 2011Co-Authors: Aaron L. Fenner, C. Michael BullAbstract:Many animals use chemical signals for communication between conspecifics and for territory marking. The pygmy bluetongue lizard is normally solitary, focussing activity around the entrance of its burrow, from where it ambushes prey, and rarely contacts other individuals. In this paper we examined whether Lizards in laboratory experiments alter their behaviour in the presence of scats from conspecifics. In the first experiment, when Lizards were offered a choice of two vacant burrows with or without a scat close to the entrance, they tongue flicked more often at the burrow entrance when the scat was present, and more often chose to occupy the burrow with the scat. An interpretation is that Lizards use scat signals to recognise burrows that may be suitable because they have previously been occupied by a conspecific, but that they approach those burrows cautiously in case a resident is still present and likely to resist a takeover. Scats from male Lizards were inspected (by both sexes) for longer than scats of female Lizards. In the second experiment, when resident Lizards were presented with scats outside of their burrows, they inspected and tongue flicked at those scats more often if the scat came from a male than a female lizard, but there was no definitive evidence from our experiments that Lizards differentiated in their response to scats from Lizards that were found close to or far from the test lizard. The results were consistent with a communication system in which Lizards use scats to advertise their presence, independent of any direct contact.
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Non-invasive lizard identification using signature curves
TENCON 2009 - 2009 IEEE Region 10 Conference, 2009Co-Authors: Damian Tohl, Sharmil Randhawa, Leili Shamimi, C. Michael BullAbstract:A novel non-invasive method is proposed to help identify the endangered Pygmy Bluetongue Lizard. This would be preferable to the commonly used, invasive, toe-clipping method, which could be unreliable if the lizard was to lose a toe or foot naturally. Each lizard has a unique and permanent scale pattern which can be used to identify individual Lizards. The proposed method involves a novel technique to derive a signature curve from the Hough transform output of the lizard scale pattern such that the signature curve is scale and shift invariant. It has been found that a lizard can be successfully identified by comparing its signature curve with those signature curves of all registered Lizards stored in a database.
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Interactions between climate, host refuge use, and tick population dynamics
Parasitology Research, 2006Co-Authors: Gregory D. Kerr, C. Michael BullAbstract:The relationship between Australian sleepy lizard ( Tiliqua rugosa ) microhabitat use and tick ( Amblyomma limbatum ) population dynamics was investigated. Over 3 years (2002–2004) between 23 and 50 Lizards were radio-tracked up to four times a week to record microhabitat use and each fortnight to determine tick loads. Daily maximum temperature was highly predictive of lizard microhabitat use. In hotter fortnights Lizards used larger bushes and burrows for refuge. Peak background tick infestation levels and pulses of attachment coincided with higher ambient temperature. Male ticks attached throughout the year independent of season. Engorged females detached late in spring, summer and autumn, when climate regularly restricted Lizards to a few thermally conservative refuges. Peak nymph and larval attachment occurred over summer and into autumn. Climate-dependent timing and type of host refuge use may influence tick population density. In more temperate summers Lizards may avoid refuges with potentially high parasite loads.
Bryan G Fry - One of the best experts on this subject based on the ideXlab platform.
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early evolution of the venom system in Lizards and snakes
Nature, 2006Co-Authors: Nicolas Vidal, Janette A. Norman, Freek J. Vonk, Holger Scheib, S. F. Ryan Ramjan, Sanjaya Kuruppu, Bryan G Fry, Kim Y C Fung, Blair S HedgesAbstract:Among extant reptiles only two lineages are known to have evolved venom delivery systems, the advanced snakes and helodermatid Lizards (Gila Monster and Beaded Lizard). Evolution of the venom system is thought to underlie the impressive radiation of the advanced snakes (2,500 of 3,000 snake species). In contrast, the lizard venom system is thought to be restricted to just two species and to have evolved independently from the snake venom system. Here we report the presence of venom toxins in two additional lizard lineages (Monitor Lizards and Iguania) and show that all lineages possessing toxin-secreting oral glands form a clade, demonstrating a single early origin of the venom system in Lizards and snakes. Construction of gland complementary-DNA libraries and phylogenetic analysis of transcripts revealed that nine toxin types are shared between Lizards and snakes. Toxinological analyses of venom components from the Lace Monitor Varanus varius showed potent effects on blood pressure and clotting ability, bioactivities associated with a rapid loss of consciousness and extensive bleeding in prey. The iguanian lizard Pogona barbata retains characteristics of the ancestral venom system, namely serial, lobular non-compound venom-secreting glands on both the upper and lower jaws, whereas the advanced snakes and anguimorph Lizards (including Monitor Lizards, Gila Monster and Beaded Lizard) have more derived venom systems characterized by the loss of the mandibular (lower) or maxillary (upper) glands. Demonstration that the snakes, iguanians and anguimorphs form a single clade provides overwhelming support for a single, early origin of the venom system in Lizards and snakes. These results provide new insights into the evolution of the venom system in squamate reptiles and open new avenues for biomedical research and drug design using hitherto unexplored venom proteins.
Ellis R. Loew - One of the best experts on this subject based on the ideXlab platform.
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The importance of ultraviolet and near-infrared sensitivity for visual discrimination in two species of lacertid Lizards
Journal of Experimental Biology, 2015Co-Authors: Melissa Martin, Jean-françois Le Galliard, Sandrine Meylan, Ellis R. LoewAbstract:Male and female Lacertid Lizards often display conspicuous coloration that is involved in intraspecific communication. However, visual systems of Lacertidae have rarely been studied and the spectral sensitivity of their retinal photoreceptors remains unknown. Here, we characterise the spectral sensitivity of two Lacertid species from contrasting habitats: the wall lizard Podarcis muralis and the common lizard Zootoca vivipara. Both species possess a pure-cone retina with one spectral class of double cones and four spectral classes of single cones. The two species differ in the spectral sensitivity of the LWS cones, the relative abundance of UVS single cones (potentially more abundant in Z. vivipara) and the coloration of oil droplets. Wall Lizards have pure vitamin A1-based photopigments, whereas common Lizards possess mixed vitamin A1 and A2 photopigments, extending spectral sensitivity into the near infrared, which is a rare feature in terrestrial vertebrates. We found that spectral sensitivity in the UV and near infrared improves discrimination of small variations in throat coloration among Z. vivipara. Thus, retinal specialisations optimise chromatic resolution in common Lizards, indicating that the visual system and visual signals might co-evolve.
Colin M Donihue - One of the best experts on this subject based on the ideXlab platform.
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habitat shapes the thermoregulation of mediterranean Lizards introduced to replicate experimental islets
Journal of Thermal Biology, 2019Co-Authors: Panayiotis Pafilis, Colin M Donihue, Anthony Herrel, Grigoris Kapsalas, Menelia Vasilopouloukampitsi, Anneclaire Fabre, Johannes FoufopoulosAbstract:Both environmental temperatures and spatial heterogeneity can profoundly affect the biology of ectotherms. In Lizards, thermoregulation may show high plasticity and may respond to environmental shifts. In the context of global climate change, Lizards showing plastic thermoregulatory responses may be favored. In this study, we designed an experiment to evaluate the extent to which lizard thermoregulation responds to introduction to a new environment in a snapshot of time. In 2014, we captured individuals of the Aegean Wall lizard (Podarcis erhardii) from Naxos Island (429.8 km2) and released them onto two small, lizard-free islets, Galiatsos (0.0073 km2) and Kampana (0.004 km2) (Aegean Sea, Greece). In 2017, we returned to the islets and estimated the effectiveness (E), accuracy and precision of thermoregulation measuring operative, preferred (Tpref) and body temperatures. We hypothesized that the three habitats would differ in thermal quality and investigated the extent to which Lizards from Naxos demonstrate plasticity when introduced to the novel, islet habitats. Thermal parameters did not differ between Galiatsos and Naxos and this was reflected in the similar E and Tpref. However, Lizards from Kampana deviated in all focal traits from Naxos, resulting in higher E and a preference for higher Tpref. In sum, Naxos Lizards shifted their thermoregulatory profile due to the idiosyncratic features of their new islet habitat. Our results advocate a high plasticity in lizard thermoregulation and suggest that there is room for effective responses to environmental changes, at least for Podarcis Lizards in insular habitats.
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aegean wall Lizards switch foraging modes diet and morphology in a human built environment
Ecology and Evolution, 2016Co-Authors: Colin M DonihueAbstract:Foraging mode is a functional trait with cascading impacts on ecological communities. The foraging syndrome hypothesis posits a suite of concurrent traits that vary with foraging mode; however, comparative studies testing this hypothesis are typically interspecific. While foraging modes are often considered typological for a species when predicting foraging-related traits or mode-specific cascading impacts, intraspecific mode switching has been documented in some Lizards. Mode-switching Lizards provide an opportunity to test foraging syndromes and explore how intraspecific variability in foraging mode might affect local ecological communities.Because lizard natural history is intimately tied to habitat use and structure, I tested for mode switching between populations of the Aegean wall lizard, Podarcis erhardii, inhabiting undisturbed habitat and human-built rock walls on the Greek island of Naxos. I observed foraging behavior among 10 populations and tested lizard morphological and performance predictions at each site. Furthermore, I investigated the diet of Lizards at each site relative to the available invertebrate community.I found that Lizards living on rock walls were significantly more sedentary-sit and wait-than Lizards at nonwall sites. I also found that head width increased in females and the ratio of hindlimbs to forelimbs in both sexes increased as predicted. Diet also changed, with nonwall Lizards consuming a higher proportion of sedentary prey. Lizard bite force also varied significantly between sites; however, the pattern observed was opposite to that predicted, suggesting that bite force in these Lizards may more closely relate to intraspecific competition than to diet.This study demonstrates microgeographic variability in lizard foraging mode as a result of human land use. In addition, these results demonstrate that foraging mode syndromes can shift intraspecifically with potential cascading effects on local ecological communities.
