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- Sceloporus undulatus (4)
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Articles 1 - 20 of 20
Full-Text Articles in Life Sciences
Direct Evidence Of Phospholipids In Gecko Footprints And Spatula– Substrate Contact Interface Detected Using Surface-Sensitive Spectroscopy, Ping Hsu, Liehui Ge, Xiaopeng Li, Alyssa Stark, Chrys Wesdemiotis, Peter Niewiarowski, Ali Dhinojwala
Direct Evidence Of Phospholipids In Gecko Footprints And Spatula– Substrate Contact Interface Detected Using Surface-Sensitive Spectroscopy, Ping Hsu, Liehui Ge, Xiaopeng Li, Alyssa Stark, Chrys Wesdemiotis, Peter Niewiarowski, Ali Dhinojwala
Dr. Peter H. Niewiarowski
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 derWaals 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 …
Gecko Adhesion As A Model System For Integrative Biology, Interdisciplinary Science, And Bioinspired Engineering, Peter Niewiarowski, K. Autumn, J. Puthoff
Gecko Adhesion As A Model System For Integrative Biology, Interdisciplinary Science, And Bioinspired Engineering, Peter Niewiarowski, K. Autumn, J. Puthoff
Dr. Peter H. Niewiarowski
Geckos possess a superlative climbing adaptation in the form of hierarchical arrays of adhesive nanostructures on the underside of their toes. These structures permit rapid, robust, and reliable adhesion to nearly any substrate during full-speed locomotion. We review the fundamental principles and properties of this system, describe its ecological and evolutionary aspects, and offer our assessment of the field alongside suggestions for future research in this direction.
Reduction Of Water Surface Tension Significantly Impacts Gecko Adhesion Underwater, Peter Niewiarowski, Ali Dhinojwala, Alyssa Stark, Brandon Mcclung
Reduction Of Water Surface Tension Significantly Impacts Gecko Adhesion Underwater, Peter Niewiarowski, Ali Dhinojwala, Alyssa Stark, Brandon Mcclung
Dr. Peter H. Niewiarowski
The gecko adhesive system is dependent on weak van der Waals interactions that are multiplied across thousands of fine hair-like structures (setae) on geckos' toe pads. Due to the requirements of van der Waals forces, we expect that any interruption between the setae and substrate, such as a water layer, will compromise adhesion. Our recent results suggest, however, that the air layer (plastron) surrounding the superhydrophobic toe pads aid in expelling water at the contact interface and create strong shear adhesion in water when in contact with hydrophobic surfaces. To test the function of the air plastron, we reduced the …
Histochemical And Ultrastructural Analyses Of Adhesive Setae Of Lizards Indicate That They Contain Lipids In Addition To Keratins, L. Alibardi, D. Edward, R. Bouhenni, Ali Dhinojwala, Peter Niewiarowski
Histochemical And Ultrastructural Analyses Of Adhesive Setae Of Lizards Indicate That They Contain Lipids In Addition To Keratins, L. Alibardi, D. Edward, R. Bouhenni, Ali Dhinojwala, Peter Niewiarowski
Dr. Peter H. Niewiarowski
ABSTRACT We studied the distribution of lipid material and organelles in the epidermal layers of toe pads from two species of lizards representing the two main lizard families in which adhesive scansors are found (gekkonids and polychrotids), the dull day gecko, Phelsuma dubia and the green anole, Anolis carolinensis. Although lipids are a conspicuous component of the mesos layer of squamate reptiles and function in reducing cutaneous water loss, their distribution has not been specifically studied in the highly elaborated epidermal surface of adhesive toe pads. We found that, in addition to the typical cutaneous water loss-resistant mesos and alpha-layer …
Self-Drying: A Gecko's Innate Ability To Remove Water From Wet Toe Pads, Alyssa Stark, Eva Paoloni, Peter Niewiarowski, Ali Dhinojwala, N Wucinich
Self-Drying: A Gecko's Innate Ability To Remove Water From Wet Toe Pads, Alyssa Stark, Eva Paoloni, Peter Niewiarowski, Ali Dhinojwala, N Wucinich
Dr. Peter H. Niewiarowski
When the adhesive toe pads of geckos become wet, they become ineffective in enabling geckos to stick to substrates. This result is puzzling given that many species of gecko are endemic to tropical environments where water covered surfaces are ubiquitous. We hypothesized that geckos can recover adhesive capabilities following exposure of their toe pads to water by walking on a dry surface, similar to the active self-cleaning of dirt particles. We measured the time it took to recover maximum shear adhesion after toe pads had become wet in two groups, those that were allowed to actively walk and those that …
The Role Of Surface Chemistry In Adhesion And Wetting Of Gecko Toe Pads, Ali Dhinojwala, Peter Niewiarowski, Ila Badge, Alyssa Stark, Eva Paoloni
The Role Of Surface Chemistry In Adhesion And Wetting Of Gecko Toe Pads, Ali Dhinojwala, Peter Niewiarowski, Ila Badge, Alyssa Stark, Eva Paoloni
Dr. Peter H. Niewiarowski
An array of micron-sized setal hairs offers geckos a unique ability to walk on vertical surfaces using van der Waals interactions. Although many studies have focused on the role of surface morphology of the hairs, very little is known about the role of surface chemistry on wetting and adhesion. We expect that both surface chemistry and morphology are important, not only to achieve optimum dry adhesion but also for increased efficiency in self-cleaning of water and adhesion under wet conditions. Here, we used a plasma-based vapor deposition process to coat the hairy patterns on gecko toe pad sheds with polar …
Surface Chemistry And Self-Drying In The Gecko Adhesive System. Integrative And Comparative Biology, Peter Niewiarowski, Alyssa Stark, N Wucinich, I Badge, Ali Dhinojwala, E Paoloni
Surface Chemistry And Self-Drying In The Gecko Adhesive System. Integrative And Comparative Biology, Peter Niewiarowski, Alyssa Stark, N Wucinich, I Badge, Ali Dhinojwala, E Paoloni
Dr. Peter H. Niewiarowski
No abstract provided.
Reciprocal Transplant Reveals Sources Of Variation In Growth Rates Of The Lizard Sceloporus Undulatus, Peter Niewiarowski, Willem Roosenburg
Reciprocal Transplant Reveals Sources Of Variation In Growth Rates Of The Lizard Sceloporus Undulatus, Peter Niewiarowski, Willem Roosenburg
Dr. Peter H. Niewiarowski
Geographic variation in life history phenotypes between population of a single species is often assumed to reflect genetic divergence caused by natural selection. The relative contribution of genetic and environmental sources of phenotypic variation is plasticity induced by proximate environmental variation and genetic divergence is fundamental to understanding the ecological and evolutionary significance of geographic variation.
The Effect Of Surface Water And Wetting On Gecko Adhesion, Peter Niewiarowski, A. Y., T. Sullivan
The Effect Of Surface Water And Wetting On Gecko Adhesion, Peter Niewiarowski, A. Y., T. Sullivan
Dr. Peter H. Niewiarowski
Despite profound interest in the mechanics and performance of the gecko adhesive system, relatively few studies have focused on performance under conditions that are ecologically relevant to the natural habitats of geckos. Because geckos are likely to encounter surfaces that are wet, we used shear force adhesion measurements to examine the effect of surface water and toe pad wetting on the whole-animal performance of a tropical-dwelling gecko (Gekko gecko). To test the effect of surface wetting, we measured the shear adhesive force of geckos on three substrate conditions: dry glass, glass misted with water droplets and glass fully submerged in …
Surface Wettability Plays A Significant Role In Gecko Adhesion Underwater, Alyssa Stark, Ila Badge, N Wucinich, T Sullivan, Peter Niewiarowski, Ali Dhinojwala
Surface Wettability Plays A Significant Role In Gecko Adhesion Underwater, Alyssa Stark, Ila Badge, N Wucinich, T Sullivan, Peter Niewiarowski, Ali Dhinojwala
Dr. Peter H. Niewiarowski
Although we now have thousands of studies focused on the nano-, micro-, and whole-animal mechanics of gecko adhesion on clean, dry substrates, we know relatively little about the effects of water on gecko adhesion. For many gecko species, however, rainfall frequently wets the natural surfaces they navigate. In an effort to begin closing this gap, we tested the adhesion of geckos on submerged substrates that vary in their wettability. When tested on a wet hydrophilic surface, geckos produced a significantly lower shear adhesive force (5.4 ± 1.33 N) compared with a dry hydrophilic surface (17.1 ± 3.93 N). In tests …
Effects Of Temperature And Time Of Day On The Resting Metabolic Rates Of Paedomorphic And Metamorphic Mole Salamanders, Ambystoma Talpoideum, Peter Niewiarowski, C. Currens, H. Whiteman
Effects Of Temperature And Time Of Day On The Resting Metabolic Rates Of Paedomorphic And Metamorphic Mole Salamanders, Ambystoma Talpoideum, Peter Niewiarowski, C. Currens, H. Whiteman
Dr. Peter H. Niewiarowski
Mole salamanders, ambystoma talpoideum, are one of several species that exhibit facultative paedomorphosis.
Phylogenetic Comparative Analysis Of Life-History Variation Among Populations Of The Lizard Sceloporus Undulatus: An Example And Prognosis, Peter Niewiarowski, Michael Angilletta, Adam Leache
Phylogenetic Comparative Analysis Of Life-History Variation Among Populations Of The Lizard Sceloporus Undulatus: An Example And Prognosis, Peter Niewiarowski, Michael Angilletta, Adam Leache
Dr. Peter H. Niewiarowski
Over the past 15 years, phylogenetic comparative methods (PCMs) have become standard in the study of life-history evolution. To date, most studies have focused on variation among species or higher taxonomic levels, generally revealing the presence of significant phylogenetic effects as well as residual variation potentially attributable to adaptive evolution.
The Effect Of Water On The Gecko Adhesive System, Alyssa Stark, Peter Niewiarowski, Ali Dhinojwala, I Badge
The Effect Of Water On The Gecko Adhesive System, Alyssa Stark, Peter Niewiarowski, Ali Dhinojwala, I Badge
Dr. Peter H. Niewiarowski
No abstract provided.
Faster But Not Stickier: Invasive House Geckos Can Out-Sprint Resident Mournful Geckos In Moorea, French Polynesia, Peter Niewiarowski, Alyssa Stark, Brandon Mcclung, Briana Chambers
Faster But Not Stickier: Invasive House Geckos Can Out-Sprint Resident Mournful Geckos In Moorea, French Polynesia, Peter Niewiarowski, Alyssa Stark, Brandon Mcclung, Briana Chambers
Dr. Peter H. Niewiarowski
The House Gecko, Hemidactylus frenatus, is one of the world's most invasive vertebrate species and is spreading rapidly across the South Pacific, displacing other species of geckos that are native or were already resident. We studied the adhesion and locomotor capabilities of H. frenatus and the resident Lepidodactylus lugubris on the island of Moorea in French Polynesia where they are syntopic. Our goal was to determine whether H. frenatus could stick or sprint faster than L. lugubris, two types of performance measures that could underlie superiority of H. frenatus in foraging and agonistic interactions hypothesized in other studies. The clinging …
Bergmann's Clines In Ectotherms: Illustrating A Life-History Perspective With Sceloporine Lizards, Michael Angilletta, Peter Niewiarowski, Arthur Dunham, Adam Leache, Warren Porter
Bergmann's Clines In Ectotherms: Illustrating A Life-History Perspective With Sceloporine Lizards, Michael Angilletta, Peter Niewiarowski, Arthur Dunham, Adam Leache, Warren Porter
Dr. Peter H. Niewiarowski
The generality and causes of Bergmann's rule have been debated vigorously in the last few years, but Bergmann's clines are rarely explained in the context of life-history theory. We used both traditional and phylogenetic comparative analyses to explore the causes of latitudinal and thermal clines in the body size of the eastern fence lizard (Sceloporus undulatus). The proximate mechanism for larger body sizes in colder environments is delayed maturation, which results in a greater fecundity but a lower survival to maturity. Life-history theory predicts that a higher survivorship of juveniles in colder environments can favor the evolution of a Bergmann's …
Sticky Gecko Feet: The Role Of Temperature And Humidity, Peter H. Niewiarowski, Stephanie Lopez, Liehui Ge, Emily Hagan, Ali Dhinojwala
Sticky Gecko Feet: The Role Of Temperature And Humidity, Peter H. Niewiarowski, Stephanie Lopez, Liehui Ge, Emily Hagan, Ali Dhinojwala
Dr. Peter H. Niewiarowski
Gecko adhesion is expected to be temperature insensitive over the range of temperatures typically experienced by geckos. Previous work is limited and equivocal on whether this expectation holds. We tested the temperature dependence of adhesion in Tokay and Day geckos and found that clinging ability at 12 degrees C was nearly double the clinging ability at 32 degrees C. However, rather than confirming a simple temperature effect, our data reveal a complex interaction between temperature and humidity that can drive differences in adhesion by as much as two-fold. Our findings have important implications for inferences about the mechanisms underlying the …
Responses Of Mole Salamanders To Clearcutting: Using Field Experiments In Forest Management, Anne Chazal, Peter Niewiarowski
Responses Of Mole Salamanders To Clearcutting: Using Field Experiments In Forest Management, Anne Chazal, Peter Niewiarowski
Dr. Peter H. Niewiarowski
Impacts of forest management practices on amphibian populations have received growing attention in the last 10 yr. However, to date, measured responses include only comparisons of species diversity indices and population counts without true spatial and temporal controls. We used an experimental approach to test for differences in growth rate, fecundity, age at maturity, and whole-body storage lipids in individual mole salamanders, Ambystoma talpoideum, placed in differently managed habitats. Four 100-m(2) field enclosures were built in each of two habitats, a 4-mo-old clearcut and an adjacent 40-yr-old pine forest. On 19 July 1994, 80 recently metamorphosed and individually marked, weighed, …
Cold Acclimation Strategy Is Highly Variable Among The Sunfishes (Centrarchidae), Deidra R. Tschantz, Elizabeth L. Crockett, Peter H. Niewiarowski, Richard L. Londraville
Cold Acclimation Strategy Is Highly Variable Among The Sunfishes (Centrarchidae), Deidra R. Tschantz, Elizabeth L. Crockett, Peter H. Niewiarowski, Richard L. Londraville
Dr. Peter H. Niewiarowski
We tested the hypothesis that the physiological strategy for acclimating to low body temperature is similar among closely related fish. Largemouth bass (Micropterus salmoides), green sunfish (Lepomis cyanellus), bluegill sunfish (Lepomis macrochirus), black crappie (Pomonix nigromaculatus), and white crappie (Pomonix annularis), all members of the family Centrarchidae, were acclimated to 5degrees and 25degreesC. Morphometric variables (total mass, total length, organ masses) and enzyme activities (hexokinase; lactate dehydrogenase; and cytochrome oxidase in heart, liver, and muscle) were measured in 5degreesC- and 25degreesC- acclimated fish at 5degrees and 25degreesC assay temperatures. Each species displayed a distinct physiological response to cold acclimation that …
Energy Budgets, Growth Rates, And The Rmal Constraints: Toward An Integrative Approach To The Study Of Life-History Variation, Peter H. Niewiarowski
Energy Budgets, Growth Rates, And The Rmal Constraints: Toward An Integrative Approach To The Study Of Life-History Variation, Peter H. Niewiarowski
Dr. Peter H. Niewiarowski
Variation in thermal constraints on activity has been hypothesized to be an important ecological source of geographic variation in growth rates of juvenile eastern fence lizards Sceloporus undulatus. However, most of the evidence to support this hypothesis is either inferential or indirect. In this study, I quantitatively compared thermal constraints on activity and their relationship to growth rates of free-ranging juvenile fence lizards from two extremes of the range of variation in growth rate (Nebraska and New Jersey) used in a reciprocal transplant experiment. I also examined energy allocation made to growth and storage by yearling lizards. Reduced growth rates …
Phenotypic Effects Of Leptin In An Ectotherm: A New Tool To Study The Evolution Of Life Histories And Endothermy?, Richard L. Londraville, Michelle L. Balk, Peter H. Niewiarowski
Phenotypic Effects Of Leptin In An Ectotherm: A New Tool To Study The Evolution Of Life Histories And Endothermy?, Richard L. Londraville, Michelle L. Balk, Peter H. Niewiarowski
Dr. Peter H. Niewiarowski
Leptin is a hormone that regulates energy expenditure and body mass in mammals, and it has attracted considerable attention because of its potential in treating human obesity. Comprehensive data from both pathological and non-pathological systems strongly support a role for leptin in regulating energy metabolism, in thermoregulation and in regulating the onset of puberty. We report here that daily injections of recombinant murine leptin in fence lizards (Sceloporus undulatus) produce phenotypic effects similar to those observed when leptin injections are given to mice, Lizards injected with leptin had body temperatures 0.6 degrees C higher, ate 30 % less food and …