| interactive effects of thyroxine and experimental location on running endurance, tissue masses, and enzyme activities in captive versus field-active lizards (sceloporus undulatus). | this study investigates the effects of exogenous thyroxine (t4) on running endurance, tissue masses, and the activities of citrate synthase (cs), pyruvate kinase (pk), cytosolic alpha-glycerophosphate dehydrogenase (alpha-gpdh), and beta-hydroxyacyl coenzyme a dehydrogenase (hoad) in sceloporus undulatus (eastern fence lizard). the enzymes were assayed to indicate maximal catabolic activities that support exercise. parallel experiments were done on captive and field-active groups to determine wh ... | 1991 | 2026310 |
| seasonal activity and host associations of ixodes scapularis (acari: ixodidae) in southeastern missouri. | based on tick collections recovered from wild vertebrates and by dragging, the seasonal occurrence of adult blacklegged ticks, ixodes scapularis say, extended from october through may in southeastern missouri. adult activity was bimodal with the higher peak occurring in november followed by a lower peak in february. the activity of immature i. scapularis had the general pattern of that found in the northeast where lyme disease is hyperendemic, with larval activity (july) peaking after that of ny ... | 1999 | 10593072 |
| molecular systematics of the eastern fence lizard (sceloporus undulatus): a comparison of parsimony, likelihood, and bayesian approaches. | phylogenetic analysis of large datasets using complex nucleotide substitution models under a maximum likelihood framework can be computationally infeasible, especially when attempting to infer confidence values by way of nonparametric bootstrapping. recent developments in phylogenetics suggest the computational burden can be reduced by using bayesian methods of phylogenetic inference. however, few empirical phylogenetic studies exist that explore the efficiency of bayesian analysis of large data ... | 2002 | 11943092 |
| development of a terrestrial vertebrate model for assessing bioavailability of cadmium in the fence lizard (sceloporus undulatus) and in ovo effects on hatchling size and thyroid function. | in the terrestrial environment, standardized protocols are available for measuring the exposure and effects of contaminants to invertebrates, but none currently exist for vertebrates. in an effort to address this, we proposed that developing lizard embryos may be used as a terrestrial vertebrate model. lizard eggs may be particularly susceptible to soil contamination and in ovo exposure may affect hatchling size, mortality, as well as thyroid function. toxicant-induced perturbations of thyroid f ... | 2004 | 14675843 |
| observations on the natural occurrence of plasmodium floridense, a saurian malaria parasite, in sceloporus undulatus undulatus. | | 1951 | 14824938 |
| the course of natural and induced infections of plasmodium floridense thompson and huff in sceloporus undulatus undulatus (latreille). | | 1952 | 14952700 |
| natriuretic peptides are negative modulators of adrenocortical cell function of the eastern fence lizard (sceloporus undulatus). | elucidation of the role of natriuretic peptides (nps) in vertebrate adrenal steroidogenesis has been facilitated by the use of freshly dispersed adrenocortical cells. our recent characterization of lizard adrenocortical cells [carsia, r.v., john-alder, h.b., 2003. seasonal alterations in adrenocortical cell function associated with stress-responsiveness and sex in the eastern fence lizard (sceloporus undulatus). horm. behav. 43, 408-420] provided the opportunity to examine the influence of atria ... | 2006 | 16212963 |
| bacteriocidal activity of lizard and mouse serum for borrelia lonestari, putative agent of a lyme-like illness (aka stari or masters disease) in missouri. | to determine responses of borrelia lonestari and borrelia burgdorferi to eastern fence lizard (sceloporus undulatus) and swiss-webster mouse (mus musculus) sera. | 2005 | 16259394 |
| convergent evolution of embryonic growth and development in the eastern fence lizard (sceloporus undulatus). | theory predicts that cold environments will select for strategies that enhance the growth of ectotherms, such as early emergence from nests and more efficient use of resources. we used a common garden experiment to detect parallel clines in rates of embryonic growth and development by eastern fence lizards (sceloporus undulatus). using realistic thermal conditions, we measured growth efficiencies and incubation periods of lizards from five populations representing two distinct clades. in both cl ... | 2006 | 16817545 |
| ascertainment bias in spatially structured populations: a case study in the eastern fence lizard. | despite increased interest in applying single nucleotide polymorphism (snp) data to questions in natural systems, one unresolved issue is to what extent the ascertainment bias induced during the snp discovery phase will impact available analysis methods. although most studies addressing ascertainment bias have focused on human populations, it is not clear whether existing methods will work when applied to other species with more complex demographic histories and more significant levels of popula ... | 2007 | 17611259 |
| the role of lizards in the ecology of lyme disease in two endemic zones of the northeastern united states. | we examined the role of lizards in the ecology of lyme disease in new york and maryland. we collected data on vector tick infestations, measured lizard "realized" reservoir competence for the lyme disease spirochete borrelia burgdorferi, and estimated lizard population density. these data were incorporated into a model that predicts a host's ability to influence the prevalence of b. burgdorferi in the tick population, a primary risk factor in the epidemiology of lyme disease. published data on o ... | 2007 | 17626342 |
| sublethal effects of invasive fire ant venom on a native lizard. | invasive species can impose novel selection pressures on natives, such as toxins to which native taxa are not adapted. native species may survive such invasions by evolving mechanisms to avoid toxin exposure or increase toxin tolerance. red imported fire ants (solenopsis invicta) employ an alkaloid-based venom to defend their colonies and capture prey. in this study we aim to characterize the sublethal effects of invasive fire ant venom on a native vertebrate, the eastern fence lizard (sceloporu ... | 2010 | 19722273 |
| invader danger: lizards faced with novel predators exhibit an altered behavioral response to stress. | animals respond to stressors by producing glucocorticoid stress hormones, such as corticosterone (cort). cort acts too slowly to trigger immediate behavioral responses to a threat, but can change longer-term behavior, facilitating an individual's survival to subsequent threats. to be adaptive, the nature of an animal's behavior following elevated cort levels should be matched to the predominant threats that they face. seeking refuge following a stressful encounter could be beneficial if the pred ... | 2011 | 21549122 |
| minimal role of eastern fence lizards in borrelia burgdorferi transmission in central new jersey oak/pine woodlands. | the eastern fence lizard, sceloporus undulatus , is widely distributed in eastern and central north america, ranging through areas with high levels of lyme disease, as well as areas where lyme disease is rare or absent. we studied the potential role of s. undulatus in transmission dynamics of lyme spirochetes by sampling ticks from a variety of natural hosts at field sites in central new jersey, and by testing the reservoir competence of s. undulatus for borrelia burgdorferi in the laboratory. t ... | 2014 | 24871138 |
| how do duration, frequency, and intensity of exogenous cort elevation affect immune outcomes of stress? | stress is typically characterized as "acute" (lasting from minutes to hours) or "chronic" (lasting from days to months). these terms are of limited use as they are inconsistently used and only encompass one aspect of the stressor (duration). short and long duration stress are generally thought to produce specific outcomes (e.g. acute stress enhances while chronic stress suppresses immune function). we propose that aspects of stress other than duration, such as frequency and intensity, are import ... | 2015 | 26209864 |
| immune responses of eastern fence lizards (sceloporus undulatus) to repeated acute elevation of corticosterone. | prolonged elevations of glucocorticoids due to long-duration (chronic) stress can suppress immune function. it is unclear, however, how natural stressors that result in repeated short-duration (acute) stress, such as frequent agonistic social encounters or predator attacks, fit into our current understanding of the immune consequences of stress. since these types of stressors may activate the immune system due to increased risk of injury, immune suppression may be reduced at sites where individu ... | 2014 | 24852352 |
| evaluation of western fence lizards (sceloporus occidentalis) and eastern fence lizards (sceloporus undulatus) as laboratory reptile models for toxicological investigations. | a need is recognized for one or more laboratory reptile models for use in ecotoxicological studies and risk assessments. maintenance of breeding populations of most reptile species under laboratory conditions is not practical because of their size and slow maturation rate. however, a number of species of spiny lizards (sceloporus sp.) are small, mature quickly, and reproduce under laboratory conditions. we evaluated three populations of western fence lizards (s. occidentalis) and four population ... | 2002 | 12013135 |
| effect of temperature on feeding period of larval blacklegged ticks (acari: ixodidae) on eastern fence lizards. | ambient temperature can influence tick development time, and can potentially affect tick interactions with pathogens and with vertebrate hosts. we studied the effect of ambient temperature on duration of attachment of larval blacklegged ticks, ixodes scapularis say, to eastern fence lizards, sceloporus undulatus (bosc & daudin). feeding periods of larvae that attached to lizards under preferred temperature conditions for the lizards (warm treatment: temperatures averaged 36.6°c at the top of the ... | 2014 | 26309322 |
| gonadal modulation of in vitro steroidogenic properties of dispersed adrenocortical cells from sceloporus lizards. | effects of adrenal corticosteroids on reproductive and endocrine functions of the gonads are well known, but reciprocal effects of gonadal hormones on the hypothalamo-pituitary-adrenal (hpa) axis and on adrenocortical steroidogenesis in particular have received much less attention. we investigated effects of gonadectomy and testosterone (t) replacement on adrenocortical cell function in a year-long field study of male sceloporus undulatus (eastern fence lizard) and in a shorter term laboratory s ... | 2008 | 18708060 |
| optimization of pcr conditions to amplify microsatellite loci in the bunchgrass lizard (sceloporus slevini) genomic dna. | microsatellites, also called simple sequence repeats (ssrs), repetitions of nucleotide motifs of 1-5 bases, are currently the markers of choice due to their abundant distribution in the genomes, and suitability for high-throughput analysis. a total of five different primer pairs were optimized for polymerase chain reaction (pcr) to amplify microsatellite loci in total genomic dna of bunchgrass lizards (sceloporus slevini) collected from three sites in southeastern arizona; the sonoita plain, chi ... | 2011 | 21281503 |
| trans-generational but not early life exposure to stressors influences offspring morphology and survival. | environmental changes, such as the introduction of non-native species, can impose novel selective pressures. this can result in changes in fitness-relevant traits within an individual's lifetime or across multiple generations. we investigated the effects of early life versus trans-generational exposure to a predatory invasive insect stressor, the red imported fire ant (solenopsis invicta), on the morphology and survival of the eastern fence lizard (sceloporus undulatus). we captured gravid lizar ... | 2018 | 29189938 |
| sex hormones and the development of sexual size dimorphism: 5α-dihydrotestosterone inhibits growth in a female-larger lizard (sceloporus undulatus). | sexual differences in adult body size [sexual size dimorphism (ssd)] and color (sexual dichromatism) are widespread, and both male- and female-biased dimorphisms are observed even among closely related species. a growing body of evidence indicates testosterone can regulate growth, thus the development of ssd, and sexual dichromatism. however, the mechanism(s) underlying these effects are conjectural, including possible conversions of testosterone to estradiol (e2) or 5α-dihydrotestosterone (dht) ... | 2017 | 28912255 |
| ancestry trumps experience: transgenerational but not early life stress affects the adult physiological stress response. | exposure to stressors can affect an organism's physiology and behavior as well as that of its descendants (e.g. through maternal effects, epigenetics, and/or selection). we examined the relative influence of early life vs. transgenerational stress exposure on adult stress physiology in a species that has populations with and without ancestral exposure to an invasive predator. we raised offspring of eastern fence lizards (sceloporus undulatus) from sites historically invaded (high stress) or unin ... | 2017 | 27864050 |
| irresistible ants: exposure to novel toxic prey increases consumption over multiple temporal scales. | as species become increasingly exposed to novel challenges, it is critical to understand how evolutionary (i.e., generational) and plastic (i.e., within lifetime) responses work together to determine a species' fate or predict its distribution. the introduction of non-native species imposes novel pressures on the native species that they encounter. understanding how native species exposed to toxic or distasteful invaders change their feeding behavior can provide insight into their ability to cop ... | 2016 | 27000944 |
| ultrastructural analysis of spermiogenesis in the eastern fence lizard, sceloporus undulatus (squamata: phrynosomatidae). | studies on reptilian sperm morphology have shown that variation exists at various taxonomic levels but studies on the ontogeny of variation are rare. sperm development follows a generalized bauplan that includes acrosome development, nuclear condensation and elongation, and flagellar development. however, minute differences can be observed such as the presence/absence of manchette microtubules, structural organization during nuclear condensation, and presence/absence of a nuclear lacuna. the pur ... | 2016 | 26690819 |
| rise and fall of a hybrid zone: implications for the roles of aggression, mate choice, and secondary succession. | hybridization can be an important evolutionary force by generating new species and influencing evolution of parental species in multiple ways, including introgression and the consequences of hybrid vigor. determining the ecological processes underlying evolution in hybrid zones is difficult however because it requires examining changes in both genotypic frequencies over time and corresponding ecological information, data that are rarely collected together. here, we describe genetic and ecologica ... | 2014 | 24381182 |
| latitudinal and seasonal variation in reproductive effort of the eastern fence lizard (sceloporus undulatus). | geographic variation in life-history traits among populations of wide-ranging species is influenced by both spatial and temporal aspects of the environment. rarely, however, are the effects of both aspects examined concurrently. we collected gravid female lizards (sceloporus undulatus) from northern (indiana), central (mississippi) and southern (florida) populations, spanning nearly the full latitudinal range of the species, to examine among population differences in strategies of reproductive e ... | 2014 | 24148228 |
| the consequences of lifetime and evolutionary exposure to toxic prey: changes in avoidance behaviour through ontogeny. | responses to novel threats (e.g. invasive species) can involve genetic changes or plastic shifts in phenotype. there is controversy over the relative importance of these processes for species survival of such perturbations, but we are realizing they are not mutually exclusive. native eastern fence lizards (sceloporus undulatus) have adapted to top-down predation pressure imposed by the invasive red imported fire ant (solenopsis invicta) via changes in adult (but not juvenile) lizard antipredator ... | 2012 | 22882278 |
| effects of breeding season, testosterone and acth on the corticosterone response of free-ranging male fence lizards (sceloporus undulatus). | an attenuated stress response during the breeding season has been reported for several vertebrate species, but the underlying physiological mechanism has received little attention, particularly in reptiles. modulation could involve changes in the capacity of the adrenal gland to secrete glucocorticoids in addition to upstream changes in the pituitary or hypothalamus. in this study the magnitude of the corticosterone response to capture and confinement was compared between the breeding and postbr ... | 2011 | 21703273 |
| male territoriality and 'sex confusion' in recently adapted lizards at white sands. | the evolution of intersexual interactions, like mate choice, during ecological speciation has received widespread attention. however, changes in intrasexual interactions, like male territoriality, during ecological divergence are largely unexamined. we conducted field experiments with adaptively diverged populations of the eastern fence lizard (sceloporus undulatus) to determine whether territorial males behaved differently towards ecologically similar vs. dissimilar intruders. we performed tria ... | 2010 | 20695966 |
| stress and aversive learning in a wild vertebrate: the role of corticosterone in mediating escape from a novel stressor. | elevated plasma corticosterone during stressful events is linked to rapid changes in behavior in vertebrates and can mediate learning and memory consolidation. we tested the importance of acute corticosterone elevation in aversive learning of a novel stressor by wild male eastern fence lizards (sceloporus undulatus). we found that inhibiting corticosterone elevation (using metyrapone, a corticosterone synthesis blocker) during an encounter with a novel attacker impaired immediate escape response ... | 2010 | 19922261 |
| spatial dynamics of nesting behavior: lizards shift microhabitats to construct nests with beneficial thermal properties. | because temperature affects the growth, development, and survival of embryos, oviparous mothers should discriminate carefully among available nesting sites. we combined a radiotelemetric study of animal movements with a spatial mapping of environmental temperatures to test predictions about the nesting behavior of the eastern fence lizard (sceloporus undulatus). females made large excursions from their typical home ranges to construct nests in exposed substrates. these excursions appeared to be ... | 2009 | 19886501 |
| hormones, performance and fitness: natural history and endocrine experiments on a lizard (sceloporus undulatus). | we used the "morphology-performance-fitness" paradigm (arnold, 1983) as our framework to investigate endocrine control of performance and fitness in sceloporus undulatus (eastern fence lizard). focusing on males, we used the "natural experiments" of seasonal, sexual, and developmental variation in growth and in exercise endurance to identify testosterone and corticosterone as potential modulators of performance and related traits of interest. we followed with experimental manipulations of testos ... | 2009 | 21665829 |
| transgressive aggression in sceloporus hybrids confers fitness through advantages in male agonistic encounters. | 1. we investigated agonistic behaviour and associated characteristics of sceloporus woodi (florida scrub lizard), sceloporus undulatus (eastern fence lizard) and their hybrids using staged territorial encounters. 2. these sceloporus hybrids exhibit transgressive aggression and transgressive head-girth relative to the parental species and the transgressive aggression was specifically associated with an advantage in agonistic encounters. our results suggest a hybrid advantage in natural habitats w ... | 2010 | 19682141 |
| energy budgets, growth rates, and thermal constraints: toward an integrative approach to the study of life-history variation. | 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 rat ... | 2001 | 18707251 |
| a multilocus perspective on colonization accompanied by selection and gene flow. | the colonization of novel habitats involves complex interactions between founder events, selection, and ongoing migration, and can lead to diverse evolutionary outcomes from local extinction to adaptation to speciation. although there have been several studies of the demography of colonization of remote habitats, less is known about the demographic consequences of colonization of novel habitats within a continuous species range. populations of the eastern fence lizard, sceloporus undulatus, are ... | 2007 | 17976180 |
| rapid assimilation of yolk enhances growth and development of lizard embryos from a cold environment. | selection for rapid growth and development in cold environments results in a geographic pattern known as countergradient variation. the eastern fence lizard, sceloporus undulatus, exhibits countergradient variation in embryonic growth and development along latitudinal clines. to identify the proximate causes of countergradient variation, we compared the energy budgets of embryos from a cold environment (virginia) and a warm environment (south carolina) during development at a realistic thermal c ... | 2007 | 17872995 |
| energetics of lizard embryos are not canalized by thermal acclimation. | in some species of ectotherms, temperature has little or no effect on the amount of energy expended during embryonic development. this phenomenon can result from either of two mechanisms: (1) a shorter incubation period at higher temperatures, which offsets the expected increase in metabolic rate, or (2) a compensatory decrease in the rate at which embryos expend energy for maintenance. to distinguish the relative importance of these two mechanisms, we quantified the acute and chronic effects of ... | 2006 | 16691523 |
| testosterone inhibits growth in juvenile male eastern fence lizards (sceloporus undulatus): implications for energy allocation and sexual size dimorphism. | in the eastern fence lizard, sceloporus undulatus, female-larger sexual size dimorphism develops because yearling females grow faster than males before first reproduction. this sexual growth divergence coincides with maturational increases in male aggression, movement, and ventral coloration, all of which are influenced by the sex steroid testosterone (t). these observations suggest that male growth may be constrained by energetic costs of activity and implicate t as a physiological regulator of ... | 2013 | 15957108 |
| seasonal alterations in adrenocortical cell function associated with stress-responsiveness and sex in the eastern fence lizard (sceloporus undulatus). | we characterized steroidogenic properties of dispersed adrenocortical cells from field-active male and female eastern fence lizards (sceloporus undulatus) to investigate whether alterations in cell function could, in part, explain seasonal variation in baseline and stress-induced plasma corticosterone (b). lizards were collected during the breeding and postbreeding seasons and shortly prior to hibernation. dispersed cells in vitro produced b, aldosterone (aldo), and progesterone in response to 8 ... | 2003 | 12695115 |
| variation in metabolic rate between populations of a geographically widespread lizard. | in geographically widespread ectotherms, variation in life history phenotypes may be caused by differences in maintenance metabolism of individuals. i estimated daily and annual maintenance metabolism of eastern fence lizards, sceloporus undulatus, from two populations with markedly different life histories; lizards in south carolina grow faster, mature earlier, and have greater annual reproductive output than lizards in new jersey. i measured diel cycles of resting metabolic rate (rmr) at four ... | 2006 | 11226010 |
| androgen receptor-immunoreactivity in the forebrain of the eastern fence lizard (sceloporus undulatus). | androgen receptor (ar) distribution in the lizard forebrain and optic tectum was examined using pg21 immunohistochemistry. in the male eastern fence lizard, ar-immunoreactive (-ir) nuclei were observed in the medial preoptic area, ventromedial and arcuate hypothalamic nuclei, periventricular hypothalamus, premammillary nucleus, bed nucleus of the stria terminalis, and ventral posterior amygdala. punctate immunostaining of neuronal processes (axons and/or dendrites) was concentrated in the cortex ... | 2000 | 11011019 |