Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| the organization of the hippocampus of the fence lizard: a light microscopic study. | the hippocampus of the fence lizard (sceloporus undulatus) is composed of two laminated regions that are readily distinguishable on the basis of position and perikaryal size in nissl preparations: the small-celled (hsc) and the large-celled (hlc) hippocampal divisions. based upon cellular and fibrillar characteristics, the layers of the hsc are: (1) the superficial plexiform layer; (2) the cellular layer; (3) the deep plexiform layer; (4) the layer of deep fibers, or alveus; and, (5) the ventric ... | 1978 | 701493 |
| an electrophoretic study of inter- and intrapopulation genetic variation within the northern fence swift, sceloporus undulatus hyacinthinus. | 1976 | 1000935 | |
| neurofilament and glycogen changes during cold acclimation in the trochlear nucleus of lizards (sceloporus undulatus). | in lizards (sceloporus undulatus), long term (13 or 19 weeks) acclimation to an environment of 6 degrees c produces a striking increase in the argyrophilic neurofibrillar network in most large perikarya of the trochlear nucleus. in electron micrographs the cells contain numerous bundles of 10-30 regularly-spaced 90 a neurofilaments. in the cells from warm acclimated animals, a plexus of neurofibrils is seen by light microscopy. the electron micrographs show scattered neurofilaments and fewer, th ... | 1975 | 1151443 |
| growth and behavior of thyroid-deficient lizards (sceloporus undulatus). | this study investigates thyroid control of growth and energy metabolism plus growth-dependent and growth-independent behavioral effects of thyroid manipulation in lizards. experiments were done on surgically thyroidectomized (tx) and sham-operated (sh) yearling sceloporus undulatus enclosed in their natural habitat. lizards were placed in an outdoor enclosure in early august. growth rate was measured and behavior was observed until mid-october. subsequently, lizards were returned to the lab for ... | 1992 | 1398024 |
| hormonal control of polymorphic and sexually dimorphic coloration in the lizard sceloporus undulatus erythrocheilus. | this study investigated the influence of sex steroids on the expression of seasonally labile and sexually dimorphic coloration in the red-lipped plateau lizard. the responses of ventral blue and polymorphic facial coloration to exogenous steroid administration were assessed. though facial color is usually dimorphic in nature, males and females did not differ in the degree to which they expressed facial coloration following administration of testosterone (t). both sexes developed significantly mo ... | 1992 | 1490591 |
| the western fence lizard sceloporus occidentalis: evidence of field exposure to borrelia burgdorferi in relation to infestation by ixodes pacificus (acari: ixodidae). | the role of the western fence lizard sceloporus occidentalis in the enzootiology of the lyme disease spirochete borrelia burgdorferi was evaluated in the hopland and ukiah areas of mendocino county, california. in 1989, half of 74 lizards collected monthly from april to october at hopland were infested by the immature western black-legged tick ixodes pacificus at a mean intensity of 6.0 ticks per lizard. the prevalence of infestation of lizards by immature i. pacificus (36 of 73) at ukiah was si ... | 1992 | 1524146 |
| 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 |
| virulence of lizard malaria: the evolutionary ecology of an ancient parasite-host association. | the negative consequences of parasitic infection (virulence) were examined for two lizard malaria parasite-host associations: plasmodium agamae and p. giganteum, parasites of the rainbow lizard, agama agama, in sierra leone, west africa; and p. mexicanum in the western fence lizard, sceloporus occidentalis, in northern california. these malaria species vary greatly in their reproductive characteristics: p. agamae produces only 8 merozoites per schizont, p. giganteum yields over 100, and p. mexic ... | 1990 | 2235062 |
| survey of birds and lizards for ixodid ticks (acari) and spirochetal infection in northern california. | a total of 138 birds (24 species) was captured in an oak woodland between december 1988 and june 1989 at the university of california, sierra foothill range field station, yuba county, calif. ticks were not found on 71 birds captured between december 1988 and march 1989. five subadult ixodes pacificus cooley & kohls were removed from 3 of 67 birds caught between april and june 1989. these three birds, an orange-crowned warbler (vermivora celata (say], a lazuli bunting (passerina amoena (say], an ... | 1990 | 2280384 |
| thyroid regulation of resting metabolic rate and intermediary metabolic enzymes in a lizard (sceloporus occidentalis). | this study investigates the effects of physiological increments in plasma thyroxine (t4) at three levels of biological organization in thyroid-intact and thyroidectomized captive western fence lizards, sceloporus occidentalis. two doses of t4-loaded pellets elevated plasma t4 in thyroid-intact lizards from 4.8 +/- 0.47 to 10.7 +/- 2.25 and 20.4 +/- 5.77 ng/ml (mean +/- se). surgical thyroidectomy reduced t4 to 1.8 +/- 0.23 ng/ml, and subsequent t4 pellet implantation raised t4 to 14.8 +/- 4.30 n ... | 1990 | 2295423 |
| susceptibility of the western fence lizard (sceloporus occidentalis) to the lyme borreliosis spirochete (borrelia burgdorferi). | attempts to infect juvenile and adult western fence lizards (sceloporus occidentalis) with the lyme borreliosis spirochete (borrelia burgdorferi) were largely unsuccessful. spirochetes could not be isolated from the blood and various tissues of 14 lizards 21-32 days after they had been inoculated ip (n = 8) or sc (n = 6) with 10(6) or 10(8) b. burgdorferi representing 3 tick isolates, although 1 lizard apparently developed a transitory spirochetemia lasting 2 days. similarly, spirochetes could n ... | 1990 | 2301709 |
| lyme disease in california: interrelationship of ixodes pacificus (acari: ixodidae), the western fence lizard (sceloporus occidentalis), and borrelia burgdorferi. | the relationship of immature western black-legged ticks, ixodes pacificus cooley and kohls, to the western fence lizard, sceloporus occidentalis baird and girard, and to the lyme disease spirochete, borrelia burgdorferi, was investigated in chaparral and woodland-grass habitats in northern california from 1984 to 1986. immature ticks were found on lizards in spring and summer, but the prevalence and abundance of ticks on this host were considerably greater in spring. the peak of larval abundance ... | 1989 | 2769705 |
| the sex ratio of plasmodium gametocytes. | sex ratio theory usually predicts an equilibrium sex ratio and equal proportions of males and females in a population, including the progenitors of the reproductive cells of protozoans. this proposal was tested with three species of malarial parasites of lizards, plasmodium mexicanum of the western fence lizard, and p. agamae and p. giganteum of the african rainbow lizard, using single samples from naturally infected lizards, repeated samples from free-ranging lizards (p. mexicanum only), and re ... | 1989 | 2771445 |
| plasma androgens and their association with the reproductive cycle of the male fence lizard, sceloporus undulatus. | seasonal variation in plasma androgen levels was determined for males of the lizard sceloporus undulatus. plasma androgens peaked in both spring and in fall prior to brumation, coinciding with periods of maximum testicular enlargement and advanced spermatogenic development. plasma androgen concentrations were minimal during summer, following testicular regression and breeding in spring. epididymal masses were positively correlated to plasma androgen levels, while abdominal fat body masses demons ... | 1985 | 2866872 |
| differentiation and development of the reproductive system in the iguanid lizard, sceloporus undulatus. | embryos of the lizard sceloporus undulatus were sampled throughout incubation, and the differentiation and development of the reproductive system was documented histologically. the undifferentiated gonads possess both a cortex and medulla, both of which contain germ cells until embryonic stage 34. beginning at stage 34, the cortex of the presumptive ovary thickens, and cortical germ cells are more abundant. by the time of hatching, the ovarian cortex is 6 to 10 cells thick and filled with oogoni ... | 1988 | 3240847 |
| larval nematodes (ascarops sp., spirurida, spirocercidae) in liver granulomata of the western fence lizard, sceloporus occidentalis (iguanidae). | prevalence of larval nematodes (ascarops sp., spirurida, spirocercidae) and associated granulomata are reported from livers of wild populations of the western fence lizard, sceloporus occidentalis. granulomata were circumscribed by layers of fibrocytes. the encysted nematode was surrounded by masses of histiocytes, cellular debris and cells with pyknotic nuclei. | 1988 | 3411718 |
| experimental transmission of plasmodium mexicanum by bites of infected lutzomyia vexator (diptera: psychodidae). | lutzomyia vexator is an efficient experimental vector of plasmodium mexicanum, infecting 69.2% (9/13) of the sceloporus undulatus lizards with as few as one bite. sporozoites were present in the salivary glands by day 6.5 postfeed and infective by day 8 postfeed at 27 degrees c. the prepatent period was relatively long, ranging from 23 to 40 days for bite-induced infections and appears to be related to the number of sporozoites injected. the acute phase of the infection is initially exponential ... | 1987 | 3504905 |
| changes in oviducal vascularity during the reproductive cycle of three oviparous lizards (eumeces obsoletus, sceloporus undulatus and crotaphytus collaris). | histologically derived estimates and ink suspension vascular casts were used to examine oviducal vascular changes. vascularity peaked during gravidity and was correlated with maximal plasma progesterone concentrations. the vascular increase in the oviducal tissue was attributed exclusively to increased capillary densities. the greatest change occurred in the anterior uterus where incubation and egg shell secretion occur. similar patterns of change in vascularity occurred in the infundibulum, alt ... | 2013 | 3656274 |
| corpora lutea and oviposition in the lizard sceloporus undulatus. | 1973 | 4762871 | |
| morphological effects of thermal acclimation on hippocampal dendrites in the fence lizard: a golgi and em study. | 1974 | 4830471 | |
| the occurrence and development of plasmodium mexicanum in the western fence lizard sceloporus occidentalis. | 1970 | 5420333 | |
| cyclic nucleotides of cone-dominant retinas. reduction of cyclic amp levels by light and by cone degeneration. | dark-adapted retinas or whole eyes of 13-line ground squirrels (citellus tridecemlineatus) and western fence lizards (sceloporus occidentalis) contain higher levels of cyclic amp than of cyclic gmp. in these cone-dominant retinas, light reduces cyclic amp content selectively. freezing of dark- or light-adapted retinas or eyes also reduces cyclic amp content, with only minimal changes in cyclic gmp levels. in addition, exposure of frozen retinas of dark-adapted ground squirrel to light results in ... | 1981 | 6256308 |
| species typical display behavior following stimulation of the reptilian striatum. | seventy unanesthetized, unrestrained western fence lizards (sceloporus occidentalis) were electrically stimulated through implanted electrodes. behavior elicited included the species typical assertion display, elements of the challenge display and elementary locomotor responses: circling, rolling and curling. the assertion and challenge displays were elicited from telencephalic sites whereas the elementary locomotor effects were elicited from electrodes in the brain stem. assertion displays were ... | 1982 | 6891077 |
| lizards infected with malaria: physiological and behavioral consequences. | in northern california, western fence lizards, sceloporus occidentalis, are frequently parasitized by plasmodium mexicanum, which causes malaria. animals with this naturally occurring malarial infection are anemic: immature erythrocytes in peripheral blood become abundant (1 to 30 percent), and blood hemoglobin concentration decreases 25 percent. maximal oxygen consumption decreases 15 percent and aerobic scope drops 29 percent in infected lizards; both correlate with blood hemoglobin concentrat ... | 1982 | 7112113 |
| western fence lizard (sceloporus occidentalis) chemical signals. ii. a replication with naturally breeding adults and a test of the cowles and phelan hypothesis of rattlesnake olfaction. | the capacity of naturally breeding western fence lizards (sceloporus occidentalis biseriatus) to discriminate and respond to conspecific and control chemical cues was examined. lizards were presented with markings and exudates of male and female donors, as well as cologne (a pungency control) and water, in a successive discrimination procedure. behavioral actions quantified after exposure to the different chemical cue types included lingual extrusions (tongue flicks and substrate licks), rapid n ... | 1981 | 7338721 |
| diel activity of nymphal dermacentor occidentalis and ixodes pacificus (acari: ixodidae) in relation to meteorological factors and host activity periods. | relation of diel activity and questing behavior of nymphal dermacentor occidentalis marx and ixodes pacificus cooley & kohls to meteorological factors was investigated in a shaded versus a sun-exposed outdoor arena. oak-woodland soil covered partially with leaf litter and small rocks, and 24 vertically oriented grass stems 2.5, 5.0, 10.0, and 20.0 cm tall were provided as substrate and potential questing sites. tick activity and weather conditions were monitored bihourly during 15 diel (24-h) ex ... | 1995 | 7616519 |
| external and internal influences on indices of physiological stress: ii. seasonal and size-related variations in blood composition in free-living lizards, sceloporus occidentalis. | seasonal changes in blood composition (plasma osmolality, total plasma protein, hematocrit) in two free-living populations of fence lizards, sceloporus occidentalis, one living in a very arid environment (pearblossom, ca) and another in a milder desert (bend, or), were analyzed. in this analysis, two features of reptilian physiology and ecology were incorporated: ontogenetic variation in blood composition and seasonal variation in body-size distribution. the population living in the arid environ ... | 1995 | 7622998 |
| external and internal influences on indices of physiological stress. i. seasonal and population variation in adrenocortical secretion of free-living lizards, sceloporus occidentalis. | the plasma levels of glucocorticoid hormones (e.g., corticosterone and cortisol) are often used as an index of physiological stress. however, under natural conditions, glucocorticoid secretion can respond to both environmental influences (e.g., extreme climatic conditions) and internal influences (populational differences and annual seasonal cycles). to distinguish between these kinds of influences, we examined seasonal variation in basal levels of corticosterone and the adrenocortical response ... | 1995 | 7852947 |
| immature ixodes scapularis (acari: ixodidae) parasitizing lizards from the southeastern u.s.a. | preserved museum specimens of 13 lizard and 3 snake species common in the southeastern u.s.a. were examined for immature ixodes scapularis say ticks. five eumeces and 4 ophisaurus lizard species yielded an infestation prevalence of 17.8% for species of eumeces and 29.0% for species of ophisaurus. mean intensity of larvae and nymphs was 7.1 and 2.7, respectively, for species of eumeces, and 6.3 and 1.4, respectively, for species of ophisaurus. collection dates of the lizards ranged from january t ... | 1993 | 8410539 |
| sequences of the lizard cdnas encoding lactate dehydrogenase (ldh) isozymes a (muscle) and b (heart). | the nucleotide and deduced amino acid sequences of cdnas encoding l-lactate dehydrogenase (ldh) isozymes a (muscle) and b (heart) from the lizard, sceloporus undulatus, were determined. the evolutionary relationships among ldh isozymes from animals, plants and bacteria are presented. | 1996 | 8666293 |
| characterization of the clinical and anatomical pathological changes associated with hepatozoon mocassini infections in unnatural reptilian hosts. | laboratory-reared aedes aegypti mosquitoes were employed in the successful transmission of hepatozoon mocassini from a cotton-mouth moccasin (agkistrodon piscivorus leucostoma) to 3 lizard species (sceloporus undulatus, eumeces obsoletus and sceloporus poinsetti). marked to severe lethargy and anorexia developed in the s. undulatus, e. obsoletus and s. poinsetti at 15, 38, and 96 days postinfection (pi), respectively. all 3 lizards developed a leukocytosis and had increased plasma aspartate amin ... | 1996 | 8690537 |
| borreliacidal factor in the blood of the western fence lizard (sceloporus occidentalis). | in some populations of the western black-legged tick, ixodes pacificus, the prevalence of infection with lyme disease spirochetes (borrelia burgdorferi) in nymphal ticks exceeds those in adult ticks by 3-4-fold. experiments were conducted to determine if the reduced spirochetal prevalence in adult ticks is due to the presence of anti-borrelial antibodies or to another borreliacidal factor in the blood of the western fence lizard, sceloporus occidentalis, a primary host of subadult i. pacificus, ... | 1998 | 9488334 |
| the challenge hypothesis and seasonal changes in aggression and steroids in male northern fence lizards (sceloporus undulatus hyacinthinus). | the challenge hypothesis has been very successful in explaining patterns of testosterone secretion in response to social stimuli in avian species. however, there have been few studies in nonavian vertebrates. we tested the challenge hypothesis in male northern fence lizards (sceloporus undulatus hyacinthinus). these males are highly territorial and nonparental. consequently, the challenge hypothesis predicts that plasma testosterone concentrations will be insensitive to aggressive interactions. ... | 1998 | 9698502 |
| effects of testosterone on locomotor performance and growth in field-active northern fence lizards, sceloporus undulatus hyacinthinus. | the role of steroids in locomotor performance and growth was examined in free-living lizards. male northern fence lizards (sceloporus undulatus hyacinthinus) with experimentally elevated plasma testosterone concentrations had greater sprint speed (+24%) and burst stamina (+17%) than sham-implanted males after 14-23 d in the field. this enhanced performance was associated with significant energetic costs, as the testosterone-implanted lizards had reduced growth rates, and, in a companion experime ... | 2013 | 9754527 |
| seasonal specificity of hormonal, behavioral, and coloration responses to within- and between-sex encounters in male lizards (sceloporus undulatus). | this study reports the gender and seasonal specificity of hormonal, behavioral, and coloration responses displayed by "resident" male lizards (sceloporus undulatus) exposed to male or female "intruders" during staged encounters in outdoor enclosures. resident males were engaged in staged encounters with males or females for 1 h per day on 9 consecutive days during the breeding and postbreeding seasons. male-specific responses occurred during the breeding but not the postbreeding season. these in ... | 1999 | 10433885 |
| abundance of ticks (acari: ixodidae) infesting the western fence lizard, sceloporus occidentalis, in relation to environmental factors. | we examined the impact of environmental characteristics, such as habitat type, topographic exposure and presence of leaf litter, on the abundance of ixodes pacificus ticks infesting the western fence lizard (sceloporus occidentalis) at the university of california hopland research and extension center (hrec), mendocino county, california. a total of 383 adult lizards were slip-noosed and examined for tick infestation in april and may 1998. at least 94% of the lizards were infested by ticks and a ... | 1999 | 10581712 |
| oxygen consumption by mitochondria from an endotherm and an ectotherm. | comparisons of metabolic properties of mitochondria from an endothermic and an ectothermic vertebrate were performed. oxygen (o2) consumption rates of liver mitochondria from laboratory mice and western fence lizard (sceloporus occidentalis) were determined over a range of temperatures (10, 20, 30 and 37 degrees c) and in the presence of a variety of substrates. at 37 degrees c the o2 consumption rate of mouse mitochondria was 4-11 times higher than lizard mitochondria in the presence of five of ... | 1999 | 10582317 |
| 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 |
| phenotypic effects of leptin in an ectotherm: a new tool to study the evolution of life histories and endothermy? | 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 ... | 2000 | 10607539 |
| comparative study of tongue protrusion in three iguanian lizards, sceloporus undulatus, pseudotrapelus sinaitus and chamaeleo jacksonii. | the goal of this study was to investigate the function of the hyolingual muscles used during tongue protraction in iguanian lizards. high-speed videography and nerve-transection techniques were used to study prey capture in the iguanid sceloporus undulatus, the agamid pseudoptrapelus sinaitus and the chameleonid chamaeleo jacksonii. denervation of the mandibulohyoideus muscle slips had an effect only on p. sinaitus and c. jacksonii, in which tongue protrusion or projection distance was reduced. ... | 2000 | 10952882 |
| 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 |
| life history of a malaria parasite (plasmodium mexicanum) in its host, the western fence lizard (sceloporus occidentalis): host testosterone as a source of seasonal and among-host variation? | the course of infection of a malaria parasite (plasmodium mexicanum) is highly variable in its host, the fence lizard (sceloporus occidentalis). however, a seasonal trend is superimposed on this variation such that gametocyte production is intensified during mid- to late summer. host testosterone levels follow a similar seasonal fluctuation and are variable among individual lizards. we sought to determine if testosterone levels affect seasonal and among-host variation in 11 p. mexicanum life his ... | 2000 | 11128477 |
| transmission success of the malaria parasite plasmodium mexicanum into its vector: role of gametocyte density and sex ratio. | the life-cycle of plasmodium depends on transmission of the parasite from the vertebrate host into its vector when the insect takes a bloodmeal. transmission success may depend in part on the parasite's gametocyte density and sex ratio in the blood. p. mexicanum, a parasite of fence lizards in california, usa, exploits the sandfly lutzomyia vexator as its vector. in experimental transmissions using naturally infected lizards as donors of blood, transmission success (measured as percentage of vec ... | 2000 | 11155927 |
| a comparative study of mammalian and reptilian alternative pathway of complement-mediated killing of the lyme disease spirochete (borrelia burgdorferi). | the potential bactericidal activity of the alternative complement pathway of mammalian and reptilian sera to borrelia burgdorferi sensu stricto (s.s.) was evaluated in vitro. complement-mediated killing was observed when cultured spirochetes were inoculated into sera from the western fence lizard (sceloporus occidentalis) and from the southern alligator lizard (elgaria multicarinata), but not when they were inoculated into serum from either the deer mouse (peromyscus maniculatus) or from humans. ... | 2000 | 11191895 |
| 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 |
| characterization of gastrointestinal chitinase in the lizard sceloporus undulatus garmani (reptilia: phrynosomatidae). | most studies on chitinase activity in lizards have been concerned with palaearctic (european) and laurasian (middle eastern and asian) taxa. several genera of old world lizards, anguis, uromastix, chamaeleo and lacerta, have been shown to possess chitinolytic activity. to date, only one new world lizard, anolis carolinensis, has been reported to exhibit chitinolytic activity. in the present study, chitinase activity was characterized in a second new world taxon, sceloporus undulatus garmani, a n ... | 2001 | 11290449 |
| landscape features associated with infection by a malaria parasite (plasmodium mexicanum) and the importance of multiple scale studies. | in a 3-year study, we examined landscape features (aspect, slope, sun exposure, canopy cover, type of ground cover, and nearest water source) that were potentially related to prevalence of infection with plasmodium mexicanum in fence lizards (sceloporus occidentalis) within a 4.5 ha study area in northern california, usa. logistic regression analysis showed that ground cover type was the primary mediator of the probability of p. mexicanum infection. infected lizards were captured more often in r ... | 2001 | 11393823 |
| physiological control of warming and cooling during simulated shuttling and basking in lizards. | differences in warming and cooling rates in basking lizards have long been thought to be brought about by adjustments in heart rate and blood flow. we examined the physiological control of warming and cooling in iguana iguana, sceloporus undulatus, and three species of cordylus by measuring time constants, heart rate, and superficial capillary blood flow. previously, techniques have not been available to measure time constants in shuttling animals. using a combination of rapid measurements of te ... | 2007 | 11517453 |
| birds and their ticks in northwestern california: minimal contribution to borrelia burgdorferi enzootiology. | birds and their attendant ticks were surveyed for infection with the lyme disease spirochete borrelia burgdorferi, in chaparral and woodland-grass habitats in northwestern california from march to july, 1998 to 1999. in total, 234 birds were captured and recaptured (15%); nearly 2.5 times more birds were captured in chaparral than in woodland-grass. overall, 34 species representing 15 families were collected during this study; of these, 24 species were caught in chaparral, 19 in woodland-grass, ... | 2001 | 11534638 |
| prevalence and abundance of ixodes pacificus immatures (acari: ixodidae) infesting western fence lizards (sceloporus occidentalis) in northern california: temporal trends and environmental correlates. | the prevalence and abundance of immature ixodes pacificus ticks on western fence lizards (sceloporus occidentalis) were examined in relation to time of year, host attributes (i.e., age, gender, and presence or absence of blood parasites), and 5 environmental characteristics, including topographic exposure and ground cover substrate, over a 2-year period in northern california. lizards were infested with subadult ticks from early march until late july or early august, with peak median numbers of ... | 2001 | 11780813 |
| nymphs of the western black-legged tick (ixodes pacificus) collected from tree trunks in woodland-grass habitat. | nymphs of the western black-legged tick, ixodes pacificus, were found on the trunks of trees during spring and summer in northwestern california. in a woodland-grass habitat, large- and medium-sized (> 130 cm and 80-130 cm in circumference, respectively), moss-covered oak (quercus spp.) trees supported ticks significantly more often than trees without these characteristics. additionally, trees with basal leaf-litter and lacking shade (at time of sampling) were significantly associated with the p ... | 2001 | 11813653 |
| 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 |
| comparative study of the innervation patterns of the hyobranchial musculature in three iguanian lizards: sceloporus undulatus, pseudotrapelus sinaitus, and chamaeleo jacksonii. | the neuroanatomy and musculature of the hyobranchial system was studied in three species of iguanian lizards: sceloporus undulatus, pseudotrapelus sinaitus, and chamaeleo jacksonii. the goal of this study was to describe and compare the innervation and arrangement of the hyobranchial musculature in the context of its function during tongue protrusion. a comparison of the hyobranchial innervation patterns revealed a relatively conserved innervation pattern in s. undulatus and p. sinaitus, and a m ... | 2002 | 11997887 |
| 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 |
| low oxygen: a constraint on the evolution of viviparity in reptiles. | the evolution of reptilian viviparity (live bearing) from oviparity (egg laying) is thought to require transitional stages of increasingly longer periods of embryonic development in utero, that is, longer periods of egg retention by the gravid female. studies on sceloporine lizards demonstrate that embryonic responses to egg retention that is extended beyond the time of normal oviposition range from developmental arrest to normal development. the present study was designed to test the hypothesis ... | 2013 | 12024290 |
| gametocyte sex ratio of a malaria parasite: experimental test of heritability. | the gametocyte sex ratio of plasmodium mexicanum, a malaria parasite of western fence lizards, was studied in a modified garden experiment. each of 6 naturally infected lizards was used to initiate 20 replicate-infections in naive western fence lizards. a significant donor effect was observed for the sex ratios of recipient infections at their maximal parasitemia, and this effect was associated with the sex ratio of the donor infection. in 20 infections in which sex ratio was followed during the ... | 2002 | 12099417 |
| dose-response and time course relationships for vitellogenin induction in male western fence lizards (sceloporus occidentalis) exposed to ethinylestradiol. | the long-term goal of this research is to develop and validate an in vivo reptile model for endocrine-mediated toxicity using fence lizards (sceloporus spp.). one of the best defined estrogenic responses in oviparous vertebrates is induction of the yolk precursor protein, vitellogenin (vtg). in this study, dose-response and time course relationships for vtg induction were determined in male western fence lizards (sceloporus occidentalis) given intraperitoneal injections of 17alpha-ethinylestradi ... | 2002 | 12109741 |
| relative importance of lizards and mammals as hosts for ixodid ticks in northern california. | abstract lizards and mammals were trapped and examined for ticks from august 1992 to june 1993 in two habitat types, chaparral and woodland-grass, in northern california. five tick species were collected from mammals (dermacentor occidentalis, haemaphysalis leporispalustris, ixodes pacificus, i. spinipalpis, i. woodi), but only i. pacificus was found on lizards. dermacentor occidentalis, i. pacificus, and i. woodi occurred in both habitats, whereas h. leporispalustris and i. spinipalpis were fou ... | 2002 | 12475082 |
| manipulation of the vertebrate host's testosterone does not affect gametocyte sex ratio of a malaria parasite. | gametocyte sex ratio of the malaria parasite plasmodium mexicanum is variable in its host, the western fence lizard (sceloporus occidentalis), both among infections and within infections over time. we sought to determine the effect of host physiological quality on the gametocyte sex ratio in experimentally induced infections of p. mexicanum. adult male lizards were assigned to 4 treatment groups: castrated, castrated + testosterone implant, sham implant, and unmanipulated control. no significant ... | 2003 | 12659329 |
| 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 |
| hot rocks or no hot rocks: overnight retreat availability and selection by a diurnal lizard. | i used radio telemetry to determine the effects of substrate size and composition on overnight retreat site selection by western fence lizards (sceloporus occidentalis). in watersheds of northern california (usa), these lizards occupy two habitat types differing in substrate characteristics: rocky cobble bars found in the dry, active channels of rivers and grassy upland meadows. rocky substrates, found almost exclusively on cobble bars, provided warmer potential retreat sites than all available ... | 2003 | 12802672 |
| effects of 17alpha-ethinylestradiol on immune parameters in the lizard sceloporus occidentalis. | we examined the effect of 17alpha-ethinylestradiol on immunity of the western fence lizard, sceloporus occidentalis. injection of 17alpha-ethinylestradiol resulted in dose-dependent suppression of peripheral blood leukocyte levels as determined by cell counts, whereas total spleen cell levels were decreased only at higher doses of 17alpha-ethinylestradiol. in contrast, spleen cell proliferation was enhanced by 17alpha-ethinylestradiol as measured by reduction of mtt to formazan following a two-w ... | 2003 | 12900939 |
| further observations on the fine structure of the parietal eye of lizards. | an electron microscopical study of the third eye of the western fence lizard, sceloporus occidentalis, fixed with 1 per cent osmium tetroxide, ph 7.4-7.6, for 16 to 20 hours at 0 degrees c., revealed the following new facts. the fibrillar system of the retinal photoreceptor consists of nine double fibrils enclosed in a sheath. pigment cells and lens cells possess similar systems. two short cylindrical centrioles are associated with the fibrillar apparatus: one, from which striated rootlets exten ... | 1960 | 13725484 |
| parietal eye nerve in the fence lizard. | a nerve from the parietal eye of the western fence lizard, sceloporus occidentalis, is described as leaving inconspicuously from the third-eye and extending caudally under the dura mater and then ventrally along the left anterolateral surface of the epiphysis to the habenular commissure of the brain. the existence of a parietal nerve must be considered in interpreting the effects of parietalectomy. | 1959 | 13819089 |
| 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 |
| bacteriolytic activity of selected vertebrate sera for borrelia burgdorferi sensu stricto and borrelia bissettii. | an in vitro assay to evaluate the bacteriolytic activity of the complement pathway was applied to 2 strains of borrelia bissettii, co501 and dn127, and compared with that of b. burgdorferi sensu stricto b31. sera from mule deer (odocoileus hemionus) and the western fence lizard (sceloporus occidentalis) were completely borreliacidal for b. burgdorferi and for both strains of b. bissettii. serum from bobwhite quail (colinus virginianus) was nonlytic for b. burgdorferi and partially lytic for b. b ... | 2003 | 14740924 |
| 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 | |
| life-history studies on two molecular strains of mesocestoides (cestoda: mesocestoididae): identification of sylvatic hosts and infectivity of immature life stages. | life-cycle studies were conducted on 2 molecular strains of mesocestoides tapeworms that represent different evolutionary lineages (clades a and b). wild carnivores, reptiles, and rodents were examined for tapeworm infections at 2 enzootic sites: (1) san miguel island (smi), a small island off the coast of southern california and (2) hopland research and extension center (hrec), a field station in northern california. results indicate that deer mice (peromyscus maniculatus) and coyotes (canis la ... | 2004 | 15040675 |
| phylogenetic comparative analysis of life-history variation among populations of the lizard sceloporus undulatus: an example and prognosis. | 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. recently, population-level phylogenetic hypotheses have become available for many species, making it possible to apply pcms directly to th ... | 2004 | 15119445 |
| mitochondrial dna sequences of five squamates: phylogenetic affiliation of snakes. | complete or nearly complete mitochondrial dna sequences were determined from four lizards (western fence lizard, warren's spinytail lizard, terrestrial arboreal alligator lizard, and chinese crocodile lizard) and a snake (texas blind snake). these genomes had a typical gene organization found in those of most mammals and fishes, except for a translocation of the glutamine trna gene in the blind snake and a tandem duplication of the threonine and proline trna genes in the spinytail lizard. althou ... | 2004 | 15449546 |
| 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 |
| 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 |
| testosterone has opposite effects on male growth in lizards (sceloporus spp.) with opposite patterns of sexual size dimorphism. | sexual size dimorphism (ssd) has received considerable attention from evolutionary biologists, but relatively little is known about the physiological mechanisms underlying sex differences in growth that lead to ssd. testosterone (t) stimulates growth in many male-larger vertebrates, but inhibits growth in the female-larger lizard sceloporus undulatus. thus, opposite patterns of ssd may develop in part because of underlying differences in the hormonal regulation of male growth. in the present stu ... | 2005 | 16326949 |
| effect of acute exposure to malathion and lead on sprint performance of the western fence lizard (sceloporus occidentalis). | there are few ecotoxicological studies involving reptiles, despite the fact that anthropogenic pollutants have been identified as a major threat to reptile populations worldwide. particularly lacking are effects-based studies in reptiles exposed to known concentrations of contaminants. we hypothesized that acute exposure to neurotoxic metals and pesticides could influence locomotor performance of reptiles. to test this hypothesis, we exposed western fence lizards (sceloporus occidentalis) to two ... | 2006 | 16465557 |
| seasonal effects on circulating leptin in the lizard sceloporus undulatus from two populations. | characterizing leptin's structure and function in mammals has been the subject of thousands of studies since 1994. recently, the study of leptin has expanded to include its distribution in non-mammalian taxa, and the role that leptin plays in the reproductive axis. we demonstrated in a previous study that sceloporus undulatus, fence lizards (ectotherms), express a leptin-like protein. in the current study we quantified seasonal variation in this putative leptin among free-ranging fence lizards f ... | 2006 | 16483813 |
| 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 |
| indomethacin influences arginine vasotocin-induced parturition and oviposition in lizards (sceloporus jarrovi and sceloporus undulatus ). | the effect of the prostaglandin blocker indomethacin on arginine vasotocin-induced birth was examined. gravid female, oviparous (sceloporus undulatus ) and viviparous (sceloporus jarrovi ) lizards were pretreated with saline or indomethacin, a potent blocker of pg synthesis. pretreatment was followed by an intraperitoneal injection of avt. pretreatment with indomethacin significantly delayed the onset of avt-induced oviposition in s. undulatus , whereas it had no effect on latency to birth in s. ... | 1990 | 16726777 |
| 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 |
| isolation and partial characterization of proteins involved in maternal transfer of selenium in the western fence lizard (sceloporus occidentalis). | selenium from dietary exposure is efficiently transferred from mother to offspring in oviparous vertebrates, where it can cause severe teratogenic effects. we isolated and partially characterized proteins involved in maternal transfer of selenium in the oviparous lizard sceloporus occidentalis using size-exclusion chromatography, inductively coupled plasma-mass spectrometry, and polyacrylamide gel electrophoresis. selenium from dietary selenomethionine exposure was incorporated into at least thr ... | 2006 | 16833149 |
| refractoriness of the western fence lizard (sceloporus occidentalis) to the lyme disease group spirochete borrelia bissettii. | the western fence lizard, sceloporus occidentalis, is refractory to experimental infection with borrelia burgdorferi sensu stricto, one of several lyme disease spirochetes pathogenic for humans. another member of the lyme disease spirochete complex, borrelia bissettii, is distributed widely throughout north america and a similar, if not identical, spirochete has been implicated as a human pathogen in southern europe. to determine the susceptibility of s. occidentalis to b. bissettii, 6 naïve liz ... | 2006 | 16995383 |
| direct and indirect effects of environmental temperature on the evolution of reproductive strategies: an information-theoretic approach. | for ectotherms, environmental temperature affects the optimal size and number of offspring via multiple mechanisms. first, temperature influences the performance of offspring, which directly affects the optimal size of offspring. second, temperature influences maternal body size, which indirectly affects the optimal size and/or number of offspring when larger females acquire more energetic resources or provide better parental care. although traditional statistical approaches might distinguish th ... | 2006 | 17004215 |
| incubation temperature and phenotypic traits of sceloporus undulatus: implications for the northern limits of distribution. | cold environmental temperature is detrimental to reproduction by oviparous squamate reptiles by prolonging incubation period, negatively affecting embryonic developmental processes, and by killing embryos in eggs directly. because low soil temperature may prevent successful development of embryos in eggs in nests, the geographic distributions of oviparous species may be influenced by the thermal requirements of embryos. in the present study, we tested the hypothesis that low incubation temperatu ... | 2007 | 17102996 |
| hybridization between multiple fence lizard lineages in an ecotone: locally discordant variation in mitochondrial dna, chromosomes, and morphology. | we investigated a hybrid zone between two major lineages of fence lizards (sceloporus cowlesi and sceloporus tristichus) in the sceloporus undulatus species complex in eastern arizona. this zone occurs in an ecotone between great basin grassland and conifer woodland habitats. we analysed spatial variation in mtdna (n=401; 969 bp), chromosomes (n=217), and morphology (n=312; 11 characters) to characterize the hybrid zone and assess species limits. a fine-scale population level phylogenetic analys ... | 2007 | 17305859 |
| impaired terrestrial and arboreal locomotor performance in the western fence lizard (sceloporus occidentalis) after exposure to an ache-inhibiting pesticide. | we examined the effects of a commonly used ache-inhibiting pesticide on terrestrial and arboreal sprint performance, important traits for predator avoidance and prey capture, in the western fence lizard (sceloporus occidentalis). lizards were exposed to carbaryl (2.5, 25, and 250 microg/g) and were raced before and 4, 24, and 96 h after dosing. in the terrestrial setting, exposure to low concentrations of carbaryl had stimulatory effects on performance, but exposure to the highest concentration ... | 2007 | 17360091 |
| detection of borrelia burgdorferi dna in lizards from southern maryland. | lizards serve as hosts for ixodes ticks in the western and southeastern united states and may affect the transmission cycles of borrelia burgdorferi in these regions. in maryland, the role of lizards in the maintenance and transmission cycle of this pathogen has not been examined. we tested 29 lizards (sceloporus undulatus and eumeces spp.) and 21 ticks from these lizards for the presence of b. burgdorferi. eight lizards were positive by polymerase chain reaction (pcr) for at least one b. burgdo ... | 2007 | 17417956 |
| ability of transstadially infected ixodes pacificus (acari: ixodidae) to transmit west nile virus to song sparrows or western fence lizards. | the hypothesis that ixodes pacificus cooley & kohls (acari: ixodidae) may serve as a reservoir and vector of west nile virus (family flaviviridae, genus flavivirus, wnv) in california was tested by determining the ability of this tick species to become infected with the ny99 strain of wnv while feeding on viremic song sparrows, to maintain the infection transstadially, and then to transmit wnv to recipient naive song sparrows and western fence lizards during the nymphal stage. the percentage of ... | 2007 | 17427704 |
| assessment of lead uptake in reptilian prey species. | as part of an investigation determining the trophically available fraction of metals in a model terrestrial food web, i.e., invertebrate prey to western fence lizards (sceloporus occidentalis), we evaluated the ability of several invertebrate prey to bioaccumulate lead and to form metals-rich granules, which are hypothesized to be non-available to predators. crickets (acheta domestica), tenebroid beetle larvae (tenebrio molitor), and isopods (porcellio scaber) were selected as model prey organis ... | 2007 | 17490716 |
| experimental test for premunition in a lizard malaria parasite (plasmodium mexicanum). | premunition in plasmodium spp. is the prevention of superinfection by novel genotypes entering an already established infection in a vertebrate host. evidence for premunition was sought for the lizard malaria parasite, p. mexicanum, in its natural host, the fence lizard, sceloporus occidentalis. clonal diversity (= alleles for the haploid parasite) was determined with the use of 3 microsatellite markers. both naturally infected lizards (n = 25) and previously noninfected lizards (n = 78) were in ... | 2007 | 17539410 |
| selenomethionine biotransformation and incorporation into proteins along a simulated terrestrial food chain. | selenium is an essential trace element in vertebrates, but there is a narrow concentration range between dietary requirement and toxicity threshold. although a great deal is known about the biochemistry of se from a nutritional perspective, considerably less attention has been focused on the specific biochemistry of se as an environmental toxicant. recent advances in hyphenated analytical techniques have provided the capability of quantifying specific chemical forms of se in biological tissues a ... | 2007 | 17547184 |
| clonal diversity of a lizard malaria parasite, plasmodium mexicanum, in its vertebrate host, the western fence lizard: role of variation in transmission intensity over time and space. | within the vertebrate host, infections of a malaria parasite (plasmodium) could include a single genotype of cells (single-clone infections) or two to several genotypes (multiclone infections). clonal diversity of infection plays an important role in the biology of the parasite, including its life history, virulence, and transmission. we determined the clonal diversity of plasmodium mexicanum, a lizard malaria parasite at a study region in northern california, using variable microsatellite marke ... | 2007 | 17594442 |
| effects of repeated exposure to malathion on growth, food consumption, and locomotor performance of the western fence lizard (sceloporus occidentalis). | effects of repeated pollutant exposure on growth, locomotor performance, and behavior have rarely been evaluated in reptiles. we administered three doses of malathion (2.0, 20, or 100mg/kg body weight) to western fence lizards (sceloporus occidentalis) over an 81day period. eight and 23% mortality occurred at 20 and 100mg/kg (p=0.079) and 85% of lizards in the 100mg/kg group exhibited clinical symptoms of poisoning. growth, food consumption, body condition index, and terrestrial locomotor perfor ... | 2008 | 17611009 |
| 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 |
| sceloporus occidentalis: preferred body temperature of the western fence lizard. | given equal thermal opportunities during four seasonal test periods, western fence lizards active above ground preferred constant body temperature throughout the year. lizards recovered from subsurface retreats in the fall exhibited a mean body temperature significantly lower than that for sequestered lizards recorded during winter, spring, and summer. | 1966 | 17754818 |
| 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 |
| 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 |
| linking traits to energetics and population dynamics to predict lizard ranges in changing environments. | i present a dynamic bioenergetic model that couples individual energetics and population dynamics to predict current lizard ranges and those following climate warming. the model predictions are uniquely based on first principles of morphology, life history, and thermal physiology. i apply the model to five populations of a widespread north american lizard, sceloporus undulatus, to examine how geographic variation in traits and life histories influences ranges. this geographic variation reflects ... | 2008 | 18171140 |
| effect of exogenous corticosterone on respiration in a reptile. | release of glucocorticoids (gcs) enables organisms to meet energy requirements during stressful situations by regulating intermediary metabolism. in the absence of compensatory mechanisms, increased metabolic activity (e.g., protein catabolism, lipolysis, and gluconeogenesis) should translate to increases in whole animal metabolism, and therefore energy expenditures, by organisms. however, to our knowledge, no study has estimated the total energy cost of elevated plasma gcs in any organism. here ... | 2008 | 18249406 |