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ecoimmune reallocation in a native lizard in response to the presence of invasive, venomous fire ants in their shared environment.exposure to stressors over prolonged periods can have fitness-relevant consequences, including suppression of immune function. we tested for effects of presence of an invasive species threat on a broad panel of immune functions of a coexisting lizard. eastern fence lizards (sceloporus undulatus) have been exposed to invasive fire ants (solenopsis invicta) for over 80 years. fire ants sting and envenomate lizards, causing physiological stress, but we do not have a comprehensive understanding of t ...202033038069
effects of temperature on plasma corticosterone in a native lizard.the glucocorticoid stress response is frequently used to indicate vertebrate response to the environment. body temperature may affect glucocorticoid concentrations, particularly in ectotherms. we conducted lab manipulations and field measurements to test the effects of body temperature on plasma corticosterone (predominant glucocorticoid in reptiles) in eastern fence lizards (sceloporus undulatus). first, we acclimated lizards to one of 4 treatments: 22 °c, 29 °c, 33 °c, or 36 °c, and measured c ...202033004871
downsizing for downtown: limb lengths, toe lengths, and scale counts decrease with urbanization in western fence lizards (sceloporus occidentalis).urbanization induced habitat loss and alteration causes significant challenges for the survival of many species. identifying how species respond to urbanization can yield insights for the conservation of wildlife, but research on reptiles has been narrowly-focused. we compared morphology among four populations of western fence lizards (sceloporus occidentalis) to determine whether a common native species affected by urbanization exhibits morphological differences consistent with habitat use. we ...201932774080
the lizard gut microbiome changes with temperature and is associated with heat tolerance.vertebrates harbor trillions of microorganisms in the gut, collectively termed the gut microbiota, which affect a wide range of host functions. recent experiments in lab-reared vertebrates have shown that changes in environmental temperature can induce shifts in the gut microbiota, and in some cases these shifts have been shown to affect host thermal physiology. however, there is a lack of information about the effects of temperature on the gut microbiota of wild-caught vertebrates. moreover, in ...202032591376
transcriptome sequencing reveals signatures of positive selection in the spot-tailed earless lizard.the continual loss of threatened biodiversity is occurring at an accelerated pace. high-throughput sequencing technologies are now providing opportunities to address this issue by aiding in the generation of molecular data for many understudied species of high conservation interest. our overall goal of this study was to begin building the genomic resources to continue investigations and conservation of the spot-tailed earless lizard. here we leverage the power of high-throughput sequencing to ge ...202032542006
plastic sexual ornaments: assessing temperature effects on color metrics in a color-changing reptile.conspicuous coloration is an important subject in social communication and animal behavior, and it can provide valuable insight into the role of visual signals in social selection. however, animal coloration can be plastic and affected by abiotic factors such as temperature, making its quantification problematic. in such cases, careful consideration is required so that metric choices are consistent across environments and least sensitive to abiotic factors. a detailed assessment of plastic trait ...202032433700
establishment of brown anoles (anolis sagrei) across a southern california county and potential interactions with a native lizard species.the brown anole, anolis sagrei, is a native species to the caribbean; however, a. sagrei has invaded multiple parts of the usa, including florida, louisiana, hawai'i and more recently california. the biological impacts of a. sagrei invading california are currently unknown. evidence from the invasion in taiwan shows that they spread quickly and when immediate action is not taken eradication stops being a viable option. in orange county, california, five urban sites, each less than 100 ha, were s ...202032296613
endocrine stress response of eastern fence lizards in fire-disturbed landscapes.landscape disturbances can alter habitat structure and resource availability, often inducing physiological responses by organisms to cope with the changing conditions. quantifying the endocrine stress response through measurement of glucocorticoids has become an increasingly common method for determining how organisms physiologically respond to challenges imposed by their environment. we tested the hypothesis that eastern fence lizards cope with fire disturbance effects by modulating their secre ...201931857811
obtaining plasma to measure baseline corticosterone concentrations in reptiles: how quick is quick enough?there is growing interest in the use of glucocorticoid (gc) hormones to understand how wild animals respond to environmental challenges. blood is the best medium for obtaining information about recent gc levels; however, obtaining blood requires restraint and can therefore be stressful and affect gc levels. there is a delay in gcs entering blood, and it is assumed that blood obtained within 3 min of first disturbing an animal reflects a baseline level of gcs, based largely on studies of birds an ...202031733208
melanization, α-melanocyte stimulating hormone and steroid hormones in male western fence lizards from nine populations.hormones can mediate suites of correlated traits. melanocortins regulate melanin synthesis and elements of the melanocortin system can directly, and indirectly, affect a number of other traits, such as stress reactivity. trait correlations within the melanocortin system have been studied mainly in birds and mammals but less so in reptiles. we examined adult male western fence lizards (sceloporus occidentalis) and if melanization was correlated with plasma levels of three hormones, including pept ...202031563645
gestation alters the gut microbiota of an oviparous lizard.mammalian pregnancy can alter the diversity, membership and structure of the maternal gut microbiota, but it is unclear whether this phenomenon occurs in vertebrates with different reproductive strategies. we conducted 16s rrna bacterial inventories to investigate whether oviparous lizards exhibit shifts in gut microbiota similar to those observed in mammals. using wild-caught eastern fence lizards from alabama, usa, we collected and extracted fecal dna from gravid and non-gravid individuals ove ...201931210275
contrasting responses of lizards to divergent ecological stressors across biological levels of organization.it is frequently hypothesized that animals employ a generalized "stress response," largely mediated by glucocorticoid (gc) hormones, such as corticosterone, to combat challenging environmental conditions. under this hypothesis, diverse stressors are predicted to have concordant effects across biological levels of an organism. we tested the generalized stress response hypothesis in two complementary experiments with juvenile and adult male eastern fence lizards (sceloporus undulatus). in both exp ...201931127305
maternal corticosterone increases thermal sensitivity of heart rate in lizard embryos.while it is well established that maternal stress hormones, such as corticosterone (cort), can induce transgenerational phenotypic plasticity, few studies have addressed the influence of maternal cort on pre-natal life stages. we tested the hypothesis that experimentally increased cort levels of gravid female eastern fence lizards ( sceloporus undulatus) would alter within-egg embryonic phenotype, particularly heart rates. we found that embryos from cort-treated mothers had heart rates that incr ...201930958207
glucocorticoids do not influence a secondary sexual trait or its behavioral expression in eastern fence lizards.secondary sexual traits and associated behaviors can be influenced by environmental factors such as exposure to stressors. such effects may be mediated by the physiological stress response, which is typified by the release of glucocorticoid hormones. the effects of glucocorticoids on sexual traits such as plumage and display coloration have most commonly been studied in isolation rather than in conjunction with other pertinent aspects of signalling, such as behavior and habitat use, though these ...201930914721
population history with invasive predators predicts innate immune function response to early-life glucocorticoid exposure in lizards.early-life stress can suppress immune function, but it is unclear whether transgenerational stress exposure modulates the immune consequences of early stress. in populations where, historically, the immune system is frequently activated, e.g. persistent stressors that cause injury, it may be maladaptive to suppress immune function after early-life stress. thus, the relationship between early-life stress and immune function may vary with population-level historical stressor exposure. we collected ...201930659082
multiple environmental stressors induce complex transcriptomic responses indicative of phenotypic outcomes in western fence lizard.the health and resilience of species in natural environments is increasingly challenged by complex anthropogenic stressor combinations including climate change, habitat encroachment, and chemical contamination. to better understand impacts of these stressors we examined the individual- and combined-stressor impacts of malaria infection, food limitation, and 2,4,6-trinitrotoluene (tnt) exposures on gene expression in livers of western fence lizards (wfl, sceloporus occidentalis) using custom wfl ...201830518325
presence of an invasive species reverses latitudinal clines of multiple traits in a native species.understanding the processes driving formation and maintenance of latitudinal clines has become increasingly important in light of accelerating global change. many studies have focused on the role of abiotic factors, especially temperature, in generating clines, but biotic factors, including the introduction of non-native species, may also drive clinal variation. we assessed the impact of invasion by predatory fire ants on latitudinal clines in multiple fitness-relevant traits-morphology, physiol ...201930488524
morphological features of the yolk processing pattern in the eastern fence lizard, sceloporus undulatus (phrynosomatidae).features of embryonic development in birds traditionally have been assumed to be shared by sauropsids in general. herein, we document a pattern of yolk processing and cellularization in the eastern fence lizard (sceloporus undulatus) that is fundamentally different from that of birds. in the avian pattern, cells of the yolk sac lining phagocytose, and digest yolk material. these cells release products of digestion into underlying blood vessels for transport back to the embryo. in contrast, micro ...201830350360
maternal stress alters the phenotype of the mother, her eggs and her offspring in a wild-caught lizard.while biomedical researchers have long appreciated the influence of maternally derived glucocorticoids (gcs) on offspring phenotype, ecologists have only recently begun exploring its impact in wild animals. interpreting biomedical findings within an ecological context has posited that maternal stress, mediated by elevations of maternal gcs, may play an adaptive role preparing offspring for a stressful or rigorous environment. yet, the influence of maternal stress on offspring phenotype has been ...201830074248
survival and reproductive costs of repeated acute glucocorticoid elevations in a captive, wild animal.organisms are continuously encountering both predictable and unpredictable ecological stressors within their environment. the activation of the hypothalamic-pituitaryadrenal (stress) axis is a fundamental process allowing animals to cope with and respond to such encounters. a main consequence of hpa axis activation is the release of glucocorticoid hormones. although short-term glucocorticoid elevations lead to changes in physiological and behavioral processes that are often adaptive, our underst ...201830016628
sex-dependent effects of maternal stress: stressed moms invest less in sons than daughters.multigenerational effects can have important and sex-dependent effects on offspring. sex allocation theory predicts that females should differentially invest in sons and daughters depending on sex-specific fitness returns and costs of investment. maternal stress-relevant (glucocorticoid) hormones may be one mechanism driving this effect. we investigated how maternal stress hormones differentially affected sons and daughters by manipulating levels of the glucocorticoid, corticosterone (cort), in ...201829992777
bergmann's clines in ectotherms: illustrating a life-history perspective with sceloporine lizards.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 ...200429641924
epigenetic response to environmental change: dna methylation varies with invasion status.epigenetic mechanisms may be important for a native species' response to rapid environmental change. red imported fire ants (solenopsis invicta santschi, 1916) were recently introduced to areas occupied by the eastern fence lizard (sceloporus undulatus bosc & daudin, 1801). behavioral, morphological and physiological phenotypes of the eastern fence lizard have changed following invasion, creating a natural biological system to investigate environmentally induced epigenetic changes. we tested for ...201629492288
parallel behavioral and morphological divergence in fence lizards on two college campuses.the spread of urban development has dramatically altered natural habitats, modifying community relationships, abiotic factors, and structural features. animal populations living in these areas must perish, emigrate, or find ways to adjust to a suite of new selective pressures. those that successfully inhabit the urban environment may make behavioral, physiological, and/or morphological adjustments that represent either evolutionary change and/or phenotypic plasticity. we tested for effects of ur ...201829444102
comparative life histories of holbrookia maculata and sceloporus undulatus in western nebraska.the life histories of the iguanid lizards holbrookia maculata and sceloporus undulatus were studied in western nebraska during 1978-1984. the two species differ in their reproductive strategies and age-specific survival. the reproductive strategy of h. maculata is invariant from year to year. yearlings consistently produced a single clutch and older females (≥2 yr) consistently produced two clutches. the reproductive strategy of s. undulatus is opportunistic. clutch frequency of s. undulatus var ...198729357151
lead bioaccumulation in texas harvester ants (pogonomyrmex barbatus) and toxicological implications for texas horned lizard (phrynosoma cornutum) populations of bexar county, texas.uptake of lead from soil was examined in order to establish a site-specific ecological protective concentration level for the texas horned lizard (phrynosoma cornutum) at the former humble refinery in san antonio, texas. soils, harvester ants, and rinse water from the ants were analyzed at 11 texas harvester ant (pogonomyrmex barbatus) mounds. soil concentrations at the harvester ant mounds ranged from 13 to 7474 mg/kg of lead dry weight. ant tissue sample concentrations ranged from < 0.82 to 21 ...201829305803
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 ...201829189938
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) ...201728912255
fear no colors? observer clothing color influences lizard escape behavior.animals often view humans as predators, leading to alterations in their behavior. even nuanced aspects of human activity like clothing color affect animal behavior, but we lack an understanding of when and where such effects will occur. the species confidence hypothesis posits that birds are attracted to colors found on their bodies and repelled by non-body colors. here, we extend this hypothesis taxonomically and conceptually to test whether this pattern is applicable in a non-avian reptile and ...201728792983
riverine barriers to gene flow and the differentiation of fence lizard populations. 198128563593
absence of measurable malaria-induced mortality in western fence lizards (sceloporus occidentalis) in nature: a 4-year study of annual and over-winter mortality.theoretical models of parasite virulence often quantify virulence by mortality. however, there is a lack of empirical studies of parasite-induced host mortality because it is often difficult to quantify in natural populations. i have estimated annual and over-winter mortality in a population of fence lizards (sceloporus occidentalis) infected with a malaria parasite, plasmodium mexicanum, in northern california. the duration of time a lizard was observed (an estimate of life-span) throughout the ...200128547496
lowering metabolic rate mitigates muscle atrophy in western fence lizards.extended periods of skeletal muscle disuse can cause a significant loss of contractile proteins, which compromises the ability to generate force, mechanical work or power, thus compromising locomotor performance. several hibernating organisms can resist muscle atrophy despite months of inactivity. this resistance has been attributed to a reduction in body temperature and metabolic rate and activation of physiological pathways that counteract pathways of protein degradation. however, in these sys ...201728507191
in space and time: territorial animals are attracted to conspecific chemical cues.territorial animals lay scent marks around their territories to broadcast their presence, but these olfactory signals can both attract and repel con-specifics. attraction or aversion can have a profound impact in terms of space use and thereby influence an individual's access to resources and mates. here, we test the impact of chemical signals on the long-term space use and activity of receivers, comparing the response of males and females, territory holders, and temporary visitors insceloporus ...201728413237
are invasive species stressful? the glucocorticoid profile of native lizards exposed to invasive fire ants depends on the context.invasive species represent a substantial threat to native species worldwide. research on the impacts of invasive species on wild living vertebrates has focused primarily on population-level effects. the sublethal, individual-level effects of invaders may be equally important but are poorly understood. we investigated the effects of invasive fire ants (solenopsis invicta) on the physiological stress response of a native lizard (sceloporus undulatus) within two experimental contexts: directly expo ...201728384419
life-history traits of the lizard sceloporus undulatus from two populations raised in a common laboratory environment.hatchling sceloporus undulatus elongatus from washington co., utah and s. u. garmani from woods co., oklahoma were raised to maturity and reproduction under identical laboratory conditions with ad libitum food availability. growth, allometry, age and size of maturity, clutch size and egg mass were compared among lab-raised cohorts from the two populations, among lab-raised and field-caught animals (including their field-caught mothers) and, for growth, with values obtained by previously publishe ...199328313779
reproductive ecology of red-chinned lizards (sceloporus undulatus erythrocheilus) in southcentral colorado: comparisons with other populations of a wide-ranging species.we studied the reproductive ecology of a population of sceloporus undulatus erythrocheilus near walsenburg, co during the summers of 1987-1990. reproductive activity commences soon after emergence in early may and continues until the middle of july. females mature in their second year following hatching at an age of 20-21 months and a size of 60-63 mm snout-vent length (svl). two clutches, averaging10.9 eggs, are produced per year. larger females produce larger clutches with an increase of one e ...199228312878
parasites and showy males: malarial infection and color variation in fence lizards.hamilton and zuk (1982) proposed that the quality of male showy traits reflects genetically-based resistance to parasites and can be used by females to select mates that are less prone to parasitic attack. the hypothesis requires that a particular state of a variable showy trait should be associated with parasite infection. we tested this idea with a population of western fence lizards, sceloporus occidentalis, infected with the malarial parasite, plasmodium mexicanum. ventral color pattern is s ...198928312354
thermal sensitivity of sprint-running in the lizard sceloporus undulatus: support for a conservative view of thermal physiology.the thermal sensitivity of sprint-running ability was investigated in two populations of sceloporus undulatus that occupy thermally distinct habitats. integration of field and laboratory data indicates that lizards inhabiting a cool, high-elevation habitat are frequently active at body temperatures that retard sprint-running velocity, which could affect adversely their ability to evade predators and to capture prey. these negative effects might be expected to select for local adaptation of therm ...198528311593
malarial parasitism and male competition for mates in the western fence lizard, sceloporus occidentalis.the effect of malarial parasitism on the ability of male western fence lizards, sceloporus occidentalis, to compete for access to females was assessed experimentally. pairs of male lizards, one infected with the malarial parasite, plasmodium mexicanum, and the other not infected, were matched by size and color and placed in large seminatural outdoor enclosures along with an adult female lizard. infected males displayed to females and to other males less often than did noninfected male lizards. n ...198728311520
an experimental manipulation of food and water: growth and time-space utilization of hatchling lizards (sceloporus undulatus).at a site in western nebraska, we studied the effects of supplemental food and water on growth, survival, and habitat utilization of hatchling iguanid lizards, sceloporus undulatus. hatchlings were randomly assigned to one of four experimental groups and received either (1) supplemental food only, (2) supplemental water only, (3) supplemental food and water, or (4) neither supplemental food nor water (control). neither supplemental food nor supplemental water affected growth rate in length, grow ...198728311405
size distributions and sex ratios of colonizing lizards.this paper reports the body size distributions and sex ratios of four species of phyrnosomatid lizard that colonized experimentally created density sinks. the experiments were conducted in western colorado in 1992, and lizards colonizing the habitats in 1993 were compared to those removed in 1992 and those present in 1991. lizards colonizing the density sinks were able to disperse from adjacent habitat. for two of the species (urosaurus ornatus and sceloporus undulatus), colonizing lizards were ...199828307519
evidence for concerted movement of nuclear and mitochondrial clines in a lizard hybrid zone.moving hybrid zones provide compelling examples of evolution in action, yet long-term studies that test the assumptions of hybrid zone stability are rare. using replicated transect samples collected over a 10-year interval from 2002 to 2012, we find evidence for concerted movement of genetic clines in a plateau fence lizard hybrid zone (sceloporus tristichus) in arizona. cline-fitting analyses of snp and mtdna data both provide evidence that the hybrid zone shifted northward by approximately 2 k ...201728133829
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 ...201727864050
tick microbiome and pathogen acquisition altered by host blood meal.lyme disease, a zoonotic disease, is the most prevalent vector-borne disease in the northern hemisphere. diversity of the vector (tick) microbiome can impact pathogen transmission, yet the biotic and abiotic factors that drive microbiome diversity are largely unresolved, especially under natural, field conditions. we describe the microbiome of ixodes pacificus ticks, the vector for lyme disease in the western united states, and show a strong impact of host blood meal identity on tick microbiome ...201727858931
survival by genotype: patterns at mc1r are not black and white at the white sands ecotone.measuring links among genotype, phenotype and survival in the wild has long been a focus of studies of adaptation. we conducted a 4-year capture-recapture study to measure survival by genotype and phenotype in the southwestern fence lizard (sceloporus cowlesi) at the white sands ecotone (transition area between white sands and dark soil habitats). we report several unanticipated findings. first, in contrast with previous work showing that cryptic blanched coloration in s. cowlesi from the heart ...201727775197
populations of the lizard, sceloporus occidentalis, that differ in melanization have different rates of wound healing.mechanisms underlying production of animal coloration can affect key traits besides coloration. melanin, and molecules regulating melanin, can directly and indirectly affect other phenotypic traits, such as immune function. we asked whether melanization and a whole-organism measure of immune function are associated with wound healing. working with two populations of adult male western fence lizards, sceloporus occidentalis, we compared one high-elevation and one low-elevation population in calif ...201627597293
lizards fail to plastically adjust nesting behavior or thermal tolerance as needed to buffer populations from climate warming.although observations suggest the potential for phenotypic plasticity to allow adaptive responses to climate change, few experiments have assessed that potential. modeling suggests that sceloporus tristichus lizards will need increased nest depth, shade cover, or embryonic thermal tolerance to avoid reproductive failure resulting from climate change. to test for such plasticity, we experimentally examined how maternal temperatures affect nesting behavior and embryonic thermal sensitivity. the te ...201727558698
heat tolerance during embryonic development has not diverged among populations of a widespread species (sceloporus undulatus).the frequency and magnitude of heat waves have increased in recent decades, imposing additional stresses on organisms in extreme environments. most reptilian embryos are regularly exposed to thermal stress because they develop in shallow, warm soils for weeks to months. we studied cardiac performance during warming to infer lethal temperatures for embryonic lizards in the sceloporus undulatus complex. embryos from four populations throughout the geographical range (new jersey, south carolina, co ...201327293602
phenotypic correlates of melanization in two sceloporus occidentalis (phrynosomatidae) populations: behavior, androgens, stress reactivity, and ectoparasites.mechanisms underlying production of animal coloration can affect key traits besides coloration. melanin, and molecules regulating melanin, can directly and indirectly affect other phenotypic traits including aggression, stress-reactivity, and immune function. we studied correlation of melanization with these other traits, comparing within- and between-population differences of adult male western fence lizards, sceloporus occidentalis. we compared one high- and one low-elevation population in cal ...201627137079
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 ...201627000944
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 ...201626690819
direct and indirect effects of petroleum production activities on the western fence lizard (sceloporus occidentalis) as a surrogate for the dunes sagebrush lizard (sceloporus arenicolus).the dunes sagebrush lizard (sceloporus arenicolus) is a habitat specialist of conservation concern limited to shin oak sand dune systems of new mexico and texas (usa). because much of the dunes sagebrush lizard's habitat occurs in areas of high oil and gas production, there may be direct and indirect effects of these activities. the congeneric western fence lizard (sceloporus occidentalis) was used as a surrogate species to determine direct effects of 2 contaminants associated with oil and gas d ...201626456391
sylvatic infestation of oklahoma reptiles with immature ixodes scapularis (acari: ixodidae).reptiles were collected in nine counties in oklahoma from september 2002 to may 2004 and examined for ixodes scapularis (say) larvae and nymphs to determine seasonal incidence and prevalence of these ticks. in total, 209 reptile specimens consisting of nine species of lizards and seven species of snakes were collected. plestiodon fasciatus (l.) was the most numerous species collected (55%) followed by sceloporus undulatus (latreille) (17%) and scincella lateralis (say) (11%). less than 10 indivi ...201526336240
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 ...201426309322
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 ...201526209864
effects of temperature on feeding duration, success, and efficiency of larval western black-legged ticks (acari: ixodidae) on western fence lizards.the western black-legged tick (ixodes pacificus) is a common tick species throughout the western usa and is the major vector for borrelia burgdorferi, the lyme disease causing bacterium. western fence lizards (sceloporus occidentalis) are a major host for juvenile i. pacificus, but are incompetent hosts for b. burgdorferi, which makes this host-parasite relationship of particular interest. in order to shed further light on this complex host-parasite relationship, we investigated the effects of t ...201526188858
nutritional modulation of igf-1 in relation to growth and body condition in sceloporus lizards.nutrition and energy balance are important regulators of growth and the growth hormone/insulin-like growth factor (gh/igf) axis. however, our understanding of these functions does not extend uniformly to all classes of vertebrates and is mainly limited to controlled laboratory conditions. lizards can be useful models to improve our understanding of the nutritional regulation of the gh/igf-1 axis because many species are relatively easy to observe and manipulate both in the laboratory and in the ...201525709095
leukocyte profiles for western fence lizards, sceloporus occidentalis, naturally infected by the malaria parasite plasmodium mexicanum.plasmodium mexicanum is a malaria parasite that naturally infects the western fence lizard, sceloporus occidentalis , in northern california. we set out to determine whether lizards naturally infected with this malaria parasite have different leukocyte profiles, indicating an immune response to infection. we used 29 naturally infected western fence lizards paired with uninfected lizards based on sex, snout-to-vent length, tail status, and the presence-absence of ectoparasites such as ticks and m ...201424945903
unraveling the relative importance of oral and dermal contaminant exposure in reptiles: insights from studies using the western fence lizard (sceloporus occidentalis).despite widespread recognition of significant data deficiencies, reptiles remain a relatively understudied taxon in ecotoxicology. to conduct ecological risk assessments on reptiles frequently requires using surrogate taxa such as birds, but recent research suggests that reptiles have significantly different exposure profiles and toxicant sensitivity. we exposed western fence lizards, sceloporus occidentalis, to the same quantities of three model chemicals via oral (gavage) and dermal (ventral s ...201424941063
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 ...201424871138
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 ...201424852352
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 ...201424381182
bearded ladies: females suffer fitness consequences when bearing male traits.a central assumption in evolutionary biology is that females of sexually dimorphic species suffer costs when bearing male secondary sexual traits, such as ornamentation. nevertheless, it is common in nature to observe females bearing rudimentary versions of male ornaments (e.g. 'bearded ladies'), as ornaments can be under similar genetic control in both sexes. here, we provide evidence that masculinized females incur both social and reproductive costs in nature. male fence lizards (sceloporus un ...201324196514
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 ...201424148228
establishment efficiency among clones of the malaria parasite, plasmodium mexicanum, for mixed-clone infections in its natural lizard host.within genetically diverse infections of malaria parasites ( plasmodium spp.), the relative proportions of genetic clones in the vertebrate host's blood can influence clonal competition, transmission success, gametocyte sex ratio, and virulence. clonal proportions depend on establishment success of each clone when they enter a new host and on subsequent differences in rates of asexual replication and clearance. both of these life history traits could be influenced by clone genotype. to assess ge ...201323841469
permeability of roads to movement of scrubland lizards and small mammals.a primary objective of road ecology is to understand and predict how roads affect connectivity of wildlife populations. road avoidance behavior can fragment populations, whereas lack of road avoidance can result in high mortality due to wildlife-vehicle collisions. many small animal species focus their activities to particular microhabitats within their larger habitat. we sought to assess how different types of roads affect the movement of small vertebrates and to explore whether responses to ro ...201323772966
effect of host lizard anemia on host choice and feeding rate of larval western black-legged ticks (ixodes pacificus).although ticks are known to exhibit preferences among host species, there is little evidence that ticks select hosts within a species based on physiological condition. it may be beneficial for ticks to choose hosts that are easier to feed upon if the ticks can perceive indicative chemical or other signals from the host. for example, if ticks can detect host hematocrit they may choose hosts with high hematocrit, facilitating a faster blood meal. it may similarly be adaptive for ticks to avoid ane ...201323760685
eco-epidemiological factors contributing to the low risk of human exposure to ixodid tick-borne borreliae in southern california, usa.little is known about the eco-epidemiology of lyme disease in southern california, a region where the incidence is much lower than it is in northern california. here, we sought to discover the previously unknown microhabitats of nymphs of the primary vector, the western black-legged tick (ixodes pacificus), in 3 moderately to heavily-utilized state parks in the santa monica mountains in los angeles county; to elucidate the seasonal distribution and abundance of adults of i. pacificus and another ...201323643357
transmission, host specificity, and seasonal occurrence of cyrtosomum penneri (nematoda: atractidae) in lizards from florida.experimental infections and field-collected lizards were used to investigate issues of transmission, host specificity, and seasonal occurrence in the nematode cyrtosomum penneri (cosmocercoidea: atractidae). anolis sagrei (87 males, 42 females) were captured from the florida southern college campus, polk county, florida, from october 2010 to september 2011, and 8,803 c. penneri were collected from their intestines. during the breeding season all sexually mature (svl ≥ 34 mm) a. sagrei were infec ...201323020090
multiple environmental stressors elicit complex interactive effects in the western fence lizard (sceloporus occidentalis).evaluation of multiple-stressor effects stemming from habitat degradation, climate change, and exposure to chemical contaminants is crucial for addressing challenges to ecological and environmental health. to assess the effects of multiple stressors in an understudied taxon, the western fence lizard (sceloporus occidentalis) was used to characterize the individual and combined effects of food limitation, exposure to the munitions constituent 2,4,6-trinitrotoluene (tnt), and plasmodium mexicanum ...201222975894
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 ...201222882278
the effect of exogenous testosterone on ectoparasite loads in free-ranging western fence lizards.numerous factors impact the dynamics of host-parasite relationships, such as host sex, hormonal state, reproductive condition, host health, and behavior. in particular, males from a variety of taxa frequently carry heavier parasite burdens than females, particularly during breeding season when testosterone concentrations are elevated. using western fence lizards (sceloporus occidentalis), we tested the hypothesis that high circulating testosterone concentrations in male lizards induce high tick ...201222689269
impacts of an introduced forest pathogen on the risk of lyme disease in california.global changes such as deforestation, climate change, and invasive species have the potential to greatly alter zoonotic disease systems through impacts on biodiversity. this study examined the impact of the invasive pathogen that causes sudden oak death (sod) on the ecology of lyme disease in california. the lyme disease bacterium, borrelia burgdorferi, is maintained in the far western united states by a suite of animal reservoirs including the dusky-footed woodrat (neotoma fuscipes) and deer mo ...201222607076
how do host sex and reproductive state affect host preference and feeding duration of ticks?parasitism is one of the most notable forms of symbiosis in the biological world, with nearly all organisms hosting parasites. in many vertebrates, males have higher ectoparasite burdens than females, especially when testosterone concentrations are elevated. furthermore, reproductive females may have higher ectoparasite burdens than non-reproductive females. it is possible that testosterone-stimulated behaviors in males and offspring investment by females incur energetic costs that inhibit immun ...201222526292
ecological release in white sands lizards.ecological opportunity is any change that allows populations to escape selection from competition and predation. after encountering ecological opportunity, populations may experience ecological release: enlarged population size, broadened resource use, and/or increased morphological variation. we identified ecological opportunity and tested for ecological release in three lizard colonists of white sands, new mexico (sceloporus undulatus, holbrookia maculata, and aspidoscelis inornata). first, we ...201122393523
sex and species differences in plasma testosterone and in counts of androgen receptor-positive cells in key brain regions of sceloporus lizard species that differ in aggression.we studied neuroendocrine correlates of aggression differences in adults of two sceloporus lizard species. these species differ in the degree of sex difference in aggressive color signals (belly patches) and in aggression: sceloporus undulatus (males blue, high aggression; females white, low aggression) and sceloporus virgatus (both sexes white, lower aggression). we measured plasma testosterone and counted cells expressing androgen receptor-like immunoreactivity to the affinity-purified polyclo ...201222230767
evolution of thermal physiology and growth rate between populations of the western fence lizard (sceloporus occidentalis).hatchling sceloporus occidentalis from northern populations (central oregon) grow more slowly than hatchlings from southern populations (southern california) in nature. in this study, i determine whether this difference in growth rate results from differences in thermal environment and/or in thermoregulatory behavior. to determine the degree to which the thermal environment affects growth rate among populations, i reared hatchings from the northern and southern populations in a cycling thermal r ...199022160116
geographic variation in the effects of heat exposure on maximum sprint speed and hsp70 expression in the western fence lizard sceloporus occidentalis.we examined whether western fence lizards sceloporus occidentalis occurring in thermally divergent environments display differential responses to high temperature in locomotor performance and heat-shock protein (hsp) expression. we measured maximum sprint speed in s. occidentalis from four populations at paired latitudes and elevations before and after exposure to an experimental heat treatment and then quantified hind-limb muscle hsp70 expression. lizards collected from northern or high-elevati ...201122030850
multi-locus estimates of population structure and migration in a fence lizard hybrid zone.a hybrid zone between two species of lizards in the genus sceloporus (s. cowlesi and s. tristichus) on the mogollon rim in arizona provides a unique opportunity to study the processes of lineage divergence and merging. this hybrid zone involves complex interactions between 2 morphologically and ecologically divergent subspecies, 3 chromosomal groups, and 4 mitochondrial dna (mtdna) clades. the spatial patterns of divergence between morphology, chromosomes and mtdna are discordant, and determinin ...201121980539
the impact of gene-tree/species-tree discordance on diversification-rate estimation.molecular phylogenies are often used to test hypotheses about the tempo and mode of speciation and extinction. one commonly used statistic is pybus and harvey's γ, which measures the density of ordered internode distances on an ultrametric tree to infer earlier (negative γ) or later (positive γ) bursts of diversification. however, coalescent theory predicts that γ might be biased toward negative values (inferring early bursts of diversification) when using gene trees rather than species trees. g ...201121729043
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 ...201121703273
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 ...200921665829
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 ...201121549122
relative clonal proportions over time in mixed-genotype infections of the lizard malaria parasite plasmodium mexicanum.vertebrate hosts of malaria parasites (plasmodium) often harbour two or more genetically distinct clones of a single species, and interaction among these co-existing clones can play an important role in plasmodium biology. however, how relative clonal proportions vary over time in a host is still poorly known. experimental mixed-clone infections of the lizard malaria parasite, plasmodium mexicanum, were followed in its natural host, the western fence lizard using microsatellite markers to determ ...201121396372
impact of the experimental removal of lizards on lyme disease risk.the distribution of vector meals in the host community is an important element of understanding and predicting vector-borne disease risk. lizards (such as the western fence lizard; sceloporus occidentalis) play a unique role in lyme disease ecology in the far-western united states. lizards rather than mammals serve as the blood meal hosts for a large fraction of larval and nymphal western black-legged ticks (ixodes pacificus-the vector for lyme disease in that region) but are not competent reser ...201121325326
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 ...201121281503
toxic effects of oral 2-amino-4,6-dinitrotoluene in the western fence lizard (sceloporus occidentalis).the compound 2-amino-4,6-dinitrotoluene (2a-dnt) was evaluated under laboratory conditions in the western fence lizard (sceloporus occidentalis) to assess the potential for reptile toxicity. oral ld(50) values were 1406 and 1867 mg/kg for male and female lizards, respectively. based on responses from a 14-day subacute study, a 60-day subchronic experiment followed where lizards were orally dosed at 0, 5, 15, 20, 25, 30 mg/kg-d. at day 60, number of days and survivors, food consumption, and chang ...201121067851
effects of an invasive forest pathogen on abundance of ticks and their vertebrate hosts in a california lyme disease focus.invasive species, including pathogens, can have important effects on local ecosystems, including indirect consequences on native species. this study focuses on the effects of an invasive plant pathogen on a vertebrate community and ixodes pacificus, the vector of the lyme disease pathogen (borrelia burgdorferi) in california. phytophthora ramorum, the causative agent of sudden oak death, is a non-native pathogen killing trees in california and oregon. we conducted a multi-year study using a grad ...201020941513
the physiological basis of geographic variation in rates of embryonic development within a widespread lizard species.the duration of embryonic development (e.g., egg incubation period) is a critical life-history variable because it affects both the amount of time that an embryo is exposed to conditions within the nest and the seasonal timing of hatching. variation in incubation periods among oviparous reptiles might result from variation in either the amount of embryogenesis completed before laying or the subsequent developmental rates of embryos. selection on incubation duration could change either of those t ...201020718676
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 ...201020695966
energetics of lizard embryos at fluctuating temperatures.most animals experience fluctuations in temperature during development, but studies of energetics have ignored the potential influence of these thermal fluctuations. we measured the energetics of sceloporus undulatus lizard embryos under two conditions that differ realistically in the mean and variance of temperature (diel cycles of 20 degrees -30 degrees and 20 degrees -34 degrees c). our goal was to determine whether embryos in warm nests would expend more energy to develop than embryos in coo ...201020687844
species tree discordance traces to phylogeographic clade boundaries in north american fence lizards (sceloporus).i investigated the impacts of phylogeographic sampling decisions on species tree estimation in the sceloporus undulatus species group, a recent radiation of small, insectivorous lizards connected by parapatric and peripatric distribution across north america, using a variety of species tree inference methods (bayesian estimation of species trees, bayesian untangling of concordance knots, and minimize deep coalescences). phylogenetic analyses of 16 specimens representing 4 putative species within ...200920525608
can mechanism inform species' distribution models?two major approaches address the need to predict species distributions in response to environmental changes. correlative models estimate parameters phenomenologically by relating current distributions to environmental conditions. by contrast, mechanistic models incorporate explicit relationships between environmental conditions and organismal performance, estimated independently of current distributions. mechanistic approaches include models that translate environmental conditions into biologica ...201020482574
tissue-carbon incorporation rates in lizards: implications for ecological studies using stable isotopes in terrestrial ectotherms.carbon stable isotope (delta(13)c) analysis can be used to infer the origin and to estimate the flow of nutrient resources through animals and across ecological compartments. these applications require knowledge of the rates at which carbon is incorporated into animal tissues and diet-to-tissue discrimination factors (delta(13)c). studies of carbon dynamics in terrestrial vertebrates to date have focused almost solely on endothermic animals; ectotherms such as reptiles have received little atten ...201020441446
bayesian species delimitation using multilocus sequence data.in the absence of recent admixture between species, bipartitions of individuals in gene trees that are shared across loci can potentially be used to infer the presence of two or more species. this approach to species delimitation via molecular sequence data has been constrained by the fact that genealogies for individual loci are often poorly resolved and that ancestral lineage sorting, hybridization, and other population genetic processes can lead to discordant gene trees. here we use a bayesia ...201020439743
toxicity of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (hmx) in three vertebrate species.the explosive, octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine or high-melting explosive (hmx), has been found in soils in areas used for testing and training by the military. many of these areas contain habitat for valued wildlife species. in an effort to better understand the environmental consequences from exposure, a reptilian (western fence lizard [sceloporus occidentalis]), an amphibian (red-backed salamander [plethodon cinereus]), and a mammalian species (rabbit [oryctolagus cuniculus]) ...201020012743
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 ...201019922261
geographic genetic differentiation of a malaria parasite, plasmodium mexicanum, and its lizard host, sceloporus occidentalis.gene flow, and resulting degree of genetic differentiation among populations, will shape geographic genetic patterns and possibly local adaptation of parasites and their hosts. some studies of plasmodium falciparum in humans show substantial differentiation of the parasite in locations separated by only a few kilometers, a paradoxical finding for a parasite in a large, mobile host. we examined genetic differentiation of the malaria parasite plasmodium mexicanum, and its lizard host, sceloporus o ...201019916631
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 ...200919886501
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 ...201019722273
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