| choroid plexus, ependyma and arachnoidea express receptors for vitamin d: differences between "seasonal" and "non-seasonal" breeders. | autoradiographic studies with [3h]1,25-dihydroxyvitamin d3 demonstrated nuclear high affinity binding sites (receptors) in epithelial cells of choroid plexus, ependyma and arachnoid in "seasonal" breeders of various vertebrate phyla, namely xiphophorus helleri, hyla crucifer, xenopus laevis, bufo woodhousei, chrysemys scripta, anolis carolinensis, nerodia sipedon and phodopus sungorus, but vitamin d receptors were undetectable in these tissues in non-seasonal breeders, such as zebra finch, labor ... | 1992 | 1329147 |
| sch 23390: d-1 modulation of oral dyskinesias induced in snakes by xenopus skin mucus. | the granular gland skin secretion of xenopus laevis induces seven involuntary oral dyskinesias and climbing behavior in the water snake nerodia sipedon. in a previous study the d-2 receptor antagonist, haloperidol (hal), selectively potentiated mucus-induced yawning and chewing but attenuated fixed gaping; other oral behaviors were unaffected; hal alone induced no dyskinesias and failed to modify mucus-induced decreases in tongue flicking, cage climbing and activity. as skin compounds have neuro ... | 1990 | 2217512 |
| neuroleptic modulation of oral dyskinesias induced in snakes by xenopus skin mucus. | the skin mucus of the african clawed frog xenopus laevis promotes escape from the american water snake nerodia sipedon by inducing oral dyskinesias. as xenopus mucus contains peptides and indoleamines with known neuroleptic properties, and because neuroleptics are the chief cause of drug-induced orofacial dyskinesias in humans, the hypothesis was tested that the neuroleptic haloperidol (hal) would induce oral dyskinesias when given alone and would potentiate dyskinesias in nerodia if injected pr ... | 1989 | 2626458 |
| histological aspects of natural eustrongyloid infections of the northern water snake, nerodia sipedon. | encapsulated as well as unencapsulated fourth stage larvae of eustrongylides sp. were found in four northern water snakes, nerodia sipedon, from virginia. unencapsulated nematodes occurred within muscle, subcutaneous tissue and in the coelom. encapsulated nematodes occurred in three forms: recently encapsulated, degenerating, or sclerotic; they were found on the mesentery, in muscle and subcutaneous tissue. encapsulation was associated with muscular hypotrophy, fibroplasia and eosinophilia. | 1986 | 3503139 |
| plasma concentrations of chloramphenicol in snakes. | plasma chloramphenicol concentrations after a subcutaneous injection were studied in 87 snakes of 16 different species. the biological half-life of chloramphenicol varied from 3.3 hours in the indigo snake (drymarchon corais couperi) to 22.1 hours in the midland water snake (nerodia sipedon). a single dosage of 50 mg of chloramphenicol/kg of body weight produced plasma concentrations greater than 5 micrograms/ml for nearly 72 hours in 2 species of water snakes (nerodia erythrogaster, nerodia sip ... | 1985 | 4083608 |
| seasonal effects of mammalian gonadotropins (bfsh and blh) on plasma androgen levels in male water snakes, nerodia sipedon. | | 1982 | 6127185 |
| the development of hepatozoon sipedon sp. nov. (apicomplexa: adeleina: hepatozoidae) in its natural host, the northern water snake (nerodia sipedon sipedon), in the culicine vectors culex pipiens and c. territans, and in an intermediate host, the northern leopard frog (rana pipiens). | the life cycle of hepatozoon sipedon sp. nov. was studied in two snake species, the northern water snake and the eastern garter snake, in its mosquito hosts culex pipiens and c. territans, and in the northern leopard frog. gametogenesis, fertilization and sporogony occurred within fat body cells in the haemocoel of mosquitoes that had fed on infected water snakes. mature oocysts averaging 263 microns in diameter and containing more than 500 sporocysts were observed in mosquitoes 28 days post-fee ... | 1994 | 7855120 |
| effects of monoamine oxidase inhibitors and dopamine agonists on the behavior of mammal- and frog-eating snakes. | skin mucus of the frog, xenopus laevis, induces climbing and attenuates tongue flicking in nerodia sipedon; these effects are induced alone and are potentiated by l-deprenyl, a monoamine oxidase type b inhibitor (mao-bi), but not by clorgyline, an mao type a inhibitor (mao-ai). both mao-a and mao-b metabolize dopamine, with mao-b having the higher affinity; mao-a selectively metabolizes serotonin and norepinephrine and mao-b is selective for phenylethylamine. it was hypothesized that clorgyline ... | 1994 | 7912837 |
| ultrastructural features of cystic and merogonic stages of hepatozoon sipedon (apicomplexa: adeleorina) in northern leopard frogs (rana pipiens) and northern water snakes (nerodia sipedon) from ontario, canada. | the cystic and merogonic stages of the haemogregarine hepatozoon sipedon, infecting northern water snakes (nerodia sipedon sipedon) and northern leopard frogs (rana pipiens), respectively, in ontario, canada, were investigated by transmission electron microscopy. cysts, which were observed in the liver of northern leopard frogs (rana pipiens) after these anurans ingested mosquitoes (culex pipiens) containing oocysts of the parasite, harboured two cystozoites, each of which contained a large crys ... | 1998 | 9703677 |
| temporal and spatial patterns of contaminants in lake erie watersnakes (nerodia sipedon insularum) before and after the round goby (apollonia melanostomus) invasion. | temporal and spatial trends in contaminant concentrations were assessed in lake erie watersnakes, a threatened (usa)/endangered (canada) species restricted to western lake erie. temporal changes in plasma contaminant levels were determined in 1990 and 2003, and spatial patterns in 2003 at 12 sites, throughout the species' range. during this period, the watersnakes' diet changed from fish (75%) and amphibians (25%) that avoid zebra mussels, to round gobies (95%) that feed extensively on zebra mus ... | 2008 | 18771794 |
| stable isotope tracer reveals that viviparous snakes transport amino acids to offspring during gestation. | viviparity and placentation have evolved from oviparity over 100 times in squamate reptiles (lizards and snakes). the independent origins of placentation have resulted in a variety of placental morphologies in different taxa, ranging from simple apposition of fetal and maternal tissues to endotheliochorial implantation that is homoplasious with mammalian placentation. because the eggs of oviparous squamates transport gases and water from the environment and calcium from the eggshell, the placent ... | 2012 | 22323198 |
| bioenergetic components of reproductive effort in viviparous snakes: costs of vitellogenesis exceed costs of pregnancy. | reproductive effort has been defined as the proportion of an organism's energy budget that is allocated to reproduction over a biologically meaningful time period. historically, studies of reproductive bioenergetics considered energy content of gametes, but not costs of gamete production. although metabolic costs of vitellogenesis (mcv) fundamentally reflect the primary bioenergetic cost of reproductive allocation in female reptiles, the few investigations that have considered costs of reproduct ... | 2011 | 21884815 |
| the behavioural response of adult petromyzon marinus to damage-released alarm and predator cues. | using semi-natural enclosures, this study investigated (1) whether adult sea lamprey petromyzon marinus show avoidance of damage-released conspecific cues, damage-released heterospecific cues and predator cues and (2) whether this is a general response to injured heterospecific fishes or a specific response to injured p. marinus. ten replicate groups of 10 adult p. marinus, separated by sex, were exposed to one of the following nine stimuli: deionized water (control), extracts prepared from adul ... | 2014 | 24773541 |
| chlorinated hydrocarbon concentrations in plasma of the lake erie water snake (nerodia sipedon insularum) and northern water snake (nerodia sipedon sipedon) from the great lakes basin in 1998. | from the great lakes basin, concentrations of 59 congener-specific polychlorinated biphenyls (pcbs) and 14 organochlorine pesticides were measured in blood plasma of northern water snake (nerodia sipedon sipedon) and lake erie water snake (nerodia sipedon insularum), which is endangered in canada. in 1998, four male adult lake erie water snakes were sampled from pelee island, western lake erie; four male northern water snakes were sampled at little lake, about 20 km north of parry sound in centr ... | 2000 | 11031311 |
| population mixing and the adaptive divergence of quantitative traits in discrete populations: a theoretical framework for empirical tests. | empirical tests for the importance of population mixing in constraining adaptive divergence have not been well grounded in theory for quantitative traits in spatially discrete populations. we develop quantitative-genetic models to examine the equilibrium difference between two populations that are experiencing different selective regimes and exchanging individuals. these models demonstrate that adaptive divergence is negatively correlated with the rate of population mixing (m, most strongly so w ... | 2001 | 11327154 |
| morphology, ultrastructure and taxonomic status of toddia sp. in northern water snakes (nerodia sipedon sipedon) from ontario, canada. | inclusions characteristic of an infection caused by toddia sp. were found in the erythrocytes and erythroblasts of 15 of 26 northern water snakes (nerodia sipedon sipedon) collected near kingston, ontario, canada. erythrocytes contained translucent inclusions, small acidophilic bodies, and square-shaped crystalloid structures. erythrocytes infected with toddia sp. were more rounded than uninfected erythrocytes and had pycnotic nuclei. we observed icosahedral virus particles measuring 195 to 210 ... | 1994 | 8028100 |
| color pattern polymorphism in the lake erie water snake, nerodia sipedon insularum. | populations of the water snake, nerodia sipedon, on islands in western lake erie are polymorphic for color pattern. these populations include banded, intermediate, and unbanded morphs while surrounding mainland populations consist solely of the banded morph. the hypothesis that this polymorphism is maintained by strong selection and migration pressures is widely accepted. unbanded morphs are apparently more cryptic along island shorelines while banded morphs are more cryptic on the mainland. mig ... | 1987 | 28568759 |
| projecting invasion risk of non-native watersnakes (nerodia fasciata and nerodia sipedon) in the western united states. | species distribution models (sdms) are increasingly used to project the potential distribution of introduced species outside their native range. such studies rarely explicitly evaluate potential conflicts with native species should the range of introduced species expand. two snake species native to eastern north america, nerodia fasciata and nerodia sipedon, have been introduced to california where they represent a new stressor to declining native amphibians, fish, and reptiles. to project the p ... | 2014 | 24964204 |
| bioaccumulation of polychlorinated biphenyls in ranid frogs and northern water snakes from a hazardous waste site and a contaminated watershed. | livers of bullfrogs (rana catesbeiana) from a polychlorinated biphenyl (pcb) contaminated watershed and hazardous waste site located in pickens county, south carolina, contained significantly higher concentrations of pcbs (2.33 and 2.26 ppm, respectively) than those from a reference site (0.05 ppm). green frogs (r. clamitans) from the two contaminated sites also accumulated higher levels of pcbs (2.37 and 3.88 ppm, respectively) than those from the reference site (0.02 ppm). no temporal variatio ... | 2000 | 10718571 |
| microgeographic population genetic structure in the northern water snake, nerodia sipedon sipedon detected using microsatellite dna loci. | we describe the isolation and genetic characterization of eight microsatellite dna loci from the northern water snake, nerodia sipedon sipedon and use these loci to analyse levels of genetic differentiation between local (< 2 km apart) populations of these snakes in ontario. these loci are variable, with expected heterozygosities ranging from 0.28 to 0.91, and can correctly exclude nonsires in parentage analyses with a high probability (0.998). population analyses reveal significant deviation fr ... | 1999 | 10065548 |
| good species despite massive hybridization: genetic research on the contact zone between the watersnakes nerodia sipedon and n. fasciata in the carolinas, usa. | genomic markers generated with the amplified fragment length polymorphism method revealed extensive, panmictic-like hybridization along the narrow contact zone between the water snakes nerodia sipedon and nerodia fasciata in the carolinas, usa. however, asymmetric distributions of diagnostic markers between both species and low frequencies of backcrossed hybrids with a high value of interspecific mixture infer selection against certain genotypes. this is consistent with a pronounced genetic and ... | 2008 | 18346128 |
| effects of maternally-transferred methylmercury on stress physiology in northern water snake (nerodia sipedon) neonates. | biomagnification of methylmercury in aquatic systems can cause elevated tissue mercury (hg) and physiological stress in top predators. mercury is known to affect stress hormone levels in mammals, birds and fish. in this study, the effects of maternally-transferred methylmercury on the stress physiology of northern water snake (nerodia sipedon) neonates were tested. gravid females were dosed via force-fed capsules during late gestation with 0, 0.01, or 10 µg methylmercury per gram of body mass. p ... | 2016 | 26886428 |
| size matters: individual variation in ectotherm growth and asymptotic size. | body size, and, by extension, growth has impacts on physiology, survival, attainment of sexual maturity, fecundity, generation time, and population dynamics, especially in ectotherm animals that often exhibit extensive growth following attainment of sexual maturity. frequently, growth is analyzed at the population level, providing useful population mean growth parameters but ignoring individual variation that is also of ecological and evolutionary significance. our long-term study of lake erie w ... | 2016 | 26730712 |
| splenopancreatic ductal adenocarcinoma with multiorgan metastasis in a northern water snake (nerodia sipedon). | a 16-yr-old northern water snake (nerodia sipedon) presented with a large, firm midcoelomic swelling. a complete blood count, survey radiographs, coelomic ultrasound, and fine needle aspirate of the mass were performed. survey radiographs revealed a soft tissue opacity mass. ultrasonographic examination confirmed the presence of the mass but could not aid in its visceral localization. after 2 weeks, the snake presented again because of continued anorexia and poor quality of life. euthanasia was ... | 2014 | 25000716 |
| snake lower jaw skin: extension and recovery of a hyperextensible keratinized integument. | the skin of squamates consists of a keratinized epidermis divided into thick scale and thinner, folded interscale regions underlain by a dermis containing a complex array of fibrous connective tissues. we examined the skin of the lower jaw of watersnakes (nerodia sipedon) to determine how skin morphology changes when highly stretched during ingestion of large prey. video records of skin behavior in the lower jaws of watersnakes feeding on fish or anesthetized watersnakes being stretched on an in ... | 2014 | 24497479 |
| like mother, like offspring: maternal and offspring wound healing correlate in snakes. | immune function early in life can be influenced by parental effects and the environment, but it remains unclear how these two factors may interact to influence immunocompetence. we evaluated maternal and environmental contributions to offspring healing ability in a viviparous reptile, the northern watersnake (nerodia sipedon). we measured wound healing rates, a highly integrative and biologically relevant measure of innate immunity, of females and their offspring collected from sites contaminate ... | 2013 | 23804668 |
| assessing multiple endpoints of atrazine ingestion on gravid northern watersnakes (nerodia sipedon) and their offspring. | ecotoxicological studies that focus on a single endpoint might not accurately and completely represent the true ecological effects of a contaminant. exposure to atrazine, a widely used herbicide, disrupts endocrine function and sexual development in amphibians, but studies involving live-bearing reptiles are lacking. this study tracks several effects of atrazine ingestion from female northern watersnakes (nerodia sipedon) to their offspring exposed in utero. twenty-five gravid n. sipedon were fe ... | 2014 | 23436772 |
| altered behavior of neonatal northern watersnakes (nerodia sipedon) exposed to maternally transferred mercury. | little is known about effects of maternally transferred contaminants in snakes. the purpose of this study was to evaluate sublethal effects of maternally transferred mercury (hg) on neonatal northern watersnakes (nerodia sipedon). we captured 31 gravid females along a historically hg-contaminated river. following birth, we measured litter hg concentrations and assessed locomotor performance, foraging ability (i.e., number of prey eaten, latency to first strike, strike efficiency, and handling ti ... | 2013 | 23419772 |
| inter- and intraspecific variation in mercury bioaccumulation by snakes inhabiting a contaminated river floodplain. | although mercury (hg) is a well-studied contaminant, knowledge about hg accumulation in snakes is limited. the authors evaluated hg bioaccumulation within and among four snake species (northern watersnakes, nerodia sipedon; queen snakes, regina septemvittata; common garter snakes, thamnophis sirtalis; and rat snakes, elaphe obsoleta [pantherophis alleghaniensis]) from a contaminated site on the south river (waynesboro, va, usa) and two nearby reference sites. total hg (thg) concentrations in nor ... | 2013 | 23401211 |
| high levels of maternally transferred mercury do not affect reproductive output or embryonic survival of northern watersnakes (nerodia sipedon). | maternal transfer is an important exposure pathway for contaminants because it can directly influence offspring development. few studies have examined maternal transfer of contaminants, such as mercury (hg), in snakes, despite their abundance and high trophic position in many ecosystems where hg is prevalent. the objectives of the present study were to determine if hg is maternally transferred in northern watersnakes (nerodia sipedon) and to evaluate the effects of maternal hg on reproduction. t ... | 2013 | 23233365 |
| effects of acute temperature change, confinement and housing on plasma corticosterone in water snakes, nerodia sipedon (colubridae: natricinae). | body temperature affects many aspects of reptilian behavior and physiology, but its effect on hormonal secretion has been little studied, especially in snakes. major objectives of this study were to determine if acute changes in body temperature during confinement influenced plasma corticosterone levels and if initial body temperatures upon capture in the field were related to baseline corticosterone levels in water snakes (nerodia sipedon). water snakes were bled upon capture in the field and a ... | 2009 | 19051318 |
| dynamic changes in body form during swimming in the water snake nerodia sipedon. | video records of swimming water snakes show that during moderate to rapid swimming, the rear half to two-thirds of the trunk is compressed laterally, approaching the body form of some sea snakes. body form of swimming snakes differed significantly from their shape when resting on a flat surface or when anesthetized and suspended in water. the extent of lateral flattening is positively correlated with swimming speed, a relationship generally supported by tests of trunk models in a flow tank. in n ... | 2008 | 17993267 |
| polychlorinated biphenyls and organochlorine pesticides in plasma and the embryonic development in lake erie water snakes (nerodia sipedon insularum) from pelee island, ontario, canada (1999). | from three locations along a 34-km shoreline of pelee island, ontario, 30 gravid female lake erie water snakes (nerodia sipedon insularum) were sampled to determine the organochlorine (oc) contaminant levels in plasma and the number of live and dead embryos present in the body cavity. plasma was analyzed for 59 polychlorinated biphenyl (pcb) congeners and 14 organochlorine pesticides. concentrations of pesticides were low (< or =0.1 ng/g wet wt) in all snakes, but there was significant variation ... | 2006 | 16823523 |
| prenatal sex ratios and expression of sexually dimorphic traits in three snake species. | variation in intrauterine exposure to hormones associated with variation in the sex of litter mates has well-established and far-reaching effects on sexual development in some mammals. research on this phenomenon in reptiles is scant, but suggests that lizards may follow the mammalian model whereas snakes may be affected differently. we examined sex-specific expression of four sexually dimorphic traits (tail length, head length, ventral scale count, swimming speed) in three species of snakes (ne ... | 2006 | 16788914 |
| unlearned appetite controls: watersnakes (nerodia) take smaller meals when they have the choice. | studies of appetite in mammals emphasize that meal size is learned, but lactation and parental care constrain testing of naive individuals. neonatal reptiles, in contrast, are self-sufficient foragers. the authors examined the effect of prey size on meal size in primivorous (at first feeding) northern watersnakes (nerodia sipedon). when offered an excess of small prey (2%-20% of snake mass), neonates ate significantly smaller meals (m = 23.5% of snake mass) than when offered a single huge item ( ... | 2005 | 16131259 |
| heavy metal concentrations in northern water snakes (nerodia sipedon) from east fork poplar creek and the little river, east tennessee, usa. | we compared the levels of arsenic, cadmium, chromium, lead, manganese, mercury, and selenium in the blood, kidney, liver, muscle, and skin of northern water snakes (nerodia sipedon) collected from the upper reach of east fork poplar creek (efpc) within the united states department of energy's (usdoe's) y-12 national security complex with concentrations in tissues of northern water snakes from a reference reach of the little river downstream from the great smoky mountains national park in east te ... | 2005 | 16001153 |
| use of skin and blood as nonlethal indicators of heavy metal contamination in northern water snakes (nerodia sipedon). | relatively little is known about contaminants in reptiles, particularly snakes. the concentrations of arsenic, cadmium, chromium, lead, manganese, mercury, and selenium were examined in blood and skin of 46 northern water snakes (nerodia sipedon) in tennessee and correlated with concentrations in internal tissues (liver, kidney, muscle) to determine if blood or skin could serve as a nonlethal indicator of internal metal exposure or body burden. snakes were collected from the east fork poplar cre ... | 2005 | 16001147 |
| variation in seasonal ultrastructure of sexual granules in the renal sexual segment of the northern water snake, nerodia sipedon sipedon. | the renal sexual segment of the kidney (rss) can be found in many male squamate reptiles, encompassing the distal region of the nephron and, in some cases, collecting ducts. this sexually dimorphic structure exhibits varying degrees of hypertrophy and regression throughout the year. although researchers have been aware of and have investigated this unique structure for over a century, its ultimate function remains under discussion. in many studies hypertrophy and regression of the rss have been ... | 2004 | 15164368 |
| color-pattern variation in lake erie water snakes: the role of gene flow. | in an effort to clarify the evolutionary processes influencing color-pattern variation in lake erie island water snake (nerodia sipedon) populations, rates of gene flow among island and mainland populations were estimated from patterns of allozymic variation detected using electrophoresis. rates of gene flow were high with nm, the number of migrants per generation, averaging 25.5 among island sites, 9.2 between the ontario mainland and the islands, and 3.6 between the ohio mainland and the islan ... | 1995 | 28564875 |
| color-pattern variation in lake erie water snakes: prediction and measurement of natural selection. | a classic example of natural selection, that of color-pattern variation in lake erie island populations of water snakes, was reexamined to overcome shortcomings resulting from classification of snakes into discrete color-pattern categories and use of cross-sectional data. four continuously varying color-pattern components (db, the number of dorsal blotches; lb, the number of lateral blotches; rows, the height of lateral blotches measured in scale rows; and vext, the extent of ventral pigmentatio ... | 1993 | 28567998 |
| effects of mammalian gonadotropins (ofsh and olh) on testicular development in the immature water snake, nerodia sipedon. | ovine fsh (ofsh) or ovine lh (olh) was injected into immature male nerodia sipedon and was assessed as to its effects on testicular development and steroid synthesis as indicated by the subsequent development of the renal sexual segment, a known secondary sexual character. fsh-injected animals had significantly larger testis mass, seminiferous tubule diameter, and epithelial height when compared to lh-injected and control groups. while fsh induced testicular development, lh induced lipid accumul ... | 1986 | 3100384 |
| effect of bilateral vagotomy on the ventilatory responses of the water snake nerodia sipedon. | the effects of bilateral vagotomy on pulmonary ventilation, o2 consumption, and heart rate were determined for the water snake, nerodia sipedon, breathing room air at 15, 25, and 30 degrees c and breathing 5.2% co2 in air at 25 degrees c. at all body temperatures, vagotomy resulted in a four- to sevenfold increase in tidal volume in snakes breathing room air. at the same time, ventilatory frequency decreased such that pulmonary ventilation was unchanged after vagotomy. heart rate increased appro ... | 1984 | 6421179 |
| seasonal androgenesis in the male water snake, nerodia sipedon. | | 1981 | 7239157 |
| snakes as novel biomarkers of mercury contamination: a review. | mercury (hg) is an environmental contaminant that has been reported in many wildlife species worldwide. the organic form of hg bioaccumulates in higher trophic levels, and thus, long-lived predators are at risk for higher hg exposure. although ecological risk assessments for contaminants such as hg include pertinent receptor species, snakes are rarely considered, despite their high trophic status and potential to accumulate high levels of hg. our current knowledge of these reptiles suggests that ... | 2020 | 30879139 |
| prevalence of ophidiomyces ophiodiicola, the causative agent of snake fungal disease, in the interior plateau ecoregion of tennessee, usa. | the fungal pathogen ophidiomyces ophiodiicola, the causative agent of snake fungal disease, has been implicated in declines of north american snake populations since 2006 and the geographic range of this pathogen is still not fully known. in tennessee, o. ophiodiicola has been detected since 2012, but large portions of the state have not been surveyed for this pathogen. our primary objective was to monitor the prevalence of o. ophiodiicola in the interior plateau ecoregion of tennessee by swabbi ... | 2020 | 32348203 |
| effects of snake fungal disease on short-term survival, behavior, and movement in free-ranging snakes. | pathogenic fungi are increasingly associated with epidemics in wildlife populations. snake fungal disease (sfd) is an emerging threat to snakes, taxa that are elusive and difficult to sample. thus, assessments of the impacts of sfd on populations have rarely occurred. we used a field technique to enhance detection, passive integrated transponder (pit) telemetry, and a multistate capture-mark-recapture model to assess sfd effects on short-term (within-season) survival, movement, and surface activ ... | 2020 | 33142002 |
| traditional trapping methods outperform edna sampling for introduced semi-aquatic snakes. | given limited resources for managing invasive species, traditional survey methods may not be feasible to implement at a regional scale. environmental dna (edna) sampling has proven to be an effective method for detecting some invasive species, but comparisons between the detection probability of edna and traditional survey methods using modern occupancy modeling methods are rare. we developed a qpcr assay to detect two species of watersnake (nerodia fasciata and nerodia sipedon) introduced to ca ... | 2019 | 31265475 |
| angles and waves: intervertebral joint angles and axial kinematics of limbed lizards, limbless lizards, and snakes. | segmentation gives rise to the anterior-posterior axis in many animals, and in vertebrates this axis comprises serially arranged vertebrae. modifications to the vertebral column abound, and a recurring, but functionally understudied, change is the elongation of the body through the addition and/or elongation of vertebrae. here, we compared the vertebral and axial kinematics of the robustly limbed fire skink (riopa fernandi) representing the ancestral form, the limbless european glass lizard (oph ... | 2019 | 31146904 |
| sunning themselves in heaps, knots, and snarls: the extraordinary abundance and demography of island watersnakes. | snakes represent a sizable fraction of vertebrate biodiversity, but until recently, data on their demography have been sparse. consequently, generalizations regarding patterns of variation are weak and the potential for population projections is limited. we address this information gap through an analysis of spatial and temporal variation in demography (population size, annual survival, and realized population growth) of the lake erie watersnake, nerodia sipedon insularum, and a review of snake ... | 2018 | 30151166 |