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Axel Moehrenschlager - One of the best experts on this subject based on the ideXlab platform.
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Annual Northern Leopard Frog occupancy trends from 2009–2013 in spring (20 April–02 June) and summer (21 July–30 August) in southern Alberta.
2015Co-Authors: Lea A. Randall, Des H. V. Smith, Breana L. Jones, David R. C. Prescott, Axel MoehrenschlagerAbstract:-2 LL = -2 log likelihood; K = number of parameters; AIC = Akaike Information Criterion; wi = Akaike weight; ψ = occupancy; ɣ = colonization; ε = extinction. Variance inflation factor ĉ = 1.Annual Northern Leopard Frog occupancy trends from 2009–2013 in spring (20 April–02 June) and summer (21 July–30 August) in southern Alberta.
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Seasonal and annual Northern Leopard Frog occupancy dynamics in southern Alberta from 2009–2013 spring (20 April–02 June) and summer (21 July–30 August) visual surveys.
2015Co-Authors: Lea A. Randall, Des H. V. Smith, Breana L. Jones, David R. C. Prescott, Axel MoehrenschlagerAbstract:-2 LL = -2 log likelihood; K = number of parameters; AIC = Akaike Information Criterion; wi = Akaike weight; ψ = occupancy; ɣ = colonization. Variance inflation factor ĉ = 1.Seasonal and annual Northern Leopard Frog occupancy dynamics in southern Alberta from 2009–2013 spring (20 April–02 June) and summer (21 July–30 August) visual surveys.
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Annual Northern Leopard Frog occupancy trends with site selection criteria (SSC) from 2009–2013 in spring (20 April–02 June) and summer (21 July–30 August) in southern Alberta.
2015Co-Authors: Lea A. Randall, Des H. V. Smith, Breana L. Jones, David R. C. Prescott, Axel MoehrenschlagerAbstract:-2 LL = -2 log likelihood; K = number of parameters; AIC = Akaike Information Criterion; wi = Akaike weight; ψ = occupancy; ɣ = colonization; ε = extinction. Variance inflation factor ĉ = 1.Annual Northern Leopard Frog occupancy trends with site selection criteria (SSC) from 2009–2013 in spring (20 April–02 June) and summer (21 July–30 August) in southern Alberta.
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Top five Northern Leopard Frog detection probability models for 2009–2013 spring (20 April–02 June) or summer (21 July–30 August) visual surveys in southern Alberta.
2015Co-Authors: Lea A. Randall, Des H. V. Smith, Breana L. Jones, David R. C. Prescott, Axel MoehrenschlagerAbstract:-2 LL = -2 log likelihood; K = number of parameters; AIC = Akaike information criterion; wi = Akaike weights; p = probability of detection; wind chill (Wchill); air temperature (AT); maximum (Wmax) and average (Wavg) wind speed; water surface temperature (WT); humidity (HM); Julian date of survey (JD). Variance inflation factor ĉ = 1.Top five Northern Leopard Frog detection probability models for 2009–2013 spring (20 April–02 June) or summer (21 July–30 August) visual surveys in southern Alberta.
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asynchronous breeding and variable embryonic development period in the threatened northern Leopard Frog lithobates pipiens in the cypress hills alberta canada conservation and management implications
Canadian Field-Naturalist, 2014Co-Authors: Lea A. Randall, Axel Moehrenschlager, Lynne D Chalmers, Anthony P RussellAbstract:Understanding breeding phenology is critical for establishing monitoring strategies, comprehending population dynamics, and developing conservation actions for at-risk species, such as the Northern Leopard Frog ( Lithobates pipiens ). The timing of spawning and hatching in the Northern Leopard Frog may be highly variable depending on regional environmental conditions, which can make establishing the timing of surveys difficult. In spring 2006, eggs were laid over 30 days (24 April to 23 May) and hatching occurred over 2 weeks (14–28 May) at three neighbouring ponds in Cypress Hills, Alberta, Canada. Although spawning occurred over a month, all eggs hatched within a 2-week period, indicating variable embryo development rate. Among 26 egg masses, eggs laid later in the season developed approximately four times faster than those laid earlier, and Akaike information criterion-ranked models suggested that both Julian date and water temperature were important predictors of embryo development rate: later spawning date and warmer water were associated with faster rates. Some egg masses survived colder temperatures than previously reported for this species. Asynchronous breeding and variable development rates reveal the need to conduct multiple surveys over the breeding season, even within a small geographic area, to document reliably the presence of egg masses and identify breeding habitat. Identification of key breeding habitat is necessary to mitigate human-caused disturbances of such regionally imperiled species.
Lea A. Randall - One of the best experts on this subject based on the ideXlab platform.
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Annual Northern Leopard Frog occupancy trends from 2009–2013 in spring (20 April–02 June) and summer (21 July–30 August) in southern Alberta.
2015Co-Authors: Lea A. Randall, Des H. V. Smith, Breana L. Jones, David R. C. Prescott, Axel MoehrenschlagerAbstract:-2 LL = -2 log likelihood; K = number of parameters; AIC = Akaike Information Criterion; wi = Akaike weight; ψ = occupancy; ɣ = colonization; ε = extinction. Variance inflation factor ĉ = 1.Annual Northern Leopard Frog occupancy trends from 2009–2013 in spring (20 April–02 June) and summer (21 July–30 August) in southern Alberta.
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Seasonal and annual Northern Leopard Frog occupancy dynamics in southern Alberta from 2009–2013 spring (20 April–02 June) and summer (21 July–30 August) visual surveys.
2015Co-Authors: Lea A. Randall, Des H. V. Smith, Breana L. Jones, David R. C. Prescott, Axel MoehrenschlagerAbstract:-2 LL = -2 log likelihood; K = number of parameters; AIC = Akaike Information Criterion; wi = Akaike weight; ψ = occupancy; ɣ = colonization. Variance inflation factor ĉ = 1.Seasonal and annual Northern Leopard Frog occupancy dynamics in southern Alberta from 2009–2013 spring (20 April–02 June) and summer (21 July–30 August) visual surveys.
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Annual Northern Leopard Frog occupancy trends with site selection criteria (SSC) from 2009–2013 in spring (20 April–02 June) and summer (21 July–30 August) in southern Alberta.
2015Co-Authors: Lea A. Randall, Des H. V. Smith, Breana L. Jones, David R. C. Prescott, Axel MoehrenschlagerAbstract:-2 LL = -2 log likelihood; K = number of parameters; AIC = Akaike Information Criterion; wi = Akaike weight; ψ = occupancy; ɣ = colonization; ε = extinction. Variance inflation factor ĉ = 1.Annual Northern Leopard Frog occupancy trends with site selection criteria (SSC) from 2009–2013 in spring (20 April–02 June) and summer (21 July–30 August) in southern Alberta.
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Top five Northern Leopard Frog detection probability models for 2009–2013 spring (20 April–02 June) or summer (21 July–30 August) visual surveys in southern Alberta.
2015Co-Authors: Lea A. Randall, Des H. V. Smith, Breana L. Jones, David R. C. Prescott, Axel MoehrenschlagerAbstract:-2 LL = -2 log likelihood; K = number of parameters; AIC = Akaike information criterion; wi = Akaike weights; p = probability of detection; wind chill (Wchill); air temperature (AT); maximum (Wmax) and average (Wavg) wind speed; water surface temperature (WT); humidity (HM); Julian date of survey (JD). Variance inflation factor ĉ = 1.Top five Northern Leopard Frog detection probability models for 2009–2013 spring (20 April–02 June) or summer (21 July–30 August) visual surveys in southern Alberta.
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asynchronous breeding and variable embryonic development period in the threatened northern Leopard Frog lithobates pipiens in the cypress hills alberta canada conservation and management implications
Canadian Field-Naturalist, 2014Co-Authors: Lea A. Randall, Axel Moehrenschlager, Lynne D Chalmers, Anthony P RussellAbstract:Understanding breeding phenology is critical for establishing monitoring strategies, comprehending population dynamics, and developing conservation actions for at-risk species, such as the Northern Leopard Frog ( Lithobates pipiens ). The timing of spawning and hatching in the Northern Leopard Frog may be highly variable depending on regional environmental conditions, which can make establishing the timing of surveys difficult. In spring 2006, eggs were laid over 30 days (24 April to 23 May) and hatching occurred over 2 weeks (14–28 May) at three neighbouring ponds in Cypress Hills, Alberta, Canada. Although spawning occurred over a month, all eggs hatched within a 2-week period, indicating variable embryo development rate. Among 26 egg masses, eggs laid later in the season developed approximately four times faster than those laid earlier, and Akaike information criterion-ranked models suggested that both Julian date and water temperature were important predictors of embryo development rate: later spawning date and warmer water were associated with faster rates. Some egg masses survived colder temperatures than previously reported for this species. Asynchronous breeding and variable development rates reveal the need to conduct multiple surveys over the breeding season, even within a small geographic area, to document reliably the presence of egg masses and identify breeding habitat. Identification of key breeding habitat is necessary to mitigate human-caused disturbances of such regionally imperiled species.
Serena D Rogers - One of the best experts on this subject based on the ideXlab platform.
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the disappearing northern Leopard Frog lithobates pipiens conservation genetics and implications for remnant populations in western nevada
Ecology and Evolution, 2012Co-Authors: Serena D Rogers, Mary M PeacockAbstract:Global amphibian declines suggest a major shift in the amount and quality of habitat for these sensitive taxa. Many species that were once widespread are now experiencing declines either in part of or across their historic range. The northern Leopard Frog (Rana [Lithobates] pipiens] has undergone significant declines particularly in the western United States and Canada. Leopard Frog population losses in Nevada are largely due to habitat fragmentation and the introduction of nonnative fish, amphibian, and plant species. Only two populations remain in the Truckee and Carson River watersheds of western Nevada which represents the western boundary of this species range. We used sequence data for an 812 base pair fragment of the mitochondrial NADH dehydrogenase 1 (ND1) gene to support a native origin for western Nevada populations. All Frogs had a single haplotype (W07) from the distinct western North America ND1 haplotype clade. Data from seven polymorphic microsatellite loci show that Truckee and Carson River populations are highly differentiated from each other and from Leopard Frogs collected from eastern Nevada sites. Lack of gene flow among and distinct color morphs among the western Nevada populations likely predates the current geographical isolation. Comparisons with other peripheral L. pipiens populations show western Nevada populations have similar levels of gene diversity despite their contemporary isolation (HE 0.411, 0.482). Restoration of Leopard Frog populations in these watersheds will be challenging given well-entrenched nonnative bullFrog populations and major changes to the riparian zone over the past century. Declines of once common amphibian species has become a major conservation concern. Contemporary isolation of populations on a species range periphery such as the Leopard Frog populations in the Truckee and Carson rivers further exacerbate extirpation risk as these populations are likely to have fewer genetic resources to adaptively respond to rapidly changing biotic and abiotic environments.
William H Karasov - One of the best experts on this subject based on the ideXlab platform.
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digestive efficiency of northern Leopard Frog lithobates pipiens tadpoles during development reared on a laboratory diet
Herpetologica, 2016Co-Authors: Sarah M Gleason, Jeremiah M Yahn, William H KarasovAbstract:Abstract: In rasping aquatic feeders, like many tadpoles, it is challenging to measure both the food consumed and excreta produced and thereby calculate digestive efficiency. The goals of this study were to measure the apparent digestive efficiency of Northern Leopard Frog (Lithobates pipiens) tadpoles on an artificial laboratory diet and test the use of putative inert markers to calculate digestibility. The diet used was commercial ground rabbit chow (primary ingredient: alfalfa meal) suspended in agar and gelatin. If dietary ash (8.35% of diet dry mass) were a perfect inert marker, then its concentration in digesta, excreta, or both, should increase as organic matter is absorbed from the food, making the ratio of ash in food to ash in digesta or excreta an index of how much of the food mass is indigestible. Ash content in digesta dissected from the distalmost portion of the tadpoles’ intestine was about twice as concentrated as in food, indicating a 50% dry matter digestibility (DMD). This compared wel...
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effects of chronic polybrominated diphenyl ether exposure on gonadal development in the northern Leopard Frog rana pipiens
Environmental Toxicology and Chemistry, 2012Co-Authors: Nathan D Van Schmidt, Tawnya L Cary, Manuel E Ortizsantaliestra, William H KarasovAbstract:Polybrominated diphenyl ethers (PBDEs) are bioaccumulative, persistent organic pollutants used as flame retardants in consumer goods. Concentrations of PBDEs in North American wildlife have been increasing for decades and been shown to have estrogenic effects on sexual development. No studies, however, have examined the effects of PBDEs on the sexual development of North American Frogs at ecologically relevant concentrations. This study examined the effects of five dietary concentrations of DE-71 (0, 1.1, 6.1, 71.4, and 634 ng ΣPBDEs/g diet), a technical PBDE mixture, on the gonadal development of the northern Leopard Frog, Rana pipiens. Tadpoles were exposed chronically from the time they became free-swimming until metamorphosis. Frogs were killed either at metamorphic climax or 10 weeks after completing metamorphosis, processed for histology, and examined for alterations in sexual development. The experimental group exposed to PBDEs at 1.1 ng/g had a significantly larger proportion of females compared with the expected 50:50 sex ratio. At 10 weeks post-metamorphosis, male Frogs exposed to 6.1 and 71.4 ng/g had significantly smaller testes, but all other measure of gonadal development tested showed no effects. No intersex or increased incidence of gonadal abnormality were detected. These findings indicate that PBDEs may disrupt sexual differentiation in Frogs at low, environmentally relevant concentrations. Environ. Toxicol. Chem. 2012;31:347–354. © 2011 SETAC
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effect of mono ortho and di ortho substituted polychlorinated biphenyl pcb congeners on Leopard Frog survival and sexual development
Chemosphere, 2008Co-Authors: Mariana Beatriz Jofre, William H KarasovAbstract:Abstract We tested the effect of mono- ortho and di- ortho PCB congeners on northern Leopard Frog ( Rana pipiens ) hatching success, survival and sexual development. Embryos and tadpoles were exposed to two levels (0.5 and 50 μg/l) of two PCBs. PCBs 101 and 70 were selected because they were present in amphibians collected in the Fox River–Green Bay ecosystem and they have the theoretical structural requirements to be able to bind to the estrogen receptor and mediate estrogenic responses. The exposure of Leopard Frog embryos and tadpoles to PCB 70 and 101 did not significantly affect hatchability, survival, deformities or growth. There were significant departures from the expected 50:50 sex ratio in tadpoles/Froglets exposed to PCB 101 and PCB 70. In all the cases of significant departure, the bias was towards higher number of females. Decrease in the proportion of male gonads and increase in the proportion of intersex gonads were observed with increasing PCB tissue concentrations. The effects of PCB congeners on sexual differentiation occur at concentrations higher than observed in Frogs in the Fox River/Green Bay ecosystem.
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Sublethal effects of lead on northern Leopard Frog (Rana pipiens) tadpoles
Environmental Toxicology and Chemistry, 2006Co-Authors: Te-hao Chen, Jackson A. Gross, William H KarasovAbstract:Northern Leopard Frogs (Rana pipiens) were exposed to environmentally relevant concentrations of lead in water (3, 10, and 100 μg/L as lead nitrate) from the embryonic stage to metamorphosis. Survival, growth, deformity, swimming ability, metamorphosis, and lead tissue concentrations were evaluated. Tadpole growth was significantly slower in the early stages (Gosner stages 25–30) in 100 μg/L treatment. More than 90% of tadpoles in the 100 μg/L treatment developed lateral spinal curvature, whereas almost all the tadpoles in the other groups were morphologically normal. Spinal deformity was associated with abnormal swimming behavior. Maximum swimming speed of tadpoles in the 100 μg/L treatment was significantly lower than that in the other groups. No significant effect of lead exposure was found on percentage metamorphosis, snout-vent length, mortality, and sex ratio of metamorphs. Time to metamorphosis was delayed in 100 μg/L treatment. Lead tissue concentrations in the tadpoles ranged from 0.1 to 224.5 mg/kg dry mass, were positively related to lead concentrations in the water, and fell within the range of tissue concentrations of wild tadpoles found in previous studies. According to our results, the current U.S. Environmental Protection Agency freshwater-quality chronic criterion for lead (2.5 μg/L) is appropriate to protect northern Leopard Frog larvae.
Jason T Hoverman - One of the best experts on this subject based on the ideXlab platform.
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chronic per polyfluoroalkyl substance exposure under environmentally relevant conditions delays development in northern Leopard Frog rana pipiens larvae
Environmental Toxicology and Chemistry, 2020Co-Authors: Wesley R Flynn, Chloe De Perre, Linda S Lee, Maria S Sepulveda, Michael Iacchetta, Jason T HovermanAbstract:Per-/polyfluoroalkyl substances (PFAS) are pervasive in aquatic systems globally and capable of causing detrimental effects on human and wildlife health. However, most studies are conducted under artificial conditions that are not representative of environmental exposures. Environmental exposures are characterized by multiple routes of exposure, low aquatic PFAS levels, and greater environmental variability than laboratory tests. Determining whether these factors influence toxicity is critical for understanding the effects of PFAS on aquatic life, including amphibians. Our goal was to assess the impact of PFAS on an amphibian under semirealistic conditions. We reared northern Leopard Frog (Rana pipiens) larvae in outdoor mesocosms containing sediment spiked to low, medium, and high levels (nominally 10, 100, or 1000 ppb dry wt) of perfluorooctanesulfonic acid (PFOS) or perfluorooctanoic acid (PFOA) for 30 d. Larvae in all PFOS treatments and the medium-PFOA treatment were approximately 1.5 Gosner stages less developed than control animals after 30 d. Notably, these developmental delays were observed at PFOS concentrations in the water as low as 0.06 ppb, which is considerably lower than levels associated with developmental effects in laboratory studies. Our results suggest that deriving toxicity values from laboratory studies examining aquatic exposure only may underestimate the effects of environmental PFAS exposure. Environ Toxicol Chem 2020;00:1-6. © 2020 SETAC.
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uptake and depuration of four per polyfluoroalkyl substances pfass in northern Leopard Frog rana pipiens tadpoles
Environmental Science and Technology Letters, 2017Co-Authors: Gary M Hoover, Michael F Chislock, Brian J Tornabene, Samuel C Guffey, Youn Jeong Choi, Chloe De Perre, Jason T Hoverman, Linda S Lee, Maria S SepulvedaAbstract:Per/polyfluoroalkyl substances (PFASs) are persistent organic contaminants that are ubiquitous in surface waters. To date, their effects on aquatic systems, especially amphibians, are poorly understood. We examined the uptake and depuration of perfluorooctanesulfonate (PFOS), perfluorohexanesulfonate (PFHxS), perfluorooctanoic acid (PFOA), and 6:2 fluorotelomer sulfonate (6:2 FTS) in northern Leopard Frog (Rana pipiens) tadpoles. Whole-body concentrations were examined every 10 d during constant aqueous exposure to targeted concentrations of 10, 100, and 1000 μg/L for 40 d and for 30 d during depuration. Effects of PFAS exposure on length and development were also examined. Rapid uptake led to steady state concentrations by 10 d for most exposures. PFOS accumulated to the highest levels with whole-body bioconcentration factor (BCF) values at 40 d ranging from 19.6 to 119.3. The remaining PFASs were not found to bioconcentrate (BCF < 1.0 at 40 d). Furthermore, some BCF values decreased during the exposure ...
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Uptake and Depuration of Four Per/Polyfluoroalkyl Substances (PFASS) in Northern Leopard Frog Rana pipiens Tadpoles
2017Co-Authors: Gary M Hoover, Michael F Chislock, Brian J Tornabene, Samuel C Guffey, Youn Jeong Choi, Chloe De Perre, Jason T Hoverman, Linda S Lee, Maria S. SepúlvedaAbstract:Per/polyfluoroalkyl substances (PFASs) are persistent organic contaminants that are ubiquitous in surface waters. To date, their effects on aquatic systems, especially amphibians, are poorly understood. We examined the uptake and depuration of perfluorooctanesulfonate (PFOS), perfluorohexanesulfonate (PFHxS), perfluorooctanoic acid (PFOA), and 6:2 fluorotelomer sulfonate (6:2 FTS) in northern Leopard Frog (Rana pipiens) tadpoles. Whole-body concentrations were examined every 10 d during constant aqueous exposure to targeted concentrations of 10, 100, and 1000 μg/L for 40 d and for 30 d during depuration. Effects of PFAS exposure on length and development were also examined. Rapid uptake led to steady state concentrations by 10 d for most exposures. PFOS accumulated to the highest levels with whole-body bioconcentration factor (BCF) values at 40 d ranging from 19.6 to 119.3. The remaining PFASs were not found to bioconcentrate (BCF < 1.0 at 40 d). Furthermore, some BCF values decreased during the exposure phase, suggesting dilution due to growth and/or changes in toxicokinetics over ontogeny. During depuration, half-lives ranged from 1.2 to 3.3 d for all compounds. All PFASs tended to induce developmental delays, though statistical significance was only seen for PFOS and PFHxS. These sublethal effects observed at environmentally relevant concentrations are concerning and merit further study