scholarly journals Status, Appropriate Sampling Scheme, and Movement in the Tiger Salamander (Ambystoma tigrinum) in Yellowstone National Park

2002 ◽  
Vol 26 ◽  
pp. 80-81
Author(s):  
Charles Peterson ◽  
Stephen Spear
Keyword(s):  
Spatial Scale ◽  
Average Distance ◽  
Current Trend ◽  
Amphibian Declines ◽  
Current Status ◽  
Ambystoma Tigrinum ◽  
Terrestrial Habitat ◽  
Amphibian Species ◽  
Core Habitat ◽  
Breeding Pond

Due to the current trend of amphibian declines (Wake 1998, Alford and Richards 1999, Semlitsch 2000), the monitoring and study of amphibian populations has become increasingly necessary. To properly do such studies, we must consider several issues. Some of these include the detectability of the species at a site, current status of the population, and the spatial scale for sampling of a population. Determining the detectability of a species is important to consider because some amphibian species may have different difficulties of detection. Therefore, if a species is difficult to observe, it may occupy a greater number of sites than a survey indicates (MacKenzie et al. 2002). The appropriate spatial scale is also important for monitoring studies. For example, in a pond breeding amphibian, do one or two breeding ponds with the appropriate terrestrial habitat constitute the correct sampling area for a population, or does a population utilize multiple ponds within a larger terrestrial area? If the sampling scale is not appropriate, then any conclusions made may be inaccurate (Wiens 1989). In addition, understanding the terrestrial habitat use of pond breeding amphibians is important for both monitoring and conservation reasons. Many pond-breeding amphibians use the ponds for breeding and then utilize terrestrial zones around the pond for the rest of the year. The total area that is encompassed by these terrestrial zones is known as the terrestrial "buffer zone" or core habitat area for that population (Semlitsch 1998). To identify these core habitat areas, we must know not only the distance that the amphibians physically move from the breeding pond, but also the type of habitat that they will use. For example, short, steep slopes or rivers can serve as a barrier to amphibian movement (Laan and Verboom 1990, Storfer 1999), even if they are within the movement range of a population. Understanding individual movement may also give insights into the spatial population structure of the species. If we can identify the average distance of movement, we can then extrapolate if a breeding pond is likely to have an isolated subpopulation based on its distance from other ponds.

scholarly journals Fungal infection, decline and persistence in the only obligate troglodytic Neotropical salamander

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9763
Author(s):  
Mizraim Olivares-Miranda ◽  
Vance T. Vredenburg ◽  
Julio C. García-Sánchez ◽  
Allison Q. Byrne ◽  
Erica B. Rosenblum ◽  
...  
Keyword(s):  
Batrachochytrium Dendrobatidis ◽  
Infection Intensity ◽  
Sampling Technique ◽  
Sympatric Species ◽  
Amphibian Declines ◽  
Small Range ◽  
Museum Specimens ◽  
Amphibian Species ◽  
Extant Population ◽  
Epidemic Wave

The fungal pathogen Batrachochytrium dendrobatidis (Bd) is implicated in global mass die-offs and declines in amphibians. In Mesoamerica, the Bd epidemic wave hypothesis is supported by detection of Bd in historic museum specimens collected over the last century, yet the timing and impact of the early stages of the wave remain poorly understood. Chiropterotriton magnipes, the only obligate troglodytic Neotropical salamander, was abundant in its small range in the decade following its description in 1965, but subsequently disappeared from known localities and was not seen for 34 years. Its decline is roughly coincident with that of other populations of Neotropical salamanders associated with the invasion and spread of Bd. To determine the presence and infection intensity of Bd on C. magnipes and sympatric amphibian species (which are also Bd hosts), we used a noninvasive sampling technique and qPCR assay to detect Bd on museum specimens of C. magnipes collected from 1952 to 2012, and from extant populations of C. magnipes and sympatric species of amphibians. We also tested for the presence of the recently discovered Batrachochytrium salamandivorans (Bsal), another fungal chytridiomycete pathogen of salamanders, using a similar technique specific for Bsal. We did not detect Bd in populations of C. magnipes before 1969, while Bd was detected at low to moderate prevalence just prior to and during declines. This pattern is consistent with Bd-caused epizootics followed by host declines and extirpations described in other hosts. We did not detect Bsal in any extant population of C. magnipes. We obtained one of the earliest positive records of the fungus to date in Latin America, providing additional historical evidence consistent with the Bd epidemic wave hypothesis. Genotyping results show that at least one population is currently infected with the Global Panzootic Lineage of Bd, but our genotyping of the historical positive samples was unsuccessful. The lack of large samples from some years and the difficulty in genotyping historical Bd samples illustrate some of the difficulties inherent in assigning causality to historical amphibian declines. These data also provide an important historical baseline for actions to preserve the few known remaining populations of C. magnipes.

Ammonia, Urea and H+ Distribution and the Evolution of Ureotelism in Amphibians

1989 ◽  
Vol 144 (1) ◽  
pp. 215-233 ◽  
Author(s):  
CHRIS M. WOOD ◽  
R. S. MUNGER ◽  
D. P. TOEWS
Keyword(s):  
Cell Membrane ◽  
Teleost Fish ◽  
Transmembrane Potential ◽  
Rana Catesbeiana ◽  
Ammonia Excretion ◽  
Cell Membrane Permeability ◽  
Ambystoma Tigrinum ◽  
Amphibian Species ◽  
Necturus Maculosus ◽  
Excretion Rates

In theory, the distribution of ammonia across cell membranes (Tammi/Tamme) between intracellular and extracellular fluids (ICF and ECF) may be determined by the transmembrane pH gradient (as in mammals), the transmembrane potential (as in teleost fish), or both, depending on the relative permeability of the membranes to NH3 and NH4+ (pNH3/pNH4+). The resting distributions of H+ (via [14C]DMO), ammonia and urea between plasma and skeletal muscle, and the relative excretion rates of ammonia-N and urea-N, were measured in five amphibian species (Bufo marinus, Ambystoma tigrinum, Rana catesbeiana, Necturus maculosus and Xenopus laevis). Although ureai/ureae ratios were uniformly close to 1.0, Tammi/Tamme. ratios correlated directly with the degree of ammoniotelism in each species, ranging from 9.1 (Bufo, 10% ammoniotelic) to 16.7 (Xenopus, 79% ammoniotelic). These values are intermediate between ratios of about 30 (low pNH3/pNH4+) in ammoniotelic teleost fish and about 3 (high pNH3/pNH4+) in ureotelic mammals. The results indicate that amphibians represent a transitional stage in which ammonia distribution is influenced by both the pHi-pHe gradient and the membrane potential, and that a reduction in cell membrane permeability to NH4+ (i.e. increased pNH3/pNH4+) was associated with the evolution of ureotelism. Hyperosmotic saline exposure increased urea excretion 10-fold in Xenopus, while ammonia excretion remained unchanged. Tammi/Tamme fell, but this response was attributable to an abolition of the pHi-pHe gradient, rather than a physiological change in the cell membrane pNH3/pNH4+.

VARIATION IN TERRESTRIAL HABITAT USE BY FOUR POOL-BREEDING AMPHIBIAN SPECIES

2005 ◽  
Vol 69 (4) ◽  
pp. 1481-1493 ◽  
Author(s):  
JONATHAN V. REGOSIN ◽  
BRYAN S. WINDMILLER ◽  
REBECCA N. HOMAN ◽  
J. MICHAEL REED
Keyword(s):  
Habitat Use ◽  
Terrestrial Habitat ◽  
Amphibian Species

Human-provoked amphibian decline in central Italy and the efficacy of protected areas

2010 ◽  
Vol 37 (7) ◽  
pp. 547 ◽  
Author(s):  
Manuela D'Amen ◽  
Biancamaria Pietrangeli ◽  
Marco A. Bologna
Keyword(s):  
Protected Areas ◽  
Multiple Stressors ◽  
Population Decline ◽  
Central Italy ◽  
Negative Relationship ◽  
Climatic Conditions ◽  
Amphibian Declines ◽  
Additive Models ◽  
Management Approach ◽  
Amphibian Species

Context Today, more than 32% of amphibian species are threatened and more than 43% face a steep decline in numbers. Most species are being affected simultaneously by multiple stressors and habitat protection is often inadequate to prevent declines. Aims The main goal of the present research was to understand the consequences of alternative human land use in producing landscape disturbance for amphibians. At the same time, we also evaluated the effect of changing climatic conditions as additional potential drivers of population decline. Another goal was to determine whether and to what extent the existing nature reserves have been effective in protecting species in recent decades. Methods We used generalised additive models (GAMs) to investigate the association between the state (stable/decline) of amphibian populations in 5 × 5 km cells in central Italy and proxies of different typology of anthropogenic stressors, climatic variables and protection measures. Key results We found a significant association between anthropogenic landscape modifications and species decline. This negative relationship was revealed with agricultural predictors for the majority of the species, whereas urban fabrics had a slightly smaller impact. We found significant associations between amphibian declines and climatic variation, particularly the increasing number of dry days. Protected areas protected declines of two species only. Conclusions Our results showed that the status of amphibians in this region warrants greater attention than has been given previously. The detrimental effect of agricultural practices, combined with increasing aridity, makes amphibian populations particularly susceptible to extinction, and the conservation measures applied till now are inadequate for species protection in this region. Implications Our results should stimulate the implementation of environmental policies that focus not only on the protection of single habitats, but also on ensuring the environmental quality of the surrounding landscapes. Moreover, an adaptive management approach should be applied to take into account future modification of hydrology and climate.

scholarly journals Effects of Road De-Icing Salts on Two Amphibian Species, Rana Sylvatica and Rana Pipiens, and Their Trematode Parasites

2021 ◽  
Author(s):  
Dino Milotic
Keyword(s):  
Rana Sylvatica ◽  
Amphibian Declines ◽  
High Salt ◽  
Amphibian Species ◽  
Wood Frogs ◽  
Leopard Frogs ◽  
Larval Amphibians ◽  
Potential Contaminant ◽  
Northern Leopard Frogs ◽  
Host Parasite

With ongoing amphibian declines, it is essential to determine possible contributors such as diseases and environmental contaminants that may increase susceptibility. A potential contaminant is road salt (mainly NaCl), which leaches into aquatic environments. I examined whether road salts make larval amphibians (tadpoles) more susceptible to trematode parasite infection, and also how these affect free-living trematode infectious stages (cercariae). I exposed Rana sylvatica (wood frogs) and R. pipiens (northern leopard frogs) to control, medium (400 mg/L), and high salt (800 mg/L) treatments, and then to trematodes. High salt tended to reduce wood frog anti-parasite behaviour and resistance to infection but the opposite was seen for R. pipiens, although these tadpoles had elevated lymphocyte counts in high salinity. Trematodes were differentially affected by increased salinities. The results suggest that host-parasite-environment interactions are complex, with species differentially affected by contaminants, which may lead to community shifts in predominant hosts and parasite species.

scholarly journals The Advent of Salivary Breast Cancer Biomarker Detection Using Affinity Sensors

Sensors ◽  
2019 ◽  
Vol 19 (10) ◽  
pp. 2373 ◽  
Author(s):  
Imad Abrao Nemeir ◽  
Joseph Saab ◽  
Walid Hleihel ◽  
Abdelhamid Errachid ◽  
Nicole Jafferzic-Renault ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Low Cost ◽  
Current Trend ◽  
High Sensitivity ◽  
Breast Cancer Diagnosis ◽  
Current Status ◽  
Attractive Alternative ◽  
Early Screening ◽  
Screening Programs ◽  
Sensitivity And Selectivity

Breast Cancer is one of the world’s most notorious diseases affecting two million women in 2018 worldwide. It is a highly heterogeneous disease, making it difficult to treat. However, its linear progression makes it a candidate for early screening programs, and the earlier its detection the higher the chance of recovery. However, one key hurdle for breast cancer screening is the fact that most screening techniques are expensive, time-consuming, and cumbersome, making them impractical for use in several parts of the world. One current trend in breast cancer detection has pointed to a possible solution, the use of salivary breast cancer biomarkers. Saliva is an attractive medium for diagnosis because it is readily available in large quantities, easy to obtain at low cost, and contains all the biomarkers present in blood, albeit in lower quantities. Affinity sensors are devices that detect molecules through their interactions with biological recognition molecules. Their low cost, high sensitivity, and selectivity, as well as rapid detection time make them an attractive alternative to traditional means of detection. In this review article, we discuss the current status of breast cancer diagnosis, its salivary biomarkers, as well as the current trends in the development of affinity sensors for their detection.

scholarly journals Response to Comment on “Amphibian fungal panzootic causes catastrophic and ongoing loss of biodiversity”

Science ◽  
2020 ◽  
Vol 367 (6484) ◽  
pp. eaay2905 ◽  
Author(s):  
Ben C. Scheele ◽  
Frank Pasmans ◽  
Lee F. Skerratt ◽  
Lee Berger ◽  
An Martel ◽  
...  
Keyword(s):  
Infectious Disease ◽  
Alternative Assessment ◽  
Amphibian Declines ◽  
Amphibian Species ◽  
Evaluation Of Evidence

Lambert et al. question our retrospective and holistic epidemiological assessment of the role of chytridiomycosis in amphibian declines. Their alternative assessment is narrow and provides an incomplete evaluation of evidence. Adopting this approach limits understanding of infectious disease impacts and hampers conservation efforts. We reaffirm that our study provides unambiguous evidence that chytridiomycosis has affected at least 501 amphibian species.

Agroecosystem energy, ecological human imprint and economic sustainability: Analysis and impacts

2021 ◽  
pp. 147-177
Author(s):  
Safwat H. Shakir Hanna ◽  
Gian Paolo Cesaretti
Keyword(s):  
Population Growth ◽  
Natural Resources ◽  
Human Population ◽  
Current Trend ◽  
Life Cycles ◽  
Current Status ◽  
World Population ◽  
Human Beings ◽  
Human Population Growth ◽  
The Earth

Agroecosystem energy is an essential part of the natural resources available to humans for use and the continuation of Earth's life cycle. Without energy, life on this Earth will stop, and the drivers of all ecological life cycles will not be able to continue function. Energy is an essential factor that makes the working process of human survivability possible. According to World Population Clock, the current status of human population growth is in an alarming situation (i.e., 7.81 billion people and continues to increase) [World Population Clock 2020 Accessed September 20, 2020][ World Population Clock, 2020). Therefore, the ecological human imprint will impact all Earth's natural resources, in the forms of more consumptions and demands that will have impacts on the global social and economic issues globally. Sustainability will be accomplished if we live within the concept of Nature, controlling our human population growth to reduce the impacts on natural resources' demands. In this respect, sustainability will not be achieved by economic growth alone; instead, the biosphere natural resources must replenish it and allow the natural resources to regenerate itself to support the growing human population. The present paper will assess the agroecosystem energy continuing ongoing demands and availability concerning human population growth by modeling different scenarios. According to our model, the human population growth will reach 10 billion people or more by the year 2050 at the current trend, and we may be faced with shortening the availability of energy. It is important to stress that the energy should be replenished through non-tradition energy supply, and we have to concentrate on renewable energy, which we can develop to the extent of harvesting this energy in efficient ways. An example of the needs of energy in the agroecosystem is to calculate how much enough the Earth has to support the human beings. In this regard, if each human being is in need of 2000 calories/per day on average, this means that globally the Earth has to produce more than 5694 trillion calories per year. The question is whether the Earth can create these calories to support 7.81 billion people, and we need more calories when the human population grows to be more than 7.81 bil lion people. Therefore, engineering of the Earth agroecosystem should be significant, and we have to think about how we accomplish it. Additionally, we need to sustain our environment by conserving our water resources and keeping our global climate environmentally in the best condition to maintain international economic and social standards. Further, in this paper, we will discuss the impacts of changing different parameters that affect global agroecosystem energy.

Is there a 'right' spatial scale? Improving pedological multi- scale modelling by optimizing input data grain size: A Case Study using Average Local Variance.

2020 ◽  
Author(s):  
Christopher Scarpone ◽  
Anders Knudby ◽  
Stephanie Melles ◽  
Andrew Millward
Keyword(s):  
Grain Size ◽  
Spatial Scale ◽  
Prediction Accuracy ◽  
Input Data ◽  
Prediction Models ◽  
Digital Data ◽  
Current Status ◽  
Data Provider ◽  
Local Variance ◽  
Early Results

<p>Current soil mapping practitioners are faced with a plethora of choices of digital data for input to their modelling approaches; these data have local to global extents and are highly variable in their grain size. Deciding at what scale to represent individual covariates for a specific project, therefore, can be difficult and confusing. Moreover, a lack of accessible methodology and tools focused on determining an optimal input data scales (grain size) has led to the current status quo, which is to use data at the scale delivered by the data provider. Soil prediction models are typically applied using the grain size of the coarsest variable, scaling other data to match. In this study, average local variance was investigated as a method to determine optimal grain size(s) for input variables to a soil contaminant prediction model. The Meuse dataset was used, and heavy metal soil contamination was mapped using RandomForest. A Data Cube was employed to handle data inputs of varying grain size. Two scenarios were investigated for model prediction accuracy: (1) contaminant predictions made using data with optimized grain size, and (2) contaminant predictions made using input data where grain size was unchanged, “as received” from the data provider. Both model predictions were assessed using a cross-validation approach. Early results indicate that optimization of grain size based on average local variance can improve prediction accuracy and point toward the importance of understanding the spatial heterogeneity of an input variable and how it changes with different grain sizes prior to incorporation in a predictive model. This research lays a foundation for the creation of an automated approach practitioners can use to help untangle the relationship between the intrinsic spatial scale for a process of interest and how that process is represented in the scale of input data.</p>

Metacercariae of Clinostomum attenuatum in Ambystoma tigrinum mavortium, Bufo cognatus and Spea multiplicata from west Texas

2004 ◽  
Vol 78 (4) ◽  
pp. 373-376 ◽  
Author(s):  
D.L. Miller ◽  
C.R. Bursey ◽  
M.J. Gray ◽  
L.M. Smith
Keyword(s):  
New Mexico ◽  
Light Microscopy ◽  
Great Plains ◽  
First Record ◽  
Ambystoma Tigrinum ◽  
Amphibian Species ◽  
Tiger Salamanders ◽  
Spea Multiplicata ◽  
West Texas ◽  
Bufo Cognatus

AbstractTissues from barred tiger salamanders (Ambystoma tigrinum mavortium), Great Plains toads (Bufo cognatus) and New Mexico spadefoots (Spea multiplicata) collected from 16 playa wetlands in Texas during 1999 and 2000 were examined by light microscopy. Digenean cysts were primarily distributed subcutaneously throughout the specimens and occasionally coelomic invasion was noted. The parasites within the cysts were 1.5–2 mm in diameter, with a thin (c. 10 μm wide) eosinophilic-staining tegument, two suckers (oral and ventral), posteriorly located primordial genitalia and paired digestive caeca. These digeneans were identified as the metacercariae of Clinostomum attenuatum. This is the first record of Clinostomum attenuatum in these amphibian species.

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