scholarly journals Using stochastic epidemiological models to evaluate conservation strategies for endangered amphibians

2017 ◽  
Vol 14 (133) ◽  
pp. 20170480 ◽  
Author(s):  
Brian Drawert ◽  
Marc Griesemer ◽  
Linda R. Petzold ◽  
Cheryl J. Briggs
Keyword(s):  
Large Fraction ◽  
Treatment Strategies ◽  
Host Density ◽  
Conservation Strategies ◽  
Population Declines ◽  
Demographic Stochasticity ◽  
Amphibian Species ◽  
Time Treatment ◽  
Conservation Measures ◽  
Fungal Load

Recent outbreaks of chytridiomycosis, the disease of amphibians caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), have contributed to population declines of numerous amphibian species worldwide. The devastating impacts of this disease have led researchers to attempt drastic conservation measures to prevent further extinctions and loss of biodiversity. The conservation measures can be labour-intensive or expensive, and in many cases have been unsuccessful. We developed a mathematical model of Bd outbreaks that includes the effects of demographic stochasticity and within-host fungal load dynamics. We investigated the impacts of one-time treatment conservation strategies during the disease outbreak that occurs following the initial arrival of Bd into a previously uninfected frog population. We found that for all versions of the model, for a large fraction of parameter space, none of the one-time treatment strategies are effective at preventing disease-induced extinction of the amphibian population. Of the strategies considered, treating frogs with antifungal agents to reduce their fungal load had the greatest likelihood of a beneficial outcome and the lowest risk of decreasing the persistence of the frog population, suggesting that this disease mitigation strategy should be prioritized over disinfecting the environment or reducing host density.

scholarly journals Is Hay for the Birds? Investigating Landowner Willingness to Time Hay Harvests for Grassland Bird Conservation

Animals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 1030
Author(s):  
Matthew Gruntorad ◽  
Katherine Graham ◽  
Nico Arcilla ◽  
Christopher Chizinski
Keyword(s):  
Great Plains ◽  
Critical Factor ◽  
Information Support ◽  
Conservation Strategies ◽  
Bird Conservation ◽  
Willingness To Participate ◽  
Population Declines ◽  
Grassland Bird ◽  
The North ◽  
Hunting Activity

Birds in agricultural environments have exhibited steep global population declines in recent decades, and effective conservation strategies targeting their populations are urgently needed. In grasslands used for hay production, breeding birds’ nest success improves substantially if hay harvests are delayed until after mid-July. However, few studies have investigated private hay producers’ willingness to alter their harvesting practices, which is a critical factor for bird conservation where most land is privately owned, such as in the North American Great Plains. We surveyed Nebraska hay producers to examine whether livestock production, wildlife knowledge, and hunting activity affects their willingness to alter haying practices for bird conservation. The majority (60%) of respondents expressed willingness to delay harvesting hay to allow birds time to nest successfully. Livestock producers and those more knowledgeable about wildlife were more willing to delay hay harvests, whereas active hunters were less willing to do so. Our findings suggest that a majority of private producers show a high potential for engaging in grassland bird conservation activities. Landowners’ willingness to participate in bird conservation programs and actions could be further encouraged through extension and education efforts connecting hay producers with information, support, and funding for bird conservation.

scholarly journals Changes in landscape composition influence the decline of a threatened woodland caribou population

2020 ◽  
Author(s):  
Heiko Wittmer ◽  
B McLellan ◽  
R Serrouya ◽  
C Apps
Keyword(s):  
Large Scale ◽  
Spatial Scales ◽  
Apparent Competition ◽  
Timber Harvesting ◽  
Conservation Strategies ◽  
Home Ranges ◽  
Vital Rates ◽  
Population Declines ◽  
Woodland Caribou ◽  
Habitat Alterations

Large-scale habitat loss is frequently identified with loss of biodiversity, but examples of the direct effect of habitat alterations on changes in vital rates remain rare. Quantifying and understanding the relationship between habitat composition and changes in vital rates, however, is essential for the development of effective conservation strategies. It has been suggested that the decline of woodland caribou Rangifer tarandus caribou populations in North America is precipitated by timber harvesting that creates landscapes of early seral forests. Such habitat changes have altered the predator-prey system resulting in asymmetric predation, where predators are maintained by alternative prey (i.e. apparent competition). However, a direct link between habitat condition and caribou population declines has not been documented. We estimated survival probabilities for the threatened arboreal lichen-feeding ecotype of woodland caribou in British Columbia, Canada, at two different spatial scales. At the broader scale, observed variation in adult female survival rates among 10 distinct populations (range = 0.67-0.93) was best explained by variation in the amount of early seral stands within population ranges and population density. At the finer scale, home ranges of caribou killed by predators had lower proportions of old forest and more mid-aged forest as compared with multi-annual home ranges where caribou were alive. These results are consistent with predictions from the apparent competition hypothesis and quantify direct fitness consequences for caribou following habitat alterations. We conclude that apparent competition can cause rapid population declines and even extinction where changes in species composition occur following large scale habitat change. © 2007 The Authors. Journal compilation © 2007 British Ecological Society.

scholarly journals Ancestral chytrid pathogen remains hypervirulent following its long coevolution with amphibian hosts

2019 ◽  
Vol 286 (1904) ◽  
pp. 20190833 ◽  
Author(s):  
Minjie Fu ◽  
Bruce Waldman
Keyword(s):  
Batrachochytrium Dendrobatidis ◽  
Population Declines ◽  
Amphibian Species ◽  
South Korean ◽  
Global Pandemic ◽  
Litoria Caerulea ◽  
Experimental Treatments ◽  
Amphibian Chytrid Fungus ◽  
Genomic Recombination ◽  
Blank Solution

Many amphibian species around the world, except in Asia, suffer morbidity and mortality when infected by the emerging infectious pathogen Batrachochytrium dendrobatidis (Bd). A lineage of the amphibian chytrid fungus isolated from South Korean amphibians (BdAsia-1) is evolutionarily basal to recombinant global pandemic lineages (BdGPL) associated with worldwide amphibian population declines. In Asia, the Bd pathogen and its amphibian hosts have coevolved over 100 years or more. Thus, resilience of Asian amphibian populations to infection might result from attenuated virulence of endemic Bd lineages, evolved immunity to the pathogen or both. We compared susceptibilities of an Australasian amphibian, Litoria caerulea , known to lack resistance to BdGPL, with those of three Korean species, Bufo gargarizans , Bombina orientalis and Hyla japonica , after inoculation with BdAsia-1, BdGPL or a blank solution. Subjects became infected in all experimental treatments but Korean species rapidly cleared themselves of infection, regardless of Bd lineage. They survived with no apparent secondary effects. By contrast, L. caerulea , after infection by either BdAsia-1 or BdGPL, suffered deteriorating body condition and carried progressively higher Bd loads over time. Subsequently, most subjects died. Comparing their effects on L. caerulea , BdAsia-1 induced more rapid disease progression than BdGPL. The results suggest that genomic recombination with other lineages was not necessary for the ancestral Bd lineage to evolve hypervirulence over its long period of coevolution with amphibian hosts. The pathogen's virulence may have driven strong selection for immune responses in endemic Asian amphibian host species.

Genetic markers reveal high PIT tag retention rates in giant salamanders (Cryptobranchus alleganiensis)

2012 ◽  
Vol 33 (2) ◽  
pp. 313-317 ◽  
Author(s):  
Shem D. Unger ◽  
Nicholas G. Burgmeier ◽  
Rod N. Williams
Keyword(s):  
Cost Effective ◽  
Retention Rates ◽  
Population Declines ◽  
Pit Tag ◽  
Amphibian Species ◽  
Pit Tags ◽  
Tag Retention ◽  
Cryptobranchus Alleganiensis ◽  
Genetic Tagging ◽  
Secondary Methods

Estimation of population size using mark-recapture (MRR) methods are based on the fundamental assumption that individuals retain their marks throughout the course of study. Passive Integrated Transponder (PIT) tags are useful as a cost effective, reliable marking method in many amphibian and reptile species. Few studies however, use secondary methods to evaluate tag retention rates. Failure to do so can lead to biased population estimates, erroneous conclusions, and thus poor management decisions. Surprisingly, estimates of PIT tag retention are currently lacking for the majority of amphibian species, many of which are experiencing population declines. Herein, we use genetic tagging to assess the retention of PIT tags of the eastern hellbender (Cryptobranchus alleganiensis alleganiensis). We captured and tagged 78 individuals across 35 sites. Recapture rate was 24% and genetic tagging revealed 100% tag retention across all recaptured individuals.

scholarly journals Amphibians of varzea environments and floating meadows of the oxbow lakes of the Middle Purus River, Amazonas, Brazil

2016 ◽  
Vol 16 (1) ◽  
Author(s):  
Werther Pereira Ramalho ◽  
Murilo Sousa Andrade ◽  
Lucicléia Railene Assis de Matos ◽  
Lisandro Juno Soares Vieira
Keyword(s):  
Conservation Strategies ◽  
Oxbow Lakes ◽  
Historical Knowledge ◽  
Amphibian Species ◽  
The Family ◽  
Data Deficient ◽  
Distribution And Ecology ◽  
Amazonas State ◽  
Rare Endemic ◽  
Amazonian Lowlands

Despite the historical knowledge on amphibians of the Purus River basin, basic information on assemblages is fragmented, with gaps in knowledge existing at various scales, which limits conservation strategies. This study provides information on the composition, richness and abundance of the amphibian fauna in varzea environments and floating meadows of the oxbow lakes of the Middle Purus River between the Boca do Acre and Pauiní municipalities, Amazonas, Brazil. We sampled six oxbow lakes using forty-seven 200-meter transects, distributed among the "floating meadows," "high varzea" and "low varzea," from April to January 2014. We recorded 59 species, with the family Hylidae being predominant. This amphibian fauna represents approximately 19% of the species known for the Amazon, 28% for Amazonas State and 45% of the species recorded so far in the Purus River, increasing the richness of the basin to 132 species. Eight species were considered rare, and 29 are endemic to the Amazon. This study adds to the knowledge on the amphibian species of the Amazonian lowlands, including the expansion of known distributions, as well as increases the knowledge of several species that are locally rare, endemic and/or that are data deficient regarding distribution and ecology.

scholarly journals Wildlife conservation and reproductive cloning

Reproduction ◽  
2004 ◽  
Vol 127 (3) ◽  
pp. 317-324 ◽  
Author(s):  
William V Holt ◽  
Amanda R Pickard ◽  
Randall S Prather
Keyword(s):  
Wildlife Conservation ◽  
Reproductive Technologies ◽  
Conservation Strategies ◽  
Success Rates ◽  
Amphibian Species ◽  
Reproductive Cloning ◽  
Developmental Abnormalities ◽  
Large Numbers ◽  
Experimental Use ◽  
Cloning Technology

Reproductive cloning, or the production of offspring by nuclear transfer, is often regarded as having potential for conserving endangered species of wildlife. Currently, however, low success rates for reproductive cloning limit the practical application of this technique to experimental use and proof of principle investigations. In this review, we consider how cloning may contribute to wildlife conservation strategies. The cloning of endangered mammals presents practical problems, many of which stem from the paucity of knowledge about their basic reproductive biology. However, situations may arise where resources could be targeted at recovering lost or under-represented genetic lines; these could then contribute to the future fitness of the population. Approaches of this type would be preferable to the indiscriminate generation of large numbers of identical individuals. Applying cloning technology to non-mammalian vertebrates may be more practical than attempting to use conventional reproductive technologies. As the scientific background to cloning technology was pioneered using amphibians, it may be possible to breed imminently threatened amphibians, or even restore extinct amphibian species, by the use of cloning. In this respect species with external embryonic development may have an advantage over mammals as developmental abnormalities associated with inappropriate embryonic reprogramming would not be relevant.

scholarly journals Recovery and resiliency of skin microbial communities on the southern leopard frog (Lithobates sphenocephalus) following two biotic disturbances

2020 ◽  
Vol 2 (1) ◽  
Author(s):  
Denita M. Weeks ◽  
Matthew J. Parris ◽  
Shawn P. Brown
Keyword(s):  
Microbial Communities ◽  
Fungal Pathogen ◽  
Bacterial Species ◽  
Leopard Frog ◽  
Multiple Time ◽  
Population Declines ◽  
Community Interactions ◽  
Amphibian Species ◽  
Functional Relationships ◽  
Species Specific

Abstract Background Microorganisms have intimate functional relationships with invertebrate and vertebrate taxa, with the potential to drastically impact health outcomes. Perturbations that affect microbial communities residing on animals can lead to dysbiosis, a change in the functional relationship, often associated with disease. Batrachochytrium dendrobatidis (Bd), a fungal pathogen of amphibians, has been responsible for catastrophic amphibian population declines around the globe. Amphibians harbor a diverse cutaneous microbiome, including some members which are known to be antagonistic to Bd (anti-Bd). Anti-Bd microorganisms facilitate the ability of some frog populations to persist in the presence of Bd, where other populations that lack anti-Bd microorganisms have declined. Research suggests disease-antagonistic properties of the microbiome may be a function of microbial community interactions, rather than individual bacterial species. Conservation efforts have identified amphibian-associated bacteria that exhibit anti-fungal properties for use as ‘probiotics’ on susceptible amphibian populations. Probiotic application, usually with a single bacterial species, may benefit from a greater understanding of amphibian species-specific microbiome responses to disturbances (e.g. dysbiosis vs. recovery). We assessed microbiome responses to two microbial disturbance events over multiple time points. Results Exposing Lithobates sphenocephalus (southern leopard frog) adults to the biopesticidal bacteria Bacillus thuringiensis, followed by exposure to the fungal pathogen Bd, did not have long term impacts on the microbiome. After initial shifts, microbial communities recovered and returned to a state that resembled pre-disturbance. Conclusions Our results indicate microbial communities on L. sphenocephalus are robust and resistant to permanent shifts from some disturbances. This resiliency of microbial communities may explain why L. sphenocephalus is not experiencing the population declines from Bd that impacts many other species. Conservation efforts may benefit from studies outlining amphibian species-specific microbiome responses to disturbances (e.g. dysbiosis vs. recovery). If microbial communities on a threatened amphibian species are unlikely to recover following a disturbance, additional measures may be implemented to ameliorate the impacts of physical and chemical stressors on host-associated microbial communities.

The effects of UV-B radiation and endocrine-disrupting chemicals (EDCs) on the biology of amphibians

2001 ◽  
Vol 9 (2) ◽  
pp. 61-80 ◽  
Author(s):  
D Crump
Keyword(s):  
Meta Analysis ◽  
Endocrine Disrupting Chemicals ◽  
Reproductive Toxicity ◽  
Abnormal Development ◽  
Data Sets ◽  
Population Declines ◽  
Amphibian Species ◽  
Endocrine Disrupting ◽  
Polycyclic Aromatic ◽  
The 1960S

Statistical meta-analysis of large and diverse data sets has indicated that amphibians have been declining worldwide since the 1960s. Exposure to UV-B radiation (280–320 nm) and endocrine-disrupting chemicals (EDCs) have been considered as possible hypotheses to explain the observed declines. Equivocal conclusions have been reached with respect to the effects of UV-B on amphibian populations. Field and laboratory studies employing both ecologically relevant and enhanced UV-B levels have been conducted using a variety of amphibian species and reports differ with respect to the most sensitive developmental stage and the ultimate implications. UV-B radiation has also been shown to interact with other stressors (e.g., pesticides, polycyclic aromatic hydrocarbons, low pH) resulting in decreased survivorship for several amphibian species. Limited evidence of reproductive toxicity of xenobiotics in amphibians exist; however, early exposure to EDCs could cause abnormal development of the amphibian reproductive system, inhibit vital hormone messages that drive metamorphosis, and ultimately contribute to the decline of some amphibian populations. The available evidence suggests that more than one agent is contributing to amphibian population declines and the following review narrows the focus to address the existing data on the effects of UV-B, alone and in combination with other stressors, and EDCs on amphibian survivorship and development. Key words: amphibians, UV-B radiation, endocrine-disrupting chemicals, declines, review.

scholarly journals Body size mediates latitudinal population differences in response to Bd infection in two amphibian species.

2021 ◽  
Author(s):  
Sara Meurling ◽  
Maria Cortazar-Chinarro ◽  
Mattias Siljestam ◽  
David Ahlen ◽  
Erik Agren ◽  
...  
Keyword(s):  
Body Size ◽  
Batrachochytrium Dendrobatidis ◽  
Geographical Origin ◽  
Bufo Bufo ◽  
Northern Region ◽  
Population Declines ◽  
Rana Arvalis ◽  
Amphibian Species ◽  
Survival Difference ◽  
Species Survival

Populations of the same species may differ in their sensitivity to pathogens but the factors behind this variation are poorly understood. Moreover, infections may cause sub-lethal fitness effects even in species resistant or tolerant to disease. The chytrid fungus Batrachochytrium dendrobatidis (Bd), is a generalist pathogen which has caused amphibian population declines worldwide. In many species, Bd infection causes the disease chytridiomycosis, often leading to high mortality. We investigated how geographical origin affects tolerance to Bd by exposing newly metamorphosed individuals of two North European amphibians (moor frog Rana arvalis, common toad Bufo bufo) from two latitudinal regions to two different BdGPL strains. Bd exposure strongly lowered survival in B. bufo, and in both species survival was lower in the northern region, this difference being much stronger in B. bufo. Northern individuals were smaller in both species, and the survival difference between the regions was size-mediated with smaller individuals being more sensitive to Bd. In both species, Bd exposure led to sub-lethal effects in terms of reduced growth suggesting that even individuals surviving the infection may have reduced fitness mediated by smaller body size. Bd strain affected size-dependent mortality differently in the two regions. We discuss the possible mechanisms how body size and geographical origin can contribute to the present results.

scholarly journals Personalized medicine in chronic kidney disease by detection of monogenic mutations

2019 ◽  
Vol 35 (3) ◽  
pp. 390-397 ◽  
Author(s):  
Dervla M Connaughton ◽  
Friedhelm Hildebrandt
Keyword(s):  
Chronic Kidney Disease ◽  
Kidney Disease ◽  
Large Fraction ◽  
Single Gene ◽  
Molecular Genetic ◽  
Genetic Diagnosis ◽  
Treatment Strategies ◽  
Genetic Diagnostics ◽  
Incomplete Penetrance ◽  
Age Related

Abstract A large fraction of early-onset chronic kidney disease (CKD) is known to be monogenic in origin. To date, ∼450 monogenic (synonymous with single-gene disorders) genes, if mutated, are known to cause CKD, explaining ∼30% of cases in pediatric cohorts and ∼5–30% in adult cohorts. However, there are likely hundreds of additional monogenic nephropathy genes that may be revealed by whole-exome or -genome sequencing. Although the discovery of novel CKD-causing genes has accelerated, significant challenges in adult populations remain due to broad phenotypic heterogeneity together with variable expressivity, incomplete penetrance or age-related penetrance of these genes. Here we give an overview of the currently known monogenic causes for human CKD. We also describe how next-generation sequencing facilitates rapid molecular genetic diagnostics in individuals with suspected genetic kidney disease. In an era of precision medicine, understanding the utility of genetic testing in individuals with a suspected inherited nephropathy has important diagnostic and prognostic implications. Detection of monogenic causes of CKD permits molecular genetic diagnosis for patients and families and opens avenues for personalized treatment strategies for CKD. As an example, detection of a pathogenic mutation in the gene HNF1B not only allows for the formal diagnosis of CKD, but can also facilitate screening for additional extrarenal manifestations of disease, such as maturity-onset diabetes of youth, subclinical abnormal liver function tests, neonatal cholestasis and pancreatic hypoplasia. It also provides the driving force towards a better understanding of disease pathogenesis, potentially facilitating targeted new therapies for individuals with CKD.

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