Natural stressors and disease risk: does the threat of predation increase amphibian susceptibility to ranavirus?

2012 ◽  
Vol 90 (7) ◽  
pp. 893-902 ◽  
Author(s):  
N.A. Haislip ◽  
J.T. Hoverman ◽  
D.L. Miller ◽  
M.J. Gray
Keyword(s):  
Predation Risk ◽  
Stress Responses ◽  
Species Interactions ◽  
Disease Risk ◽  
Natural Populations ◽  
Emerging Infectious Diseases ◽  
Host Susceptibility ◽  
Continuous Exposure ◽  
Amphibian Species ◽  
Predator Cues

Emerging infectious diseases have been identified as threats to biodiversity, yet our understanding of the factors contributing to host susceptibility to pathogens within natural populations remains limited. It has been proposed that species interactions within communities affect host susceptibility to pathogens, thereby contributing to disease emergence. In particular, predation risk is a common natural stressor that has been hypothesized to compromise immune function of prey through chronic stress responses possibly leading to increased susceptibility to pathogens. We examined whether predation risk experienced during the development of four larval anuran species increases susceptibility (mortality and infection) to ranaviruses, a group of viruses responsible for amphibian die-offs. Using controlled laboratory experiments, we exposed each species to a factorial combination of two virus treatments (no virus or virus) crossed with three predator-cue treatments (no predators, larval dragonflies, or adult water bugs). All four amphibian species reduced activity by 22%–48% following continuous exposure to predator cues. In addition, virus exposure significantly reduced survival by 17%–100% across all species. However, exposure to predator cues did not interact with the virus treatments to elevate mortality or viral load. Our results suggest that the expression of predator-induced plasticity in anuran larvae does not increase ranaviral disease risk.

scholarly journals Host Diversity and Potential Transmission Pathways of SARS-CoV-2 at the Human-Animal Interface

Pathogens ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 180 ◽  
Author(s):  
Hayden D. Hedman ◽  
Eric Krawczyk ◽  
Yosra A. Helmy ◽  
Lixin Zhang ◽  
Csaba Varga
Keyword(s):  
Public Health ◽  
Close Contact ◽  
Natural Infection ◽  
Emerging Infectious Diseases ◽  
Reservoir Host ◽  
Host Susceptibility ◽  
Public Health Issue ◽  
Severe Illness ◽  
Host Diversity ◽  
Transmission Pathways

Emerging infectious diseases present great risks to public health. The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), causing coronavirus disease 2019 (COVID-19), has become an urgent public health issue of global concern. It is speculated that the virus first emerged through a zoonotic spillover. Basic research studies have suggested that bats are likely the ancestral reservoir host. Nonetheless, the evolutionary history and host susceptibility of SARS-CoV-2 remains unclear as a multitude of animals has been proposed as potential intermediate or dead-end hosts. SARS-CoV-2 has been isolated from domestic animals, both companion and livestock, as well as in captive wildlife that were in close contact with human COVID-19 cases. Currently, domestic mink is the only known animal that is susceptible to a natural infection, develop severe illness, and can also transmit SARS-CoV-2 to other minks and humans. To improve foundational knowledge of SARS-CoV-2, we are conducting a synthesis review of its host diversity and transmission pathways. To mitigate this COVID-19 pandemic, we strongly advocate for a systems-oriented scientific approach that comprehensively evaluates the transmission of SARS-CoV-2 at the human and animal interface.

Widespread infection of the Eastern red-spotted newt (Notophthalmus viridescens) by a new species of Amphibiocystidium, a genus of fungus-like mesomycetozoan parasites not previously reported in North America

Parasitology ◽  
2007 ◽  
Vol 135 (2) ◽  
pp. 203-215 ◽  
Author(s):  
T. R. RAFFEL ◽  
T. BOMMARITO ◽  
D. S. BARRY ◽  
S. M. WITIAK ◽  
L. A. SHACKELTON
Keyword(s):  
New Species ◽  
North America ◽  
Infectious Diseases ◽  
Emerging Infectious Diseases ◽  
Seasonal Distribution ◽  
Notophthalmus Viridescens ◽  
Amphibian Species ◽  
Mortality And Morbidity ◽  
Causative Agents ◽  
A New Species

SUMMARYGiven the worldwide decline of amphibian populations due to emerging infectious diseases, it is imperative that we identify and address the causative agents. Many of the pathogens recently implicated in amphibian mortality and morbidity have been fungal or members of a poorly understood group of fungus-like protists, the mesomycetozoans. One mesomycetozoan, Amphibiocystidium ranae, is known to infect several European amphibian species and was associated with a recent decline of frogs in Italy. Here we present the first report of an Amphibiocystidium sp. in a North American amphibian, the Eastern red-spotted newt (Notophthalmus viridescens), and characterize it as the new species A. viridescens in the order Dermocystida based on morphological, geographical and phylogenetic evidence. We also describe the widespread and seasonal distribution of this parasite in red-spotted newt populations and provide evidence of mortality due to infection.

scholarly journals Sex Differentiation in Amphibians: Effect of Temperature and Its Influence on Sex Reversal

2021 ◽  
pp. 1-11
Author(s):  
Adrián Ruiz-García ◽  
Álvaro S. Roco ◽  
Mónica Bullejos
Keyword(s):  
Sexual Differentiation ◽  
Sex Differentiation ◽  
Environmental Contaminants ◽  
Natural Populations ◽  
Sex Reversal ◽  
The Other ◽  
Effect Of Temperature ◽  
Amphibian Species ◽  
Expected Increase

The role of environmental factors in sexual differentiation in amphibians is not new. The effect of hormones or hormone-like compounds is widely demonstrated. However, the effect of temperature has traditionally been regarded as something anecdotal that occurs in extreme situations and not as a factor to be considered. The data currently available reveal a different situation. Sexual differentiation in some amphibian species can be altered even by small changes in temperature. On the other hand, although not proven, it is possible that temperature is related to the appearance of sex-reversed individuals in natural populations under conditions unrelated to environmental contaminants. According to this, temperature, through sex reversal (phenotypic sex opposed to genetic sex), could play an important role in the turnover of sex-determining genes and in the maintenance of homomorphic sex chromosomes in this group. Accordingly, and given the expected increase in global temperatures, growth and sexual differentiation in amphibians could easily be affected, altering the sex ratio in natural populations and posing major conservation challenges for a group in worldwide decline. It is therefore particularly urgent to understand the mechanism by which temperature affects sexual differentiation in amphibians.

scholarly journals Consumer sexual dimorphism promotes coexistence among competing resources

2019 ◽  
Author(s):  
Stephen P. De Lisle ◽  
Gonzalo Hernando ◽  
Daniel I. Bolnick
Keyword(s):  
Sexual Dimorphism ◽  
Species Interactions ◽  
Natural Populations ◽  
Salient Feature ◽  
Apparent Competition ◽  
Species Variation ◽  
Ecological Communities ◽  
Key Factor ◽  
Classical Models ◽  
Resource Dynamics

AbstractWithin-species variation is a salient feature of natural populations, of substantial importance for species interactions. However, the community consequences of sexual dimorphism, one of the most ubiquitous sources of within-species variance, remains poorly understood. Here, we extend classical models of consumer-resource dynamics to explore the ecological consequences of consumer sexual dimorphism. We show that sexual dimorphism in consumer attack rates on two different resource species promotes coexistence between those resources, mitigating the effects of both apparent competition and direct interspecific competition. Consumer sexual dimorphism can prevent exclusion of a resource with inferior growth rates because reduction in any of the two resources reduces consumer density, generating negative frequency dependence that stabilizes coexistence between resources. Our work highlights ecological sex differences as a potentially key factor governing the assembly of ecological communities, illustrating that the specific source of within-species variance can have important implications for community ecology.

scholarly journals Impact of essential workers in the context of social distancing for epidemic control

PLoS ONE ◽  
2021 ◽  
Vol 16 (8) ◽  
pp. e0255680
Author(s):  
William R. Milligan ◽  
Zachary L. Fuller ◽  
Ipsita Agarwal ◽  
Michael B. Eisen ◽  
Molly Przeworski ◽  
...  
Keyword(s):  
Healthcare Workers ◽  
Disease Risk ◽  
Large Fraction ◽  
Emerging Infectious Diseases ◽  
Disease Spread ◽  
Individual Probability ◽  
Key Characteristics ◽  
Essential Services ◽  
Human Costs ◽  
Target Intervention

New emerging infectious diseases are identified every year, a subset of which become global pandemics like COVID-19. In the case of COVID-19, many governments have responded to the ongoing pandemic by imposing social policies that restrict contacts outside of the home, resulting in a large fraction of the workforce either working from home or not working. To ensure essential services, however, a substantial number of workers are not subject to these limitations, and maintain many of their pre-intervention contacts. To explore how contacts among such “essential” workers, and between essential workers and the rest of the population, impact disease risk and the effectiveness of pandemic control, we evaluated several mathematical models of essential worker contacts within a standard epidemiology framework. The models were designed to correspond to key characteristics of cashiers, factory employees, and healthcare workers. We find in all three models that essential workers are at substantially elevated risk of infection compared to the rest of the population, as has been documented, and that increasing the numbers of essential workers necessitates the imposition of more stringent controls on contacts among the rest of the population to manage the pandemic. Importantly, however, different archetypes of essential workers differ in both their individual probability of infection and impact on the broader pandemic dynamics, highlighting the need to understand and target intervention for the specific risks faced by different groups of essential workers. These findings, especially in light of the massive human costs of the current COVID-19 pandemic, indicate that contingency plans for future epidemics should account for the impacts of essential workers on disease spread.

scholarly journals Deforestation-driven food-web collapse linked to emerging tropical infectious disease,Mycobacterium ulcerans

2016 ◽  
Vol 2 (12) ◽  
pp. e1600387 ◽  
Author(s):  
Aaron L. Morris ◽  
Jean-François Guégan ◽  
Demetra Andreou ◽  
Laurent Marsollier ◽  
Kevin Carolan ◽  
...  
Keyword(s):  
Land Use ◽  
Food Web ◽  
Disease Risk ◽  
Risk Estimation ◽  
Emerging Infectious Diseases ◽  
Bacterial Pathogen ◽  
Life Cycles ◽  
Mycobacterium Ulcerans ◽  
Tropical Rain Forests ◽  
Rapid Urbanization

Generalist microorganisms are the agents of many emerging infectious diseases (EIDs), but their natural life cycles are difficult to predict due to the multiplicity of potential hosts and environmental reservoirs. Among 250 known human EIDs, many have been traced to tropical rain forests and specifically freshwater aquatic systems, which act as an interface between microbe-rich sediments or substrates and terrestrial habitats. Along with the rapid urbanization of developing countries, population encroachment, deforestation, and land-use modifications are expected to increase the risk of EID outbreaks. We show that the freshwater food-web collapse driven by land-use change has a nonlinear effect on the abundance of preferential hosts of a generalist bacterial pathogen,Mycobacterium ulcerans. This leads to an increase of the pathogen within systems at certain levels of environmental disturbance. The complex link between aquatic, terrestrial, and EID processes highlights the potential importance of species community composition and structure and species life history traits in disease risk estimation and mapping. Mechanisms such as the one shown here are also central in predicting how human-induced environmental change, for example, deforestation and changes in land use, may drive emergence.

Contrasted influences of moon phases on the reproduction and movement patterns of four amphibian species inhabiting different habitats in central Italy

2014 ◽  
Vol 35 (2) ◽  
pp. 247-254 ◽  
Author(s):  
Leonardo Vignoli ◽  
Manuela D’Amen ◽  
Francesca Della Rocca ◽  
Marco A. Bologna ◽  
Luca Luiselli
Keyword(s):  
Predation Risk ◽  
Central Italy ◽  
Habitat Type ◽  
Reproductive Phenology ◽  
Moon Phase ◽  
The Moon ◽  
Amphibian Species ◽  
Moon Phases ◽  
Fitness Effects ◽  
Open Habitat

Many studies have provided evidence that prey adjust their behaviour to adaptively balance the fitness effects of reproduction and predation risk. Nocturnal terrestrial animals should deal with a range of environmental conditions during the reproductive season at the breeding sites, including a variable amount of natural ambient light. High degrees of illumination are expected to minimize those behaviours that might increase the animal detection by predators. Therefore, under habitat variable brightness conditions and in different ecosystems, the above mentioned behaviours are expected to depend on the variation in predation risk. Although moon effects on amphibian biology have been recognized, the direction of this influence is rather controversial with evidences of both increased and depressed activity under full moon. We tested in four nocturnal amphibian species (Hyla intermedia, Rana dalmatina, Rana italica, Salamandrina perspicillata) the effects of different (i) light conditions and (ii) habitats (open land vs. dense forest) on the reproductive phenology. Our results showed that the effects of the lunar cycle on the study species are associated with the change in luminosity, and there is no evidence of an endogenous rhythm controlled by biological clocks. The habitat type conditioned the amphibian reproductive strategy in relation to moon phases. Open habitat breeders (e.g., ponds with no canopy cover) strongly avoided conditions with high brightness, whereas forest habitat breeders were apparently unaffected by the different moon phases. Indeed, for all the studied species no effects of the moon phase itself on the considered metrics were found. Rather, the considered amphibian species seem to be conditioned mainly by moonlight irrespective of the moon phase. The two anurans spawning in open habitat apparently adjust their oviposition timing by balancing the fitness effects of the risk to be detected by predators and the reproduction.

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