Determining the Drivers of Species and Population Extinction in the Emerging Infectious Disease of Bats, White-nose Syndrome PDF Download

Author:
Publisher:
ISBN: 9781321933178
Category :
Languages : en
Pages : 60

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Book Description
Emerging infectious diseases pose a key threat to wildlife, and the number of disease emergence events is increasing. Despite the importance of disease in wildlife conservation, understanding the drivers of population and species extinction from disease has not been tested in an empirical framework. My research incorporates empirical and theoretical approaches to understand factors that influence pathogen transmission and disease impacts. Here, we focus on the emerging fungal disease of bats, white-nose syndrome, which has caused widespread declines in bat populations across Eastern North America. Our findings highlight the importance of social behavior, microclimate conditions, and seasonality in driving impacts from this disease. We find that while seasonal transmission is broadly similar across species, winter differences in pathogen growth drive variation in species impacts from disease. Species appear to have different transmission mechanism which influences the likelihood they will persist in the face of white-nose syndrome. We also identify a species, the Northern long-eared bat, which is likely to go extinct if rapid management action is not taken. These data provide critical information needed to manage wildlife disease epidemics, enabling management action prior to species extinction.

Author: Tina L. Cheng
Publisher:
ISBN: 9780355334098
Category :
Languages : en
Pages : 122

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Book Description
Emerging infectious diseases can place severe pressures on wildlife populations, leading to major population declines, local extirpation, and species extinctions. However, variability in disease impacts, existing among species and across a spatial and temporal scale, can help us identify species or populations persisting with disease either via resistance, tolerance, pathogen evasion, or by existing within environmental refugia. Understanding mechanisms leading to host persistence can inform conservation management priorities and strategies. White-nose Syndrome (WNS) is a recently emerged disease caused by the fungal pathogen, Pseudogymnoascus destructans (Pd), that has led to severe declines in hibernating bat populations in North America. This work examines patterns and mechanisms associated with variability in WNS impacts with implications for the conservation of affected species. My first chapter investigates spatial heterogeneity in initial impacts of Pd spread across half of continental North America. We found that WNS-related impacts were lessened in the southwestern regions of North America, suggesting potential spatial refugia from WNS-related impacts but only for Perimyotis subflavus. We found that annual air surface temperatures driving Pd growth explained, in part, this spatial variation in WNS-related impacts. Despite evidence for lessened WNS-related declines in the southwest, impacts to bat populations are severe throughout North America for most bat species. My second chapter examines colonies of M. lucifugus that have experienced variability in declines over time, persisting potentially due to host-specific responses. Specifically, I investigate if differences in early winter fat reserves could explain survivorship and persistence of M. lucifugus colonies with WNS. We found that bats persisting with WNS in 2016 were significantly fatter than bats colonies sampled during WNS arrival in 2008 and 2009 at four out of our six sampled sites. At another two sites, we found that bats were either fatter in 2008 and 2009 compared to 2016. We used hibernation energetic models to estimate the amount of fat afforded to survival and found that increased fat reserves from bats measured in 2016 could reduce mortality by 65%. These data suggest that increased fat reserves can explain, in part, the persistence of M. lucifugus colonies with WNS. Lastly, my third chapter experimentally investigates one possible cause of variability in WNS impacts, variation host susceptibility via protective bacteria in the skin microbiome. In this chapter, I explore the efficacy of using a probiotic bacterium, harvested from the skin of a species experiencing lessened WNS impacts, Eptesicus fuscus , as a conservation tool applied to a more highly affected bat species, M. lucifugus. We found relative increases in survival for probiotic-treated groups compared to our sham control group. We also found evidence for decreased fungal infection and severity in probiotic-treated groups. Our results suggest that probiotic treatment can reduce incidence of White-nose Syndrome in M. lucifugus although timing of treatment is an important factor. Together, this work finds that variability in spatial, species-specific, and temporal impacts from WNS can inform conservation efforts. Namely, this work suggests that bat conservation should involve a multi-pronged approach that protects colonies where bats are persisting with WNS via habitat restoration, and potentially treating bats for threatened populations not persisting with WNS. Given the continued threat of WNS to bats as it spreads throughout North America, using a variety of tools to combat this disease may be critical to prevent disease-induced extinction and the local extirpation of affected bat species.

Author: Marianne Gagnon
Publisher:
ISBN:
Category :
Languages : en
Pages : 137

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Book Description
Emerging infectious diseases of wildlife are among the greatest threats to biodiversity. Indeed, when pathogens are introduced into naïve host populations, they can impose novel selective pressures that may cause severe host declines or even extinction. However, disease impacts may vary both within and among host species. Thus, one of the key goals for management is to identify factors that drive variation in host susceptibility to infection, as they may improve our understanding of hosts' potential to develop disease resistance and/or tolerance and inform conservation strategies aimed at facilitating host persistence. For instance, Pseudogymnoascus destructans (Pd) - an invasive pathogenic fungus that causes white-nose syndrome (WNS) in hibernating bats - is highly virulent, has killed millions of bats in North America, and continues to spread at an alarming rate. Yet, the continued persistence of bat colonies in contaminated areas despite initial mass mortality events suggests variation in survival among infected individuals. I thus aimed to better understand intraspecific drivers of variation in bat susceptibility to WNS and their implications for population persistence and management in affected areas. Specifically, my objectives were to: 1) evaluate the extent to which variation in hibernaculum microclimate temperature and humidity affects Pd infection severity and disease progression in affected bats during hibernation, 2) compare how bats from colonies that vary in duration of exposure to Pd and from different age classes behaviorally respond to the infection, and examine how these behavioral changes affect host fitness and 3) model the population dynamics of remnant bat populations to assess the likeliness of persistence and the potential effectiveness of management interventions in affected colonies. I addressed these objectives through field research, experimental infection studies, and demographic modeling of the little brown myotis (Myotis lucifugus). In my dissertation, I first provide causal evidence of environmentally-driven variation in pathogen growth and infection severity on bats in the field. Both warmer and more humid microclimates contribute to the severity of the infection by promoting the production of conidia, the erosion of wing tissues, and, therefore, the transmission potential and virulence of Pd. I then document potential mechanistic links between Pd-induced behavioral change and host fitness. Higher infection levels, independent of bats' past exposure to Pd or age class, may cause individuals to groom longer, prolong euthermic arousals, accelerate the depletion of fat reserves, and ultimately increase mortality risk. Finally, I predict that populations will face a high risk of extirpation in the next decade or two if no management action is taken, but that interventions such as environmental control of Pd and hibernaculum microclimate manipulation can prevent short-term population collapse in remnant bat populations. Together, these studies provide key, mechanistic insight into the pathology of WNS and the probability of persistence of affected bat colonies, while highlighting the importance of prioritizing winter habitat preservation and enhancement for the conservation of hibernating bats.

Author: Riley Fehr Bernard
Publisher:
ISBN:
Category : Bats
Languages : en
Pages : 107

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Book Description
This dissertation investigates regional differences in the behavior and activity of bats in eastern North America during the white-nose syndrome epizootic, specifically in the understudied region of the Southeastern United States. An introductory section provides a brief review of the history of whitenose syndrome, an emerging infectious disease in bats, and its introduction into North America. Chapter one provides the first documented evidence of bat activity outside of hibernacula throughout winter. The research presented in chapter two attempts to explain the variation in load and prevalence of P. destructans among species, sites and between years. Finally, chapter three examines the differences in the species affected by white-nose syndrome in the Southeast, as well as the regional variation in the timing and severity of decline in bat communities during summer. A conclusion section at the end of this dissertation summarizes the main findings and provides directions for future research.

Author: Lin-Fa Wang
Publisher: John Wiley & Sons
ISBN: 1118818784
Category : Science
Languages : en
Pages : 405

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Book Description
Approximately 75% of emerging infectious diseases are zoonoses, and the rate of emergence of zoonotic diseases is on the rise. Bats are being increasingly recognised as an important reservoir of zoonotic viruses of different families, including SARS coronavirus, Nipah virus, Hendra virus and Ebola virus. Understanding bats’ role in emerging zoonotic diseases is crucial to this rapidly expanding area of research. Bats and Viruses: A New Frontier of Emerging Infectious Diseases provides an updated overview of research focusing on bat biology and the role bats play as hosts of many major zoonotic viruses. The text covers bat biology, immunology, and genomics. Chapters also delve into the various major bat-borne virus families, including lyssaviruses, paramyxoviruses, coronaviruses, filoviruses and reoviruses, among others. Edited by leaders in the field, Bats and Viruses: A New Frontier of Emerging Infectious Diseases is a timely, invaluable reference for bat researchers studying microbiology, virology and immunology, as well as infectious disease workers and epidemiologists, among others.

Author: Joseph R. Hoyt
Publisher:
ISBN: 9781321087680
Category :
Languages : en
Pages : 32

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Emerging infectious diseases are a key threat to wildlife. Several fungal skin pathogens have recently emerged and caused widespread mortality in vertebrate species, including amphibians, bats, rattlesnakes, and platypus. The importance of the skin microbiome in host-pathogen interactions is increasingly understood to play a large role in determining the course of disease in a host. White-nose syndrome, caused by the fungal skin pathogen Pseudogymnoascus destructans, threatens several hibernating bat species with extinction and there are no known effective treatments. We co-cultured bacteria and P. destructans from the skin microbiome of four bat species to identify bacterial isolates that might inhibit or kill P. destructans. We then conducted two reciprocal challenge experiments in vitro with six candidate bacteria (all in the genus Pseudomonas) that inhibited P. destructans growth across a range of bacterial and fungal concentrations to quantify the effect of these bacteria on the growth of P. destructans. All six Pseudomonas isolates significantly inhibited growth of P. destructans compared to the non-inhibitory control bacteria, and two isolates performed significantly better than others in suppressing P. destructans growth for more than 35 days. In both challenge experiments, the extent of suppression of P. destructans growth was dependent on the concentration of P. destructans and the initial concentration of the bacterial isolate. These results show that bacteria found naturally occurring on bats can inhibit the growth of P. destructans and have promise for development as a biocontrol for bats exposed to white-nose syndrome. In addition, the presence of these bacteria may influence disease outcome among individuals, populations, and species.

Author: Amy Kristine Wray
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Book Description
The spread of infectious disease in wildlife represents an emerging threat to biodiversity. Particularly among predators, the effects of emerging infectious diseases not only include population declines and potential extirpation, but also can result in top-down effects on prey communities. In North America, several hibernating bat species face serious population declines due to the emergence of white-nose syndrome, a devastating disease caused by the fungal pathogen Pseudogymnoascus destructans. While arthropodivorous bats are often lauded for providing ecosystem services in the form of agricultural pest suppression, other regulatory effects on the arthropod food web as a whole have seldom been assessed. In light of the impending westward spread of white-nose syndrome and corresponding predicted bat population declines, this dissertation seeks to characterize the role of bats as top predators in the nocturnal arthropod food web and to assess the broader ecological consequences of disease-related bat population declines. Specifically, this research focuses on two common bat species, the little brown bat (Myotis lucifugus) and the big brown bat (Eptesicus fuscus), to explore the response of bats to changing prey abundance (Chapter 1), changes in bat foraging patterns over the past century (Chapter 2), top-down consequences of bat declines on arthropod communities (Chapter 3), and the possibility of the functional replacement of one bat species by another (Chapter 4). Overall, this dissertation demonstrates that the function of bats in the nocturnal arthropod food web is complex, and that declines among little brown bats in particular can have top-down effects which are unlikely to be ameliorated by other persisting bat species. As such, these results emphasize the necessity of promoting the conservation of bats and other aerial arthropodivores, while highlighting their importance as predators that influence their respective food webs.

Author: United States. Congress. House. Committee on Natural Resources. Subcommittee on Insular Affairs, Oceans, and Wildlife
Publisher:
ISBN:
Category : Nature
Languages : en
Pages : 80

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Author: United States. Congress. House. Committee on Natural Resources. Subcommittee on Fisheries, Wildlife, Oceans, and Insular Affairs
Publisher:
ISBN:
Category : Medical
Languages : en
Pages : 64

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Book Description

Author: Joseph R. Hoyt
Publisher:
ISBN: 9780355671445
Category :
Languages : en
Pages : 64

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Book Description
Emerging infectious diseases present a major threat to wildlife populations and have the ability to drive once common species towards extinction. Increasing globalization has resulted in accelerated change in climate, increased anthropogenic movement, and land-use alterations leading to the emergence of infectious diseases in both humans, agriculture and wildlife. Studying disease dynamics at different contexts and scales can provide insight into alternative levers of conservation action. White-nose syndrome, a disease of hibernating bats, was first detected in single tourist cave in northern New York. Pseudogymnoascus destructans the fungal pathogen responsible for WNS has since spread across much of eastern North America causing the collapse of hibernating bat populations. P. destructans was likely introduced to North America from Eurasia, where it is widely distributed, and has likely been present for thousands of years. The data in this dissertation provide insight into the factors determining temporal variation in mortality from WNS. In addition, we will also provide insight into the mechanisms that contribute to species differences in pathogen transmission. More broadly this research provides a synthesis of data across multiple WNS disease contexts, and highlight the substantial conservation insight that can be gained through this approach.