{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/143650"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/143650","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"Determining the role of density-dependent effects in disease induced population impacts","abstract":"Emerging infectious diseases have contributed to the loss of biodiversity and threaten conservation efforts across the globe. Managing infectious diseases can be challenging in wildlife, often due to the complex nature of pathogen transmission in muti-host systems that can lead to varied decline and recovery patterns. Common disease management strategies focus on the reduction of pathogen transmission at low host densities to be effective. Density-dependent contact rates are generally assumed to be the mechanism driving these decline patterns. However, other density-dependent processes that influence transmission probability could also influence mortality in a density-dependent manner. Here we examine the processes by which population density contributes to the observed declines of bats infected with white-nose syndrome, a fungal disease that has decimated bat populations across North America. We evaluated the contribution of both density-dependent transmission rates and density-dependent environmental exposure on pathogen prevalence and host population declines. Our analyses indicate that the importance of population density varies depending on the phase of the epidemic, and that density-dependent declines are not observed in years when we see density-dependent transmission. Instead, we find that the amount of pathogen a host is exposed to in the environment is density-dependent and likely contributes to the observed patterns of decline. This research contributes to our general understanding of the role of density-dependent processes in disease dynamics and can help inform when certain disease mitigation efforts will be most effective.","abstract_html":"Emerging infectious diseases have contributed to the loss of biodiversity and threaten conservation efforts across the globe. Managing infectious diseases can be challenging in wildlife, often due to the complex nature of pathogen transmission in muti-host systems that can lead to varied decline and recovery patterns. Common disease management strategies focus on the reduction of pathogen transmission at low host densities to be effective. Density-dependent contact rates are generally assumed to be the mechanism driving these decline patterns. However, other density-dependent processes that influence transmission probability could also influence mortality in a density-dependent manner. Here we examine the processes by which population density contributes to the observed declines of bats infected with white-nose syndrome, a fungal disease that has decimated bat populations across North America. We evaluated the contribution of both density-dependent transmission rates and density-dependent environmental exposure on pathogen prevalence and host population declines. Our analyses indicate that the importance of population density varies depending on the phase of the epidemic, and that density-dependent declines are not observed in years when we see density-dependent transmission. Instead, we find that the amount of pathogen a host is exposed to in the environment is density-dependent and likely contributes to the observed patterns of decline. This research contributes to our general understanding of the role of density-dependent processes in disease dynamics and can help inform when certain disease mitigation efforts will be most effective.","abstract_has_math":false,"creators":["Newell, Rose Gabrielle"],"institution":"Virginia Tech","degree_name":"Master of Science","degree_level":"masters","degree_discipline":"Biological Sciences","degree_department":"Biological Sciences","school":null,"contributors":[],"advisors":[],"committee_chairs":["Hoyt, Joseph R."],"committee_members":["Hawley, Dana Michelle","Langwig, Kate Elizabeth"],"year":2026,"date_issued":"2026-07-14","date_published":"2026-07-14","updated_at":"2026-07-24T05:56:30Z","subjects":["Disease ecology","white-nose syndrome","density dependence"],"languages":["en"],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["vt_gsexam:46339"],"render_values":[{"text":"vt_gsexam:46339","href":null,"code":true}]}]},"links":{"outbound_url":"https://hdl.handle.net/10919/143650","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.committeechair","label":"Committee Chair","values":["Hoyt, Joseph R."]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Hawley, Dana Michelle","Langwig, Kate Elizabeth"]},{"key":"dc:contributor.department","label":"Department","values":["Biological Sciences"]},{"key":"dc:creator","label":"Author","values":["Newell, Rose Gabrielle"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2026-07-15T08:00:14Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2026-07-15T08:00:14Z"]},{"key":"dc:date.issued","label":"Date","values":["2026-07-14"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Tech"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Biological Sciences"]},{"key":"thesis:degree_level","label":"Degree Level","values":["masters"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Virginia Polytechnic Institute and State University"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Disease ecology","white-nose syndrome","density dependence"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["In Copyright"]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://rightsstatements.org/vocab/InC/1.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["vt_gsexam:46339"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://hdl.handle.net/10919/143650"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Emerging infectious diseases have contributed to the loss of biodiversity and threaten conservation efforts across the globe. Managing infectious diseases can be challenging in wildlife, often due to the complex nature of pathogen transmission in muti-host systems that can lead to varied decline and recovery patterns. Common disease management strategies focus on the reduction of pathogen transmission at low host densities to be effective. Density-dependent contact rates are generally assumed to be the mechanism driving these decline patterns. However, other density-dependent processes that influence transmission probability could also influence mortality in a density-dependent manner. Here we examine the processes by which population density contributes to the observed declines of bats infected with white-nose syndrome, a fungal disease that has decimated bat populations across North America. We evaluated the contribution of both density-dependent transmission rates and density-dependent environmental exposure on pathogen prevalence and host population declines. Our analyses indicate that the importance of population density varies depending on the phase of the epidemic, and that density-dependent declines are not observed in years when we see density-dependent transmission. Instead, we find that the amount of pathogen a host is exposed to in the environment is density-dependent and likely contributes to the observed patterns of decline. This research contributes to our general understanding of the role of density-dependent processes in disease dynamics and can help inform when certain disease mitigation efforts will be most effective."]},{"key":"dc:description.abstractgeneral","label":"General Abstract","values":["The emergence of infectious diseases can cause high levels of wildlife fatality and population declines. The speed and extent of a disease can depend on the number of individuals that are in a specific area. If the spread of a pathogen depends on how many individuals are present, larger populations will generally experience more severe population declines. Many disease management strategies assume that pathogen spread increases with population size, but exactly what factors contribute to this pattern is not well understood. Here we look at how population size contributes to the high declines of bats across North America from a fungal disease called white-nose syndrome (WNS). Using bat hibernation sites that varied in population size when the disease arrived, we examine how the number of bats in a site ultimately affects the number of bats that become infected and how much pathogen ends up in the environment (e.g. on cave walls). During the first year the pathogen is present in a site, when little disease related death occurs, we find that the number of bats in a site influences the fraction of bats that are infected with the pathogen. However, during the second year when the most severe declines occur, bat population size no longer determines how many bats get infected. Instead, the amount of pathogen present in the environment appears to be most important. Many pathogens that affect wildlife can persist in the environment for long periods of time, suggesting this process could be more broadly important."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Master of Science"]},{"key":"dc:format.medium","label":"Dc Format Medium","values":["ETD"]},{"key":"dc:title","label":"Title","values":["Determining the role of density-dependent effects in disease induced population impacts"]}]}],"canonical_facts":{"dc:contributor.committeechair":["Hoyt, Joseph R."],"dc:contributor.committeemember":["Hawley, Dana Michelle","Langwig, Kate Elizabeth"],"dc:contributor.department":["Biological Sciences"],"dc:creator":["Newell, Rose Gabrielle"],"dc:date.accessioned":["2026-07-15T08:00:14Z"],"dc:date.available":["2026-07-15T08:00:14Z"],"dc:date.issued":["2026-07-14"],"dc:description.abstract":["Emerging infectious diseases have contributed to the loss of biodiversity and threaten conservation efforts across the globe. Managing infectious diseases can be challenging in wildlife, often due to the complex nature of pathogen transmission in muti-host systems that can lead to varied decline and recovery patterns. Common disease management strategies focus on the reduction of pathogen transmission at low host densities to be effective. Density-dependent contact rates are generally assumed to be the mechanism driving these decline patterns. However, other density-dependent processes that influence transmission probability could also influence mortality in a density-dependent manner. Here we examine the processes by which population density contributes to the observed declines of bats infected with white-nose syndrome, a fungal disease that has decimated bat populations across North America. We evaluated the contribution of both density-dependent transmission rates and density-dependent environmental exposure on pathogen prevalence and host population declines. Our analyses indicate that the importance of population density varies depending on the phase of the epidemic, and that density-dependent declines are not observed in years when we see density-dependent transmission. Instead, we find that the amount of pathogen a host is exposed to in the environment is density-dependent and likely contributes to the observed patterns of decline. This research contributes to our general understanding of the role of density-dependent processes in disease dynamics and can help inform when certain disease mitigation efforts will be most effective."],"dc:description.abstractgeneral":["The emergence of infectious diseases can cause high levels of wildlife fatality and population declines. The speed and extent of a disease can depend on the number of individuals that are in a specific area. If the spread of a pathogen depends on how many individuals are present, larger populations will generally experience more severe population declines. Many disease management strategies assume that pathogen spread increases with population size, but exactly what factors contribute to this pattern is not well understood. Here we look at how population size contributes to the high declines of bats across North America from a fungal disease called white-nose syndrome (WNS). Using bat hibernation sites that varied in population size when the disease arrived, we examine how the number of bats in a site ultimately affects the number of bats that become infected and how much pathogen ends up in the environment (e.g. on cave walls). During the first year the pathogen is present in a site, when little disease related death occurs, we find that the number of bats in a site influences the fraction of bats that are infected with the pathogen. However, during the second year when the most severe declines occur, bat population size no longer determines how many bats get infected. Instead, the amount of pathogen present in the environment appears to be most important. Many pathogens that affect wildlife can persist in the environment for long periods of time, suggesting this process could be more broadly important."],"dc:description.degree":["Master of Science"],"dc:format.medium":["ETD"],"dc:identifier.other":["vt_gsexam:46339"],"dc:identifier.uri":["https://hdl.handle.net/10919/143650"],"dc:language.iso":["en"],"dc:publisher":["Virginia Tech"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:subject":["Disease ecology","white-nose syndrome","density dependence"],"dc:title":["Determining the role of density-dependent effects in disease induced population impacts"],"dc:type":["Thesis"],"thesis:degree_discipline":["Biological Sciences"],"thesis:degree_level":["masters"],"thesis:degree_name":["Master of Science"],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-24T05:56:30Z"}