Figure Credit: Matthew Webster
Article:
Barrile, G. M., Chalfoun, A. D., and Walters, A. W. (2021). Infection status as the basis for habitat choices in a wild amphibian. The American Naturalist, 197(1), 128–137. https://doi.org/10.1086/711927 |
Disease & Host BehaviorInfectious disease has traditionally been overlooked as an important evolutionary force shaping animal habitat and space use. Indeed, linking host behavior and disease dynamics remains a central issue in wildlife disease ecology. Rigorous integration necessitates concomitant measurements of individual space use and infection status, both of which can be difficult to sample in wild populations. Here are a couple examples of our work linking host behavior and disease dynamics:
Abstract. Animals challenged with disease may select specific habitat conditions that help prevent or reduce infection. Whereas preinfection avoidance of habitats with a high risk of disease exposure has been documented in both captive and free-ranging animals, evidence of switching habitats after infection to support the clearing of the infection is limited to laboratory experiments. The extent to which wild animals proximately modify habitat choices in response to infection status thus remains unclear. We investigated preinfection behavioral avoidance and postinfection habitat switching using wild, radio-tracked boreal toads (Anaxyrus boreas boreas) in a population challenged with Batrachochytrium dendrobatidis (Bd), a pathogenic fungus responsible for a catastrophic panzootic affecting hundreds of amphibian species worldwide. Boreal toads did not preemptively avoid microhabitats with conditions conducive to Bd growth. Infected individuals, however, selected warmer, more open habitats, which were associated with elevated body temperature and the subsequent clearing of infection. Our results suggest that disease can comprise an important selective pressure on animal habitat and space use. Habitat selection models, therefore, may be greatly improved by including variables that quantify infection risk and/or the infection status of individuals through time. |
Article:
Barrile, G. M., Chalfoun, A. D., and Walters, A. W. (2021). Livestock grazing, climatic variation, and breeding phenology jointly shape the disease dynamics and survival in a wild amphibian. Biological Conservation, 261:109247. https://doi.org/10.1016/j.biocon.2021.109247 |
Disease & DemographyUnderstanding the drivers of wildlife epizootics and how disease influences host population dynamics is critical for developing informed management practices. Here are a couple examples of our work on the influence of disease on host population demography:
Abstract. Wildlife responses to infectious disease can be influenced by environmental stressors that alter host-pathogen dynamics. We investigated how livestock grazing, climatic variation, and breeding phenology influence disease prevalence and annual survival in boreal toad (Anaxyrus boreas boreas) populations challenged with Batrachochytrium dendrobatidis (Bd), a fungal pathogen implicated in global amphibian declines. We conducted a five-year (2015–2019) capture-recapture study of boreal toads (n = 1301) inhabiting pastures grazed by cattle in western Wyoming, USA. We employed structural equation models to determine whether the effects of climatic variation on Bd prevalence were direct or mediated through effects on breeding phenology and multi-state models to explore the interplay of grazing, weather, and Bd infection on adult survival. Higher winter snowpack was linked with shorter spring breeding seasons, which were associated with lower Bd prevalence. Boreal toads infected with Bd suffered increased mortality, but only at relatively cool temperatures. Although cattle grazing created warmer microclimates, likely by reducing vegetation cover, grazing-induced habitat changes did not scale up to influence adult survival. Our results suggest that boreal toads in cooler environments face increased risk of disease-induced mortality, possibly because infected individuals are not able to elevate body temperature to reduce or clear infection. More generally, we demonstrate that host-pathogen dynamics can be shaped jointly by independent and interactive effects of livestock grazing, breeding season length, and climatic variation. Future investigations of wildlife responses to disease therefore may benefit from considering anthropogenic land use and climatic regimes, including the effect of weather on host phenology. |
Article:
Barrile, G. M., Augustine, D. J., Porensky, L. M., Duchardt, C. J., Shoemaker, K. T., Hartway, C. R., Derner, J. D., Hunter, E., and Davidson, A D. (2023). A big data–model integration approach for predicting epizootics and population recovery in a keystone species. Ecological Applications, 33(4), e2827. https://doi.org/10.1002/eap.2827 |
Abstract. Infectious diseases pose a significant threat to global health and biodiversity. Yet, predicting the spatiotemporal dynamics of wildlife epizootics remains challenging. Disease outbreaks result from complex nonlinear interactions among a large collection of variables that rarely adhere to the assumptions of parametric regression modeling. We adopted a nonparametric machine learning approach to model wildlife epizootics and population recovery, using the disease system of colonial black-tailed prairie dogs (BTPD, Cynomys ludovicianus) and sylvatic plague as an example. We synthesized colony data between 2001 and 2020 from eight USDA Forest Service National Grasslands across the range of BTPDs in central North America. We then modeled extinctions due to plague and colony recovery of BTPDs in relation to complex interactions among climate, topoedaphic variables, colony characteristics, and disease history. Extinctions due to plague occurred more frequently when BTPD colonies were spatially clustered, in closer proximity to colonies decimated by plague during the previous year, following cooler than average temperatures the previous summer, and when wetter winter/springs were preceded by drier summers/falls. Rigorous cross-validations and spatial predictions indicated that our final models predicted plague outbreaks and colony recovery in BTPD with high accuracy (e.g., AUC generally >0.80). Thus, these spatially explicit models can reliably predict the spatial and temporal dynamics of wildlife epizootics and subsequent population recovery in a highly complex host–pathogen system. Our models can be used to support strategic management planning (e.g., plague mitigation) to optimize benefits of this keystone species to associated wildlife communities and ecosystem functioning. This optimization can reduce conflicts among different landowners and resource managers, as well as economic losses to the ranching industry. More broadly, our big data–model integration approach provides a general framework for spatially explicit forecasting of disease-induced population fluctuations for use in natural resource management decision-making.
|
Article:
Sergeyev, M., Barrile, G. M., Augustine, D. J., Porensky, L. M., Duchardt, C. J., Shoemaker, K. T., Hartway, C. R., and Davidson, A D. (In Review). PDOG MAPR: A decision support tool to inform management of prairie dog ecosystems. Access Shiny app here: moped.shinyapps.io/PDOGMAPR/ |
Abstract. Anthropogenic impacts are destabilizing ecosystems globally. North America’s Central Grasslands are among the most threatened ecosystems in the world, having been transformed by agriculture, fencing, and loss of its biodiversity. Black-tailed prairie-dogs (Cynomys ludovicianus) are a keystone species of the Central Grasslands, creating key habitat for suites of associated species and serving as important prey for predators. Populations of prairie dogs exhibit boom and bust cycles, characterized by rapid large-scale collapse of prairie dog colonies due to introduced plague, followed by periods of growth and recovery from plague epizootics. These population cycles adversely affect biodiversity at their minimum and increase competition with livestock at their maximum. Management of this grassland system is challenged by its multi-use landscapes, complex jurisdictional boundaries, and diverse stakeholder interests. Objective, data-driven approaches are much needed to help inform management and conservation decisions. Here, we introduce PDOG MAPR, an interactive, web-based decision support tool (R Shiny App) developed to inform management of the prairie dog-plague system. To illustrate the utility of our PDOG MAPR decision support tool in helping stakeholders attain desired objectives, we present two case studies, one conducted at Thunder Basin National Grassland, WY, USA and the other at the Comanche National Grassland, CO, USA. We compared colony dynamics under different management scenarios including varying degrees of plague mitigation and lethal boundary control of colonies. Under no management, PDOG MAPR predicted that colonies would exhibit high growth rates and plague-induced collapses, mirroring the boom-bust cycles now observed post-plague. The addition of management in simulations was successful in preventing major plague collapses and subduing colony growth during non-plague years. In this paper, we detail how our PDOG MAPR tool can be used to help stabilize prairie dog colonies and achieve diverse management goals. Identifying management practices that reduce volatility in prairie dog populations can support grassland health and associated biodiversity as well as reduce competition with livestock, facilitating human-wildlife coexistence across the Central Grasslands. Further, additional decision support can help stakeholders manage increasingly complex and destabilized ecosystems.
|
Article:
Barrile, G. M., Walters, A. W., Webster, M. E., and Chalfoun, A. D. (2021). Informed breeding dispersal following stochastic changes to patch quality in a pond-breeding amphibian. Journal of Animal Ecology, 90(8), 1878–1890. https://doi.org/10.1111/1365-2656.13503 |
Responses to DisturbanceUnderstanding how animals respond to natural and anthropogenic disturbances is critical for developing effective conservation strategies. Here are some examples of our work on how wildlife respond behaviorally and demographically to disturbance:
Abstract. The unidirectional movement of animals between breeding patches (i.e. breeding dispersal) has profound implications for the ecological and evolutionary dynamics of spatially structured populations. In spatiotemporally variable environments, individuals are expected to adjust their dispersal decisions according to information gathered on the environmental and/or social cues that reflect the fitness prospects in a given breeding patch (i.e. informed dispersal). A paucity of empirical work limited our understanding of the ability of animals to depart from low-quality breeding patches and settle in high-quality breeding patches. We examined the capacity of individuals to respond to stochastic changes in habitat quality via informed breeding dispersal in a pond-breeding amphibian. We conducted a 5-year (2015–2019) capture–recapture study of boreal toads Anaxyrus boreas boreas (n = 1,100) that breed in beaver ponds in western Wyoming, USA. During early spring of 2017, an extreme flooding event destroyed several beaver dams and resulted in the loss of breeding habitat. We used multi-state models to investigate how temporal changes in pond characteristics influenced breeding dispersal, and determine whether movement decisions were in accordance with prospects for reproductive fitness. Boreal toads more often departed from low-quality breeding ponds (without successful metamorphosis) and settled in high-quality breeding ponds (with successful metamorphosis). Movement decisions were context-dependent and associated with pond characteristics altered by beaver dam destruction. Individuals were more likely to depart from shallow ponds with high vegetation cover and settle in deep ponds with low vegetation cover. The probability of metamorphosis was related to the same environmental cues, suggesting that boreal toads assess the fitness prospects of a breeding patch and adjust movement decisions accordingly (i.e. informed breeding dispersal). We demonstrated that stochastic variability in environmental conditions and habitat quality can underpin dispersal behaviour in amphibians. Our study highlighted the mechanistic linkages between habitat change, movement behaviour and prospects for reproductive performance, which is critical for understanding how wild animals respond to rapid environmental change. |
Article:
Barrile, G. M., Chalfoun, A. D, Estes-Zumpf, W., and Walters, A. W. (2022). Wildfire influences individual growth and breeding dispersal, but not survival and recruitment in a montane amphibian. Ecosphere, 13(8), e4212. https://doi.org/10.1002/ecs2.4212 |
Abstract. Global wildfire regimes are changing rapidly, with widespread increases in the size, frequency, duration, and severity of wildfires. Whereas the effects of wildfire on ecological state variables such as occupancy, abundance, and species diversity are relatively well documented, changes in population vital rates (e.g., survival, recruitment) and individual responses (e.g., growth, movement) to wildfire are more limited because of the detailed information needed on the same individuals both pre- and post-fire. We capitalized on the 2018 Roosevelt wildfire, which occurred during our 6-year (2015–2020) capture–mark–recapture study of boreal toads (Anaxyrus boreas boreas; n = 1415) in the Bridger-Teton National Forest, USA, to evaluate the responses of population vital rates and individual metrics to wildfire. We employed robust design capture–recapture models to compare the growth, dispersal, survival, and recruitment of adult boreal toads pre- and post-fire at burned versus unburned sites. At burned locations, growth increased 2 years post-fire compared with the year directly following wildfire and was higher 2 years post-fire than any other interval during our study period. Boreal toads dispersed to alternative breeding patches more at burned sites than unburned sites and dispersal increased 2 years post-fire compared with the year directly following wildfire. Annual survival and recruitment neither differed between pre- and post-fire years nor among pre-fire years, the year following wildfire, and 2 years post-fire. We demonstrate that, in certain contexts, dispersal can play a major role in changes to state variables (e.g., abundance) after wildfire, as opposed to other vital rates such as survival and recruitment. Our study represents an important step toward understanding the biological processes that underlie observed patterns in state variables following wildfire, which ultimately will be critical for the effective management of species in landscapes experiencing shifts in fire activity.
|
Article:
Barrile, G. M., Walters, A. W., and Chalfoun, A. D. (2022). Stage-specific environmental correlates of reproductive success in Boreal Toads (Anaxyrus boreas boreas). Journal of Herpetology, 56(1), 34–44. https://doi.org/10.1670/21-023 |
Abstract. Compensatory recruitment can facilitate the persistence of populations experiencing high adult mortality. Because early life-stages of many taxa, including amphibians, are difficult to mark and recapture, sources of variation in survival at these stages often are unknown, which creates barriers to improving in situ recruitment rates. We leveraged count data and open N-mixture models to examine the environmental factors associated with the hatching of egg clutches, tadpole survival, and probability of metamorphosis in Boreal Toads (Anaxyrus boreas boreas) that inhabit pastures leased for cattle grazing in western Wyoming, USA. We conducted weekly surveys and measured a suite of environmental variables at 20 breeding ponds during May–September 2018. The hatching of egg clutches was most strongly related to pond surface area, as clutches often desiccated at smaller ponds. Weekly tadpole survival was lowest in ponds with high abundance of aquatic predators. Predation did not preclude metamorphosis, which was more strongly associated with higher dissolved oxygen and vegetation cover. Cattle grazing reduced vegetation cover in and around breeding ponds, which resulted in lower levels of dissolved oxygen. Grazing-induced habitat changes are therefore likely to negatively influence tadpole metamorphosis both via indirect effects on dissolved oxygen, and direct effects on vegetation cover, which also serves as feeding sites and escape cover from predators. We demonstrate the success of three critical phases in early life-stage development (egg hatching, tadpole survival, metamorphosis) was associated with different environmental factors. The inclusion of stage-specific responses in demographic analyses is therefore critical for a thorough understanding of what limits populations.
|
Article:
LeCheminant, A. G., Barrile, G. M., Albeke, S. E., and Walters, A. W. (2021). Movement dynamics and survival of stocked Colorado River Cutthroat Trout (Oncorhynchus clarkii pleuriticus). Transactions of the American Fisheries Society, 150(6), 679–693. https://doi.org/10.1002/tafs.10322 |
Fish Movement & DemographyUnderstanding fish movement and population dynamics in highly altered environments is critical to the conservation of aquatic systems. Here are a couple examples of our work on fish movement and vital rates:
Abstract. The ability of native fish to establish self-sustaining populations when reintroduced to vacant habitats is variable. We evaluated factors that potentially affect the reintroduction success of juvenile Colorado River Cutthroat Trout Oncorhynchus clarkii pleuriticus that were reintroduced to an isolated watershed and were experiencing suboptimal survival and recruitment. We conducted a 3-year mark–recapture study to model annual apparent survival probability as it related to (1) different ex situ rearing strategies and (2) initial release among different habitat types. The use of PIT tags also enabled the quantification of loss via emigration. Apparent survival was highest for small fish that were minimally exposed to ex situ rearing conditions, stocked in small, headwater stream reaches. However, maximum estimates of apparent survival remained low (≤0.38 ± 0.05 [estimate ± SE]) regardless of rearing treatment, stocking location, or interactive effects between covariates. Emigration of stocked fish (<1%) from the study area did not appear to limit their establishment. Our results suggest that variation in stocking and rearing strategy may have some effect on translocation success and the interaction between rearing and stocking strategy highlights the importance of considering the life history stage of stocked individuals when identifying stocking sites. Consistently low annual survival values may be indicative of a larger issue, requiring in-depth evaluation of adaptive potential within our brood source and other factors that potentially limit population persistence. |
Article:
Barrile, G. M., Bernard, R. F., Wilcox, R. C., Becker, J. A., Dillon, M. E., Thomas-Kuzilik, R. R., Bombaci, S. P., and Merkle, B. G. (2023). Equity, community, and accountability: leveraging a department-level climate survey as a tool for action. PLoS ONE, 18(8): e0290065. https://doi.org/10.1371/journal.pone.0290065 |
Enhancing Workplace ClimateI believe that creating a positive workplace climate is a key first step in attracting, retaining, and genuinely supporting people from diverse backgrounds in the field of ecology. Here is an example of our work on workplace climate:
Abstract. Organizational climate is a key determinant of diverse aspects of success in work settings, including in academia. Power dynamics in higher education can result in inequitable experiences of workplace climate, potentially harming the well-being and productivity of employees. Quantifying experiences of climate across employment categories can help identify changes necessary to create a more equitable workplace for all. We developed and administered a climate survey within our academic workplace—the Department of Zoology and Physiology at the University of Wyoming—to evaluate experiences of climate across three employment categories: faculty, graduate students, and staff. Our survey included a combination of closed-response (e.g., Likert-scale) and open-ended questions. Most department members (82%) completed the survey, which was administered in fall 2021. Faculty generally reported more positive experiences than staff. Graduate students often fell between these two groups, though in some survey sections (e.g., mental health and well-being) students reported the most negative experiences of departmental climate. Three common themes emerged from the analysis of open-ended responses: equity, community, and accountability. We discuss how these themes correspond to concrete action items for improving our departmental climate, some of which have been implemented already, while others constitute future initiatives and/or require a collective push towards systemic change in academia. Finally, service work of this type often falls outside of job descriptions, requiring individuals to either work more or trade-off productivity in other areas that are formally evaluated. With the goal of minimizing this burden for others, we detail our process and provide the materials and framework necessary to streamline this process for other departments aiming to evaluate workplace climate as a key first step in building a positive work environment for all employees. |