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Title:Modeling the health of free-living Illinois herptiles: an integrated approach incorporating environmental, physiologic, spatiotemporal, and pathogen factors
Author(s):Adamovicz, Laura
Director of Research:Allender, Matthew C.
Doctoral Committee Chair(s):Allender, Matthew C.
Doctoral Committee Member(s):Ko, CheMyong; Mahoney, Megan; Smith, Rebecca; Mitchell, Mark; Deem, Sharon
Department / Program:Comparative Biosciences
Discipline:VMS - Comparative Biosciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
Degree:Ph.D.
Genre:Dissertation
Subject(s):eastern box turtle
ornate box turtle
silvery salamander
Terrapene carolina carolina
Terrapene ornata
Ambystoma platineum
health
modeling
Abstract:Human expansion has contributed to an unprecedented global environmental crisis and significantly impacted the stability of many wildlife populations. The health of wildlife populations influences their ability to recover from a complex array of anthropogenic and natural stressors. Promotion of positive health status may improve conservation outcomes in wild animals. However, wildlife health status is dynamic and determined by a variety of factors. Studying such a complex system requires a comprehensive approach with careful consideration of multiple determinants simultaneously. The purpose of this dissertation is to holistically characterize health in three herptile species of conservation concern in Illinois by combining traditional veterinary health assessments with environmental and spatio-temporal data within a modeling framework. The main objective is to identify the best means of assessing wellness in wild herptiles to inform management strategies which support robust population health. Health was investigated in three species of conservation concern in Illinois: the eastern box turtle (Terrapene carolina carolina), the ornate box turtle (Terrapene ornata ornata), and the silvery salamander (Ambystoma platineum) over the course of three years using a combination of physical examination, qPCR pathogen screening, and clinical pathology (box turtles). Mortality events were characterized as they occurred and spatiotemporal data were used to screen for locations and times associated with pathogen presence or poor health outcomes. Diagnostic tests including hematology, plasma biochemistry, protein electrophoresis, venous blood gas, hemoglobin-binding protein, and erythrocyte sedimentation rate were investigated for clinical utility in box turtles, and a novel qPCR assay for detection of Mycoplasma sp. in box turtles was developed and validated. Health models were generated for each study species and used to identify drivers of poor health, determine the most clinically useful diagnostic tests for each species, and generate management recommendations supporting good individual and population health. Health assessment in silvery salamanders (N = 770) identified a parasite (Amphibiocystidium sp.) that has never been previously detected in the Midwest and characterized significant larval mortality due to ranavirus (FV3). Poor health was best predicted by the additive effects of year, location, FV3 detection, and the presence of fresh traumatic injuries. FV3 is considered to represent a threat to silvery salamanders in Illinois, and recommendations for future research include characterization of silvery salamander biology and ecology, continued health monitoring to identify emerging threats, and focused study on ranavirus to identify potential management interventions. Ornate box turtle (N = 168) health assessment revealed a high prevalence of shell lesions associated with predator trauma (51-59% annually). There was no association between pathogen detection (Terrapene herpesvirus 1, Terrapene adenovirus), clinical signs of illness, and clinical pathology alterations. Poor health was best predicted by the presence of active or inactive shell lesions and deviations from population median values for total leukocyte count, eosinophils, basophils, and heterophil:lymphocyte (H:L) ratios. Population viability analysis revealed that annual removal of two adult female turtles above background mortality rates dramatically increased the probability of population extinction within the next century (54-97%). Continued health assessment (including hematology), mesopredator control, and disease screening of newly introduced turtles to prevent novel pathogen ingress was recommended to support individual and population wellness for ornate box turtles. Eastern box turtle (N = 507) health assessment uncovered mortality events due to FV3 and a suspected necrotizing soft tissue infection. Detection of other pathogens (Terrapene adenovirus, Terrapene herpesvirus 1, Mycoplasma sp., Salmonella typhimurium) was not related to health status. Poor health was best predicted by the presence of active shell lesions, clinical signs of upper respiratory disease (URD), and deviations from population median values for total leukocyte count and H:L. PVA revealed that annual removal of 1 - 5 adult female turtles above background mortality rates dramatically increased the probability of population extinction within the next century for all populations, but the effects were especially pronounced in small populations from fragmented and degraded habitats. FV3 is considered a conservation threat for eastern box turtles, especially in smaller populations like the one at Kickapoo State Park which experience recurrent ranavirus outbreaks in both amphibians and turtles. Forest management to promote habitat quality, consideration of box turtle activity patterns when planning burn schedules, road signage to decrease vehicular strikes, additional research into ranavirus dynamics in natural systems, and continued health assessment to monitor trends and identify new threats were recommended to support individual and population wellness. This dissertation demonstrates the feasibility of modeling health in wildlife and illustrates its use for determining drivers of poor health, identifying clinically useful diagnostic tests, and generating management recommendations which support overall individual and population wellness, improve conservation outcomes, and promote herptile and ecosystem health.
Issue Date:2019-01-14
Type:Text
URI:http://hdl.handle.net/2142/104956
Rights Information:Copyright 2019 Laura Adamovicz
Date Available in IDEALS:2019-08-23
Date Deposited:2019-05


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