Application of genetics and genomics to wildlife epidemiology

Wildlife diseases can have significant impacts on wildlife conservation and management. Many of the pathogens that affect wildlife also have important implications for domestic animal and human health. However, management interventions to prevent or control wildlife disease are hampered by uncertainties about the complex interactions between pathogens and free-ranging wildlife. We often lack crucial knowledge about host ecology, pathogen characteristics, and host–pathogen dynamics. The purpose of this review is to familiarize wildlife biologists and managers with the application of genetic and genomic methodologies for investigating pathogen and host biology to better understand and manage wildlife diseases. The genesis of this review was a symposium at the 2013 annual Wildlife Society Conference. We reviewed the scientific literature and used our personal experiences to identify studies that illustrate the application of genetic and genomic methods to advance our understanding of wildlife epidemiology, focusing on recent research, new techniques, and innovative approaches. Using examples from a variety of pathogen types and a broad array of vertebrate taxa, we describe how genetics and genomics can provide tools to detect and characterize pathogens, uncover routes of disease transmission and spread, shed light on the ways that disease susceptibility is influenced by both host and pathogen attributes, and elucidate the impacts of disease on wildlife populations. Genetic and increasingly genomic methodologies will continue to contribute important insights into pathogen and host biology that will aid efforts to assess and mitigate the impacts of wildlife diseases on global health and conservation of biodiversity

Environmental contaminants in excrement of Iowa\u27s nesting and wintering Bald Eagles (Haliaeetus leucocephalus)

Bald Eagles (Haliaeetus leucocephalus) were rare only a few decades ago but have undergone a spectacular recovery range-wide. While their numbers have increased, there is concern about exposure of Bald Eagles to environmental contaminants. We collected excrement from nesting and wintering Bald Eagles in Iowa to examine their exposure to several contaminants and tested for differences as a function of space, time, and breeding status. We detected aluminum, copper, manganese, and zinc at levels above the quantitation limit (QL) in most excrement samples. These elements are all essential micronutrients normally found in living organisms. Arsenic and selenium are essential micronutrients for which fewer samples had levels above the QL. We also detected non-essential elements barium, cadmium, lead, and mercury in excrement samples, although only one sample had a cadmium level above the QL and only 26% of samples had lead levels above the QL. Geometric mean contaminant levels in excrement samples collected from nesting eagles during the spring were higher than for samples collected in the winter for aluminum, barium, copper, manganese, and zinc. The only difference we detected in contaminant levels in excrement samples was in manganese (higher for nest sites along the Mississippi River) and selenium (lower for nest sites along the Mississippi River) versus nest sites not associated with the Mississippi River. We also found that non-breeding eagles had higher levels of barium and manganese than nesting eagles. Our results can serve as a baseline for comparison with future studies investigating exposure of Bald Eagles to environmental contaminants

Effects of Chronic Wasting Disease on Reproduction and Fawn Harvest Vulnerability in Wisconsin White-Tailed Deer

Chronic wasting disease (CWD) is a fatal, transmissible spongiform encephalopathy that affects free-ranging and captive North American cervids. Although the impacts of CWD on cervid survival have been documented, little is known about the disease impacts on reproduction and recruitment. We used genetic methods and harvest data (2002–04) to reconstruct parentage for a cohort of white-tailed deer (Odocoileus virginianus) fawns born in spring 2002 and evaluate the effects of CWD infection on reproduction and fawn harvest vulnerability. There was no difference between CWD-positive and CWD-negative male deer in the probability of being a parent. However, CWD-positive females were more likely to be parents than CWD-negative females. Because our results are based on harvested animals, we evaluated the hypothesis that higher parentage rates occurred because fawns with CWD-positive mothers were more vulnerable to harvest. Male fawns with CWD-positive mothers were harvested earlier (.1 mo relative to their mother’s date of harvest) and farther away from their mothers than male fawns with CWDnegative mothers. Male fawns with CWD-positive mothers were also harvested much earlier and farther away than female fawns from CWD-positive mothers. Most female fawns (86%) with CWD-positive mothers were harvested from the same section as their mothers, while almost half of male and female fawns with CWD-negative mothers were farther away. We conclude that preclinical stages of CWD infection do not prohibit white-tailed deer from successfully reproducing. However, apparently higher harvest vulnerability of male fawns with CWD-positive mothers suggests that CWD infection may make females less capable of providing adequate parental care to ensure the survival and recruitment of their fawns

Ontogenetic Shifts in the Costs of Living in Groups: Focal Observations of a Pholcid Spider (Holocnemus pluchei)

Holocnemus pluchei spiders (Family Pholcidae) facultatively live in groups: sometimes they live alone and sometimes they share webs. In the field groups vary in size and composition and include spiders of all ages and either sex. Group membership is flexible and individuals move frequently among groups. To understand group formation and maintenance it is necessary to understand the costs of group membership. We used focal animal sampling to investigate the cost of group living for spiders of different ages across a range of group sizes. Both spider age and group size affected the costs incurred by group-living spiders. There was no variation among groups of different sizes in the percentage of time focal small or large spiders spent in costly behaviors (moving, web maintenance, bouncing or interactions with conspecifics), but medium-sized spiders spent more time engaged in costly behaviors with increasing group size. Medium and large spiders also had more interactions with greater numbers of different conspecifics when they were in groups larger than three, whereas small spiders interacted rarely with conspecifics regardless of group size. These results suggest that there are significant ontogenetic shifts in the costs of group living in H. pluchei

Genetic susceptibility to chronic wasting disease in free-ranging white-tailed deer: Complement component C1q and Prnp polymorphisms

The genetic basis of susceptibility to chronic wasting disease (CWD) in free-ranging cervids is of great interest. Association studies of disease susceptibility in free-ranging populations, however, face considerable challenges including: the need for large sample sizes when disease is rare, animals of unknown pedigree create a risk of spurious results due to population admixture, and the inability to control disease exposure or dose. We used an innovative matched case–control design and conditional logistic regression to evaluate associations between polymorphisms of complement C1q and prion protein (Prnp) genes and CWD infection in white-tailed deer from the CWD endemic area in southcentral Wisconsin. To reduce problems due to admixture or disease-risk confounding, we used neutral genetic (microsatellite) data to identify closely related CWD-positive (n = 68) and CWD-negative (n = 91) female deer to serve as matched cases and controls. Cases and controls were also matched on factors (sex, location, age) previously demonstrated to affect CWD infection risk. For Prnp, deer with at least one Serine (S) at amino acid 96 were significantly less likely to be CWD-positive relative to deer homozygous for Glycine (G). This is the first characterization of genes associated with the complement system in white-tailed deer. No tests for association between any C1q polymorphism and CWD infection were significant at p \u3c 0.05. After controlling for Prnp, we found weak support for an elevated risk of CWD infection in deer with at least one Glycine (G) at amino acid 56 of the C1qC gene. While we documented numerous amino acid polymorphisms in C1q genes none appear to be strongly associated with CWD susceptibility

Multi-Species Patterns Of Avian Cholera Mortality In Nebraska’s Rainwater Basin

Nebraska’s Rainwater Basin (RWB) is a key spring migration area for millions of waterfowl and other avian species. Avian cholera has been endemic in the RWB since the 1970s and in some years tens of thousands of waterfowl have died from the disease. We evaluated patterns of avian cholera mortality in waterfowl species using the RWB during the last quarter of the 20th century. Mortality patterns changed between the years before (1976–1988) and coincident with (1989–1999) the dramatic increases in lesser snow goose abundance and mortality. Lesser snow geese (Chen caerulescens caerulescens) have commonly been associated with mortality events in the RWB and are known to carry virulent strains of Pasteurella multocida, the agent causing avian cholera. Lesser snow geese appeared to be the species most affected by avian cholera during 1989–1999; however, mortality in several other waterfowl species was positively correlated with lesser snow goose mortality. Coincident with increased lesser snow goose mortality, spring avian cholera outbreaks were detected earlier and ended earlier compared to 1976–1988. Dense concentrations of lesser snow geese may facilitate intraspecific disease transmission through bird-to-bird contact and wetland contamination. Rates of interspecific avian cholera transmission within the waterfowl community, however, are difficult to determine

Iowa Acoustic Bat Surveys

To better understand and assess the bat population of Iowa, a survey is needed. One approach to surveying bats is to use acoustic detection equipment.</p