Publications by authors named "H B Ernest"

42 Publications

LOW PREVALENCE OF HAEMOSPORIDIANS IN BLOOD AND TISSUE SAMPLES FROM HUMMINGBIRDS.

J Parasitol 2021 Sep;107(5):794-798

Department of Biology, 1600 Holloway Avenue, San Francisco State University, San Francisco, California 94132.

Hummingbirds are vital members of terrestrial ecosystems, and because of their high metabolic requirements, they serve as indicators of ecosystem health. Monitoring the parasitic infections of hummingbirds is thus especially important. Haemosporidians, a widespread group of avian blood parasites, are known to infect hummingbirds, but little is known about the prevalence and diversity of these parasites in hummingbirds. The prevalence of haemosporidians in several hummingbird species was examined and we compared 4 different tissue types in detecting parasites by polymerase chain reaction (PCR). Blood samples from 339 individuals of 3 different hummingbird species were tested, and 4 individuals were found positive for haemosporidian infection, a prevalence of 1.2%. Hummingbird carcasses (n = 70) from 5 different hummingbird species were also sampled to assess differences in detection success of haemosporidians in heart, kidney, liver, and pectoral muscle tissue samples. Detection success was similar among tissue types, with haemosporidian prevalence of 9.96% in heart tissue, 9.52% in kidney tissue, 10.76% in liver tissue, and 11.76% in pectoral muscle tissue. All tissue samples positive for haemosporidian infection were from the Black-chinned Hummingbird (Archilochus alexandri). Possible reasons for low prevalence of these blood parasites could include low susceptibility to insect vectors or parasite incompatibility in these hummingbirds.
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http://dx.doi.org/10.1645/20-168DOI Listing
September 2021

Spatio-temporal analyses reveal infectious disease-driven selection in a free-ranging ungulate.

R Soc Open Sci 2021 Aug 11;8(8):210802. Epub 2021 Aug 11.

Wildlife Genomics and Disease Ecology Laboratory, Department of Veterinary Sciences, Program in Ecology, University of Wyoming, Laramie, WY 82071, USA.

Infectious diseases play an important role in wildlife population dynamics by altering individual fitness, but detecting disease-driven natural selection in free-ranging populations is difficult due to complex disease-host relationships. Chronic wasting disease (CWD) is a fatal infectious prion disease in cervids for which mutations in a single gene have been mechanistically linked to disease outcomes, providing a rare opportunity to study disease-driven selection in wildlife. In Wyoming, USA, CWD has gradually spread across mule deer () populations, producing natural variation in disease history to evaluate selection pressure. We used spatial variation and a novel temporal comparison to investigate the relationship between CWD and a mutation at codon 225 of the mule deer prion protein gene that slows disease progression. We found that individuals with the 'slow' 225F allele were less likely to test positive for CWD, and the 225F allele was more common in herds exposed to CWD longer. We also found that in the past 2 decades, the 225F allele frequency increased more in herds with higher CWD prevalence. This study expanded on previous research by analysing spatio-temporal patterns of individual and herd-based disease data to present multiple lines of evidence for disease-driven selection in free-ranging wildlife.
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http://dx.doi.org/10.1098/rsos.210802DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8355672PMC
August 2021

Host relatedness and landscape connectivity shape pathogen spread in the puma, a large secretive carnivore.

Commun Biol 2021 01 4;4(1):12. Epub 2021 Jan 4.

Department of Veterinary Population Medicine, University of Minnesota, St Paul, MN, 55108, USA.

Urban expansion can fundamentally alter wildlife movement and gene flow, but how urbanization alters pathogen spread is poorly understood. Here, we combine high resolution host and viral genomic data with landscape variables to examine the context of viral spread in puma (Puma concolor) from two contrasting regions: one bounded by the wildland urban interface (WUI) and one unbounded with minimal anthropogenic development (UB). We found landscape variables and host gene flow explained significant amounts of variation of feline immunodeficiency virus (FIV) spread in the WUI, but not in the unbounded region. The most important predictors of viral spread also differed; host spatial proximity, host relatedness, and mountain ranges played a role in FIV spread in the WUI, whereas roads might have facilitated viral spread in the unbounded region. Our research demonstrates how anthropogenic landscapes can alter pathogen spread, providing a more nuanced understanding of host-pathogen relationships to inform disease ecology in free-ranging species.
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http://dx.doi.org/10.1038/s42003-020-01548-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7782801PMC
January 2021

Pronghorn population genomics show connectivity in the core of their range.

J Mammal 2020 Aug 29;101(4):1061-1071. Epub 2020 May 29.

Wildlife Genomics and Disease Ecology Laboratory, Department of Veterinary Sciences, University of Wyoming, Laramie, WY, USA.

Preserving connectivity in the core of a species' range is crucial for long-term persistence. However, a combination of ecological characteristics, social behavior, and landscape features can reduce connectivity among wildlife populations and lead to genetic structure. Pronghorn (), for example, exhibit fluctuating herd dynamics and variable seasonal migration strategies, but GPS tracking studies show that landscape features such as highways impede their movements, leading to conflicting hypotheses about expected levels of genetic structure. Given that pronghorn populations declined significantly in the early 1900s, have only partially recovered, and are experiencing modern threats from landscape modification, conserving connectivity among populations is important for their long-term persistence in North America. To assess the genetic structure and diversity of pronghorn in the core of their range, we genotyped 4,949 genome-wide single-nucleotide polymorphisms and 11 microsatellites from 398 individuals throughout the state of Wyoming. We found no evidence of genetic subdivision and minimal evidence of isolation by distance despite a range that spans hundreds of kilometers, multiple mountain ranges, and three interstate highways. In addition, a rare variant analysis using putatively recent mutations found no genetic division between pronghorn on either side of a major highway corridor. Although we found no evidence that barriers to daily and seasonal movements of pronghorn impede gene flow, we suggest periodic monitoring of genetic structure and diversity as a part of management strategies to identify changes in connectivity.
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http://dx.doi.org/10.1093/jmammal/gyaa054DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7566746PMC
August 2020

Minimum habitat thresholds required for conserving mountain lion genetic diversity.

Ecol Evol 2020 Oct 1;10(19):10687-10696. Epub 2020 Sep 1.

California Department of Fish and Wildlife Sacramento California USA.

Jointly considering the ecology (e.g., habitat use) and genetics (e.g., population genetic structure and diversity) of a species can increase understanding of current conservation status and inform future management practices. Previous analyses indicate that mountain lion () populations in California are genetically structured and exhibit extreme variation in population genetic diversity. Although human development may have fragmented gene flow, we hypothesized the quantity and quality of remaining habitat available would affect the genetic viability of each population. Our results indicate that area of suitable habitat, determined via a resource selection function derived using 843,500 location fixes from 263 radio-collared mountain lions, is strongly and positively associated with population genetic diversity and viability metrics, particularly with effective population size. Our results suggested that contiguous habitat of ≥10,000 km may be sufficient to alleviate the negative effects of genetic drift and inbreeding, allowing mountain lion populations to maintain suitable effective population sizes. Areas occupied by five of the nine geographic-genetic mountain lion populations in California fell below this habitat threshold, and two (Santa Monica Area and Santa Ana) of those five populations lack connectivity to nearby populations. Enhancing ecological conditions by protection of greater areas of suitable habitat and facilitating positive evolutionary processes by increasing connectivity (e.g., road-crossing structures) might promote persistence of small or isolated populations. The conservation status of suitable habitat also appeared to influence genetic diversity of populations. Thus, our results demonstrate that both the area and status (i.e., protected or unprotected) of suitable habitat influence the genetic viability of mountain lion populations.
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http://dx.doi.org/10.1002/ece3.6723DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7548186PMC
October 2020
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