Genetic population substructure in bison at Yellowstone National Park

The Yellowstone National Park bison herd is 1 of only 2 populations known to have continually persisted on their current landscape since pre-Columbian times. Over the last century, the census size of this herd has fluctuated from around 100 individuals to over 3000 animals. Previous studies involving radiotelemetry, tooth wear, and parturition timing provide evidence of at least 2 distinct groups of bison within Yellowstone National Park. To better understand the biology of Yellowstone bison, we investigated the potential for limited gene flow across this population using multilocus Bayesian clustering analysis. Two genetically distinct and clearly defined subpopulations were identified based on both genotypic diversity and allelic distributions. Genetic cluster assignments were highly correlated with sampling locations for a subgroup of live capture individuals. Furthermore, a comparison of the cluster assignments to the 2 principle winter cull sites revealed critical differences in migration patterns across years. The 2 Yellowstone subpopulations display levels of differentiation that are only slightly less than that between populations which have been geographically and reproductively isolated for over 40 years. The identification of cryptic population subdivision and genetic differentiation of this magnitude highlights the importance of this biological phenomenon in the management of wildlife species.     

Genetic Characteristics and Prognosis for Existence of the European Bison Free-Living Population Created in the Orlovskoe Poles'e National Park

We present preliminary data on genetic aspects of preserving viability of the free-living population of European bison (Bison bonasus L.) created in the Orlovskoe Poles'e National Park.     

MHC-DRB3 variation in a free-living population of the European bison, Bison bonasus

MHC genes play a crucial role in pathogen recognition and are the most polymorphic genes in vertebrates. Loss of variation in these genes in bottlenecked species is thought to put their survival at risk. We examined variation at the MHC II DRB3 locus in the European bison, Bison bonasus, a species that has undergone an extreme bottleneck: the current population originated from only 12 founders. We also tested for the association of DRB3 genes with the incidence of posthitis, a disease affecting the reproductive organs of bulls and posing a new threat to the survival of the species. We found very limited MHC diversity, with only four alleles segregating in a sample of 172 individuals from a free‐ranging Białowieża population. The alleles were highly divergent and revealed the hallmark of positive selection acting on them in the past, that is, a significant excess of nonsynonymous substitutions. This excess was concentrated in putative antigen‐binding sites, suggesting that selection was driven by pathogens. However, we did not observe departures from Hardy–Weinberg equilibrium, an indicator of strong ongoing selection. Neither have we found a significant association between DRB3 alleles or genotypes and susceptibility to posthitis. Alleles conferring resistance to males may have been lost during the extreme bottleneck the species had undergone.     

Necrobacillosis in free-living male European bison in Poland

In the Bialowieza Primeval Forest (Poland) a chronic disease of the external genital organs has been observed in free-living male European bison (Bison bonasus) since 1980. Investigations on this disease started in the late 1980s. The most striking findings are necrotic and ulcerative lesions of the prepuce and penis of bison aged from 6 mo to >10 yr. Histologic examination of tissue samples from the prepuce of six bison (9-mo- to 8-yr-old), and from the penis of two bison (3- and 8-yr-old), were characteristic of necrobacillosis. Masses of slender, Gram-negative, rod-like or filamentous bacteria occurred in necrotic tissue. At the periphery of necrotic tissue filamentous bacteria were often arranged in large clusters and strands that advanced towards healthy tissue. Immunolabeling and electron microscopy also suggest that these organisms are Fusobacterium sp.     

Post-bottleneck mtDNA diversity in a free-living population of European bison: implications for conservation

A free-living population of European bison Bison bonasus in the Białowieża Primeval Forest originated from only seven founder animals after a severe bottleneck that occurred at the beginning of the 20th century. Consequently, the contemporary population of the species is characterized by low genetic diversity. We studied a total of 195 individuals (127 males and 68 females). A 1429 bp fragment of mitochondrial DNA (mtDNA) including the D-loop region was analyzed in 87 individuals and revealed only three distinct haplotypes. Nucleotide ( π ) and haplotype ( H _d) diversity values were estimated for the European bison and were compared with π and H _d estimated from three individuals of American bison Bison bison . Very low diversity values were found in the European bison in comparison with the diversity values found in the American bison. The low mtDNA variability in the European bison is in concordance with theoretical expectations for a species that has undergone a severe and recent bottleneck. A management strategy for the preservation of the rare and very rare haplotypes present in the Białowieża population of the European bison is discussed. Furthermore, all 195 individuals were investigated for heteroplasmy involving these three haplotypes, in order to detect a possible association between heteroplasmy and the incidence of males affected by posthitis , a disease that affects the male reproductive organs, leading to necrotic lesions. Heteroplasmy was found in 15 females, in 17 males affected by posthitis and in 11 non-affected males, and no significant association was found.     

Pathology of brucellosis in bison from Yellowstone National Park

Between February 1995 and June 1999, specimens from seven aborted bison (Bison bison) fetuses or stillborn calves and their placentas, two additional placentas, three dead neonates, one 2-wk-old calf, and 35 juvenile and adult female bison from Yellowstone National Park (USA) were submitted for bacteriologic and histopathologic examination. One adult animal with a retained placenta had recently aborted. Serum samples from the 35 juvenile and adult bison were tested for Brucella spp. antibodies. Twenty-six bison, including the cow with the retained placenta, were seropositive, one was suspect, and eight were seronegative. Brucella abortus biovar 1 was isolated from three aborted fetuses and associated placentas, an additional placenta, the 2-wk-old calf, and 11 of the seropositive female bison including the animal that had recently aborted. Brucella abortus biovar 2 was isolated from one additional seropositive adult female bison. Brucella abortus was recovered from numerous tissue sites from the aborted fetuses, placentas and 2-wk-old calf. In the juvenile and adult bison, the organism was more frequently isolated from supramammary (83%), retropharyngeal (67%), and iliac (58%) lymph nodes than from other tissues cultured. Cultures from the seronegative and suspect bison were negative for B. abortus. Lesions in the B. abortus-infected, aborted placentas and fetuses consisted of necropurulent placentitis and mild bronchointerstitial pneumonia. The infected 2-wk-old calf had bronchointerstitial pneumonia, focal splenic infarction, and purulent nephritis. The recently-aborting bison cow had purulent endometritis and necropurulent placentitis. Immunohistochemical staining of tissues from the culture-positive aborted fetuses, placentas, 2-wk-old calf, and recently-aborting cow disclosed large numbers of B. abortus in placental trophoblasts and exudate, and fetal and calf lung. A similar study with the same tissue collection and culture protocol was done using six seropositive cattle from a B. abortus-infected herd in July and August, 1997. Results of the bison and cattle studies were similar.     

Genetic diversity of the European bison herd from the Prioksko-Terrasny nature reserve

Maintaining the existing genetic diversity in populations is one of the most important measures for species conservation. Some components of this diversity in the bison population of the Prioksko-Terrasny Nature Reserve, including the level of preservation of the founder genetic diversity or the founder genomic equivalent (fge) of the current bison stock and the indices of similarity (mk) and genome uniqueness (gu), as well as their effects on viability of the animals from 1950-1995 were studied. The data obtained were treated and the diversity parameters were calculated with the use of the SPARKS software package. This was performed in collaboration with the Institute for Zoo Biology and Wildlife Research (Berlin, Germany). The results of the analysis indicated that, in breeding groups of the European bison, the fge, mk, and gu values should be maintained at levels higher than 1.30, lower than 40%, and higher than 10%, respectively. When selecting males for specific groups of females, the male gu should be at least 20%, and mk should be lower than 40%.     

Chemical immobilization of free-ranging North American bison (Bison bison) in Badlands National Park, South Dakota

Twenty-six free-ranging North American bison (Bison bison) (22 adult bulls, one yearling male and three adult females) were immobilized using a combination of carfentanil and xylazine. For carfentanil the dose range (mean +/- SD) was 1.8-5.0 micrograms/kg (2.4 +/- 0.7 micrograms/kg) and for xylazine 0.004-0.125 mg/kg (0.07 +/- 0.03 mg/kg). Induction time (mean +/- SE) was 14.2 +/- 2.9 min (median 8 min), while the total mean reversal time after administration of a narcotic antagonist was 9.0 +/- 1.4 min (median 8 min). Only one animal that received the highest initial dose of carfentanil (2.5 mg) showed evidence of becoming "re-narcotized." Five animals required two or more doses of carfentanil before becoming immobilized. Overall, small volumes of drug used (mean = 0.62 ml for carfentanil, 0.53 ml for xylazine) enabled the use of 1 to 2 ml darts, increasing both accuracy and impact safety. Darting success approached 100%.     

Virologic investigations of free-living European bison (Bison bonasus) from the Bialowieza Primeval Forest,Poland

We conducted virologic investigations on postmortem specimens from 261 free-living European bison (Bison bonasus) from the Bialowieza Primeval Forest, Poland collected between 1990 and 2000. Fifty-four of 94 males had balanoposthitis; none of the 167 female bison examined had reproductive tract lesions. Peripheral blood, swabs, and various tissues were analyzed for bovine viruses as well as for viral DNA by bovine herpesvirus 1 (BoHV-1) and bovine herpesvirus 4 (BoHV-4) specific polymerase chain reaction (PCR) technique. An infectious bovine rhinotracheitis like BoHV-1 strain was isolated from the spleen of a female bison calf and additionally was detected by nested PCR from splenic tissue. None of the bison had significant antibody titers against BoHV-1, bovine herpesvirus 2, BoHV-4, caprine herpesvirus 1, cervid herpesvirus 1, or bovine viral diarrhea (BVD) virus-1. However, low antibody titers in two animals indicate that this European bison population has been exposed to BVD virus or BVD-like viruses and BoHV-2.     

Cases of spermiogenesis in young European bison

Development of spermiogenesis and sizes of seminiferous tubules of the testes and epididymal duct were studied in 45 young European bisonBison bonasus (Linnaeus, 1758) males from an enclosed breeding centre and a free-ranging population in the Białowieża Forest. Of 13 males in age class II (up to two years), four showed the presence of elongated late spermatids: one male aged 15 months from the enclosed breeding centre and three from the free-ranging population (2 males aged 18 months and one about 24 months old). Of 7 males from age class III (up to 3 years), four showed spermiogenesis, of which the youngest, 26 and 32 months old, were from enclosed breeding. Spermiogenesis was observed in males with high body weight in a given age class. In males of age class I (up to one year old), the mean diameter of the seminiferous tubules was 49.8 μm, in class II — 110.7 μm, and in class III — 162 μm, the mean diameter of the epididymal duct being 110.8 μm, 187.2 μm and 273.4 μm, respectively. Measurements of seminiferous tubules and epididymal duct were significantly correlated with age and body weight of males and differed significantly between the three age classes.     

Genetic diversity of flowering dogwood in the Great Smoky Mountains National Park

In the past three decades, flowering dogwood (Cornus florida) populations have experienced severe declines caused by dogwood anthracnose. Mortality has ranged from 48% to 98%, raising the concern that the genetic diversity of this native tree has been reduced significantly. In this study, we investigated levels of genetic diversity and population structure of flowering dogwood populations in the Great Smoky Mountains National Park (GSMNP). Understanding the factors influencing geographic distribution of genetic variation is one of the major concerns for preserving biodiversity and conservation of native populations. Eighteen microsatellite loci were used to evaluate the level and distribution of genetic variation of native flowering dogwood trees throughout the GSMNP. Significant genetic structure exists at both landscape and local levels. Two genetic clusters exist within the park and are separated by the main dividing ridges of the Great Smoky Mountains. The differentiation of the clusters is subtle, but statistically significant. Gene flow, evident through low-elevation corridors, indicates that nonrandom mating occurs between related individuals despite wide dispersal of seeds. Although high mortality rate and reduced fecundity caused by dogwood anthracnose severely affected native flowering dogwood populations throughout the entire GSMNP, this study confirmed that considerable genetic diversity still exists at the population level. It seems unlikely that recent demographic dynamics have resulted in a depletion of genetic variation.     

Ancient DNA assessment of tiger salamander population in Yellowstone National Park

Recent data indicates that blotched tiger salamanders (Ambystoma tigrinum melanostictum) in northern regions of Yellowstone National Park are declining due to climate-related habitat changes. In this study, we used ancient and modern mitochondrial haplotype diversity to model the effective size of this amphibian population through recent geological time and to assess past responses to climatic changes in the region. Using subfossils collected from a cave in northern Yellowstone, we analyzed >700 base pairs of mitochondrial sequence from 16 samples ranging in age from 100 to 3300 years old and found that all shared an identical haplotype. Although mitochondrial diversity was extremely low within the living population, we still were able to detect geographic subdivision within the local area. Using serial coalescent modelling with Bayesian priors from both modern and ancient genetic data we simulated a range of probable population sizes and mutation rates through time. Our simulations suggest that regional mitochondrial diversity has remained relatively constant even through climatic fluctuations of recent millennia.     

Good to the bone: microbial community thrives within bone cavities of a bison carcass at Yellowstone National Park

The discovery of unanticipated microbial diversity in remote, often hostile environments has led to a greater appreciation of the complexity and richness of the natural world. Yellowstone National Park (YNP) has long been a focus of work on taxa that inhabit extreme environments. Here we report the finding of microbial flora that inhabit an unexpected niche: the cavities of bone remnants from a bison carcass in Norris Geyser Basin in YNP. Although bleached white on the surface, the bone cavities are bright green due to the presence of Stichococcus-like trebouxiophyte green algae. The cavities also harbour different fungi and bacteria. Stichococcus species are common lichen photobionts and the Thelebolales fungi present in the bone cavities have previously been found in association with animal remains. Scanning electron microscope analysis suggests the fungi and algae do not form lichen-like associations in the bone. Rather these taxa and the bacteria appear to be opportunists that have colonized an isolated oasis that provides nutrients and protection from desiccation and UV radiation.     

Immunolocalization of PTHrP in the European bison and pine vole testis and epididymis

The present study deals with immunohistochemical localization of PTHrP in European bison and pine vole testis and epididymis. PTHrP immunoreactivity was observed in spermatogenic cells of seminiferous tubules in European bison and pine vole testis, with the strongerst reaction occurring in spermatozoa of pine vole testis and epididymal duct. We also observed PTHrP expression in vascular smooth muscle of epididymis and testis in both animal species, as well as slightly weaker reaction in endothelial cells of European bison epididymis. PTHrP was also expressed in the smooth muscle of the epididymal duct in European bison and pine vole. In conclusion, PTHrP is a multifunctional peptide showing both paracrine and autocrine action. Its presence in vascular endothelium and smooth muscle of testis and epididymis is connected with the regulation of vascular muscle tone, thus affecting blood flow in the vessels. PTHrP expression depends on a number of local factors. Moreover, we suppose that PTHrP also contributes to the proliferation and differentiation of spermatogenic cells.     

Viral infections in free-living populations of the European wildcat

While the importance of viral infections is well studied in domestic cats, only limited information is available on their occurence and prevalence in the European wildcat (Felis silvestris silvestris). The aim of this study was to determine the prevalence of antibodies to feline coronavirus (FCoV), calicivirus (FCV), herpesvirus (FHV), parvovirus (FPV), immunodeficiency virus (FIV), leukemia virus (FeLV), and FeLV antigenemia in 51 European wildcat sera. Samples were collected between 1996 and 1997 from wildcat populations in France, Switzerland, and Germany. Antibodies to FCoV were detected in two cats (4%) and FCoV RNA was detected in feces of one of these two cats. Antibodies to FCV, FHV and FPV were found at relatively low frequencies of 16%, 4%, and 2%, respectively. Antibodies to FIV were not detected. Although antigen and antibodies to FeLV were detected in 49%, and 75%, respectively, no evidence of FeLV-associated pathology was found. From the low prevalence of FCoV, FCV, FHV and FPV infections and from the fact that the European wildcats live solitarily, it was concluded that these viral infections do not spread readily within a population. Therefore, it may be assumed that release into the wild of European wildcats bred in captivity would not bring about a high risk of introducing of these viral infections to the free-ranging wildcats. As an exception, wildcats should be tested for absence of FIV infection before release if they were at risk to acquire this infection from domestic cats.