Spatial and temporal population genetics of Swiss red foxes (Vulpes vulpes) following a rabies epizootic

Infectious disease can affect the demography of natural populations and, as a consequence, can alter the genetic variation within and between those populations. This study investigated long-term effects of rabies-induced mortality on the demography and genetic variation in two Swiss red fox populations over ten to fourteen generations. In Switzerland, the last rabies epizootic persisted from 1967 to 1999 and was continuously monitored by collecting fox carcasses throughout the country. Alongside records of rabies tests and post-mortem data, tooth samples were systematically archived for ageing. In this study, DNA from 666 individual teeth was extracted. For 279 extracts, the concentration of nuclear DNA was estimated in a quantitative PCR and found to be negatively correlated with storage time. After excluding samples with insufficient DNA concentration for reliable genotyping, 382 samples were screened using between nine and seventeen canine and red fox specific microsatellites. Tooth samples were combined with 189 modern tissue samples. By assessing the age structure continuously throughout and after the rabies epizootic for the first population, population census size and age structure were found to be altered by the high rabies-induced mortality. In contrast, no long-term trends in genetic diversity were identified although a high variation of Ho, He, F s was discovered both in short-term and longer-term. A strong isolation-by-distance pattern was revealed for the second population by comparing individual pairwise genetic with spatial distances using modern samples. Furthermore, genetic data demonstrated that dispersal was sex-biased and diverted by the topography of the landscape. When investigating isolation-by-distance patterns within the same population in 1971-73 and 1982-84 at lower population densities, density-dependant dispersal was observed. In conclusion, this study revealed no loss of genetic diversity in red foxes following a rabies epizootic despite a population bottleneck, yet highlights population density as an important factor to determine local spatial genetic structure.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Spatial and temporal population genetics of Swiss red foxes (Vulpes vulpes) following a rabies epizootic

Infectious disease can affect the demography of natural populations and, as a consequence, can alter the genetic variation within and between those populations. This study investigated long-term effects of rabies-induced mortality on the demography and genetic variation in two Swiss red fox populations over ten to fourteen generations. In Switzerland, the last rabies epizootic persisted from 1967 to 1999 and was continuously monitored by collecting fox carcasses throughout the country. Alongside records of rabies tests and post-mortem data, tooth samples were systematically archived for ageing. In this study, DNA from 666 individual teeth was extracted. For 279 extracts, the concentration of nuclear DNA was estimated in a quantitative PCR and found to be negatively correlated with storage time. After excluding samples with insufficient DNA concentration for reliable genotyping, 382 samples were screened using between nine and seventeen canine and red fox specific microsatellites. Tooth samples were combined with 189 modern tissue samples. By assessing the age structure continuously throughout and after the rabies epizootic for the first population, population census size and age structure were found to be altered by the high rabies-induced mortality. In contrast, no long-term trends in genetic diversity were identified although a high variation of Ho, He, F s was discovered both in short-term and longer-term. A strong isolation-by-distance pattern was revealed for the second population by comparing individual pairwise genetic with spatial distances using modern samples. Furthermore, genetic data demonstrated that dispersal was sex-biased and diverted by the topography of the landscape. When investigating isolation-by-distance patterns within the same population in 1971-73 and 1982-84 at lower population densities, density-dependant dispersal was observed. In conclusion, this study revealed no loss of genetic diversity in red foxes following a rabies epizootic despite a population bottleneck, yet highlights population density as an important factor to determine local spatial genetic structure

Monitoring introgression in European wildcats in the Swiss Jura

Introgression is an important evolutionary force, which can lead to adaptation and speciation on one hand, but on the other hand also to genetic extinction. It is in the latter sense that introgression is a major conservation concern, especially when domestic species reproduce with their rare wild relatives. Hence, monitoring introgression in natural populations subject to hybridization is crucial to elucidate the threat represented by introgression. Here, we monitored introgression between wildcats (Felis silvestris silvestris) and domestic cats (Felis silvestris catus) in a wildcat population in the Swiss Jura Mountains using systematically and non-invasively collected hair samples. We found 21 % admixed individuals based on 68 diagnostic nuclear SNP-markers, corresponding to a migration rate from domestic cats to wildcats of 0.02 migrants per generation. In contrast, gene flow from wildcats into domestic cats was negligible. Haphazard sampling of the same wildcat population, mostly via road kills, led to similar results. Hybridization occurred between wildcat male and domestic cat female and vice versa and, based on the occurrence of backcrosses, both female and male F1-hybrids seem viable and fertile. The observed hybridization pattern may indicate an expanding wildcat population with introgression as a byproduct of this expansion but alternative explanations cannot be excluded with the current data

A SNP chip to detect introgression in wildcats allows accurate genotyping of single hairs

Genotyping non-invasively collected samples is challenging. Nevertheless, genetic monitoring of elusive species like the European wildcat (Felis silvestris silvestris) mainly relies on such samples. Wildcats are likely threatened through introgression with domestic cats (F. silvestris catus). To determine introgression based on single cat hairs, we developed a 96.96 Fluidigm single nucleotide polymorphism (SNP) genotyping array chip. To estimate the accuracy of this method, we compared genotypes of 17 cats called with both Sanger sequencing and Fluidigm. When Sanger sequencing genotypes were considered as a reference, the genotyping error rate with Fluidigm was 0.9 %. We subsequently compared 16 hair samples to tissue samples of the same individual. When the tissue samples were used as a reference, the genotyping error rate in hair samples was 1.6 %. This low error rate allowed reliable recognition of individuals and correct assessment of introgression levels. Thus, the genotyping method presented in this paper is suitable for non-invasively collected samples. It will help conservationists to monitor the introgression rate in wildcat populations based on non-invasive hair sampling and subsequently to conduct effective conservation measures

A SNP chip to detect introgression in wildcats allows accurate genotyping of single hairs

Genotyping non-invasively collected samples is challenging. Nevertheless, genetic monitoring of elusive species like the European wildcat (Felis silvestris silvestris) mainly relies on such samples. Wildcats are likely threatened through introgression with domestic cats (F. silvestris catus). To determine introgression based on single cat hairs, we developed a 96.96 Fluidigm single nucleotide polymorphism (SNP) genotyping array chip. To estimate the accuracy of this method, we compared genotypes of 17 cats called with both Sanger sequencing and Fluidigm. When Sanger sequencing genotypes were considered as a reference, the genotyping error rate with Fluidigm was 0.9%. We subsequently compared 16 hair samples to tissue samples of the same individual. When the tissue samples were used as a reference, the genotyping error rate in hair samples was 1.6%. This low error rate allowed reliable recognition of individuals and correct assessment of introgression levels. Thus, the genotyping method presented in this paper is suitable for non-invasively collected samples. It will help conservationists to monitor the introgression rate in wildcat populations based on non-invasive hair sampling and subsequently to conduct effective conservation measures

Association Between White-Coat Effect and Blunted Dipping of Nocturnal Blood Pressure

Background In this study, we assessed whether the white-coat effect (difference between office and daytime blood pressure (BP)) is associated with nondipping (absence of BP decrease at night). Methods Data were available in 371 individuals of African descent from 74 families selected from a population-based hypertension register in the Seychelles Islands and in 295 Caucasian individuals randomly selected from a population-based study in Switzerland. We used standard multiple linear regression in the Swiss data and generalized estimating equations to account for familial correlations in the Seychelles data. Results The prevalence of systolic and diastolic nondipping (<10% nocturnal BP decrease) and white-coat hypertension (WCH) was respectively 51, 46, and 4% in blacks and 33, 37, and 7% in whites. When white coat effect and nocturnal dipping were taken as continuous variables (mm Hg), systolic (SBP) and diastolic BP (DBP) dipping were associated inversely and independently with white-coat effect (P < 0.05) in both populations. Analogously, the difference between office and daytime heart rate was inversely associated with the difference between daytime and night-time heart rate in the two populations. These results did not change after adjustment for potential confounders. Conclusions The white-coat effect is associated with BP nondipping. The similar associations between office-daytime values and daytime-night-time values for both BP and heart rate suggest that the sympathetic nervous system might play a role. Our findings also further stress the interest, for clinicians, of assessing the presence of a white-coat effect as a means to further identify patients at increased cardiovascular risk and guide treatment accordingl

Lagos Bat Virus, South Africa

Three more isolates of Lagos bat virus were recently recovered from fruit bats in South Africa after an apparent absence of this virus for 13 years. The sporadic occurrence of cases is likely due to inadequate surveillance programs for lyssavirus infections among bat populations in Africa

Urban colonization through multiple genetic lenses: The city‐fox phenomenon revisited

Urbanization is driving environmental change on a global scale, creating novel environments for wildlife to colonize. Through a combination of stochastic and selective processes, urbanization is also driving evolutionary change. For instance, difficulty in traversing human‐modified landscapes may isolate newly established populations from rural sources, while novel selective pressures, such as altered disease risk, toxicant exposure, and light pollution, may further diverge populations through local adaptation. Assessing the evolutionary consequences of urban colonization and the processes underlying them is a principle aim of urban evolutionary ecology. In the present study, we revisited the genetic effects of urbanization on red foxes (Vulpes vulpes) that colonized Zurich, Switzerland. Through use of genome‐wide single nucleotide polymorphisms and microsatellite markers linked to the major histocompatibility complex (MHC), we expanded upon a previous neutral microsatellite study to assess population structure, characterize patterns of genetic diversity, and detect outliers associated with urbanization. Our results indicated the presence of one large evolutionary cluster, with substructure evident between geographic sampling areas. In urban foxes, we observed patterns of neutral and functional diversity consistent with founder events and reported increased differentiation between populations separated by natural and anthropogenic barriers. We additionally reported evidence of selection acting on MHC‐linked markers and identified outlier loci with putative gene functions related to energy metabolism, behavior, and immunity. We concluded that demographic processes primarily drove patterns of diversity, with outlier tests providing preliminary evidence of possible urban adaptation. This study contributes to our overall understanding of urban colonization ecology and emphasizes the value of combining datasets when examining evolutionary change in an increasingly urban world

Renewed global partnerships and redesigned roadmaps for rabies prevention and control

Canine rabies, responsible for most human rabies deaths, is a serious global public health concern. This zoonosis is entirely preventable, but by focusing solely upon rabies prevention in humans, this "incurable wound" persists at high costs. Although preventing human deaths through canine rabies elimination is feasible, dog rabies control is often neglected, because dogs are not considered typical economic commodities by the animal health sector. Here, we demonstrate that the responsibility of managing rabies falls upon multiple sectors, that a truly integrated approach is the key to rabies elimination, and that considerable progress has been made to this effect. Achievements include the construction of global rabies networks and organizational partnerships; development of road maps, operational toolkits, and a blueprint for rabies prevention and control; and opportunities for scaling up and replication of successful programs. Progress must continue towards overcoming the remaining challenges preventing the ultimate goal of rabies elimination