Bartonellosis is a vector-borne disease which is increasingly threatening the health of humans and animals worldwide consequent to the growing wildlife-animals-human interactions. Little is known about the epidemiology of this disease in Tanzania. In this study we investigated and characterized Bartonella species in small mammals’ ectoparasites from potentially high-risk areas in the country. A total of 141 ectoparasites pools of mites, fleas, ticks, and lice were analyzed using conventional PCR and sequencing. Bartonella DNA was detected in 34.8 % of the tested ectoparasite pools, with mites at 32.9 %, fleas at 40 %, ticks at 12.5 %, and lice at 50 %. Phylogenetic analysis showed that the Bartonella spp. genotypes were closely related to those found in Uganda, Kenya, and South Africa. Different genotypes with independent haplotypes were observed, although most Bartonella spp. from fleas shared the same haplogroup. The confirmed presence of Bartonella elizabethae and Bartonella tribocorum in field and house rodents emphasizes the prevailing transmission risk of zoonotic infections in the study areas and beyond. Screening of humans, companion animals, and livestock in potentially high-risk areas in Tanzania is necessary in order to inform the development of responsive surveillance and control strategies.
Evolutionary information on the greater cane rat (Thryonomys swinderianus) in the Eastern and Southern African regions is scarce, making population management and conservation of the species challenging. We studied T. swinderianus populations from two spatially isolated Eastern Arc Mountains in Tanzania to link molecular and geometric–morphological evidence to characterize these populations’ diversity. Fecal samples (n = 50) and skulls (n = 99) of T. swinderianus were collected from Udzungwa (north and south) and Uluguru mountains (urban and rural sites) and analyzed using molecular and geomorphometry techniques. Molecular analysis grouped the population into three distinct clades based on the location where the samples were collected, while the morphometric method was not able to distinctively separate the populations. Both methods revealed that the population obeyed the isolation by distance model with higher genetic distance between the Udzungwa and Uluguru populations and lower distance between Uluguru urban and rural populations. Both Mahalanobis and Procrustes distances in skull landmarks between the Udzungwa and Uluguru populations were significantly higher across the dorsal, ventral, and lateral views of the skulls, suggesting strongly that molecular and morphometric methods applied together can be useful in characterizing the population traits of the least known species. Our study suggests genetic and morphometric methods could complement each other in understanding the evolutionary biology and within-species diversity of vertebrate species that do not exhibit strong intra-species differentiation.
Background and aim: African Greater Cane (ACG) rat populations are widely distributed across Africa but the ancestral origin of populations inhabiting different geographical regions is unknown. There is currently no information available on the genetic differentiation of these populations resulting from long-time geographical isolation, environmental and anthropogenic pressures they face in each region. This limits our ability to understand potential speciation processes in AGC and their implications for their conservation and of other small wild mammals exposed to similar ecological conditions in the savannah biomes in Africa. Methods: We analyzed mitochondrial genes targeting the D-loop region of AGC samples from two blocks of the Eastern Arc Mountains in Tanzania (eastern), three agro-ecological zones in Ghana (western) and four sites in South Africa (southern) to characterize the phylogeographical patterns of the species. Results: AGC populations from Tanzania revealed higher haplotype diversity than those from the two other régions. Analysis of variance (AMOVA) revealed higher genetic variations within than between populations in all geographic regions. Demographic history analysis revealed a negative and significant Tajima’s D for a single southern African population as well as close relatedness with the Eastern Africa populations, suggesting a common ancestral origin. Conclusion: This is the first study to compare maternal lineages of AGC populations from eastern, western and southern Africa and provides a basis for future genetic studies of the species, its evolutionary ecology and the conservation of these populations across their range. Conservation implications: Evidence of recent population size expansion underpinned by high genetic diversity observed in the Uluguru urban (Tanzania) Guinea savannah (Ghana) and Kwazulu Natal (South Africa) populations suggest that the AGC populations are not currently threatened, consistent with the current IUCN status. Also, the distinct haplotypes observed in each region suggest that the populations can be managed as meta-populations, thus providing opportunities for potential local game-farming programs.
Yersinia pestis is a historically important vector-borne pathogen causing plague in humans and other mammals. Contemporary zoonotic infections with Y. pestis still occur in sub-Saharan Africa, including Tanzania and Madagascar, but receive relatively little attention. Thus, the role of wildlife reservoirs in maintaining sylvatic plague and spillover risks to humans is largely unknown. The multimammate rodent Mastomys natalensis is the most abundant and widespread rodent in peri-domestic areas in Tanzania, where it plays a major role as a Y. pestis reservoir in endemic foci. Yet, how M. natalensis' immunogenetics contributes to the maintenance of plague has not been investigated to date. Here, we surveyed wild M. natalensis for Y. pestis vectors, i.e., fleas, and tested for the presence of antibodies against Y. pestis using enzyme-linked immunosorbent assays (ELISA) in areas known to be endemic or without previous records of Y. pestis in Tanzania. We characterized the allelic and functional (i.e., supertype) diversity of the major histocompatibility complex (MHC class II) of M. natalensis and investigated links to Y. pestis vectors and infections. We detected antibodies against Y. pestis in rodents inhabiting both endemic areas and areas considered non-endemic. Of the 111 nucleotide MHC alleles, only DRB*016 was associated with an increased infestation with the flea Xenopsylla. Surprisingly, we found no link between MHC alleles or supertypes and antibodies of Y. pestis. Our findings hint, however, at local adaptations towards Y. pestis vectors, an observation that more exhaustive sampling could unwind in the future.
Background and aim: African Greater Cane (ACG) rat populations are widely distributed across Africa but the ancestral origin of populations inhabiting different geographical regions is unknown. There is currently no information available on the genetic differentiation of these populations resulting from long-time geographical isolation, environmental and anthropogenic pressures they face in each region. This limits our ability to understand potential speciation processes in AGC and their implications for their conservation and of other small wild mammals exposed to similar ecological conditions in the savannah biomes in Africa. Methods: We analyzed mitochondrial genes targeting the D-loop region of AGC samples from two blocks of the Eastern Arc Mountains in Tanzania (eastern), three agro-ecological zones in Ghana (western) and four sites in South Africa (southern) to characterize the phylogeographical patterns of the species. Results: AGC populations from Tanzania revealed higher haplotype diversity than those from the two other régions. Analysis of variance (AMOVA) revealed higher genetic variations within than between populations in all geographic regions. Demographic history analysis revealed a negative and significant Tajima’s D for a single southern African population as well as close relatedness with the Eastern Africa populations, suggesting a common ancestral origin. Conclusion: This is the first study to compare maternal lineages of AGC populations from eastern, western and southern Africa and provides a basis for future genetic studies of the species, its evolutionary ecology and the conservation of these populations across their range. Conservation implications: Evidence of recent population size expansion underpinned by high genetic diversity observed in the Uluguru urban (Tanzania) Guinea savannah (Ghana) and Kwazulu Natal (South Africa) populations suggest that the AGC populations are not currently threatened, consistent with the current IUCN status. Also, the distinct haplotypes observed in each region suggest that the populations can be managed as meta-populations, thus providing opportunities for potential local game-farming programs. Keywords African Greater Cane rats , demographic history , conservation genomics , evolutionary history , game farming , mt-DNA , maternal origin
Climate change causes organisms, including species that act as parasite reservoirs and vectors, to shift their distribution to higher altitudes, affecting wildlife infestation patterns. We studied how ectoparasite distributions varied with altitude using two rodent species, Montemys delectorum and Rhabdomys dilectus, at different elevations (1500-3500 m). The ectoparasites infesting the two rodent species were influenced by the host sex, species, and temperature. We expected host density to predict parasite infestation patterns, because hosts in higher densities should have more parasites due to increased contact between individuals. However, temperature, not host density, affected ectoparasite distribution. Since temperatures decrease with elevation, parasite prevalences and abundances were lower at higher elevations, highlighting that the cold conditions at higher elevations limit reproduction and development-this shows that higher elevation zones are ideal for conservation. The rodents and ectoparasite species described in this study have been reported as vectors of diseases of medical and veterinary importance, necessitating precautions. Moreover, Mount Meru is a refuge for a number of endemic and threatened species on the IUCN Red List. Thus, the parasitic infection can also be an additional risk to these critical species as well as biodiversity in general. Therefore, our study lays the groundwork for future wildlife disease surveillance and biodiversity conservation management actions. The study found a previously uncharacterized mite species in the Mesostigmata group that was previously known to be a parasite of honeybees. Further investigations may shed light into the role of this mite species on Mount Meru.
Objectives: Plague has been a threat to human health in Tanzania since 1886. This zoonotic disease has established several endemic foci in the country, posing a risk of outbreaks. This study was conducted to investigate the presence of Yersinia pestis in small mammals in five districts. These districts were selected because of recent (Mbulu), past (40-18 years ago: Lushoto) and historic ( > 100 years ago: Iringa and Kilolo) human cases of plague. In addition, one region that has not had any reported human cases of plague was included (Morogoro-Mvomero).Methods: Blood from 645 captured small mammals was screened for antibodies against the fraction 1 (F1) antigen of Y. pestis using indirect enzyme-linked immunosorbent assay (ELISA) and competitive-blocking ELISA.Results: Specific antibodies against Y. pestis F1 antigens were detected in six (0.93%) animals belonging to Mastomys natalensis . Of these, four animals were captured in the active focus in Mbulu, and two animals were captured from an area with no history of human plague (Morogoro-Mvomero).Conclusion: These results provide evidence of the circulation of Y. pestis in small mammals in Tanzania. Furthermore, evidence of the circulation of Y. pestis in Morogoro-Mvomero highlights the importance of carrying out plague surveillance in areas with no history of human plague, which can help to predict areas where future outbreaks may occur.
Abstract The African Greater Cane rat (AGC) populations in East and West Africa bear single ancestral origin. However, to date, information is lacking on their genetic differentiation due to long-time geographical isolation and the environmental and anthropogenic pressures the populations face in each region. This gap limits our ability to understanding potential speciation in these populations. We analysed the genetic sequences of cane rat samples from Tanzania and Ghana to characterize the phylogeographic patterns of the two populations based on the mt-DNA. The D-loop sequences used comprised samples collected from two Eastern Arc Mountains in Tanzania and three agro-ecological zones in Ghana. We found a high nucleotide diversity in AGC population from Tanzania (0.022±0.003) and low nucleotide diversity in Ghana (0.013±0.003). Analysis of Molecular variance (AMOVA) showed significant genetic differentiation between AGC population from Tanzania and Ghana (Fst=0.85938, p<0.00001). Further, analysing the genetic differentiation, we found high variation by 85.94% in AGC populations between Tanzania and Ghana and low variation (14.06%) within any AGC population at individual region. Reconstructing past history of the population in each region based on the neutrality test revealed a positive (0.006) Harpending’s raggedness index for Tanzania and negative (-0.009) for Ghana. Also, Tajima’s D was negative (-0.798) for Tanzania and positive (0.041) for Ghana, indicating that the population of Tanzania is increasing while the Ghanaian is decreasing. This is the first study to compare maternal lineages of the AGC population from two regions in Africa, and provides a basis for future studies.
Management of most herbivorous small mammal species considered to be pests in Africa is still challenging partly because of the paucity of information on their biological traits that would help to manage their destructive impacts. This gap also precludes the potential for tapping species with potential food-value to improving the economy of rural communities through, for example, sustainable game farming programs in Africa. This study investigates the genetic diversity and population demography of the African Greater Cane rat (AGC), a rodent pest of crops and game species inhabiting two isolated blocks of the Eastern Arc Mountains (EAMs), Tanzania to contribute to the species management and conservation. We used non-invasive sampling techniques and DNA sequencing of the D-loop region of MtDNA (515bp) from 46 cane rats (Thryonomys swinderianus) samples to characterize the genetic diversity and structure of the species and potential population threats faced in natural habitats. We found 25 haplotypes:15 from Uluguru and 9 from Udzungwa mountains populations, containing 49 polymorphic regions (32 parsimoniously informative and 17 singleton sites). Haplotype diversity (range: 0.849–0.995) did not differ substantially across populations but the median haplotype diversity for Udzungwa South was overall lower than for other populations. Nucleotide diversity averaged 0.00641, 0.01528, 0.0111 and 0.01313, respectively for Udzungwa South, Udzungwa North, Uluguru Rural and Uluguru Urban, suggesting high genetic diversity within the four populations. Analysis of molecular variance (AMOVA) indicated significantly high genetic differences between the four populations (FST = 0.16, p = 0.00098) whereas neutrality test (FU’s Fs) values were negative, indicating historical population expansion. Similarly, the Bayesian skyline analysis indicated a recent demographic expansion suggesting limited bottlenecks in the recent past in this population. Our results show the AGC population in EAMs consists of four distinct populations which have experienced a recent population expansion, especially among the urban population due perhaps to influence of urbanization process that may have favored assisted species movements across the rural-urban landscapes. Future research should focus on understanding impact of geographical isolation on the genetic structure and diversity of this species.
There is a growing body of literature about cane rat species but most of the published work is patchy and current spatial distribution is unknown which limits its wide application in the utilization of the species for the broader commercial game industry and for improving wildlife conservation across Africa. We conducted a systematic review of 56 years (1964 - 2020) of cane rat research to understand existing research gaps, to analyze the spatiotemporal and thematic patterns, and investigated factors that influence the publication of the cane rat research in widely recognized journal outlets. We found 308 publications on the cane rat species from 14 countries authored by 39 nationalities globally. The publications increased significantly over the study period, with 97.7% of these biased geographically and thematically towards the west and central African region. Further, the published research mostly covered one species, the greater cane rat, and none had covered the biogeography, food biology, and conservation of any of the two cane rat species in situ. Also, the author's nationality had the strongest influence on publishing the research in journals with or without impact factor. These results suggest that the financial limitation and quality of the research influenced most cane rat research published in local national or regional journals which mostly had limited accessibility for widespread research use to improve applied conservation programs. Expanding coverage of the cane rat research in other species-range countries in the east and southern African regions will be necessary to tap the species as a priority commercial game to reducing exploitation pressure on the wild mammal populations particularly in the African savannas where illegal hunting for bushmeat consumption is a growing problem.
The majority of goats in Tanzania belong to the Small East African (SEA) breed, which exhibits large phenotypic variation. This study aimed to determine the genetic structure of, and relationships among four populations (Sukuma, Gogo, Sonjo, and Pare) of the SEA breed that have not been studied adequately. A total of 120 individuals (24 from each population) were analysed at eight microsatellite loci. In addition, 24 goats of the South African Boer breed were used as reference. Observed heterozygosity (Ho) ranged from 0.583 +/- 0.04 for Sukuma to 0.659 +/- 0.030 for Gogo, while expected heterozygosity (He) ranged from 0.632 +/- 0.16 for Sukuma to 0.716 +/- 0.16 for Boer. Five loci deviated from Hardy-Weinberg equilibrium (HWE) across populations. The mean number of alleles ranged from 4.75 +/- 1.58 for Pare to 6.88 +/- 3.00 for Sukuma. The mean inbreeding coefficient (F-IS) ranged from 0.003 in Sonjo to 0.148 in Sukuma. The differentiation coefficient (F-ST) was highest (0.085) between Boer and Sukuma and lowest (0.008) between Gogo and Sonjo. The largest genetic distance (0.456) was found between Sukuma and Boer, while the smallest (0.031) was between Gogo and Sonjo populations. Pare, Gogo, and Sonjo populations, formed one cluster, while Sukuma and Boer populations formed two separate clusters. From the findings, it can be concluded that the SEA goats in this study showed high in population genetic variation, which implies that there is good scope for their further improvement through selection within populations. The Sukuma population, which has fairly high inbreeding, is moderately differentiated from Pare, Sonjo, and Gogo goat populations, which showed a high level of admixture. Conservation and improvement strategies of the goats should be designed with first priority being on Sukuma goats.
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The aim of this study was to investigate the maternal genealogical pattern of chicken breeds sampled in Europe. Sequence polymorphisms of 1256 chickens of the hypervariable region (D-loop) of mitochondrial DNA (mtDNA) were used. Median-joining networks were constructed to establish evolutionary relationships among mtDNA haplotypes of chickens, which included a wide range of breeds with different origin and history. Chicken breeds which have had their roots in Europe for more than 3000 years were categorized by their founding regions, encompassing Mediterranean type, East European type and Northwest European type. Breeds which were introduced to Europe from Asia since the mid-19th century were classified as Asian type, and breeds based on crossbreeding between Asian breeds and European breeds were classified as Intermediate type. The last group, Game birds, included fighting birds from Asia. The classification of mtDNA haplotypes was based on Liu et al.'s (2006) nomenclature. Haplogroup E was the predominant clade among the European chicken breeds. The results showed, on average, the highest number of haplotypes, highest haplotype diversity, and highest nucleotide diversity for Asian type breeds, followed by Intermediate type chickens. East European and Northwest European breeds had lower haplotype and nucleotide diversity compared to Mediterranean, Intermediate, Game and Asian type breeds. Results of our study support earlier findings that chicken breeds sampled in Europe have their roots in the Indian subcontinent and East Asia. This is consistent with historical and archaeological evidence of chicken migration routes to Europe.
The study aimed to evaluate the genetic diversity of Tanzanian chicken populations through phylogenetic relationship, and to trace the history of Tanzanian indigenous chickens. Five ecotypes of Tanzanian local chickens (Ching'wekwe, Kuchi, Morogoro-medium, Pemba and Unguja) from eight regions were studied. Diversity was assessed based on morphological measurements and 29 microsatellite markers recommended by ISAG/FAO advisory group on animal genetic diversity. A principal component analysis (PCA) of morphological measures distinguished individuals most by body sizes and body weight. Morogoro Medium, Pemba and Unguja were grouped together, while Ching'wekwe stood out because of their disproportionate short shanks and ulna bones. Kuchi formed an independent group owing to their comparably long body sizes. Microsatellite analysis revealed three clusters of Tanzanian chicken populations. These clusters encompassed i) Morogoro-medium and Ching'wekwe from Eastern and Central Zones ii) Unguja and Pemba from Zanzibar Islands and iii) Kuchi from Lake Zone regions, which formed an independent cluster. Sequence polymorphism of D-loop region was analysed to disclose the likely maternal origin of Tanzanian chickens. According to reference mtDNA haplotypes, the Tanzanian chickens that were sampled encompass two haplogroups of different genealogical origin. From haplotype network analysis, Tanzanian chickens probably originated on the Indian subcontinent and in Southeast Asia. The majority of Kuchi chickens clustered in a single haplogroup, which was previously found in Shamo game birds sampled from Shikoku Island of Japan in the Kochi Prefecture. Analysis of phenotypic and molecular data, as well as the linguistic similarity of the breed names, suggests a recent introduction of the Kuchi breed to Tanzania.
Genetic diversity and population structure of 113 chicken populations from Africa, Asia and Europe were studied using 29 microsatellite markers. Among these, three populations of wild chickens and nine commercial purebreds were used as reference populations for comparison. Compared to commercial lines and chickens sampled from the European region, high mean numbers of alleles and a high degree of heterozygosity were found in Asian and African chickens as well as in Red Junglefowl. Population differentiation (FST ) was higher among European breeds and commercial lines than among African, Asian and Red Junglefowl populations. Neighbour-Net genetic clustering and structure analysis revealed two main groups of Asian and north-west European breeds, whereas African populations overlap with other breeds from Eastern Europe and the Mediterranean region. Broilers and brown egg layers were situated between the Asian and north-west European clusters. structure analysis confirmed a lower degree of population stratification in African and Asian chickens than in European breeds. High genetic differentiation and low genetic contributions to global diversity have been observed for single European breeds. Populations with low genetic variability have also shown a low genetic contribution to a core set of diversity in attaining maximum genetic variation present from the total populations. This may indicate that conservation measures in Europe should pay special attention to preserving as many single chicken breeds as possible to maintain maximum genetic diversity given that higher genetic variations come from differentiation between breeds.