Geology topics

Research about Kruger National Park

Source-linked reports with geographic coverage including Kruger National Park.

8 recordsLinked to original sources

USGS2025

Comparative genomics of Bacillus anthracis A and B-clades reveals genetic variation in genes responsible for spore germination

Bacillus anthracis , the causative agent of anthrax, is composed of three genetic clades (A, B, and C). Clade-A is the most common and distributed worldwide, B-clade has a narrow geographic distribution, and C-clade is rare. South Africa's Kruger National Park (KNP) has high diversity of B. anthracis , with strains from A and B clades described from its northernmost region, Pafuri. We employed whole genome sequencing to investigate the genomic diversity of B. anthracis strains isolated from animal carcasses ( n = 34) during the 2012–2015 outbreaks. Whole-genome single-nucleotide polymorphism (wgSNP) analysis assigned the 2012–2015 B. anthracis genomes to the A-clade branch, distributed across the branch's two minor sub-clades A.Br.005/006. Additionally, pan-genomic analysis distinguished the A- and B-clade genomes, identifying unique accessory genes. Notable genetic differences include the biosynthetic spore cell wall genes; long-chain fatty acid CoA ligases ( FaD13 ), Bacillus collagen-like protein of anthracis (BclA) involved in the exosporium germination, as well as a truncated murein DD-endopeptidase ( mepH ) found in the pXO2 plasmid of the B-clade strains. The tryptophan synthase subunit alpha gene ( trpA ), which results in a pseudogene in B-clade genomes separates the A- and B-clade genomes. These differences in biosynthetic cell wall genes suggest variation in adaptability or cell growth of the B-clade strains in the environment, further influenced by the truncation of the trpA gene involved in spore germination. The A.Br.005/006-clade strains in KNP exhibit higher genetic diversity, which may enhance their resilience to environmental stressors. In contrast, the KNP B-clade (B.Br.001/002) strains show limited genetic variation, potentially reducing their adaptability. This pattern is evident through whole-genome SNP analysis and pan-genomics investigating the evolution of B. anthracis .

Kruger National Park↗

USGS2024

Roles of host and environment in shift of primary anthrax host species in Kruger National Park

Environmental and climatic factors, as well as host demographics and behaviour, significantly influence the exposure of herbivorous mammalian hosts to pathogens such as Bacillus anthracis , the causative agent of anthrax. Until the early 1990s in Kruger National Park (KNP), kudu ( Tragelaphus strepsiceros ) was the host species most affected by anthrax, with outbreaks occurring predominantly in the dry season, particularly during drought cycles. However, the most affected host species has shifted to impala ( Aepyceros melampus ), with more frequent anthrax outbreaks during the wet season. This study investigates the roles of environmental variation and other host species in this shift. Temporal trends in environmental variables such as precipitation, soil moisture, temperature, and normalised difference vegetation index (NDVI) were analyzed in relation to anthrax occurrence (presence/ absence and counts). Additionally, correlations between host species’ densities and anthrax mortalities over time were examined. Anthrax cases in 1990 were concentrated in the central and northern regions of KNP(excluding Pafuri), primarily affected kudus; while subsequent mortalities affected mostly impala and were restricted to the far north, in Pafuri. Significant correlations were found between kudu anthrax mortality and a decrease in NDVI, average temperature, SPI-6 and SPI-12 (Standardised Precipitation Index in various time intervals. Conversely, anthrax occurrence in impalas was associated with a decline in SPI-3, and temperature rise, with increased mortality during the rainy season. Elephant density correlated negatively with kudu mortality, but a positive correlation with both impala mortality and impala density. The study concludes that environmental variables and species’ densities may alter the diversity and frequency of hosts exposed to B . anthracis . Climate extremes and alterations therein may exacerbate anthrax severity by modifying species susceptibility and their probability of exposure over time.

Kruger National Park↗

USGS2022

How lions move at night when they hunt?

Movement patterns of lions ( Panthera leo ) reveal how they hunt large herbivores in heterogeneous landscapes such as the Kruger National Park in South Africa. Large herbivores are distributed differently on the landscape and therefore have different vulnerabilities as prey for lions. For instance, blue wildebeest ( Connochaetes taurinus ) occupy small grazing lawns at night but are difficult for lions to capture because open areas lack cover for stalking. African buffalo ( Syncerus caffer ) aggregate in large herds but are less available because these herds only intermittently enter the home ranges of individual lion prides. Unlike large herds of wildebeest and buffalo, plains zebra ( Equus quagga ) move widely in small herds while browsing greater kudus ( Tragelaphus strepsiceros ) and giraffes ( Giraffa camelopardalis giraffa ) generally occur in lower densities. We used spatial data derived from GPS collars to investigate several hypotheses regarding the movements of three lion prides in response to their prey. We found that lions were most active and moved longer distances during nighttime than during daytime. Lions remained within their core home ranges on 87% of nights and wandered to the outlying areas of the home ranges every second night. Lions visited grazing lawns, that is, area of short grass, where wildebeest herds resided every second night, and moved toward the direction of buffalo herds within 2 km of vicinity. Lions spent more time near riverbanks that provided dense woody cover at night than expected but concentrated only weakly near sites with surface water where herbivores drank in the dry season. Our study contributes to understanding how lions vary their movements in response to the spatial and temporal heterogeneity in the relative availability and vulnerability of multiple prey species.

Kruger National Park↗

USGS2015

Context-dependent survival, fecundity and predicted population-level consequences of brucellosis in African buffalo

Chronic infections may have negative impacts on wildlife populations, yet their effects are difficult to detect in the absence of long-term population monitoring. Brucella abortus , the bacteria responsible for bovine brucellosis, causes chronic infections and abortions in wild and domestic ungulates, but its impact on population dynamics is not well understood. We report infection patterns and fitness correlates of bovine brucellosis in African buffalo based on (1) 7 years of cross-sectional disease surveys and (2) a 4-year longitudinal study in Kruger National Park (KNP), South Africa. We then used a matrix population model to translate these observed patterns into predicted population-level effects. Annual brucellosis seroprevalence ranged from 8·7% (95% CI = 1·8–15·6) to 47·6% (95% CI = 35·1–60·1) increased with age until adulthood (>6) and varied by location within KNP. Animals were on average in worse condition after testing positive for brucellosis ( F = −5·074, P < 0·0001), and infection was associated with a 2·0 (95% CI = 1·1–3·7) fold increase in mortality (χ 2 = 2·039, P = 0·036). Buffalo in low body condition were associated with lower reproductive success ( F = 2·683, P = 0·034), but there was no association between brucellosis and pregnancy or being observed with a calf. For the range of body condition scores observed in the population, the model-predicted growth rate was λ = 1·11 (95% CI = 1·02–1·21) in herds without brucellosis and λ = 1·00 (95% CI = 0·85–1·16) when brucellosis seroprevalence was 30%. Our results suggest that brucellosis infection can potentially result in reduced population growth rates, but because these effects varied with demographic and environmental conditions, they may remain unseen without intensive, longitudinal monitoring.

Kruger National Park↗

USGS2009

Disease, predation and demography: Assessing the impacts of bovine tuberculosis on African buffalo by monitoring at individual and population levels

Summary Understanding the effects of disease is critical to determining appropriate management responses, but estimating those effects in wildlife species is challenging. We used bovine tuberculosis (BTB) in the African buffalo Syncerus caffer population of Kruger National Park, South Africa, as a case study to highlight the issues associated with estimating chronic disease effects in a long‐lived host. We used known and radiocollared buffalo, aerial census data, and a natural gradient in pathogen prevalence to investigate if: (i) at the individual level, BTB infection reduces reproduction; (ii) BTB infection increases vulnerability to predation; and (iii) at the population level, increased BTB prevalence causes reduced population growth. There was only a marginal reduction in calving success associated with BTB infection, as indexed by the probability of sighting a known adult female with or without a calf ( P = 0·065). Since 1991, BTB prevalence increased from 27 to 45% in the southern region and from 4 to 28% in the central region of Kruger National Park. The prevalence in the northern regions was only 1·5% in 1998. Buffalo population growth rates, however, were neither statistically different among regions nor declining over time. Lions Panthera leo did not appear to preferentially kill test‐positive buffalo. The best (Akaike's Information Criterion corrected for small sample size) AIC c model with BTB as a covariate [exp(β) = 0·49; 95% CI = (0·24–1·02)] suggested that the mortality hazard for positive individuals was no greater than for test‐negative individuals. Synthesis and applications . Test accuracy, time‐varying disease status, and movement among populations are some of the issues that make the detection of chronic disease impacts challenging. For these reasons, the demographic impacts of bovine tuberculosis in the Kruger National Park remain undetectable despite 6 years of study on known individuals and 40 years of population counts. However, the rainfall and forage conditions during this study were relatively good and the impacts of many chronic diseases may be a non‐linear function of environmental conditions such that they are only detectable in stressful periods.

Kruger National Park↗

USGS2006

Assessing vaccination as a control strategy in an ongoing epidemic: Bovine tuberculosis in African buffalo

Bovine tuberculosis (BTB) is an exotic disease invading the buffalo population ( Syncerus caffer ) of the Kruger National Park (KNP), South Africa. We used a sex and age-structured epidemiological model to assess the effectiveness of a vaccination program and define important research directions. The model allows for dispersal between a focal herd and background population and was parameterized with a combination of published data and analyses of over 130 radio-collared buffalo in the central region of the KNP. Radio-tracking data indicated that all sex and age categories move between mixed herds, and males over 8 years old had higher mortality and dispersal rates than any other sex or age category. In part due to the high dispersal rates of buffalo, sensitivity analyses indicate that disease prevalence in the background population accounts for the most variability in the BTB prevalence and quasi-eradication within the focal herd. Vaccination rate and the transmission coefficient were the second and third most important parameters of the sensitivity analyses. Further analyses of the model without dispersal suggest that the amount of vaccination necessary for quasi-eradication (i.e. prevalence < 5%) depends upon the duration that a vaccine grants protection. Vaccination programs are more efficient (i.e. fewer wasted doses) when they focus on younger individuals. However, even with a lifelong vaccine and a closed population, the model suggests that >70% of the calf population would have to be vaccinated every year to reduce the prevalence to less than 1%. If the half-life of the vaccine is less than 5 years, even vaccinating every calf for 50 years may not eradicate BTB. Thus, although vaccination provides a means of controlling BTB prevalence it should be combined with other control measures if eradication is the objective.

Kruger National Park↗

USGS2004

Integrating association data and disease dynamics: an illustration using African Buffalo in Kruger National Park

Recognition is a prerequisite for non-random association amongst individuals. We explore how non-random association patterns (i.e. who spends time with whom) affect disease dynamics. We estimated the amount of time individuals spent together per month using radio-tracking data from African buffalo and incorporated these data into a dynamic social network model. The dynamic nature of the network has a strong influence on simulated disease dynamics particularly for diseases with shorter infectious periods. Cluster analyses of the association data demonstrated that buffalo herds were not as well defined as previously thought. Associations were more tightly clustered in 2002 than 2003, perhaps due to drier conditions in 2003. As a result, diseases may spread faster during drought conditions due to increased population mixing. Association data are often collected but this is the first use of empirical data in a network disease model in a wildlife population.

Kruger National Park↗

USGS2003

Ecological implications of bovine tuberculosis in African Buffalo herds

Following the recent invasion of bovine tuberculosis (BTB) into the Kruger National Park, South Africa, we conducted a study on the maintenance host, African buffalo, to investigate associations between BTB prevalence and calf:cow ratio, age structure, body condition, and endoparasite load. Statistical analyses compared herds of zero, medium (1–40%), and high (>40%) BTB prevalence. To control for ecological variation across the park we collected data in northern, central, and southern regions and restricted some analyses to particular regions of the park. Body condition declined over the course of the 2001 dry season, and buffaloes in the southern region of the park, with the highest BTB prevalence, were in worse condition than buffaloes in the northern region (which receives less annual rainfall but is still virtually BTB-free). Herd-level analyses of the entire park, the south and central regions, and just the southern region all indicated that herds of higher BTB prevalence were in worse condition and lost condition faster through the dry season than herds of lower BTB prevalence. Fecal endoparasite egg counts increased during the dry season and were associated with both decreased body condition and increased BTB prevalence. Although we did not detect any obvious effect of BTB on the age structure of the buffalo population, our findings indicate early symptoms of wider scale BTB-related ecological disturbances: buffalo herds with high BTB prevalence appear more vulnerable to drought (because of a decrease in body condition and an increase in endoparasite load), and because lions selectively kill weak buffaloes their prey base is accumulating a disproportionately high prevalence of BTB, to which lions are susceptible. Rea10.1890/02-5266d More: http://www.esajournals.org/doi/abs

Kruger National Park↗