Featured Projects:
our latest work...
Read more
Botswana Lion Genetics Project
Simon Dures
-
Botswana is one of only seven countries believed to have a lion population of over 1 000 individuals and, as such, has considerable responsibility in ensuring that it can effectively protect a stable and healthy population of these animals.
Over the past century, the lion populations of Africa have undergone dramatic contraction in range due to human encroachment, as well as considerable population reduction from hunting, both as a pest and trophy species. This has affected the size of both the overall lion meta-population in Botswana and any individual isolated populations. The consequences of such changes in population structure, amongst other effects, results in modified community composition, smaller population sizes, and decreased population connectivity.
The isolation of many populations as a result of anthropogenic barriers is highly likely to prevent individual dispersal and gene flow. Under this scenario there is a significant chance that lion populations will lose genetic diversity via increased genetic drift in small, isolated populations, increasing their susceptibility to the effects of stochastic events; in turn this can lead to the increased risk of localised extinction.
The current global lion population is believed to be around 30 000 individuals and a recent population estimate for the Okavango Delta was estimated at 1 500 individuals. Estimates of the size that a population is required to maintain a viable long term population varies from 500 to 5 000 individuals. This, however, assumes the population is not influenced by overlapping generations, unequal sex ratios, fragmented habitat and other life history and biogeographic traits.
Therefore the current population size, both locally and internationally, appears to be on the cusp of falling into unsustainable inbreeding, risking the long term sustainability of the population. If there is significant inbreeding and genetic mutation within the local populations already, as is likely, urgent conservation management will be required to sustain this charismatic population long in to the future.
1.To determine current levels of genetic variation using measures of heterozygosity (i.e., gene differences), the effective population size, and the degree of inbreeding in the resident lion population. Genetic biopsy darting followed by laboratory analysis will be used to determine this.2.To analyse past genetic differences of the populations residing in the Delta to provide some indication of past population size, how heterozygosity has changed with time and what goals conservationists should address in limiting the loss of regional genetic variation in future lion conservation planning. Genetic sampling from historic lion tropies followed by laboratory analysis used.3.To use biogeographic analysis to assess the relationship between genetic variation and current degree of lion population fragmentation, isolation / connectivity and human density through remote sensing and ground truthing of this data. -
The primary goal of this project is to develop a comprehensive understanding of the past and present genetic structure of the lion population centred in Botswana’s Okavango Delta. From this, hopefully, future genetic trends can be predicted and suitable management plans informed to mitigate any negative possible future scenarios.
In addition, the project aims to identify possible genetic risks faced by the lion population in northern Botswana; these may have developed through reduced dispersal possibilities due to natural fragmentation, fragmentation through hunting barriers, and lack of dispersal due to reduced game movements across the entire system.
Objectives
1. To determine current levels of genetic variation using measures of heterozygosity (i.e., gene differences), the effective population size, and the degree of inbreeding in the resident lion population. Genetic biopsy darting followed by laboratory analysis will be used to determine this.
2. To analyse past genetic differences of the populations residing in the Delta to provide some indication of past population size, how heterozygosity has changed with time and what goals conservationists should address in limiting the loss of regional genetic variation in future lion conservation planning. Genetic sampling from historic lion tropies followed by laboratory analysis used.
3. To use biogeographic analysis to assess the relationship between genetic variation and current degree of lion population fragmentation, isolation / connectivity and human density through remote sensing and ground truthing of this data.Methodology
Initially 60 to 100 samples from within the Delta will be collected using biopsy darts. Once sampling of this area has been completed the study will be extended to enable comparisons with lion prides in other areas.
Each individual lion will be darted and photographed. Facial whisker patterns and scarring will be used to identify individual lions to reduce repeat sampling. Where age is not already known, each individual will be placed into a cohort category based upon the ‘pinkness’ of the nose.Historical data will be gathered from museum material (e.g. Natural History Museum of Zimbabwe, Bulawayo) and from the collections of hunters. Using hair samples and ancient DNA techniques, these individuals will be analysed at the same microsatellite loci as biopsy samples, providing a historic estimate of genetic diversity.
To analyse biogeographic influences on heterozygosity we will use remote sensing and survey techniques to develop a series of independent variables that can be considered in describing lion movements and habitat (e.g. vegetation, proximity to water, prey population density, historical hunting activities, connectivity and isolation). A combination of correlation analysis and path analysis will be used to clarify those variables with the strongest influence on current levels of lion genetic differences.
Initially 60 to 100 samples from within the Delta will be collected using biopsy darts. Once sampling of this area has been completed the study will be extended to enable comparisons with lion prides in other areas.Each individual lion will be darted and photographed. Facial whisker patterns and scarring will be used to identify individual lions to reduce repeat sampling. Where age is not already known, each individual will be placed into a cohort category based upon the ‘pinkness’ of the nose.Historical data will be gathered from museum material (e.g. Natural History Museum of Zimbabwe, Bulawayo) and from the collections of hunters. Using hair samples and ancient DNA techniques, these individuals will be analysed at the same microsatellite loci as biopsy samples, providing a historic estimate of genetic diversity.To analyse biogeographic influences on heterozygosity we will use remote sensing and survey techniques to develop a series of independent variables that can be considered in describing lion movements and habitat (e.g. vegetation, proximity to water, prey population density, historical hunting activities, connectivity and isolation). A combination of correlation analysis and path analysis will be used to clarify those variables with the strongest influence on current levels of lion genetic differences.
