Population size and genetic diversity of Nigerian lions (Panthera leo)

Sammanfattning: High growth rate in human populations, agricultural developments and industrialization have impinged negatively on the natural habitats of most large carnivores, causing fragmentation, isolation and consequently reduction in population size. Lions (Panthera leo) that once roamed most parts of Southern Europe, Asia, the Middle East, North America, northern part of South America and most parts of Africa are today found only in parts of sub-Saharan Africa and at a single site in India. Even in these areas, they are increasingly confined to supposedly protected areas where their numbers are gradually decreasing. In West Africa, lions are found only in national parks, game reserves and zoological gardens. In Nigeria, the only areas known to still have wild lions are Yankari Game Reserve (YGR), in Central North East and Kainji-Lake National Park (KLNP), in the West. I investigated the trend of events into the decline of lions by reviewing lion articles as far back as possible with the aim of understanding variables responsible for their decline over the years. I employed the method of non-invasive sampling of faeces in this study to gather information about the population size of lions in Nigeria. However, studies that employ non-invasive sampling are often confronted with pitfalls due to degraded DNA and non-uniform distribution of sloughed intestinal cells of the focal species in the faeces, which can result in low genotyping success. It is therefore important to store samples in conditions that can preserve the minute DNA quantity in the faeces at the time of collection prior to laboratory analysis. I investigated which medium may be most appropriate for storage of lion faecal DNA, and I found that amplification success was highest for samples preserved in ethanol. I investigated the pattern of phylogeographic distribution of the Nigerian lions and lions in other parts of Africa and India. The aim was to understand the genetic make-up of the Nigerian lion within the West and Central African range so as to aid in future conservation and management decisions. I found that the two lion populations in Nigeria have different origins. Lions in YGR resemble more closely Cameroon lions while the population in KLNP resembles closely the lion population in Benin. Furthermore, I conducted a pilot study in YGR using lion faecal samples collected opportunistically along game viewing and patrol tracks to test the feasibility and reliability of obtaining DNA from faeces collected from a tropical environment to identify individuals. This method proved feasible as eleven individuals were identified from two polymorphic microsatellite loci. The feasibility of the pilot survey prompted the extension of the study to KLNP with the aim to estimate the population size and the level of gene flow that may exist between these two lion populations. I found that the number of individuals within YGR and KLNP are small and there was no evidence for gene flow between them. To secure the long-term persistence of wild lions in Nigeria will require immediate and concerted actions from state, national and regional stakeholders.