Molecular ecology and invasive species management: unravelling the dynamics of Lantana camara invasions in the Kruger National Park, South Africa using a molecular approach

The overall objective of my M.Sc project was to improve the current knowledge of the invasion dynamics of an invasive plant species, Lantana camara L., in South Africa's flagship protected area, Kruger National Park (KNP). Lantana camara is a global invader, occurring in approximately 60 countries and islands. The species is able to spread rapidly into regions where it has been introduced and is associated with a variety of negative impacts. Attempts at biological control of the species has had limited success owing to its uncertain taxonomy, ease of hybridisation and broad ecological amplitude.

An understanding of how L. camara establishes, spreads and disperses within protected areas will aid management efficiency, for example, by prioritizing areas for management operations. This thesis specifically explores the history, mechanisms of invasion, distribution patterns and spatial extent of dispersal of L. camara. The latter was restricted to a landscape scale, using in a river catchment system in the KNP as model system.

The thesis consists of three chapters. The first two are research chapters and the third a brief conclusion. In chapter one of the thesis I reviewed L. camara invasions in South Africa, with particular reference to the known drivers of invasive success. Specifically, the processes and factors that have contributed to the successful invasion of the species are explained using a framework developed for invasion ecology. Distribution patterns across biomes, ecoregions, and under current and changing climate scenarios in South Africa are modelled; and at a more localised scale, special emphasis is placed on the progression of spread and management of L. camara in KNP. Overall, this chapter provides priorities for research and forms the rationale for the research reported on in chapter two.

In the second chapter, I explored the use of molecular markers to assess the population genetic diversity and its distribution within and among L. camara populations, sampled within the Sabie-Sand River catchment in KNP. These estimates were then used to infer patterns of gene flow and identify the source(s) of propagules for invasions in KNP. Patterns of dispersal were then placed in context of current management practices to identify and prioritize future management units.