The Lantana camara species complex includes some of the world’s worst weeds, with serious economic and environmental impacts globally. Efforts to understand and manage invasive lantana have been hindered by its wide range of phenotypic variation and plasticity: it is challenging to define and identify taxa, and therefore to predict the impacts of any given lantana population, and to apply targeted management approaches. The extent of genetic diversity underlying this broad phenotypic diversity is unknown, so the extent to which genetic diversity has contributed to lantana’s success as a pantropical invader (e.g., by promoting adaptive potential) is also unknown.
Geographically extensive population-scale sampling combined with genome-wide marker sequencing reveals unprecedented insight into the composition and ancestry of invasive lantana. Several divergent sub-lineages are present across Australia, New Zealand, South Africa, and Hawaii, consistent with the notion that the complex comprises multiple species and their hybrids. While sub-lineages are strongly differentiated from one another, genetic diversity within major sub-lineages is low, suggesting genetic bottlenecks in sub-lineage formation.
In Australia, two major sub-lineages are dominant and widespread over approximately 3,000 km of the eastern coast; they share overlapping distributions where they commonly grow in sympatry, but rarely hybridise. This study begins to explore putatively adaptive traits among sub-lineages, and to investigate whether genetically uniform sub-lineages represent “general-purpose genotypes” or whether there is evidence for local adaptation despite their low overall genetic diversity.