Dispersal: an engine of evolutionary diversification

While human-mediated long-distance dispersal (LDD) is a threat to biodiversity, owing to the invasive success of many alien species, there is evidence to show that historical LDD has stimulated diversification by presenting novel opportunities and conditions of ecological release. This idea, however, needs testing in a phylogenetically replicated manner.

Focusing on the large Asteraceae Core Clade (ACC; 24 000 species), which radiated initially in southern Africa (SA) and globally following repeated LDD to other continents, this project will test the hypothesis that LDD stimulates diversification at global and regional scales, producing a pattern of nested radiation.

It will also evaluate the factors that modulate the effect of LDD on diversification.

We will first generate a species-level phylogenetic tree for the SA-based ACC radiation including representatives of all out-of-SA radiations.

Using this tree as a framework for comparison, we will then compare diversification between out-of-SA emigrant clades and their non-dispersed SA sisters.

We will also use this tree to identify centres of Asteraceae diversification in SA and test the role of LDD in stimulating diversification within these.

Finally, by comparing population genetic diversity and structure in three sister species pairs representing recent LDD from SA to the Mediterranean, we will test the hypothesis that founder effects delay diversification following intercontinental LDD.