Exploration of the reproductive barrier between noug (Guizotia abyssinica) and its progenitor Guizotia scabra ssp. schimperi

Domestication can be used to study the formation of barriers to reproduction because much is known about the selective forces at work during the process of domestication as well as the general timeline under which it occurs. Studying domestication may reveal how barriers to reproduction arise quickly and may give insight into speciation under natural conditions. Barriers to reproduction are very important in the context of domestication because this process is thought to occur in sympatry with the wild progenitor (Dempewolf 2011). To assess whether gene flow can readily occur between a crop and its wild progenitor, the entire reproductive barrier must be assessed. This barrier can be broken down into four parts. The pre-pollination barrier encompasses geography, habitat, mechanical and temporal isolation between the two species. The post-pollination pre-zygotic barrier includes the effects of pollen competition and genetic incompatibilities. If a hybrid is formed, it may be subject to intrinsic post-zygotic barriers of hybrid sterility and inviability. A surviving hybrid is lastly subject to external postzygotic barriers which are reductions in fitness due to the external environment (Rieseberg & Willis 2007).