Abstract

Speciation is considered as a continuous process where diverging populations go through different stages: from the initiation of reproductive isolation to its completion. However, observing the process of speciation in its entirety is generally difficult and most studies are compelled to look at a snapshot of divergence and reproductive isolation at one specific stage. Studying clades with multiple pairs of taxa varying in their extent of genetic, phenotypic and ecological divergence will be necessary to shed light on how genetic differences and reproductive isolation accumulate along the speciation continuum. Gorteria diffusa, an endemic Asteraceae from Southern Africa, represents a fascinating case of intraspecific diversification with 14 morphotypes varying mainly in floral morphology (colour, positioning and complexity of petal spots). These morphotypes present various degree of genetic divergence, are distributed in parapatry and meet at contact zones where they hybridize in various extent. In this study, we combine field, experimental and molecular approaches to study multiple hybrid zones in the species and investigate the evolution of reproductive isolation.