Secondary contact zones
Our group aims more broadly to understand the barriers to gene flow, especially at an advanced stage of the speciation process. For this we study zones of secondary contact between closely related lineages or species of butterflies in the Alps. Such secondary contact zones provide the unique opportunity to study the evolutionary processes that underlie speciation, because barriers to gene flow are often not fully established. For example, we showed that Erebia tyndarus & E. cassioides form a very narrow secondary contact zone that is moreover stable for at least half a century. Our genomic analyses showed that only few hybrids occur and that the two species are separated by the presence and absence of an endoparasitic bacterium Wolbachia.
The two subspecies of E. euryale – adyte and isarica also form narrow secondary contact zones in the Alps. Here, we could show that the two subspecies primarily fly in alternating years, suggesting that temporal isolation could be a driving factor that keeps the two species apart.