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Humboldt-Universität zu Berlin - IRI Life Sciences

IRI Colloquium: Wolfgang Miller - "Unorthodox transmission modes of endosymbionts in hybrids and the symbiotic origin of speciation"

Medical University of Vienna
When Nov 03, 2016 from 04:00 PM (Europe/Vienna / UTC100) iCal
Where Philippstr. 13, Building 18, Maud Menten Hall (3rd Floor)


Although not a new idea, recent studies suggest that differences in the composition of symbiotic microbes between hosts can lead to reproductive isolation, and as a consequence also to speciation. Despite the fact that microbes are universally present in eukaryotes, they are rarely considered as a driving force of speciation, and chances are their contribution to speciation is overlooked. Symbiotic bacteria of the genus Wolbachia are known to affect their hosts’ reproduction in adaptive manners to improve the propagation of the maternally transmitted endosymbiont throughout populations. These reproductive alterations that can result in postmating isolation via cytoplasmic incompatibilities, have recently been shown to foster also premating isolation in some host symbiont associations such as the Drosophila paulistorum species complex, giving even more reason to assume that Wolbachia can play a significant role in host speciation. 

Here we will present most recent data on the involvement of Wolbachia in host speciation using two different insect systems, i.e., Neotropical Drosophila and African tsetse flies, both presently under incipient speciation in nature, carrying closely related but incompatible Wolbachia strains. We will also show that naturally incompatible and sterile interspecies hybrids of both systems can be rescued by means of mild paternal Wolbachia-knockdown before forced mating, giving rise to fertile progeny and thereby stable hybrid lines via sib mating. Even more surprisingly, such rescued hybrid lines show complete sexual isolation to their parental lines plus unambiguous signatures of paternal inheritance of both their cytoplasmic endosymbionts, i.e., of mitochondria and Wolbachia.