Mechanisms of Reproductive Isolation During Rapid Speciation
Sina Rometsch – Hector Fellow Axel Meyer
Reproductive isolation, the ceased exchange of genetic material, is crucial for the divergence of populations into distinct species. This is commonly facilitated by an extrinsic physical barrier, but rarely it can also occur devoid of such barriers. Whether speciation proceeds by the same or different reproductive isolation mechanisms under these two geographic scenarios remains a matter of debate. We aim to contribute to this fundamental question in biology by taking advantage of a model system of speciation: the Midas cichlid fishes.
Speciation is the emergence of reproductive isolation mechanisms among groups of individuals, which ultimately leads to divergence into distinct species. While this is most commonly the result of a physical barrier that prevents the exchange of genetic material entirely (allopatry), it can also occur within the same environment devoid of such barriers (sympatry). However, determining if the same reproductive isolation mechanisms evolve in allopatry and sympatry has been difficult, most likely due to the lack of systems, where species with similar genomic backgrounds have evolved under both geographic scenarios.
The Nicaraguan Midas cichlid fishes provide a great study system to investigate the evolution of reproductive barriers because this species complex is comprised of closely related sympatric and allopatric species. To date, 13 species of Midas cichlids have been described that inhabit two ancient great lakes and several younger crater lakes that were recently colonized (~2,000 to 20,000 years ago).
This project, supervised by Hector Fellow Prof. Dr. Axel Meyer, will study different aspects of reproductive isolation: premating, postmating-prezygotic and postzygotic isolation. By combining behavioural, molecular and developmental approaches, we aim to provide comprehensive insights into different mechanisms of reproductive isolation and will contribute to the understanding of speciation – still a fundamental problem in evolutionary biology.
Midas cichlid couple defending their offspring. Picture used with courtesy of Ad Konings.
Sina RometschUniversity of Konstanz
Hector Fellow since 2011