Deep drilling in Europe's oldest and most species-rich lake provides new insights into evolution

The older and more stable an ecosystem is, the longer lived its species and the more stable the species communities are. An international research team,  led by scientists from the Justus Liebig University Giessen and the University of Cologne and with participation of Dr Aleksandra Cvetkoska (Utrecht University as well as the Netherlands Institute of Ecology, NIOO-KNAW), Dr Timme H. Donders and Prof. Friederike Wagner-Cremer from Utrecht University, gained these new insights into evolution by drilling deep into the sediments of Lake Ohrid. The 1.4 million year old lake on the border between Albania and Northern Macedonia is not only the oldest lake in Europe, but with more than 300 endemic species, i.e. species that only occur there, it is also the most species-rich.

The 1.4 million year old Lake Ohrid on the border between Albania and Northern Macedonia (Photo credit: Thomas Wilke).
The 1.4 million year old Lake Ohrid on the border between Albania and Northern Macedonia (Photo credit: Thomas Wilke)

To study the evolutionary dynamics of Lake Ohrid since its formation, the scientists combined the environmental and climate data of a 568-meter-long sediment core with the fossil records of over 150 endemic diatom species. The data showed that shortly after the formation of the lake, new species emerged within a few thousand years. Many of them died out again very quickly in the relatively small and shallow lake. The research team explains this by the fact that young lakes of small size offer many new ecological opportunities, but are also particularly sensitive to environmental changes such as fluctuations in temperature, lake level and nutrients.

Colorized scanning electron microscope image of the endemic diatom species Scoliodiscus glaber from Lake Ohrid. Size of the silica shell 0.1 mm (Photo credit: Z. Levkov)
Colorized scanning electron microscope image of the endemic diatom species Scoliodiscus glaber from Lake Ohrid. Size of the silica shell 0.1 mm (Photo credit: Z. Levkov)

After the lake became deeper and larger, the speciation and extinction processes slowed down dramatically. The scientists attribute this to fewer new habitats emerging, the species richness approaching an ecological carrying capacity and an increasing environmental and climate buffering of the lake. The finding that in the history of Lake Ohrid, a volatile assemblage of evolutionarily short-lived species developed into a stable community of long-lived species provides a new understanding of the evolutionary dynamics in ecosystems. The study, which has now been published in the journal Science Advances, will thus also have great significance for future biodiversity research.

Drilling platform for deep drilling in Lake Ohrid (Photo credit: Thomas Wilke)
Drilling platform for deep drilling in Lake Ohrid (Photo credit: Thomas Wilke)

“The unique dataset from the lake is one of the first of its kind and can be used as a test case of different evolutionary concepts and models” said Dr Aleksandra Cvetkoska. “Its unprecedented diversity in combination with the length of the record makes it truly special.”

Article

Thomas Wilke, Torsten Hauffe, Elena Jovanovska, Aleksandra Cvetkoska, Timme Donders et al., ‘Deep drilling reveals massive shifts in evolutionary dynamics after formation of ancient ecosystem’, Sciences Advances (2020) vol. 6, no. 40, eabb2943. doi.org/10.1126/sciadv.abb2943