Project Details
Projekt
The role of environment in adaptive radiations: Integrating genetic, fossil, and paleoenvironmental information to infer drivers of diatom evolution in the East African Rift lakes
Applicant
Elena Jovanovska, Ph.D.
Subject Area
Geology
Term
since 2020
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 439182658
Adaptive radiation is commonly considered as a primary process for generating much of the Earth’s biodiversity. This process operates over different temporal and geographical scales, strongly depending on natural selection, stochastic events, and historical contingencies. Radiations are a common evolutionary phenomenon in insular habitats, as exemplified by Darwin's finches on the Galapagos Islands, anole lizards on the islands of the Caribbean, and cichlid fishes in the East African Rift lakes. While the latter systems house radiations in many other groups of aquatic organisms, the mechanisms and causes of adaptive radiation have largely been examined in the cichlids. Despite great success in unraveling the dynamics and drivers of cichlid adaptive radiations, we still know very little about the contribution of abiotic and biotic factors to this process in this group as well as in the iconic examples of adaptive radiation, which is largely due to the lack of fossils. Therefore, in this project, originally requested for three years but then funded for two, we investigate adaptive radiation in diverse and fossil-rich groups of aquatic diatoms in the East African Rift lakes, the genera Diploneis and Afrocymbella. We use an integrative approach that combines molecular phylogenetics with paleontological and paleoenvironmental data from three ICDP projects to address a key question in evolutionary biology: Does the environment trigger simultaneous adaptive radiations across taxa? So far, we have been able to combine fossils and densely sampled time-calibrated molecular phylogenies to demonstrate that the two diatom groups have evolved in situ within the Rift from a common ancestor in a relatively short time. This fulfilled one of the criteria for demonstrating adaptive radiation, and also confirms previous findings on the history of lakes, and is compatible with the age of the cichlid adaptive radiations. Having completed the most time-consuming parts of the project, we will now use the phylogenetic framework in the eventual third year to infer mode and tempo of diversification and trait evolution and correlate their trajectories with paleoenvironmental variables (e.g., glacial-interglacial cycles, monsoon activities, and megadroughts) to determine potential environmental influences on adaptive radiation. The integrative analysis of genetic, morphological, paleontological, and paleoecological data will allow us not only to identify the potential of parallel adaptive radiations in different organisms, but also to more robustly assess the processes that shape the progression of adaptive radiation. In addition, we have shown that adaptive radiation in diatoms may be more prevalent than previously thought, supporting the general view that this process is a major contributor to the Earth’s biodiversity.
DFG Programme
Infrastructure Priority Programmes
International Connection
Belgium, Canada, Switzerland, USA
Cooperation Partners
Dr. Christine Cocquyt; Paul Hamilton; Professor Dr. Walter Salzburger; Professor Dr. Jeffery Stone
