[Jovanovska] 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
German Title: Die Bedeutung von Umweltfaktoren in adaptiven Radiationen: Integration genetischer, fossiler und paläoökologischer Informationen zum Verständniss der Treibkräft der Diatomeenevolution in den ostafrikanischen Rift-Seen
Current Status: approved
Main Applicant:Dr. Elena Jovanovska
Begin: 1 April, 2020
Conveyor End: 31 March, 2022
Conveyor Duration: 24
Adaptive radiation – the rapid diversification of a common ancestor into an array of closely related species as a consequence of adaptations to various ecological niches – is the process commonly considered responsible for much of the taxonomic and phenotypic richness on Earth. Some of the most iconic examples of adaptive radiation are Darwin’s finches on the Galápagos archipelago, anole lizards on the islands of the Caribbean, and cichlid fishes in the East African Rift lakes (EARL). What is unique about the EARL is that, compared to other island-like settings, they house many other groups of aquatic organisms that potentially evolved via adaptive radiation.
However, many of these are greatly understudied and their adaptive nature and rapid diversification has not yet been demonstrated, calling for an in-depth and integrative examination of these groups and the role of environment in adaptive radiations. This proposed project aims to combine information from the fossil records and paleoenvironmental data from three ICDP projects in combination with a thorough examination of the phylogeny, morphology, and ecology of extant species of diatoms from lakes Tanganyika, Malawi, and Challa to address a key question in evolutionary biology: Does the environment trigger simultaneous adaptive radiation across taxa? I propose to focus on four genera of diatoms with a documented high species richness and phenotypic diversity in the EARL. Preliminary analyses of the well-preserved fossil records including several extinct and undescribed diatom species and time-calibrated molecular phylogenies of two genera suggest a common ancestry and a rapid diversification. This is compatible with the history of the lakes as well as with the age of the enigmatic cichlid fish adaptive radiations in these lakes. Within four working packages, I will first test whether the criteria of adaptive radiations are fulfilled in diatoms and whether species diversification and phenotypic differentiation are driven by paleoenvironmental changes documented in the sediment cores. This project provides the unique opportunity to assess whether the EARL indeed house parallel adaptive radiations in different organisms, which would be an outstanding feature in comparison to other islandlike systems. In addition, I would also be able to identify common underlying drivers of volutionary radiations. The integration of extant and extinct species in a joint evolutionary analysis is expected to massively increase the accuracy of evolutionary inference. The here proposed methodological improvements and the much better understanding of the drivers of evolutionary radiations are of high interest for evolutionary biologists. Importantly, this project will contribute to the anticipated Lake Tankanyika scientific drilling project by establishing baseline data from diatom species, a crucial clade in the reconstruction of the evolutionary and ecological history of aquatic systems.
Jovanovska, Elena, Wilson, Mallory C., Hamilton, Paul B., Stone, Jeffery R. (2023). "Morphological and molecular characterization of twenty-five new Diploneis species (Bacillariophyta) from Lake Tanganyika and its surrounding areas" Phytotaxa p1-102