Establishment of a novel approach to trace Lake Tanganyika's gastropod faunal evolution

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ICDP corings have opened a new era of exploration of lake histories and have also increased their focus on biological evolution. Lake Tanganyika (LT) is Africa’s oldest and deepest lake and well known to be a global hotspot of freshwater biodiversity. LT has faced a series of marked shifts in the ecological conditions including lake-level fluctuations at different magnitudes, separation and re-joining of sub-basins, opening and closing of the basin, and varying connections to major rivers systems. The thalassoid (marine-like) gastropods of LT represent the most outstanding example of any freshwater gastropod radiation in terms of morphospace and size occupation of the shells. Remarkable, the origin of the superflock has been intensively debated but remains unclear to date.An exciting new approach for species delimitation is proteomic fingerprinting, which uses the discriminative power of specific mass profiles of peptides and small proteins generated with Matrix-Assisted Laser Desorption/Ionization Time-Of-Flight Mass Spectrometry (MALDI-TOF MS). Another novel approach – shell palaeoproteomics – holds significant potential for a new proxy system for reconstructing palaeofaunas of a lake. It extents the proteomic fingerprinting approach to non-living material, here proteins embedded in crystalline structure of mollusc shells (so-called intracrystalline proteins). By developing a protein library based on both recent and fossil shells of all gastropod (and bivalve) species of a particular region or ecosystem, palaeocommunities could be reconstructed even with reworked and largely destroyed fossil material. These conditions are often met in lake sediments and particular in those of ancient lakes such as Lake Tanganyika.The main goal of this proposal is to understand how the extraordinary biodiversity and endemicity in LT evolved by developing a new integrated analytical approach employing proteomic fingerprinting, shell palaeoproteomics, DNA barcoding and biodiversity modelling to trace species diversification and (meta-)community evolution. Based on general questions that are relevant for the overall scientific deep-drilling goal - Identifying drivers of endemic biodiversity through deep time - the following specific objectives will be targeted during this study: (1) Establishment of the proteomic fingerprinting and shell palaeoproteomics approach, (2) Identification and characterization of recent and fossil gastropod assemblages to spatially trace community gradients and turnover, and (3) Testing Pleistocene faunal affinities and limnological connections of LT to connected rivers and lakes Kivu and Rukwa.Due to the lack of well-preserved fossils in many lake sediments, the approach of using intracrystalline proteomic data from shell remnants and a library from recent taxa to model major evolutionary events in the past will be of great interest for geologists and palaeontologists.