Scientific drilling to recover sediment core and fossil samples is a promising approach to increasing our understanding of species evolution in ancient lakes. Most lake drilling efforts to date have focused on paleoclimate reconstruction. However, it is clear from the excellent fossil preservation and high temporal resolution typical of lake beds that significant advances in evolutionary biology can be made through drill core studies coordinated with phylogenetic work on appropriate taxa. Geological records can be used to constrain the age of specific lakes and the timing of evolutionarily significant events (such as lake level fluctuations and salinity crises). Fossil data can be used to test speciation and biogeographic hypotheses and flesh out phylogenetic trees, using a better-resolved fossil record to estimate timing of phylogenetic divergences. The extraordinary preservation of many fossils in anoxic lake beds holds the hope of collecting fossil DNA from the same body fossils that improve our understanding of morphological character evolution and adaptation. Moreover, fossils allow calibration of molecular clocks, which are currently largely inferential. Lake Malawi Drilling Project results provide some guideposts on what might be expected in a drilling project for studies of evolution. The extreme variability in lake level and environmental history that most ancient lakes experience (exemplified by the Lake Malawi record) demonstrates that no one drilling locality is likely to provide a complete record of phylogenetic history for a radiating lineage. Evolutionary biologists should take an active role in the design of drilling projects, which typically have interdisciplinary objectives, to ensure their sampling needs will be met by whatever sites in a lake are ultimately drilled.
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Acknowledgments This work was supported by US National Science Foundation Grant EAR0602350, and the International Continental Scientific Drilling Program and facilitated by assistance from the National Lacustrine Core Repository (LacCore). I thank my many colleagues with the Lake Malawi Scientific Drilling Project for their support, Thomas Wilke, Christian Albrecht, and Roland Schultheiss for their hospitality during my visit to Giessen, where a number of the ideas discussed here were hatched, and the organizers of SIAL 5 Sasho Trajanokvski and Thomas Wilke for the invitation to discuss these ideas at beautiful Lake Ohrid, to Doug Hafner, Jim Russell and Sasha Prokopenko for help with data for Fig. 5 and Mike McGlue for help with Fig. 6. Thanks also to Lisa Park, Peter Reinthal, Ellinor Michel, Jon Todd, and an anonymous reviewer for helpful comments on an earlier version of this manuscript.
Copyright 2012 Elsevier B.V., All rights reserved.
- Ancient lakes
- Scientific drilling