Scientific drilling and biological evolution in ancient lakes: lessons learned and recommendations for the future

Abstract

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.

The paleoclimatic and geochronologic utility of coring red beds and evaporites: a case study from the RKB core (Permian, Kansas, USA)

“…Red is not dead: the paleoclimatic value of red bedsespecially paleo-loess Lake systems have long been considered an ideal environment to tap for paleoclimatic reconstructions, as (permanent) lakes archive a continuous or near-continuous record that enables analysis at high temporal resolution of multiple metrics of paleoclimate, including proxies reconstructed from lithology, magnetism, geochemical and isotopic signals (e.g., Brigham-Grette et al 2007;Cohen 2011). In recognition of this, research drilling for continental paleoclimatic reconstructions has focused in many cases on coring of modern, long-lived lake systems (e.g., Lake Malawi, Lake El'gygytgyn, Lake Titicaca, Lake Peten Itza) with records extending in some cases to the Pliocene and even late Miocene (Cohen 2011).…”

“…In recognition of this, research drilling for continental paleoclimatic reconstructions has focused in many cases on coring of modern, long-lived lake systems (e.g., Lake Malawi, Lake El'gygytgyn, Lake Titicaca, Lake Peten Itza) with records extending in some cases to the Pliocene and even late Miocene (Cohen 2011). The time continuum of the deposits is particularly useful, but lake sediments also offer the potential to utilize several different types of organic carbon-based proxy analyses, such as compoundspecific carbon isotopic ratios, and tetraether-based proxies (e.g., TEX-86 and isoprenoid glycerol dialkyl tetra ether; e.g., Tierney 2010).…”

“…Drilling marine sediments has been long exploited to clarify climate dynamics and atmospheric-oceanic linkages, especially for the Neogene, but extending even to the Cretaceous (e.g., IODP 2008). Continental climate reconstructions also benefit greatly from drill core data, and core from modern, long-lived lacustrine systems in particular have facilitated major advances in understanding climate dynamics of Earth's recent record, from the tropics to the poles (e.g., Lowenstein et al 1999;Scholz et al 2007;Cohen 2011;Melles et al 2012).…”

Modern sedimentation patterns in Lake El'gygytgyn, NE Russia, derived from surface sediment and inlet streams samples

“…Long high-resolution lake sediment records are known to well document regional hydrologic and climatic responses to atmospheric changes (Brigham-Grette et al, 2007a), and therefore are valuable archives of climate and environmental changes (e.g. Allen et al, 1999;Gasse et al, 2011;Cohen, 2012). Given their often continuous sediment sequences, large and old lake basins play an important role in collecting sedimentological information providing a continental signature to couple with the marine realm.…”

Scientific drilling and the evolution of the earth system: climate, biota, biogeochemistry and extreme systems

“…Key subject areas for science questions that can be addressed in the realm of stratigraphy and sedimentology include largescale basin geodynamics and source-to-sink issues (e.g., sediment budgets, long-term erosion rates, subsidence analysis, fault evolution), including biogeomorphological feedbacks, such as source-sink systems at major earth/life and climatic transitions. For example, fluvial records show a fundamental shift in stratigraphic architecture associated with major phytogeographic changes (Ward et al, 2000;Davies and Gibling, 2009) -an important set of transitions in the Phanerozoic earth system (atmosphere-biosphere). At finer timescales, cyclostratigraphy applied to continental drill core holds promise for casting new light on the dynamics of earth's orbit (e.g., Olsen and Kent, 1999).…”