Yellowstone National Park: A Window into the Interplay between Geological and Biological Evolution on Earth
Life began on a young Earth 3.5-3.8 billion years ago (bya), at a time of rampant meteor impact and volcanism. Soon thereafter, oceans cooled, continents emerged and broke apart, ecosystems developed, and the genus Homo came to maturity. However, prior to the origin of multicellular life ~ 1.2 bya, single celled microbial life ruled the planet. During this greater than 2.0 bya window of geological time, both the Earth and its biology evolved significantly, often in step. This dynamic interplay between geological and biological evolution has resulting in a world that is rife with functionally diverse microbial life that is specialized for narrow ecological niches. This presentation’s focus will be on the extant volcanic terrain of the Yellowstone hot spot, its influence on geography, and its ability to bridge our understanding of the diversification of microbial life through space and time. The extreme variation in the geochemical composition of present day environments is likely to encompass those that were present on early Earth, when key metabolic processes (e.g., photosynthesis) are thought to have evolved. Yellowstone National Park (YNP), Wyoming harbors >12,000 geothermal features that vary widely in temperature and geochemical composition, both spatially and temporally. For example, temperatures in YNP geothermal features range from ambient to 93°C (boiling at elevation of YNP), pH of thermal fluid ranges from less than 1.0 (i.e., the pH of battery acid) to nearly 10 (i.e., the pH of drain cleaner), and dissolved metal concentrations vary by up to six orders of magnitude (i.e., a factor of 1,000,000). Such geochemical heterogeneity provides a field laboratory for examining the tendency for organisms to inhabit particular ecological niches and to define the range of geochemical conditions tolerated by that functional guild. Moreover, by melding evolutionary analysis of the microbial populations present in each system with detailed geochemical analysis, we can begin to bridge our understanding of the spatial variation of environments with the temporal evolution of biodiversity. We assume that since it is unlikely that a metabolic process emerged under environmental conditions that no longer support that function, such information can provide insight into the characteristics of an environment that enabled the adaptation of microbial life into new habitats.