The idea of an ecosystem taught in high school often consists of an immense variety of floras and faunas. Lush green vegetation turns brown in autumn; antelopes gallop in an open field; creeks murmur amid the forest. This serene picture stands in stark contrast to the microscopic ecosystem that exists within the clefts of rocks. There, one could find ancient microbes from hundreds to thousands of years ago. These micro-organisms include bacteria and the algae and fungi they feed on. The DNA of these robust survivors provides great insights into their evolution under shifting harsh climates over the centuries.
Professor Lowenstein and his team from Binghamton University have examined water droplets — fluid inclusions — trapped within salt crystals in rock cervices for years. Samples have been collected from the US and Italy. The team has found a plethora of creatures and plants from antiquity that have lived and withstood the extreme salinity and heat within the cracks. Temperature inside the faults could have been as high as 130 Fahrenheit. Citing from scientist Brian Schubert on the team, these microbes rely on dead cells of algae for food and energy for survival and repair of damaged DNA.
Survival of the fittest accounts for the longevity of these micro-organisms. Similar to their human counterpart, these bacteria have evolved complex protective mechanisms in addition to hibernating as an endospore over the years to endure the diverse and unforgiving climatic conditions. Researcher Schubert’s study shows that the mechanism for survival is a low level of continuous DNA repair and metabolic activity. Genetic changes in response to the environment are imprinted in their genome. Their DNA sequence thus is the best place to examine in order to unravel their evolution under climatic influences.
References
1. “Researchers kick-start ancient DNA” Biology News Net; November 22, 2010
2. “How do prokaryotes survive in fluid inclusions in halite for 30 k.y.?” Geology; December 2009; v. 37; no. 12; p. 1059-1062
