Arctic_LTREB
What controls long-term changes in freshwater microbial community composition?
Sequences contained in this archive include pyrosequences of barcoded, PCR-amplified V2 regions of bacterial 16S rRNA genes from lakes, streams, sediments, groundwater, and soils collected near the Toolik Field Station in arctic Alaska, and from other locations throughout the Arctic.  Funding for this project is provided by National Science Foundation grants DEB-0639790, DEB-0639805 and DEB-1026843.
Microbial ecology came to the forefront of biological and ecological science in the 1990s with the development of high-throughput DNA sequencing and other molecular techniques.  Recently this field entered a second age of understanding that microbial diversity was organized into patterns at various scales, consistent with ecological concepts that were once thought applicable only to macro-organisms.  Evidence of these patterns in diversity contradicts the traditional microbial hypothesis from Bass-Becking (1934) that “Everything is everywhere, but the environment selects,” and indicates that, as with larger organisms, dispersal processes influence microbial diversity even at regional and local scales.  It is clear that both dispersal and environmental conditions are related to patterns of diversity, but to date the mechanistic controls and the relative importance of these factors have not been determined.  This study aims to resolve these controls through a combination of field and lab experiments with monitoring and surveys of the phylogenetic composition and ecosystem function (metabolism) of microbial communities.  This research builds on a long-term record showing consistent spatial and temporal patterns of microbial growth and community composition in ~25 lakes and streams of the Toolik Lake Research Area in Arctic Alaska.  Using experiments coupled with established sampling protocols and routines, this research will answer 3 basic questions, and focus on the long-term aspects of dispersal events and climate change: (1) How does environment influence microbial community composition and rate of function? (2) How are distribution patterns of microbial communities in lakes, streams, and soils influenced by dispersal via down-slope water flow? (3) How are seasonal, inter-annual, and long-term shifts in microbial community composition related to temporal shifts in environmental conditions such as those caused by climate change?  Long-term investigations of microbial communities are critical for understanding patterns of diversity and their controls, especially because the most enduring dispersal events are also most rare.  Moreover, because this work is located in the Arctic it will capture the earliest biological effects of global climate change.