Document: DAV-3-57-7

Distribution and diversity of soil Crenarchaeota in the front range of the Rocky Mountains.

OLINE, D.K.*

University of Colorado, Boulder, CO 80309 USA ¹

Abstract:
Microbial communities exist at much smaller spatial scales than those of the macrobial plant and animal communities upon which most of our ecological theory is based. Biogeographical and landscape patterns of microbial distribution are ignored under the adage of "everything is everywhere, and the environment selects". Studies of microbial distribution typcially fall into two categories: 1) those at very small scales, such as different depths in a microbial mat, or 2) comparison of a small number of samples from widely scattered environments, such as different oceans. My study addressed how specific microbial communities change across environmental gradients at scales ranging from 10cm to 22km by using a nested systematic sampling design. I established transects of 10cm, 1m, 10m, 100m, and 1km at each of four sites representing the major plant community types (foothills forest, montane forest, subalpine forest, and alpine tundra) along an elevational gradient in the Front Range of the Rocky Mountains. From soil cores taken along these transects, I took a number of physical and chemical soil measurements in addition to extracting the total community DNA from the soil. I used PCR primers specific for subgroups of the terrestrial crenarchaeota, a newly identified group of Archaea with unknown metabolism, to amplify 16S rDNA sequences and denaturing gradient electrophoresis to separate the mixed community DNA into individual bands which can then be sequenced. Geostatistical analyses of soil pH, water content, and organic matter content reveal similar patterns of spatial autocorrelation with a range of a few meters; in contrast, soil biomass showed no significant autocorrelation at any scale. Preliminary data showed that there are groups of closely related sequences which are both widespread and abundant in lower elevation forest and tundra, and whose closest relatives have been identified in agricultural soil in Wisconsin. However, the subalpine forest site was dominated by members of a distinct and deeply branching clade previously identified from boreal forest soil in Finland. This is surprising, as the subalpine forest is in the midst of the elevational gradient and not at either extreme, yet there was a high degree of community turnover between it and neighboring sites.

Keywords: environmental gradients, soil, crenarchaeota, multiple scales

This abstract is being presented at: 8:00 AM in session:
Oral Session #23: Soil Ecology.