Spatial scale and pitcher plant yeast community diversity

Background/Question/Methods

    Microbial metacommunity diversity is shaped by dispersal, among other community and metacommunity processes. However, the spatial scales at which dispersal is important for microbes are not yet well understood. We investigated community and genotype diversity of pitcher plant inhabiting yeasts on several spatial scales to better understand how space and dispersal interact to shape yeast communities. We hypothesized that there is a spatial scale at which barriers to dispersal become evident in both genotype and community diversity, but that the limiting spatial scale may differ for different community members. We intensively sampled yeast communities on a 500 m scale and cloned and sequenced fungal DNA to identify community members. We also cultured representatives of one yeast species, Candida glaebosa, over a 150 km scale for DNA extraction and AFLP genomic fingerprinting. Finally, we collected pitcher plant yeast communities and individual yeast cultures from five sites throughout the United States and Canada for community pyrosequencing and individual genotyping using AFLP.

Results/Conclusions

    Despite having previously found a temporal signature of yeast colonization on a 500 m scale, we found no spatial pattern of yeast community composition in the same metacommunity. In addition, C. glaebosa genome fingerprints showed no evidence of population subdivision on a 150 km scale. Analysis of yeast communities on a continental scale tells us which yeast species are restricted in their distribution and which are ubiquitous. Preliminary results indicate that, like other pitcher plant inhabitants, yeasts appear to show reverse latitudinal diversity and abundance gradients. Individual yeast genome fingerprints further indicate which yeast species are dispersal limited at continental or sub-continental scales. In conclusion, dispersal may limit pitcher plant yeast colonization on large spatial scales, but not smaller scales. At larger scales, dispersal may limit different yeast species to greater or lesser extents. Dispersal shapes metacommunity diversity to varying degrees depending on spatial scale, and different microbial species experience dispersal in different ways.