Files in this Data Supplement:

• Supplemental file 1 - Ribotype diversity within Alphaproteobacteria for all GOS samples (Fig. S1).
  Zipped EPS file, 2MB.
• Supplemental file 2 - LIBSHUFF plots showing statistical difference in ribotype diversity between habitats (Fig. S2).
  Zipped PDF file, 536K.
• Supplemental file 3 - Rarefaction curves and Chao1 estimate curves as calculated by DOTUR (Fig. S3).
  Zipped PDF file, 255K.
• Supplemental file 4 - Reference sequences used to classify 16S rRNA homologs into taxonomic bins (Table S1).
  Zipped MS Word document, 21K.
• Supplemental file 5 - Limitations of RDP Classifier for classifying marine microbes (Table S2).
  Zipped MS Word document, 10K.
• Supplemental file 6 - Ribotype classification for each GOS sample (Table S3).
  Zipped PDF file, 255K.
• Supplemental file 7 - Comparison of ribotype diversities between this study and that of Rusch et al. (Table S4).
  Zipped MS Word document, 10K.
• Supplemental file 8 - Diversity, richness, and evenness scores for each GOS site (Table S5).
  Zipped MS Word document, 14K.
• Supplemental file 9 - Estimated genes per genome and average genome equivalents sequenced in each GOS site (Table S6).
  Zipped MS Word document, 14K.