FIG. 2.

Dendrograms with jackknife values derived from the jackknife cluster environments option of the UniFrac metric with estuarine environments excluded to test the hierarchical influence of combined categories. (A) Salinity/proximity of the coastline; (B) salinity/latitude; (C) salinity/geographic location; (D) latitude/proximity of the coastline. Numbers of sequences included in the tested habitats are given in parentheses. Not all possible combinations are displayed, since combined categories containing fewer then 10 sequences were excluded from the analyses (used abbreviations: freshwater, fre; marine, mar; hypersaline, hyp; coastal, coa; open ocean, ooc; tropics, tro; nontropics, ntr; Panama Channel, pan; Caribbean Sea, car; Galapagos Island, gal; Indian Ocean, ind; North American East Coast, nor; Sargasso Sea, sar).