Neighbor-joining tree displaying the relationship between partial McyA sequences (76 to 78 amino acids). The coding system for the clones is as follows: LE03-1163, Lake Erie, year 2003, station 1163; LE03-WLEI, Lake Erie, year 2003, station WLEI; LE04-1163, Lake Erie, year 2004, station 1163; LE04-974, Lake Erie, year 2004, station 974; LE04-882, Lake Erie, year 2004, station 882. The numbers in parentheses after the codes for the clones indicate the number of identical sequences represented by these sequences. Accession numbers are in parentheses after the names for reference sequences obtained from GenBank. Bootstrap values of >50% (for 2,000 iterations) are displayed at the branch nodes. The scale bar represents substitutions per site.