CONFIRMATION OF A PORTION OF THE SIBLEY-AHLQUIST TAPESTRY

DNA-DNA hybridization was used to compare seven taxa from five avian o rders, with an alligator as outgroup. Complete matrices of Delta T50H and Delta NPH (both symmetrized and unsymmetrized) gave the same FITCH topology, which was supported in 100% of bootstrapped and jackknifed trees. The outgroup alligator rooted the tree between anseriform-galli form and coliiform-strigiform-columbiform clades, and resolution withi n the latter favored a strigiform-columbiform association. In contrast , Delta T-m gave differing and more poorly supported FITCH resolutions for deeper nodes because the distances were compressed due to greatly reduced NPHs. An F-ratio test between FITCH and KITSCH trees based on symmetrized Jukes-Cantor-corrected Delta T(50)Hs indicated significan t rate variation among the lineages. Despite this result, the UPGMA al gorithm applied to symmetrized data gave a topology identical to the D elta T50H and Delta NPH FITCH trees, whether or not the outgroup allig ator was included. However, phenograms calculated from unsymmetrized D elta s of all three indices associated Bubo and Colius, as did the FIT CH tree based on a completed matrix reconstructed from Sibley and Ahlq uist's original data. Thus, our results support Sibley and Ahlquist's use of Delta T50H to assess ordinal patterns in avian phylogeny, repli cate a portion of their ''tapestry'' based on the same DNA-DNA hybridi zation technique, and show that for these taxa least-squares and phene tic algorithms generate much the same topology.