Confirmation of a portion of the Sibley-Ahlquist ''tapestry''

DNA-DNA hybridization was used to compare seven taxa from five avian orders, 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-galliform and coliiform-strigiform-columbiform clades, and resolution within 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 significant rate variation among the lineages. Despite this result, the UPGMA algorithm applied to symmetrized data gave a topology identical to the Delta T50H and Delta NPH FITCH trees, whether or not the outgroup alligator was included. However, phenograms calculated from unsymmetrized Delta s of all three indices associated Bubo and Colius, as did the FITCH tree based on a completed matrix reconstructed from Sibley and Ahlquist's original data. Thus, our results support Sibley and Ahlquist's use of Delta T50H to assess ordinal patterns in avian phylogeny, replicate a portion of their ''tapestry'' based on the same DNA-DNA hybridization technique, and show that for these taxa least-squares and phenetic algorithms generate much the same topology.