DNA sequencing has become the work horse of the modern taxonomist and great strides have been made in understanding the evolutionary relationships of birds by comparing the sequences of representative genes in the nuclear and/or mitochondrial genomes. However, the results are sometimes ambiguous or seem surprising based on other criteria. A report published this week in the journal Science describes a consortium effort to sequence much large region of avian genomes to improve the comparisons. Headed by Shannon Hackett, an ornithologist at The Field Museum of Natural History in Chicago, Illinois, the team determined and compared the sequences of 19 genes (~32,000 nucleotides) from a total of 169 bird species. Across the spectrum there are surprises and within the 'seabirds' the biggest to me is the fact that grebes appear totaly unaligned with loons (divers). The latter cluster closely with penguins and albatrosses/petrels and not too far from herons, storks and pelicans and similar 'totipalmate' birds. This supports the notion of a major clade of evolutionarily related waterbirds. Grebes on the other hand sit on a very distant branch of the cladogram with flamingos, consistent with prior studies (van Tuinen et al. 2001).
Hackett SJ, Kimball RT, Reddy S, Bowie RC, Braun EL, Braun MJ, Chojnowski JL, Cox WA, Han KL, Harshman J, Huddleston CJ, Marks BD, Miglia KJ, Moore WS, Sheldon FH, Steadman DW, Witt CC, Yuri T. A phylogenomic study of birds reveals their evolutionary history. Science. 2008 Jun 27;320(5884):1763-8.
M. van Tuinen, D. B. Butvill, J. A. W. Kirsch, S. B. Hedges.(2001) Convergence and divergence in the evolution of aquatic birds. Proc. R. Soc. London Ser. B 268,1345.
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