DNA–DNA hybridization is among a class of comparative techniques in molecular biology that produce distance data (versus character data) and that can be analyzed to produce phylogenetic reconstructions only using phenetic tree-building algorithms. In DNA–DNA hybridization, the percent similarity of DNA between two species is estimated by the reduction in hydrogen bonding between nucleotides of imperfectly complemented heteroduplex DNA (i.e., double stranded DNAs that are experimentally produced from single strands of two different species), compared with perfectly matched homoduplex DNA (both strands of DNA from the same species).
This revolutionary reordering was initially widely accepted by North American ornithologists, and the American Ornithologists' Union adopted some of its provisions. In other parts of the world its adoption has been more deliberative: it has been a major influence on existing classification schemes but hardly any authority adopted it in its entirety.
The classification appears to be an early example of cladistic classification because it codifies many intermediate levels of taxa: the "trunk" of the family tree is the class Aves, which branches into subclasses, which branch into infraclasses, and then "parvclasses", superorders, orders, suborders, infraorders, "parvorders", superfamilies, families, subfamilies, tribes, subtribes and finally genera and species. However the classification study did not employ modern cladistic methods, as it relies strictly on DNA-DNA hybridization as the sole measure of similarity.
The Sibley–Ahlquist arrangement differs greatly from the more traditional approach used in the Clements taxonomy.
|Basal divergences of modern birds|
in the Sibley–Ahlquist taxonomy
The major changes at order level are as follows:
Some of these changes are minor adjustments. For instance, instead of putting the swifts, treeswifts, and hummingbirds in the same order that includes nothing else, Sibley and Ahlquist put them in the same superorder that includes nothing else, consisting of one order for the hummingbirds and another for the swifts and treeswifts. In other words, they still regard the swifts as the hummingbirds' closest relatives.
Other changes are much more drastic. The penguins were traditionally regarded as distant from all other living birds. For instance, Wetmore put them in a superorder by themselves, with all other non-ratite birds in a different superorder. Sibley and Ahlquist, though, put penguins in the same superfamily as divers (loons), tubenoses, and frigatebirds. According to their view, penguins are closer to those birds than herons are to storks.
The new research suggested that the ducks and gallinaceous birds are each other's closest relatives and together form the basal lineage of neognathous (non-ratite) birds, distinct from the others which are collectively called Neoaves. The ratites and tinamous are followed by the ducks and their allies and the pheasants and their allies. Penguins, grebes and divers are placed with other groups that were traditionally considered more modern.
The Galloanseres (waterfowl and landfowl) has found widespread acceptance. The DNA evidence of Sibley–Ahlquist for the monophyly of the group is supported by the discovery of the fossil bird Vegavis iaai, an essentially modern but most peculiar waterfowl that lived near Cape Horn some 66-68 million years ago, still in the age of the dinosaurs.
Alden Holmes Miller (February 4, 1906 – October 9, 1965) was an American ornithologist and director of the Museum of Vertebrate Zoology at the University of California, Berkeley for 25 years. He published over 250 papers on the biology, distribution, and taxonomy of birds, and served as president of the American Ornithologists' Union (1953-1955) and the International Commission on Zoological Nomenclature (1964-1965), and as editor of The Condor from 1939 until his death. He was a member of the National Academy of Sciences.
Alden Miller was born February 4, 1906 in Los Angeles, California, the son of Loye H. Miller, a noted professor and researcher. He attended the University of California, Los Angeles, earning a B.A. in 1927, then enrolled in UC Berkeley, receiving an M.S. in 1928 and his PhD in 1930 under Joseph Grinnell. Ten years later he succeeded Grinnell as the director of the Museum of Vertebrate Zoology. He is noted for his studies of Lanius (the largest genus of shrikes) and juncos (sparrow-like birds). He received the Brewster Medal for his contributions to ornithology. Miller's approach to collections-based research employed "concepts, theories, practices, tools, and technologies from the laboratory, museum, and field."Miller supervised around 30 doctoral students and 15 master's students, many of whom became notable ornithologists in their own right. His doctoral students included Charles G. Sibley, who co-developed the Sibley–Ahlquist taxonomy of birds; author and conservationist A. Starker Leopold; and Richard C. Banks, founder of the Ornithological Council.Miller died of a heart attack at Clear Lake, California, on October 9, 1965, at the age of 59.Limpkin
The limpkin (Aramus guarauna), also called carrao, courlan, and crying bird, is a bird that looks like a large rail, but is skeletally closer to cranes. It is the only extant species in the genus Aramus and the family Aramidae. It is found mostly in wetlands in warm parts of the Americas, from Florida to northern Argentina. It feeds on molluscs, with the diet dominated by apple snails of the genus Pomacea. Its name derives from its seeming limp when it walks.Owl
Owls are birds from the order Strigiformes, which includes about 200 species of mostly solitary and nocturnal birds of prey typified by an upright stance, a large, broad head, binocular vision, binaural hearing, sharp talons, and feathers adapted for silent flight. Exceptions include the diurnal northern hawk-owl and the gregarious burrowing owl.
Owls hunt mostly small mammals, insects, and other birds, although a few species specialize in hunting fish. They are found in all regions of the Earth except polar ice caps and some remote islands.
Owls are divided into two families: the true (or typical) owl family, Strigidae, and the barn-owl family, Tytonidae.Sibley
Sibley may refer to:
Heliornis fulica is a small aquatic gruiforme found in the tropical and subtropical Americas from northeastern Mexico to central Ecuador and southern Brazil.It is the only living member of the genus Heliornis. The family Heliornithidae, to which it belongs, contains just two other species: the African Finfoot, Podica senegalensis, found in the Afrotropics from Sub-saharan West Africa and the Congo Basin through the Great Lakes' western shores to Southeast Africa, and the Masked or Asian Finfoot Heliopais personatus, found from eastern Indomalaya down through Sundaland to the Wallace Line.These waterfowl have broad lobes on their feet, convergent to that of grebes or coots, that they use to propel themselves in the water. They are reclusive birds, preferring well-covered slow-flowing streams and secluded waterways, sometimes swimming partly submerged, like an Anhinga.
Sungrebes are unique among birds in that males have "pouches", folds of skin under their wings in which they carry their young from hatching until the chicks are able to swim for themselves. This has led to them being called "Marsupial Birds"Sylvioidea
Sylvioidea is a superfamily of passerine birds, one of at least three major clades within the Passerida along with the Muscicapoidea and Passeroidea. It contains about 1300 species including the Old World warblers, Old World babblers, swallows, larks and bulbuls. Members of the clade are found worldwide, but fewer species are present in the Americas.