pnas.org
(molecular systematics / nest structure / echolocation / birds)
Patricia L. M. Lee, Dale H. Clayton, Richard Griffiths, and Roderic D. M. Page
Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, United Kingdom
Communicated by Richard Southwood, University of Oxford, Oxford, United Kingdom, March 11, 1996 (received for review August 14, 1995)
Swiftlets are small insectivorous birds, many of which nest in caves and are known to echolocate. Due to a lack of distinguishing morphological characters, the taxonomy of swiftlets is primarily based on the presence or absence of echolocating ability, together with nest characters. To test the reliability of these behavioral characters, we constructed an independent phylogeny using cytochrome b mitochondrial DNA sequences from swiftlets and their relatives. This phylogeny is broadly consistent with the higher classification of swifts but does not support the monophyly of swiftlets. Echolocating swiftlets (Aerodramus) and the nonecholocating “giant swiftlet” (Hydrochous gigas) group together, but the remaining nonecholocating swiftlets belonging to Collocalia are not sister taxa to these swiftlets. While echolocation may be a synapomorphy of Aerodramus (perhaps secondarily lost in Hydrochous), no character of Aerodramus nests showed a statistically significant fit to the molecular phylogeny, indicating that nest characters are not phylogenetically reliable in this group.
Present address: Department of Genetics, University of Cambridge, Downing Street, Cambridge CB2 3EH, United Kingdom.
Present address: Division of Environmental and Evolutionary Biology, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, U.K.
