Proposal (680) to South American Classification Committee
Revise the linear sequence of cuckoos (Cuculidae)
Background: Cuckoos are geographically widespread and are highly diverse in size, morphology, and in life history (most notably in reproductive biology). For reviews of the classification of cuckoos, see Sibley and Ahlquist 1990 and Sorenson and Payne 2005. Although cuckoos are monophyletic, this diversity has been expressed taxonomically in recent years by classifying cuckoos in a diversity of families (Sibley and Ahlquist 1990, Sibley and Monroe 1990) or subfamilies (Sorenson and Payne 2005, Dickinson and Remsen 2013). The AOU (AOU 1998, current SACC classification) recognizes three subfamilies of New World cuckoos, which are listed in the sequence:
I don't know the historical basis for this sequence. The sequence adopted in the 20th century varied somewhat from author to author, but a common pattern was listing the genera Coccyzus (including Saurothera), Coccycua, and Piaya before the neomorphine and crotophagine genera, consistent with the current SACC arrangement (e.g., Ridgway 1916, Cory 1919, Peters 1940, Meyer de Schauensee 1966).
New information: Sorenson and Payne (2005) provided the most comprehensive phylogenetic survey of cuckoos, based on DNA sequence data from 202 individuals of 140 species. They resolved the crotophagine taxa (Guira, Crotophaga) as sister to the neomorphine taxa (Tapera, Dromococcyx, Morococcyx, Geococcyx, and Neomorphus); and collectively Crotophaginae + Neomorphinae are sister to all other cuckoos. The Sorenson and Payne phylogeny of cuckoos is remarkably complete, but is based entirely on mitochondrial DNA.
More recent phylogenetic studies provide independent support, however, for the outlines of the Sorenson and Payne phylogeny. Hackett et al. (2008), in a broad survey of the avian radiation using 32 kb of DNA sequence data from 19 nuclear genes, sampled seven genera of cuckoos. Consistent with Sorenson and Payne, Hackett et al. recovered Crotophaga as sister to Geococcyx, and these two as sister to all other cuckoos. Using a slightly more expansive data set, Burleigh et al. (2015) reported the same result.\
Therefore, the basal node in Cuculidae is that separating Crotophaginae + Neomorphinae from all other cuckoos. Using the standard conventions for translating a branching phylogeny into a linear sequence (i.e., that the branch that includes the smaller number of taxa is listed first), and considered the global patterns of cuckoo diversity, then these two subfamilies should be listed first, not last. Using the same rationale, Crotophaginae should be listed before Neomorphinae; and within Crotophaginae, Guira should be listed before Crotophaga.
The resulting revised linear sequence of cuckoos would be:
Recommendation: SACC should adopt the revised sequence, to better reflect the available evidence for the phylogeny of cuckoos.
American Ornithologists' Union. 1998. Check-list of North American birds. Seventh edition. American Ornithologists' Union, Washington, D.C.
Burleigh, J.G., R.T. Kimball, and E.L. Braun. 2015. Building the avian tree of life using a large-scale, sparse supermatrix. Molecular Phylogenetics and Evolution 84: 53-63.
Cory, C.B. 1919. Catalogue of birds of the Americas. Part II, number 2. Field Museum of Natural History Zoological Series volume 13, part 2, number 2.
Dickinson, E.C., and J.V. Remsen, Jr. (editors). 2013. The Howard and Moore complete checklist of the birds of the world. Fourth edition. Volume 1. Non-passerines. Aves Press, Eastbourne, United Kingdom.
Hackett, S.J., R.T. Kimball, S. Reddy, R.C.K. Bowie, E.L. Braun, M.J. Braun, J.L. Chojnowski, W.A. Cox, K.-L. Han, J. Harshman, C.J. Huddleston, B.D. Marks, K.J. Miglia, W.S. Moore, F.H. Sheldon, D.W. Steadman, C.C. Witt, and T. Yuri. 2008. A phylogenomic study of birds reveals their evolutionary history. Science 320: 1763-1768.
Meyer de Schauensee, R. 1966. The species of birds of South America and their distribution. Livingston Publishing Company, Narberth, Pennsylvania.
Peters, J.L. 1940. Check-list of birds of the world. Volume IV. Harvard University Press, Cambridge, Massachusetts.
Ridgway, R. 1916. The birds of North and Middle America. Part VII. Bulletin of the United States National Museum 50, part 7.
Sibley, C.G., and J.E. Ahlquist. 1990. Phylogeny and classification of birds: a study in molecular evolution. Yale University Press, New Haven, Connecticut.
Sibley, C.G., and B.L. Monroe, Jr. 1990. Distribution and taxonomy of birds of the world. Yale University Press, New Haven, Connecticut.
Sorenson, M.D., and R.B. Payne. 2005. A molecular genetic analysis of cuckoo phylogeny. Pages 68-94 in R.B. Payne, The cuckoos. Oxford University Press, New York, New York, and Oxford, United Kingdom.
Tom Schulenberg, September 2015
Comments from Remsen: “YES. Genetic data solid, and linear sequence conforms to conventions.”
Comments from Pacheco: “YES. In short, there is now a sequence supported by different data sets.”
Comments from Stiles: “YES, to be consistent with the genetic data for the cuckoos.”
Comments from Jaramillo: “YES – Data are solid; they correlate with behavior and morphology of the birds; nothing odd or surprising here.”
Comments from Stotz: “YES grudgingly. I recognize that this follows our convention, but nothing has been moved, the relationships we recognize are unchanged, but we flip the sequence that has been used for decades. Is there are any new information in this new sequence? Not as far as I can tell.”
Comments from Zimmer: “YES, for reasons already quoted in the proposal.”
Comments from Robbins: “YES, but I fully concur with Doug’s comments!”