Proposal (383) to South American Classification Committee
Effect
on SACC:
This would split our current order Falconiformes into two, with only the
Falconidae remaining in the Falconiformes.
Background: Most classifications, including ours,
recognize a broadly defined Falconiformes to include not only the Falconidae
but also all the hawks, eagles, kites, and relatives plus Pandionidae and
Sagittariidae. Without doing a thorough
literature review, I think I can get away with saying that there has always
been some doubt about the monophyly of broad Falconiformes. Google gives something like 49,00 hits on Accipitriformes,
including an official Wikipedia entry, and Google Scholar produces 492
citations that use Accipitriformes.
Other than the obvious superficial similarities, I am not aware of any
solid genetic data that supports the monophyly of our current Falconiformes. Livezey & Zusi (2007) consider the
Strigiformes as sister to broadly defined Falconiformes, with Pandion sister to Falco +Polyborus. However, this same morphological analysis
still supports a sister relationship between Gaviiformes and Podicipediformes,
which is not consistent with any genetic dataset. Therefore, many conclude that even
sophisticated morphological analyses cannot distinguish convergence from true
relationships.
New data:
Hackett et al.’s (2008) massive analysis set new standards in gene sampling: 32 kilobases
of aligned DNA sequences that included 19 nuclear loci. They found strong support (98% Maximum
Likelihood bootstrap) for a node (“F”) that includes Falconiformes broadly
defined plus Strigiformes …. But that clade also includes Passeriformes, Psittaciformes,
Cariamiformes, Piciformes, Coraciiformes, Trogoniformes, and Coliiformes … and
thus only marks one of the major groups of modern birds. The nodes within this clade are not as
strongly supported, but Node B, with 73% bootstrap support shows Falconidae as
sister to Psittaciformes + Passeriformes.
[Tangentially, I am impressed with the similarities between falcons and parrots
that include the bony tubercle in the nares, the notched mandible, and nesting
biology – yes, I recognize that tallies of similarities do not count per
se]. The branching pattern among the
remaining groups is probably best considered a polytomy, except for Node D,
which shows Leptosomus of Madagascar
as sister to Coraciiformes + Piciformes + Trogoniformes. Sagittariidae + (Pandionidae + Accipitridae)
is supported as a monophyletic group with 100% support.
Analysis
and Recommendation: Given the absence of any non-morphological
data that I know of that supports the monophyly of broadly defined
Falconiformes, given that the best and most thorough analysis to date does not
support this monophyly, and given the long history of doubts concerning this
monophyly reflected in widespread use of Accipitriformes, I conclude that he
burden-of-proof now lies on those who would consider our Falconiformes as
monophyletic … and so I recommend a YES
on this. However, as pointed out to me
by Mike Braun, statistically one cannot reject the possibility that the
traditional Falconiformes is monophyletic – to quote from an active MS by Dave
Steadman et al. “while none of the analyses in Hackett et al. (2008) supported monophyly
of the traditional Falconiformes, these same analyses were not able to reject
monophyly of this group.” So, a NO vote would
indicate that the possibility of monophyly has to be rejected, and a YES vote
would indicate that support for them as a monophyletic group is uncorroborated
and that nonmonophyly is strongly suggested by the data.
Lit Cit
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.
LIVEZEY, B. C., AND
R. L. ZUSI. 2007. Higher-order phylogeny of modern birds (Theropoda, Aves:
Neornithes) based on comparative anatomy. II. Analysis and discussion.
Zoological J. Linnean Society 149: 1-95.
Van Remsen, November 2008
Comments
from Stiles:
“YES. The massive data from the Hackett et al. study in particular make it
clear that the traditional Falconiformes is polyphyletic, with the adaptations
for diurnal raptorial habits being convergences between the falcons et al. and
the acciptrids et al.; hence separate orders are clearly justified.”
Comments
from Nores:
“YES. Del análisis molecular
de Hackett et al. (2008) surge claramente que Accipitridae y Falconidae son dos
grupos muy diferentes, a pesar del garan parecido morfológico que presentan las
especies. Este es para mi uno de los ejemplos más notables de convergencia que
muestra que el análisis sólo morfológico, como se ha acostrumbrado hacer, no
siempre es el correcto. Lo que si, ese mismo análisis muestra que Cathartidae
está muy cerca de Accipitridae y no debería ser considerado un orden aparte.
Por esta razón, pongo ahora un NO a la propuesta No. 361, que todavía no había
contestado.”
Additional
comments from Remsen: “With respect to Manuel’s point concerning
Cathartiformes, the Hackett et al. data do not confirm a monophyletic
Accipitriformes if Cathartidae is included.
Close, yes, but not necessarily forming a monophyletic group. Further, I support Order rank for cathartids
regardless of possible sister status with accipitrids because this lineage is
as old or older than most lineages ranked as orders.”
Comments
from Jaramillo:
“YES – This is indeed an amazing example of convergence, and I accept that it
makes sense to separate Accipitriformes from Falconiformes. I have also been
impressed with similarities between parrots and falcons, once I thought about
them upon reading this paper. There is a lot there to “chew on” that makes
sense.”
Comments from Zimmer:
“YES. I also agree with Van regarding Order rank
for cathartids.”
Comments from Pacheco:
"YES. Plenamente
justificável a partir dos dados genéticos.”
