Proposal (564) to South American Classification Committee
Merge Pipile into Aburria
Effect
on SACC: This would merge the cracid genus Pipile into Aburria
Background: Our current footnote summarizes the
situation:
The genus Pipile
is merged by some (Delacour & Amadon 1973,
Haverschmidt & Mees 1994) into Aburria.
Pipile is currently treated as a
separate genus in most classifications. Genetic data (Pereira et al. 2002,
Pereira & Baker 2004) indicate that Aburria
and Pipile are sister taxa, and this
is supported by morphological data (Grau et al. 2005). New genetic data (Grau
et al. 2005) indicate that Aburria aburri
is embedded within Pipile, thus
forcing the merger of Pipile into Aburria. SACC proposal to merge Pipile into Aburria did
not pass. Frank-Hoeflich
et al. (2007) presented morphological and genetic data to support the merger of
Pipile into Aburria. Eo
et al. (2009) were unable to support the monophyly of Pipile + Aburria because A. jacutinga fell outside the group. Proposal badly needed.
The original proposal for the merger of the two genera
failed because we were not impressed with the genetic data: N=1 individual of
each species, all based on blood samples from aviaries. So, not only are the identifications of
the samples based on faith and cannot be checked, but as some who commented
noted, cracids hybridize regularly in captivity. Although Pereira, Wajntal, and Grau, in their comments to SACC, defended their
identifications because two or more co-workers were present when blood samples
were drawn, this assumes that hybrids would be phenotypically obvious.
Since then, two additional studies have appeared. Frank-Hoeflich et al. (2007) analyzed 669 bp of
cyt-b and found that jacutinga was
the sister to the others including aburri,
corroborating earlier genetic results.
However, because they analyzed one of the same two mitochondrial genes
(Grau et al. sampled cyt-b and ND-2), such a result was expected. More important from my view is that
they evidently sampled different individuals, albeit from a single aviary (Estudillo
Lopez, Mexico City) and still N=1 for the Pipile
species, thus increasing confidence that the results of Grau et al. (2005) are
valid. Their analysis of 151
osteological characters revealed no differences between the 5 Pipile taxa analyzed and Aburria – they appear in their
Figure 2 as a monophyletic group but as a 6-way polytomy within the group. However, in their analysis of 74
morphological and behavioral characters, Aburria
is the sister to all the Pipile, and
within Pipile, jacutinga is the sister to the rest … in other words supporting the
conventional, traditional view based on plumage etc. When all three data sets are combined (their Figures 3 and
4), the tree places Aburria inside Pipile, i.e., jacutinga + (aburri + ((cujubi + (((cumanensis + grayi)))))).
Eo
et al. (2008) used a supertree approach to look at the phylogeny of Galliformes
and Anseriformes in general. Supertrees
combine previously published phylogenetic trees, whether based on genetic,
morphological, or behavioral information, to produce an overall phylogeny based
on parsimony. Thus, the outcome is
derived from existing phylogenies (in this case, all the studies mentioned
above), and conflicts among studies are resolved in a complicated but objective
way. Their supertree predicted
that Aburria was sister to all Pipile except jacutinga, which appeared in a polytomy with all Penelope, i.e. is not certainly the
sister to the other Pipile + Aburria.
Discussion: The merger of Pipile
into Aburria is not a new or
controversial idea – Delacour & Amadon (1973) did it. That they are minimally sister genera
is also not controversial. If the
mtDNA tree is a true species tree, not just a gene tree (a serious problem not
addressed by the previous studies), then merger of Pipile into Aburria is
required. The species tree vs.
gene tree problem was not addressed by those previous studies because the
pitfalls of single-locus phylogenies as representing the true historical
branching patterns of populations was not appreciated by most workers until
recently, in ornithology at least.
(In fact, I worry about some of the decisions that we have made in the
past based on a single gene tree.)
I think the possibility of the mtDNA representing a gene tree rather
than a species tree is a real one in this case because (1) mtDNA is probably
more likely to have these problems because of matrilineal inheritance, and (2)
the traditional view of relationships strongly favors Aburria and Pipile as
separate; in fact, some authors have treated jacutinga as a member of a superspecies with the other Pipile, and some authors have even
treated them all as conspecific. It’s
not just the plumage similarities among Pipile
vs. the much less-patterned Aburria
but also (A) the habitat (mostly lowland, often near water for Pipile, including jacutinga according to HBW; vs. strictly montane for Aburria), and (B) the vocalizations. The piping guans are named for their
very high-pitched, rising song, and the limited recordings
of jacutinga indicate
that it shares that vocalization with the Amazonian group, at least cumanensis (by someone named Mark Robbins)
and cujubi. In contrast, as noted by Thomas Donegan in the original
proposal, the voice of Aburria aburri is bizarre and unlike that of any other cracids (my
wife, listening to this next to me, refuses to believe it’s an actual bird). (Does Aburria have the ”propeller” wing display of Pipile? <check>)
Although we’re used to examples of plumage characters misleading us with
respect to phylogeny, I am concerned that such severe vocal differences between
Aburria and Pipile may reflect a species tree better than do 2700 bp of mtDNA.
Nonetheless,
let’s just say, hypothetically, that a DNA-sequence study with additional,
nuclear loci and multiple individuals of vouchered individuals of non-aviary
origin found that Aburria was indeed
sister to traditional Pipile? Then, in the subjective world of
generic limits, would we follow Delacour & Amadon in merging the two? After all, those authors were familiar
with these birds and assumed that jacutinga
was a Pipile <need to check discussion in D&A 1973>. On the other hand, Delacour & Amadon’s
philosophy on generic limits included merging of Nothocrax into broadly defined Crax,
a treatment no one follows.
However, note that Frank-Hoeflich
et al. (2007) were unable to distinguish Pipile from
Aburria in their osteological analysis.
Recommendation:
I have none – I look forward to the discussion and will vote after
reading what others have to say.
Those with stronger backgrounds in DNA sequence analysis should speak
out on the chances that the published results are just a gene tree. Those who really know these birds
should speak out on the subjective issue of whether the two genera should be
recognized even if jacutinga is a
true Pipile.
Literature cited (if anyone needs pdfs, just let
me know)
EO,
S. H., O. R. P. BININDA-EMONDS, AND J.
P. CARROLL. 2009. A phylogenetic supertree of the fowls
(Galloanserae, Aves). Zoologica
Scripta 38: 465–481.
FRANK-HOEFLICH,
K., L. F. SILVEIRA, J. ESTUDILLO-LÓPEZ, A. M. GARCÍA-KOCH, L. ONGAY-LARIOS, AND
D. PINERO. 2007. Increased taxon and character sampling reveals novel
intergeneric relationships in the Cracidae (Aves: Galliformes). J. Zool. Syst. Evol.
Res. 45: 242-254.
GRAU,
E. T., S. L. PEREIRA, L. F. SILVEIRA, E. HÖFLING, AND A. WAJNTAL. 2005.
Molecular phylogenetics and biogeography of Neotropical piping guans (Aves:
Galliformes): Pipile Bonaparte, 1856 is synonym of Aburria
Reichenbach, 1853. Molecular Phylogenetics & Evolution 35: 637-645.
PEREIRA,
S. L., A. J. BAKER, AND A. WAJNTAL.
2002. Combined nuclear and mitochondrial DNA sequences resolve generic
relationships within the Cracidae (Galliformes, Aves). Systematic Biology 51:
946-958.
Van Remsen, October 2012
Comments from Nores: “NO. Although the molecular study of Frank-Hoeflich
et al. (2007) supports merging both genera, the molecular analysis of Eo et al. (2009) does not.
Moreover, they
are not similar in plumage and the voice
of Aburria aburri is bizarre and unlike that of any other cracid
(Thomas Donegan). In addition, I do not agree with
sampling animals from aviaries, especially cracids
which hybridize regularly in captivity.”
Comments from Robbins: “Ugh, once again a subjective decision. Aburria has a unique voice and plumage
compared to Pipile species, but does
that merit generic recognition?
Even if there are issues with using just mitochondrial data, Aburria and Pipile are obviously closely related and thus this becomes an
arbitrary decision.”
Comments from Thomas
Donegan: "The new proposal is not based in
particular on much new data which was not available on the previous
proposal. The Frank-Hoeflich study was cited and discussed in the last
iteration, although in comments and not in the proposal itself. Eo et al
(2009) subsequently found Aburria/Pipile
not to form a monophyletic group consistent with previous
studies (contra Nores' comment: see their table of non-monophyly and their
phylogeny showing jacutinga in a
polytomy involving some Penelope
among others). However, Eo et al. (2009) is a super-tree study based on
essentially same data as used in the previous studies (Frank-Hoeflich et al.
and Sergio Pereira et al.'s various papers). As a result, Laurent Raty's
comments on the last proposal as regards the particular mtDNA strand which
supports the paraphyly of the Aburria/Pipile group (and the other, which
apparently does not so much) remain applicable. I don't
totally share others' innate distrust of aviary samples and would also
note that without these, a number of these species could only be sequenced
using ancient DNA. Pereira and his team have produced some really
interesting results especially as to issues like higher-level taxonomy, which
are less likely to be affected by inter-species hybridisation. As long as
one takes into account the possibility of aviary hybridisation and hence a
conservative approach to making taxonomic changes based on the data, then that
should be enough said. For such an endangered group like cracids -
and of big birds which are difficult to catch, and hence only sample-able by
shooting - there are few other ethical alternatives. One does sometimes
find cracid body parts (e.g. casques) in farms of local people in the
field and taking samples from these should perhaps be encouraged in the future
such that fieldworkers can help collate materials in order to some more
universally acceptable study materials.
“If further studies of other DNA parts
continue to support jacutinga being
basal to aburria (and the latter
being basal to the rest of Pipile)
then there is a real issue, not a question of taste. As Robbins
notes, the solution to the issue would then be a subjective matter.
Personally, I would think it a great shame (and Latin misnomer) to give the
Piping-Guans, which all pipe and are appropriately called "Pipile", a new name (Aburria), which is onamatopoeic for a
totally different bird and type of song. Although there are no
osteological differences, there are differences in bare skin/cere extent/shape,
which actually unite aburri with jacutinga (distinguishing both from the
rest of Pipile) and
massive vocal differences between Aburria
and the rest. Subjectively, and being familiar with all three 'groups'
(if not all the Pipile taxa) in the
field, I'd rather see "Yacutinga
jacutinga" or similar as a new monotypic genus and maintain Aburria aburri and the other Pipile where they are than lump the lot
of them into Aburria. This
opinion is not based particularly on genetic distance/divergence but also on
subjective, aesthetic considerations. But similar to Pearman on another
live proposal, I am not keen on making available what would be a controversial
a new genus name. For the avoidance of doubt in the event that these
interesting discussions are published one day, this paragraph is not intended
to constitute a genus description."
Comments from Stiles: “NO. I´d rather see jacutinga
in its own genus than lump Pipile into Aburria, which to me is a very different bird. The problem here may be that with only
data for mtDNA, we may be seeing a gene tree rather than a species tree, so we
really need some nuclear data to better sort this problem out.”
Comments
from Pacheco: “NO. Undoubtedly, a
subjective matter. Besides the glaring difference vocal between Aburria and Pipile, Wattled Guan apparently does
not produce sounds with their wings (See Rios et al. 2005 at: http://www.galliformes-sg.org/cracids/bull21.pdf).