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 onomatopoeic
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).
Comments from Zimmer:
“NO. I’m having a real hard time buying that Aburria is more
closely related to all other Pipile than these are to P. jacutinga.
I can certainly accept the latter as basal to other Pipile, but aside
from differences in the extent of bare skin on the face and cere, everything
about jacutinga screams Pipile to me, including its voice, its
behavior, its overall plumage pattern and morphology, and its altitudinal
distribution (predominantly lowland, marginally into lower foothills of the
Atlantic Forest, i.e. < 1000 m), and its preference for riverine
forest. On the other hand, Aburria,
with its completely divergent voice, even more extensively feathered head
(relative to jacutinga versus all other Pipile), relatively
unpatterned plumage, lack of mechanical wing display sounds, and montane Andean
distribution seems like a fairly different beast. I could support
lumping all Pipile with Aburria into a single
genus over segregating jacutinga in a separate genus, but I’d
rather not do either. Pipile (including
jacutinga, which is most divergent and seemingly basal to the others),
without Aburria, comprises a morphologically, vocally, behaviorally and
ecologically cohesive group, and I would want to see some stronger evidence
before messing with it.”
Comments from Pérez-Emán: “NO. This
proposal is basically the same as previous 277, which did not pass. Grau et al.
(2005) estimated phylogenetic relationships of Neotropical piping guans using
three mitochondrial genes and osteological characters, analyzed independently.
Support for Aburria as sister taxon to all Pipile except jacutinga was
low. Frank-Hoeflich et al. (2007)’ s study increased taxon sampling and
combined molecular with osteological, integumentary and behavioral characters.
However, as Laurent Raty pointed out in proposal 277, they used, for Pipile
jacutinga, the same Cyt b sequence than Grau et al. (2005).
Raty also indicated that he ran independent analyses by gene (using GenBank
sequences used by Grau et al.) and only Cyt-b sequences were the ones
supporting placement of jacutinga as sister to Aburria +
rest of Pipile. Such an analysis would favor a hypothesis of results
showing a gene tree more than a species tree. In fact, I also downloaded ND2
sequences from this study and ran a maximum likelihood analysis with 1000
bootstrap pseudoreplicates. Results show a moderate support (bootstrap value,
bv, = 76) for a sister relationship of P. jacutinga to the rest of
piping guans (which are a strongly support monophyletic group, bv = 98).
Additionally, all Pipile are sister to Aburria with strong
support (99). It is important to say that Frank-Hoeflich et al.’s study showed
that osteological characters did not resolve relationships between Aburria
and Pipile and that integumentary + behavioral characters support
the idea of two different genera. The combined data phylogenetic hypothesis of
these authors is potentially biased toward the Cyt b sequence
information. Finally, Eo et al. (2009)’s study used previous published data but
without including Frank-Hoeflich et al.’s study as it is not cited in the
Supplementary Material document. Thus, I don’t think we have more information
to change our views than we had when proposal 277 was evaluated. Besides,
morphology, behavior, ecology and even molecular information (at least for ND2
phylogenetic hypothesis) still support keeping both Aburria and Pipile.”
Comments from Cadena: “NO, for
the same reasons as in proposal 277; I agree
with additional points made by Jorge here.”