Proposal (285) to South American Classification Committee
285 A. Recognize Cracidae
subfamilies Cracinae and Penelopinae
285 B.
Change linear order of Cracidae genera
Summary: These two
proposals are to adopt a new linear order for the Cracidae, based on a number
of recently published phylogenetic studies. It also gives an opportunity to
SACC to consider whether to recognise the proposed subfamilies Cracinae and
Penelopinae.
Background: To give
some background to the morphological issues behind the current linear order, I
quote from the footnote on the SACC list:
"Vaurie (1968) recognized three major
divisions within the family based on morphological criteria: the guans and chachalacas
(tribe Penelopini), the curassows (Cracini), and the (extralimital) Horned Guan
(Oreophasini). Delacour & Amadon (1973) considered the latter to be part of
the chachalaca-guan group and recognized only two major divisions, (a) the
curassows and (b) everything else. Del Hoyo (1994) recognized two subfamilies,
Cracinae for the four genera of curassows and Penelopinae for everything
else."
The current linear order of Cracid
genera on SACC is as follows. No sub-families are recognised.
Ortalis
Penelope
Pipile
Aburria
Chamaepetes
Nothocrax
Mitu
Pauxi
Crax
Recent studies:
(a) Subfamilies
Three molecular studies (Pereira et
al. 1992; Crowe et al. 2006; Hoeflich et al. 2007) have suggested that the
Cracidae fall into two broad groups:
(i) Oreophasis (extralimital),
Pauxi, Mitu, Nothocrax, Crax and (Curassows
and Horned Guan);
(ii) Chamaepetes, Penelopina
(extralimital), Penelope and Pipile/Aburria (all
other Guans). The position of Ortalis (Chachalacas) in one or the other
group is controversial. All molecular studies hold it to be related to the
Curassows (Pereira et al. 1992; Crowe et al. 2006; Hoeflich et al. 2007). All
past morphological studies (Vaurie 1968; Delacour & Amadon 1973) held it to
be related to the Guans, as does a recent study of morphological/behavioral and
combined morphological/behavioural/molecular data (Hoeflich et al. 2007). The
group including the Curassows has been termed the "Cracinae" with the
group including the Guans the "Penelopinae".
The Pereira et al. study found
relatively weak support for a Chachalaca-Curassow relationship, but strong
support for rejecting a Guan-Chachalaca relationship. The Crowe et al. study
showed strong support at the Chachalaca-Curassow node. Each of Pereira et al.
and Crowe et al. involved analysis of over 4000 base pairs from both
mitochondrial and nuclear markers. Frank-Hoeflich et al. (2007) considered
morphological / behavioural data and combined data sets in addition to
molecular data. Although their molecular data produced similar results to the
other studies (and were based on much of the same data from the other studies),
analyses of morphological and combined data sets held Ortalis to be more
closely related to the Guans than to the Curassows, although without very
strong support.
In neither paper is there a detailed
discussion of whether the Ortalis (or Oreophasis) should be given
their own subfamily. Unhelpfully, however, the name Ortalinae is preoccupied by
some Diptera genera and Ortaliinae by some Coleoptera. Ortalidainae may be an
appropriate name if a subfamily were to be recognised for the Chachalacas [this
is not a nomenclatural act].
Per the SACC introductory text,
"Most traditional subfamilies are omitted unless supported by multiple
independent data sets that mark major, deep branches within a family."
Given that the position of Ortalis is not consistent between the various
studies, it is perhaps a stretch to call the division between Cracids/Horned
Guan vs. Guans/Chachalacas or Cracids/Horned Guan/Chachalacas vs. Guans
"supported by multiple independent data sets" or involving "deep
branches". Frank-Hoeflich et al. (2007) found the relevant subfamily
clades to have relatively low posterior support values (0.78 / 0.82). However,
interestingly, when Ortalis is excluded, 1.00 support for each of the
Curassow and Guan clades is produced.
The following paragraph is based on
some interesting comments from Sergio Pereira:
"Re Cracinae and Penelopinae, I have no doubt about
Cracidae being subdivided into these two groups. [The position of Ortalis,
whether with the Curassows or Guans] is controversial for sure. But I believe
that more analysis can be done when Frank-Hoeflich's matrix becomes available
online. I'm planning to do some work on this, joining my molecular data set
with their behavioural/anatomical data set for each of the 11(12) genera. In my
Systematic Biology paper published in 2002, we performed a parametric
bootstrap test to evaluate the differences between our trees (Ortalis and
Oreophasis with curassows) and that of Vaurie (Ortalis and Oreophasis
with guans). In brief, we simulated molecular characters to test the
differences between the molecular and morphological trees. Undoubtedly,
Vaurie's tree could be strongly rejected based on the molecular data (over
10,000 analyzable sites - which still is one if the biggest data set gathered
for a group of birds so far). Unfortunately, the same test cannot be applied
the other way around: simulate the morphological data to test the molecular
tree. To summarize, although I am more inclined to suggest Ortalis and Oreophasis
with curassows, I recognize that more analyses are needed on existing data
sets."
Although the statistical analyses
give only weak support for recognition of the traditional subfamilies within
Cracinae, morphological considerations give some pause for thought. The
Cracinae have robust or hooked bills often with ornaments; are generally larger
and heavier; have elaborate ground display courtship; and have generally pied
or rufous-brown plumage. Penelopinae have thinner, straighter bills with no
ornaments; smaller bodies; shorter incubation periods; plumage is more
heterogeneous; and various species have wattles or naked throat patches
(Frank-Hoeflich et al. 2007). Ortalis sits more comfortably with the
Penelopinae in the characters described above, though vocally is different to
each of Cracinae and Penelopinae; and ecologically, Ortalis is less
forest-dependent than the guans or curassows.
(b) Linear Order of Genera
(i) Curassows
The order for genera within the Curassows
is somewhat muddled as Mitu and Pauxi were found to be
paraphyletic by each of Crowe et al., Pereira et al., Frank-Hoeflich et al. and
a further study (Pereira & Baker 2004). Certain differences in placement of
curassow genera in phylogenies are apparently influenced by a past
hybridisation event involving Mitu/Pauxi (Pereira & Baker
2004).
Pereira et al. found the relations
between Curassow genera to be as follows: Crax (Nothocrax (Mitu/Pauxi morass)),
although with only weak support at the Crax/Nothocrax node. Crowe
et al. presented a series of trees based on different analyses in which the
position of various Curassow groups varied with respect to one another. Basal
to the other taxa were either Pauxi pauxi or Nothocrax and,
in one case, Crax. Frank-Hoeflich et al. proposed Nothocrax (Crax
(Mitu/Pauxi morass)) based on each of their molecular,
morphological/behavioural and combined data sets, which is consistent with
certain of Crowe et al.'s hypotheses and only a small tweak from the Pereira et
al. study. The latter two genera have recently been proposed for merger
(Frank-Hoeflich et al. 2007) due to paraphyly, which is a separate and
difficult issue not subject of these proposals.
The position of Nothocrax at
the start of the SACC order is, whether through accident or design, consistent
with various of Crowe et al. (2006)'s trees, Pereira & Baker (2004)'s
phylogenies and all three of Frank-Hoeflich et al.'s published trees (although
not with those phylogenies mentioned above that place Crax before the other
Curassows). I would suggest retaining Nothocrax's
position in the absence of any strong reason to change it. However, in order to
place the more basal genera first, Crax should be moved to above Mitu
and Pauxi.
(ii) Guans
All molecular studies referred to
above hold Chamaepetes to be basal to the other Guan taxa on
the SACC list, with extralimital Penelopina either basal to all other
Penelopinae or sister to Chamaepetes. Penelope and [Aburria/Pipile]
were found to be sisters by each of these studies, as well as a third molecular
study (Grau et al. 2005). Analyses using only morphological/behavioural
characters, contrary to the others, found Ortalis to be embedded within
the Guans, sister to either Chamaepetes or Ortalis (Frank-Hoeflich
et al. 2007). The order Penelope, Pipile, Aburria in the
current baseline is consistent with the results of all three molecular studies
and the Frank-Hoeflich et al. combined morphological-behavioural-molecular
tree. However, Chamaepetes should more sensibly go before the other
genera, given that it is the most basal Guan taxa in the overwhelming majority
of phylogenies.
(iii) Chachalacas
As foreshadowed above, the linear
placement of the Chachalacas Ortalis requires re-evaluation. According
to three phylogenies based on molecular studies (Pereira et al. 2002; Crowe et
al. 2006; Frank-Hoeflich et al. 2007), Ortalis is sister to the
Curassows - the relevant nodes scoring 97-100 in certain jack-knife and
Bayesian analyses (Crowe et al. 2006). A Chachalaca-Guan relationship was also
strongly rejected by Pereira et al. (2002). However, according to morphological/behavioural
analyses, Ortalis is embedded in the Guans, sister to either Penelope
or Chamaepetes and per analyses combining morphological and molecular
results, is sister to all the other Neotropical Guans, although with rather
weak support (Frank-Hoeflich et al. 2007). Ortalis is currently at the
start of the SACC linear order adjacent to the guans. Among all the studies
discussed above, SACC treatment is consistent only with some (but not all) of
the Frank-Hoeflich et al. morphological phylogenies and with one of their two
combined phylogenies. The current placement of Ortalis is not consistent
with any of the phylogenies based on molecular data, some of which include
studies involving thousands of base pairs.
The most sensible approach,
consistent with almost all published studies, would be to move Ortalis in
the linear order to between the Guans and the Curassows. This could be
criticised in that the Frank-Hoeflich phylogeny involving combined data holds a
basal relationship of Ortalis to the Guans, which could mandate
retention of Ortalis at the start of the order. However, as noted in
Sergio Pereira's comments above, Ortalis' relation to the guans is
rejected strongly by molecular data. The proposed change here would render the
linear order not inconsistent with either a Curassow-Chachalaca or
Guan-Chachalaca relationship being correct - whilst the current order only
"works" if Ortalis is related to the Guans.
Conclusion on Proposal A: A Yes
vote on Proposal A would lead to the Cracinae and Penelopinae being recognised.
It is clear from published analyses that the Curassows and Guans form two
separate groups that meet the SACC requirement for subfamilies. If those were
the only Cracids, subfamily recognition would be an easy question. However, the
position of the Chachalacas clouds issues considerably. A "yes" vote
on this proposal would result in treatment of Ortalis as incertae
sedis as to subfamily position. If a vote for recognition of the subfamilies
passes, a separate three-way proposal or set of proposals can be considered as
to where Ortalis should be placed among the various options (i.e.
in Cracinae, Penelopinae or in its own subfamily / left as incertae sedis). I
make no strong recommendation either way on this proposal.
Conclusion on Proposal B: A Yes
vote on Proposal B would result in changes to the positions of Ortalis, Crax and
Chamaepetes in the linear order, as described above. The proposed
new linear order is set out below in two versions, one with subfamilies and one
without. Although linear orders are not the best way of presenting phylogenies,
this new order is considerably more informative as to Cracid relationships than
the previous linear order and therefore comes strongly recommended.
The version of the proposed linear
with subfamilies included is as follows:
Penelopinae
Chamaepetes
Penelope
Pipile (if
recognised)
Aburria
Subfamily uncertain: pending
another proposal
Ortalis
Cracinae
Nothocrax
Crax
Mitu (if
recognised)
Pauxi
The version of the proposed linear
order without subfamilies is as follows:
Chamaepetes
Penelope
Pipile (if
recognised)
Aburria
Ortalis
Nothocrax
Crax
Mitu (if
recognised)
Pauxi
References:
CROWE,
T.M., BOWIE, R.C.K., BLOOMER, P., MANDIWANA, T., HEDDERSON, T., RANDI, E.,
PEREIRA, S.L., & WAKELING , J. (2006). Phylogenetics and biogeography of,
and character evolution in gamebirds (Aves: Galliformes): effects of character
exclusion, partitioning and missing data. Cladistics 22: 495-532.
http://individual.utoronto.ca/sergiolp/pdf/Cladistics2006.pdf
FRANK-HOEFLICH,
K., SILVEIRA, L.F., ESTUDILLO-LOPEZ, J., GARCIA-KOCH. A.M., ONGAY-LARIOS, L.
& PINERO, D. 2007. Increased taxon and character sampling reveals novel
intergeneric relationships in the Cracidae (Aves: Galliformes). J. Zool. Syst.
Evol. Res. In press. http://dx.doi.org/10.1111/j.1439-0469.2007.00396.x
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., BAKER, A.J.& WAJNTAL, A. (2002). Combined nuclear and mitochondrial
DNA sequences resolve generic relationships within the Cracidae (Galliformes,
Aves). Systematic Biology 51(6): 946-958
http://individual.utoronto.ca/sergiolp/pdf/SB2002.pdf
PEREIRA,
S.L. & BAKER, A.J. (2004). Vicariant speciation of curassows (Aves,
Cracidae): a hypothesis based on mitochondrial DNA phylogeny. The Auk 121:
682-694. http://individual.utoronto.ca/sergiolp/pdf/Auk2004.pdf
Thomas
Donegan, June 2007 (with helpful comments from Sergio Pereira and Dan Brooks
and, on SACC linear order policy, from Van Remsen)
______________________________________________________________________________________________________
Comments from Stiles: "YES
(essentially for both). The two subfamilies of cracids are solidly established;
the logical thing to do with the chachalacas is to place them between the two
as "subfamily incertae sedis" given the conflicting evidence
regarding their placement. This would preserve the linear order of genera in B
and call attention to the problem of where to place the chachalacas. For now,
recognize both Mitu and Pauxi in the Cracinae, with a note that
they may be congeneric."
Comments from Cadena: "YES
on both, and I agree with Gary in that the best we can do with the chachalacas
given conflicting evidence is to place them incertae sedis."
Comments from Remsen: "NO
on A, however, as a matter of taste. Rather than have a third of the species in
the family Incertae Sedis, I prefer to wait for data that places them one way
or another. Three subfamilies would seem more logical than two plus Incertae
Sedis. Also, I'm not convinced that the split between guans and curassows is
all that deep. Clean, yes, but deep? [I need to look at branch lengths between
other groups we rank at the subfamily level.]
"YES on B. This sequence best
reflects the data published so far and adds information to our
classification."
Comments from Robbins: "YES
to both, although I put more faith in the three molecular data sets over the
combined morphological/behavior/molecular data set in placement of Ortalis,
i.e., I suspect that despite the historical inertia clouding our views, Ortalis
is indeed aligned with the curassows."
Additional comments from Donegan: "Re Van Remsen's comment on the depth of the divisions in this
family, Pereira et al. (2002) hypothesised the following periods (95%
confidence interval) for major divisions in the Cracidae: Guans vs. Other
Cracids - 26.9-40.6 million years ago (Early Oligocene) [extralimital Oreophasis:
26.6-36.1 mya (Early Oligocene)] Ortalis: 25.8-36.5 mya (Early
Oligocene).
"Other
generic-level divergences are postulated to have occurred in the Miocene
or later.
"As
the Guan / Curassow / Horned Guan / Chachalaca division took place at a similar
period and so long ago, this could support the erection in due course of a new
subfamily for Ortalis."
Comments from Zimmer: "YES
on both. I agree with Van that three subfamilies seems to be the most logical
ultimate course, but the conflicting data regarding placement of Ortalis precludes
making such a move now. Better to place Ortalis as "incertae
sedis" between the other two subfamilies until we have more definitive
data."
Comments from Nores: "(A)
NO. Considero que no debemos incluir
subfamilias en sólo algunas de las familias en la SACC list. Si lo hacemos para
algunas, lo tendríamos que hacer para todas, que sería como empezar de nuevo.
"(B.)
YES. Me parece que la propuesta está bien fundamentada con varios
trabajos moleculares coincidentes.
Nota. Quiero aquí resaltar el trabajo de Thomas Donegan
en el SACC. A pesar de que no es miembro del Comité, él está permanentemente
realizando interesantes propuestas y comentarios. Llama la atención lo
fundamentadas de sus propuestas e incluso, como en este caso, con la posibilidad
de bajar de Internet los trabajos citados. Felicitaciones."
Comments from Stotz: "
(A). NO. (B). The inability to place Ortalis clearly with respect to the
other two groups makes it seem to me that creating subfamilies is premature at
best in this case. In terms of rearranging the genera, I guess I don't
see that it provides much meaningful information on relationships; our current
order is consistent with the data on relationships among genera. Additionally,
placing Ortalis, which is essentially incertae sedis relative to the
subfamilies in Cracidae, in that middle seems like an odd approach; typically,
you'd place such a taxon at the end."
Comments from Jaramillo: "YES
(both) - In full agreement with Gary's logic [B]."
Comments from Schulenberg: "YES
(although our current order pretty well matches what we think we need?)."
Comments from Pacheco: "(A)
[No] Até que haja melhor refinamento quanto às
relações de Ortalis com as subfamílias propostas. (B) [Yes] considero a
sequência linear aqui proposta é de fato mais informativa.