Proposal (351) to South American Classification Committee
Transfer Saltator and Saltatricula from Incertae Sedis to Thraupidae
Effect on SACC: This
would transfer two genera from Incertae Sedis to Thraupidae.
Background We recently
moved Saltator from Cardinalidae (Proposal 321) and Saltatricula from Emberizidae (Proposal 322), placing them in Incertae Sedis
in adjacent positions. Passage of that proposal triggers a follow-up to move
them now into Thraupidae. There is a concurrent proposal (344) to merge Saltatricula into Saltator,
but that outcome does not affect this proposal.
Klicka et al.'s (2007) analysis included
102 genera of tanagers, emberizines, and cardinalines. The genetic sampling
consisted of 2281 bp of two mitochondrial genes, ND2 and cyt-b ... a nice
sample. Not only is Saltator not in the Cardinalidae, but there is
support for placement within the Thraupidae. The critical node (#2 in their
Fig. 1) for that placement has
strong support (> 95% Bayesian). That node places Saltator plus Saltatricula as sister to the rest of the tanagers. Saltator
rufiventris is not a Saltator but is deeply embedded within the
Thraupidae (to be addressed in another proposal).
Analysis: MtDNA is widely considered a reliable predictor
of phylogeny at these levels of taxonomy, and certainly these data sets
represent the first truly scientific estimates of the phylogeny and
classification of this group.
The only question is whether to
place them within Thraupidae or leave them as Incertae Sedis. Given that their
placement in Thraupidae is based on one node and one study (and no nuclear DNA
analyzed so far), and given that Burns, Klicka et al. will undoubtedly be
publishing more on Thraupidae and Saltator, I previously suggested a
cautious approach by placing them temporarily as Incertae Sedis, including even S. rufiventris, with all appropriate
footnotes indicating their likely relationship to Thraupidae. However, SACC
comments received on #321 were strongly in favor of a direct transfer to
Thraupidae, thus catalyzing this proposal.
However, here's John Klicka's
response:
"If
Saltator is to be placed within one of the existing nine-primaried oscine
families, it will almost certainly have to be placed among the Thraupidae. I
think that it will end up as a basal lineage within that group, but I am a bit
hesitant to move it formally based only on the data presented in our recent
paper. It probably wouldn't hurt to wait and see how the nuclear data affects
this placement; work that Kevin should have done fairly soon. "
Therefore, I recommend a continued
cautious approach and wait for the forthcoming results by voting NO.
References:
KLICKA, J., K. BURNS, AND G. M.
SPELLMAN. 2007. Defining a monophyletic Cardinalini: A molecular perspective.
Molecular Phylogenetics and Evolution 45: 1014-1032.
[See SACC Literature Cited for
others]
Van Remsen,
May 2008
________________________________________________________________________________________________________
Comments from Cadena: "YES
for reasons stated in proposal 321. Even after John's comment, I am still
comfortable with a YES vote. Sure, nuclear data would be nice, but the mtDNA
results are solid (see my comments on proposal 321), and I think we should go
with the best available information."
Comments from Stiles:
"YES. I had already indicated that I favored this move as the evidence
(even though from only one gene, one study) seemed exceptionally clean-cut. If
the nuclear data continue to indicate a very deep split between Saltator and the tanagers "proper", I
would recommend that Kevin formally propose subfamily rank for the saltators.
For the moment, I agree with Daniel that the best available evidence is to
place the saltators in Thraupidae."
Comments from Stotz:
"YES. Once we took Saltator and Saltatricula out of Cardinalidae, moving them to
Thraupidae is the obvious placement for them."
Comments from Santiago Claramunt: "I agree with John in that it is better to
wait for stronger evidence. The alternative hypothesis of a sister relationship
between Saltator and other
Cardinalidae could not be rejected (P = 0.245), and the branch uniting Saltator and thraupids is very short, and we don't
know the exact posterior probability associated. According to some simulations,
a posterior probability of 0.95 may be equivalent to a bootstrap value as low
as 60%.
"Superficially, Saltator fits naturally into Cardinalidae based on
external morphology, voice, and habits, although these "characters"
may represent convergence to a forest large-seed-eater syndrome. Genetic
similarity based on protein electrophoresis data (Tamplin et al. 1993) as well
as overall morphological similarity (Hellack & Schnell 1977) does not show Saltator to be distinct from other cardinalids.
Tordoff (1954a) mentioned that some authors considered Saltator "a thick-billed tanager". He
noted that Saltator's palatal
structure is closer to Piranga than to Cardinalis.
Given that Piranga is a cardinalid, this is not evidence of a
closer relationship to true thraupids. I need to check those other authors to
se if there is any evidence of such relationship at all.
"In conclusion, I think the committee has to be conservative
until stronger evidence is presented. I think it was premature to remove Saltator from Cardinalidae (proposal #321)."
Comments from Jaramillo: "YES
- This is where the data is pointing. If additional data causes a further
change in placement, I would prefer to adjust at that point rather than leave
these genera in Incertae Sedis for a longer period of time. I guess we are
getting to this question in an upcoming proposal, but in general I would rather
avoid use I.S."
Comments from Robbins: "NO.
Given John Klicka's comments, I vote "no" for now, and look forward
to seeing their nuclear data set."
Comments from Zimmer: "NO.
I don't think it will hurt to wait for the nuclear data set, especially in
light of Santiago's comments."
Comments from Schulenberg:
"Yes. I'm with Daniel, Gary, Doug, and Alvaro on this. The evidence points
(strongly) in this direction. And while there may be times when the use of
"incertae sedis" can not be avoided, when we really don't know
anything other than that "taxon x isn't at all what we thought it
was," I also don't like to see "incertae sedis" relied on when
we have at least some idea what the relationships of "taxon x" may
be."
Additional comments from Stiles: "The
comments by Santiago are not wholly convincing because the evidence he cites
may not be solid by modern criteria. For instance, palate types (Tordoff): the
seed-cracking habit of typical cardinalines would make for strong selection on
the form of their palates. Neither Piranga nor Saltator are specialized seed-crackers - both are
mainly frugivorous to omnivorous (both take many insects, Saltator also eats buds and young leaves); hence a
closer resemblance to Piranga than to Cardinalis in their palates is hardly surprising. The
key question, not addressed by Tordoff, is how easily it would have been for a Saltator-type palate to evolve from
a typical tanager-type palate in association with taking larger or
tougher-husked fruits. Protein electrophoresis has a very mixed record in
elucidating taxonomic relationships, as Sibley was forced to conclude after
investing many years on this method: he stated that interpreting
electrophoretic peaks was "like reading tea leaves". The record of
DNA-DNA hybridization is also pretty mixed, with results of some studies being
well supported by DNA sequence data and some not. Overall morphological
similarity may simply reflect the fact that both saltators and typical
cardinalines are both rather large and robust compared to most tanagers."
Comments from Pacheco: "NO.
A partir dos comentários, sobretudo, do
John e do Santiago, considero mais apropriado votar "Não" e aguardar
por novos dados."