Proposal (344) to South American Classification Committee
Merge Saltatricula into Saltator
Effect on SACC: This
would merge a monotypic genus into an existing large one, Saltator.
Background: This proposal is triggered by the passage of Proposal 322 to place Saltatricula next to Saltator.
Now we need to decide whether the evidence is sufficient for merger of Saltatricula into Saltator. Without repeating all of Proposal 322,
I note only the following critical sentence:
"The critical node (in their Fig. 1) for that placement [of Saltatricula in
Saltator] has strong support (> 95% Bayesian), as does the
node that supports a sister relationship to Saltator
atricollis."
Therefore, not one but two strongly
supported nodes place Saltatricula within our broadly defined genus Saltator. Six of six SACC voters who
commented on 321 were already in favor of the merger. As Doug noted, the only
question is whether to follow the Klicka et al. placement in the linear
sequence (sister to atricollis)
or put it at the end of the linear sequence. Given that the support for the
sister relationship, I recommend not only the merger placing it to follow atricollis -- this represent the best estimate of
its relationships given published data so far.
Van Remsen,
May 2007 (in consultation with John Klicka and Kevin Burns)
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Comments from Cadena: "YES
for reasons stated in proposal 322."
Comments from Stiles:
"YES. On both - merging of Saltatricula into Saltator and placing it next to S. atricollis - the genetic data are convincing; the
nodes are well supported."
Comments from Pacheco:
"YES. Vejo como uma boa solução acomodadora."
Comments from Jaramillo: "NO
- I was a bit shocked at the results mainly because I was convinced that Saltator atricollis was in fact allied to Embernagra/Emberizoides.
Upon second thought though it makes sense to me based on field experience with
these birds that Saltatricula is close to S. atricollis. That I am comfortable
with now, and now feel like I was misleading myself with Embernagra/S. atricollis.
What spurred my interest in this creature was that the first times I saw S. atricollis what went through my head was "that
ain't no Saltator." It was partly the shape, the song, the coloration …
various bits of information you get when you see a bird in life. I think that
it makes much more sense to keep Saltatricula in its own genus and add in S. atricollis there. Why have such a large and
heterogeneous Saltator? I have
not looked at the nomenclature and if Saltatricula is the valid option or if atricollis belonged to an earlier named genus, but the
two should be sisters in their own genus, not in Saltator."
Comments from Santiago Claramunt
and Luciano Naka: "We hope
we can persuade the committee members to vote NO on this proposal. The
statement that Saltatricula is
embedded into Saltator contradicts our perception based on
marked differences in size, habitat, and song between Saltatricula and typical Saltator. However, according to
Klicka et al.'s tree, Saltatricula is not deeply embedded into Saltator; it is only the position of Saltator atricollis that makes Saltator paraphyletic. In the
experience of one of us (L.N.), S.
atricollis is an atypical Saltator, and its habitat (a Cerrado
specialist) and particularly its song resemble more those of Saltatricula (a dry Chaco inhabitant) than any other Saltator. Another source of
uncertainty is the fact that Bayesian probabilities associated with branches
were not reported. A posterior probability of .99 or 1.00 indicates strong
support, but a probability of 0.95 is marginal at best (it may be equivalent to
a 65-75% bootstrap).
"Concerned about these ambiguities, we downloaded a subset of
Klicka et al. (2007) data, and we discovered that the signal for the merging of Saltatricula into Saltator is not strong. First, the mitochondrial
sequence signal is not strong for basal relationships mainly because
Transitions at third codon positions reach levels of saturation even within the
genus Saltator. Probably due to
this saturation, basal relationships changed dramatically in our re-analyses
when using different models of substitution or different tree building
algorithms, and not one of the basal branches had a bootstrap support value
over 50%. However, in all these re-analyses we recovered a sister relationship
between Saltatricula and S.
atricollis with relatively
strong support (bootstrap 80-100%) but in most cases this clade was not sister
to the other Saltator.
"In conclusion, the mitochondrial sequence data is suggesting
that Saltator is not monophyletic not because Saltatricula is embedded in Saltator, but because atricollis may not be a Saltator. For the moment, the most
conservative options are: to maintain the status quo and maintain Saltator paraphyletic until strong evidence is
obtained); or transfer atricollis to Saltatricula (which although may sound a drastic
measure, is not more drastic than merging Saltatricula into Saltator)."
Additional comments from Remsen:
"Claramunt and Naka's re-analysis, along with Alvaro's comments, has
convinced me to change my vote to NO. A proposal to treat S. atricollis in =
Saltatricula should be
the next step; I would regard that as the most conservative option in terms of
maximizing chances for having monophyletic genera."
Additional comments from Stiles: "In
view of these comments, I am also willing to vote NO, and agree that the best
course might be to remove atricollis
from Saltator and merge it into Saltatricula (an examination of synonymies in Bds.
British Museum and Hellmayr indicates that atricollis
has been placed in Tanagra, Loxia and Fringilla as well as Saltator and as none of these are appropriate now,
so there appears to be no nomenclatural impediment to this move)- this would
make Saltator monophyletic if I read things right, so
perhaps a fresh proposal is in order?"
Additional comments from Cadena: "The
points by Claramunt and Naka are very good ones, and I am happy to change my
vote to NO based on their comments. I would definitively support transferring atricollis to Saltatricula
as an alternative that seems entirely consistent with the strongly supported
nodes in the phylogeny, and that preserves a good deal of phylogenetic
information in the classification."