Proposal (787) to South American Classification Committee
Revise the generic classification and linear sequence of Anas
Background: The current
SACC checklist (Remsen et al. 2018) contains 14 species of Anas dabbling ducks:
Anas americana American Wigeon
Anas sibilatrix Chiloe Wigeon
Anas crecca Green-winged Teal
Anas andium Andean Teal
Anas flavirostris Yellow-billed Teal
Anas acuta Northern Pintail
Anas georgica Yellow-billed Pintail
Anas bahamensis White-cheeked Pintail
Anas puna Puna Teal
Anas versicolor Silver Teal
Anas discors Blue-winged Teal
Anas cyanoptera Cinnamon Teal
Anas platalea Red Shoveler
Anas clypeata Northern Shoveler
New Information: Gonzales et al. (2009) generated a phylogeny
of Anseriformes using a concatenated alignment of two mitochondrial genes (ND2
and cyt-b). Taxon sampling included most extant species of Anatini, including
all but one species recognized on the SACC checklist. The genus Anas was shown to be non-monophyletic
with strong statistical support. For well supported nodes involving SACC
species, the phylogeny of Sun et al. (2017) is concordant to that of Gonzales
et al. (2009).
An annotated version of the Gonzales et
al. phylogeny (their Fig. 1) is presented below. Colored boxes indicate clades
proposed for generic splits. Yellow stars indicate species on the SACC
checklist. The only SACC species not sampled by Gonzales et al., Anas andium, is believed to be closely
related to Anas flavirostris (see
SACC proposal #356). Anas flavirostris
oxyptera is sampled on the phylogeny and occurs in the SACC area but is not
currently recognized at the species rank on the SACC checklist (see SACC
footnote #18).
The node ages reported in Gonzales et al.
are 9.4 ± 3.0, 11.2 ± 3.2, and 13.5 ± 3.6 (Mya ± SD) for nodes A, B, and C,
respectively.
Recommendation: One
approach to resolving Anas
non-monophyly would be to merge Amazonetta,
Speculanas, Lophonetta, and Tachyeres
into Anas. However, this is not
recommended because it would require merging ancient and morphologically
distinctive lineages like Steamer-Ducks (Tachyeres
spp.) into the same genus as the typical dabbling ducks.
The other way to resolve the non-monophyly
is by splitting Anas. Dickinson and
Remsen (2013) took this approach when resurrecting Sibrionetta, Spatula, and
Mareca as annotated in the above
figure. To achieve monophyly, it is necessary to remove from Anas the species Dickinson and Remsen
transferred to Spatula, but
recognizing Mareca is not necessarily
required. Mareca was previously
recognized (e.g. AOU 1957), its species are distinctive morphologically (see,
e.g., Livezey 1991), and it was recently resurrected by the AOS NACC (Chesser
et al. 2017). Dickinson and Remsen (2013) cited the depth of phylogenetic tree
splits as their rough guide for deciding to split Sibirionetta and Mareca.
We believe that the bulk of the evidence warrants making these splits, as
follows:
(A)
transfer A. clypeata, A. cyanoptera, A.
discors, A. platalea, A. puna, and A.
versicolor to Spatula.
(B)
transfer A. americana and A. sibilatrix to Mareca.
Sub-proposal A by itself would solve the
non-monophyly problem while minimizing taxonomic changes. Sub-proposals A and B
together would replicate the taxonomy of both Dickinson and Remsen (2013) and
Chesser et al. (2017), and would make the phylogenetic depths of generic splits
more consistent within Anatini.
The Anas
non-monophyly problem can be resolved by voting for A only, or A+B. The status
quo taxonomy contains a non-monophyletic Anas,
so voting YES on A, at least, is recommended. Our recommendation would be to go
with A+B for the reasons outlined above.
(C) revise
the linear sequence of species
To conform to AOS guidelines, the linear
sequence of species currently placed in Anas
would require changes in response to the phylogeny of Gonzalez et al. (2009).
The new linear sequence would be as follows [D1] (genus names assume passage of sub-proposals A and B above):
Spatula
puna Puna Teal
Spatula
versicolor Silver Teal
Spatula
platalea Red Shoveler
Spatula
clypeata Northern Shoveler
Spatula
discors Blue-winged Teal
Spatula
cyanoptera Cinnamon Teal
Mareca
americana American Wigeon
Mareca
sibilatrix Chiloe Wigeon
Anas
bahamensis White-cheeked Pintail
Anas acuta Northern Pintail
Anas
georgica Yellow-billed Pintail
Anas crecca Green-winged Teal
Anas andium Andean Teal
Anas
flavirostris Yellow-billed Teal
Literature
Cited
Chesser, R. Terry, Kevin J. Burns, Carla
Cicero, Jon L. Dunn, Andrew W. Kratter, Irby J.
Lovette, Pamela C. Rasmussen, J. V. Remsen, Jr., James D.
Rising, Douglas F. Stotz, and Kevin Winker (2017) Fifty-eighth
supplement to the American Ornithological Society's Check-list of North
American Birds. The Auk: July 2017, Vol. 134, No. 3, pp. 751-773.
Dickinson, Edward C. and J. V. Remsen, Jr. 2013. The Howard and Moore Complete Checklist of
the Birds of the World, Volume 1: Non-passerines. Aves Press. 461 pp.
Gonzales, J., H. Düttmann, and M.
Wink. 2009. Phylogenetic relationships based on two mitochondrial genes and
hybridization patterns in Anatidae. Journal
of Zoology 279:310-318
Livezey, B. L. 1991. A phylogenetic analysis and
classification of recent dabbling ducks (tribe Anatini) based on comparative
morphology. Auk 108:471-508.
Remsen, J. V., Jr., J. I. Areta,
C. D. Cadena, S. Claramunt, A. Jaramillo, J. F. Pacheco, J. Perez-Emán, M. B.
Robbins, F. G. Stiles, D. F. Stotz, and K. J. Zimmer. Version 11 April 2018. A
classification of the bird species of South America. American Ornithologists'
Union. http://www.museum.lsu.edu/~Remsen/SACCBaseline.htm
Sun, Z., Pan, T., Hu, C., Sun, L.,
Ding, H., Wang, H., Zhang, C., Jin, H., Chang, Q., Kan, X., and B. Zhang. 2017.
Rapid and recent diversification patterns in Anseriformes birds: Inferred from
molecular phylogeny and diversification analyses. PLoS ONE 12(9):e0184529
https://doi.org/ 10.1371/journal.pone.0184529
David L. Slager and R. Terry
Chesser, April 2018
__________________________________________________________
Comments from Remsen: “A. YES.
DNA-based phylogeny requires recognizing Spatula; B. YES, to recognize genera at comparable depths in the
tree; C. YES. Required by sequencing conventions.”
Comments
from Jaramillo:
“A – YES, Spatula is clearly defined based on
morphology, as well as DNA data.
“B – YES. Similarly, Mareca is well defined by DNA and
aspects of morphology.
“C – YES as required by
convention.”
Comments
from Pacheco:
“YES to A, B. and, C. The division into three genera is more informative and
appropriate to the available phylogeny.”
Comments from Cadena: “A. YES. B. YES, though this is not necessary; keeping
these taxa in Anas would be good for
stability but given that they were split by NACC I am OK with that. C. YES.”
Comments
from Areta:
“YES to A, B, and C. However, I agree with Daniel in that moving americana
and sibilatrix
(and the recently added penelope!) from Anas to Mareca is probably not the
best possible move, especially so when analyzed in the larger context provided
by Sun et al. (2017).
“Sun et al.
(2017) make other interesting contributions:
1) They
seem to endorse a large-genus approach and suggest placing Lophonetta, Amazonetta,
Speculanas
and Tachyeres
in the genus Anas.
Indeed, the divergence times among these genera are small while morphological
and behavioral differences are large.
2) Although
Netta peposaca
is sister to Aythya,
Netta rufina
(the type species of Netta) is sister to Netta peposaca+Aythya.
This suggests that either peposaca needs a new genus or that is should be merged
with Aythya either
including or excluding rufina (Aythya has priority over Netta). I suppose erythrophthalma
will be sister to peposaca,
so the problem will linger even if we learn of where to place it in the duck
tree.
3) They
propose that the genus Dendrocygna be placed in their own family,
Dendrocygnidae.”