Revise the generic classification and linear sequence of Anas (original) (raw)
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 (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
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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:
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.
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.
They propose that the genus Dendrocygna be placed in their own family, Dendrocygnidae.”