Proposal (869) to South American Classification Committee

Revise linear sequence of species of macaws

Description of the problem:

This is a repurposed, minimally modified proposal sister to that passed in NACC (Chesser et al. 2020; 2020-B-6) for resequencing Ara macaws.

Although the Cuban Macaw Ara tricolor has been extinct since the mid-19^th century, it is the best-known of the several putative Antillean endemic macaws, all extinct and several of dubious validity (Wiley and Kirwan 2013). Based on plumage, Ara tricolor has been suggested to be closely related to the other but much larger (Forshaw and Cooper 1973) red macaws, A. macao and A. chloropterus. Unlike other Antillean macaws, there are several extant specimens of A. tricolor, 19 skins and fragments from three fossil sites (Olson and Suárez 2008). The skins have not previously been sampled for genetic analysis.

New information:

Two A. tricolor specimens are held at the Swedish Museum of Natural History, and toepads of both were sampled (Johansson et al. 2018). Complete mtDNA genomes were sequenced for five of the seven species of macaws that occur in the NACC area, all except A. ambiguus and A. chloropterus, for which partial mitochondrial sequence (16S and CO1) was obtained. Contrary to expectations that it would prove most closely related to the two extant red macaws, in this phylogeny A. tricolor is sister to the clade that includes both large red and large green macaws (A. militaris and A. macao).

Relevant portion of Figure 1 in Johansson et al. (2018), a phylogeny based on complete mitochondrial sequences. Estimated divergence dates are above the nodes and posterior probabilities below (* = 1.0 pp).

Johansson et al. (2018) also produced a phylogeny based on the partial mitochondrial data; this included all species in our area. The top half of this phylogeny is poorly supported, but the clade containing tricolor is relatively robust and supports the position of tricolor as sister to a clade containing militaris and macao, as well as the two species not sampled in the mt-genome phylogeny, ambiguus and chloropterus. This phylogeny indicates that ambiguus is sister to and very closely related to militaris, and that chloropterus is also part of this clade, but that its placement is unresolved relative to macao and militaris/ambiguus. Ara rubrogenys is poorly supported as sister to Ara severus.

Relevant portion of Figure S1 of Johansson et al. (2018), a phylogeny based on sequences of the mitochondrial genes 16S and CO1.

With acceptance of this proposal, these macaws have now been resequence as follows for the NACC area:

Ara ararauna

Ara severus

Ara tricolor

Ara militaris

Ara ambiguus

Ara macao

Ara chloropterus

In generating this linear sequence, we considered macao + chloropterus + militaris/ambiguus to form a 3-way polytomy, and placed militaris/ambiguus last because it consists of more species, and macao first because of its more northerly distribution than chloropterus.

The SACC area Ara macaws (Remsen et al. 2020) are currently sequenced as follows:

Ara ararauna

Ara glaucogularis

Ara militaris

Ara ambiguus

Ara macao

Ara chloropterus

Ara rubrogenys

Ara severus

Following SACC conventions and for congruence with NACC, the sequence should be:

Ara ararauna

Ara glaucogularis

Ara severus

Ara rubrogenys

Ara militaris

Ara ambiguus

Ara macao

Ara chloropterus

Given that the remainder of the Johansson et al. (2018) phylogeny is not densely sampled, this proposal focused only on macaws.

Recommendation:

We recommend adopting these minor sequence changes.

Literature cited:

Chesser, R.T., S.M. Billerman, K.J. Burns, C. Cicero, J.L. Dunn, A.W. Kratter, I.J. Lovette, N.A. Mason, P.C. Rasmussen, J.V. Remsen, Jr., D.F. Stotz, and K. Winker (2020). Sixty-first Supplement to the American Ornithological Society’s Check-list of North American Birds. The Auk: Ornithological Advances. https://doi.org/10.1093/auk/ukaa030.

Forshaw, J. & W. Cooper. 1973. Parrots of the world. Doubleday & Co., Garden City, New York.

Johansson, U.S., P.G.P. Ericson, M.P.K. Blom & M. Irestedt. 2018. The phylogenetic position of the extinct Cuban Macaw Ara tricolor based on complete mitochondrial genome sequences. Ibis 160: 666-672.

Olson, S.L. & W. Suárez. 2008. A fossil cranium of the Cuban Macaw Ara tricolor (Aves: Psittacidae) from Villa Clara Province, Cuba. Caribbean Journal of Science 44: 287-290.

Wiley, J.W. & G.M. Kirwan. 2013. The extinct macaws of the West Indies, with special reference to Cuban Macaw Ara tricolor. Bulletin of the British Ornithologists’ Club 133: 125-156.

Pamela C. Rasmussen, July 2020.

Comments from Remsen: “YES. Required book-keeping to follow the conventions of linear sequencing in a phylogenetic classification. The genetic data aren’t great – two mtDNA loci – but at least they represent a phylogenetic hypothesis to be tested and modified as needed … in contrast to the current sequence, which in Ara based is based on historical momentum without a explicit rationale (as far as I know).”

Comments from Robbins: “YES. I vote yes for the sequence. The analyses by Provost et al. (2017) provide stronger support for some of these nodes. If one looks at the Johansson et al. paper, it fails to cite Provost et al. Take a look at the pertinent figure in the reference: “Resolving a phylogenetic hypothesis for parrots: implications from systematics to conservation Kaiya L. Provost, Leo Joseph & Brian Tilston Smith Published online: 01 Nov 2017. Austral Ornithology.”

Comments from Stiles: “YES. The new sequence looks OK to me.”

Comments from Jaramillo: “YES. This is congruent with multiple published data including Provost et al. 2017 which was not cited in the proposal.”

Comments from Areta: “YES. The different phylogenies coincide, so we should re-sort species to follow them as developed by Pam.”

Comments from Pacheco: “YES. Consistent with the latest results.”

Comments from Claramunt: “YES. The proposed sequence follows SACC conventions. I first thought that ambiguus+militaris should be listed last as it is the most diverse clade in the 3-way polytomy but I see that is not what our criteria state.

Comments from Bonaccorso: “YES. The sequence is consistent with the evidence at hand.”