Proposal (503) to South American Classification Committee
Treat Myiopsitta luchsi as a separate species from M. monachus
In this proposal, I am revisiting territory that Nores covered in the rejected proposal #93. However, more evidence is now available, both in the form of a molecular study (Russello et al. 2008) and in the accessibility of voice information that suggests real genetic and vocal differences between the Bolivian intermontane taxon luchsi and the remainder of Myiopsitta monachus.
Molecular study: In their Figure 2 (reproduced here), Russello et al. (2008) provided a network of haplotypes of mtDNA (control region, 558 bp) from all named taxa within Myiopsitta (monachus N=38, calita N=9, cotorra N=16, and luchsi N=14; plus 64 birds from feral populations in US of unknown taxon) mostly from toe-pad sampling of AMNH specimens).
The network showed little uniqueness of haplotypes among the taxa within Myiopsitta with the strong exception of luchsi, which shared no haplotypes with any of the other named taxa (the localities from which specimens of cotorra, the closest geographic representative of lowland birds to luchsi, were taken were from Matto Grosso, Brazil, and central Paraguay). Russello et al. (2008) took this result to mean that luchsi is a monophyletic and diagnosable group that has been reproductively isolated from the rest of the members of M. monachus, despite being reported only 175 km away from the nearest population of M. m. cotorra, and proposed that it be accepted as a distinct Phylogenetic Species (and more subtly suggesting that the names cotorra and calita be synonymized with monachus, at least if one follows the PSC).
Nesting: As the proposed English name ‘Cliff Parakeet’ suggests, this species does seem to be entirely restricted to breeding sites on cliffs, despite the presence of trees and telephone poles within its range that could allow it to nest in the same manner as its lowland counterparts. However, luchsi, based on my personal experience with it, is considerably rarer than lowland monachus within its range, and its nests are smaller affairs that cluster around bromeliads and other low plant growth along steep cliffs. I have only an experience of N=1 with nesting colonies, but the one I know has remained stable over a ten-year period, with only about 2-5 pairs nesting within a complex, and perhaps only 2-3 nest complexes comprising the colony. Photographs of nests are available here:
Voice: In his comments to Proposal, Van requested voice information to change his decision. I think that is now easier to provide than it was seven years ago. See the following:
Listeners are likely to be impressed by the rather distinct vocalizations of luchsi in comparison to the lowland forms of M. monachus. The typical calls of cliff-nesting luchsi are consistently higher-pitched, less grating, and generally shorter in duration that those of the lowland birds.
Recommendation: Whereas I agree with Van’s comment in Proposal #92 that taxa in Bolivia’s dry intermontane valleys are morphologically distinct from those in the nearby open lowland habitats, there is evidence of continued genetic introgression for at least one of these (Brumfield 2005, involving Thamnophilus caerulescens, one of the species specifically named in Van’s comment). Meanwhile, Myiopsitta (monachus) luchsi shows no such introgression (Russello et al. 2008). Plumage, vocalizations, and nesting behavior differ (the last despite the presence of nesting substrate similar to that available to lowland M. monachus) between luchsi and other populations of monachus. Short of having overlapping populations, I think these data are sufficient to suggest that luchsi and other populations of monachus are distinct enough to be accepted as separate Biological Species. I recommend a vote of YES, overturning the results of Proposal #92.
Brumfield, R. T. 2005. Mitochondrial variation in Bolivian populations of the Variable Antshrike (Thamnophilus caerulescens). Auk 122:414-432.
Russello, M. A., M. L. Avery, and T. F. Wright. 2008. Genetic evidence links invasive monk parakeet populations in the United States to the international pet trade. Bio Med Central Evolutionary Biology 8:217 (pp 1-11). PDF here: <http://www.biomedcentral.com/1471-2148/8/217>
Dan Lane, October 2011
Comments from Pete Hosner: “I saw proposal #503 on the SACC page. I was also struck by the difference of luchsi vocalizations from the lowland forms. I'd like to point out some of my recordings at LNS for further examples for the committee:
http://macaulaylibrary.org/audio/132540 (probably the best one)
Comments from Stiles: “YES – the new genetic data, coupled with the differences in plumage and vocalizations (the two do sound recognizably distinct) favor splitting luchsi from monachus; again, the burden of proof is now on those who would lump them.”
Comments from Robbins: “YES. The new genetic and vocal information along with the described plumage morphology supports recognizing luchsi as a species.”
Comments from Pacheco: “YES. Given the new information (vocal, specially) added to the case I am in favor of the split.”
Comments from Cadena: “NO. Honestly, I am unimpressed by the genetic differences. True, there is no haplotype sharing, but luschi is only 4 mutational steps removed from the rest of taxa in sequences of the highly variable control region (note, by the way, that some haplotypes of luschi are two mutational steps from each other). I obviously do not advocate the use of a genetic (mtDNA) yardstick to establish species limits, but this level of divergence from all other subspecies is quite shallow. And then, of course, such divergence may simply reflect the effect of geographic isolation and need not imply reproductive isolation between forms, which is what we typically focus on. That samples from relatively close localities differ genetically based on mtDNA says little about gene flow given the nonrecombining nature of this marker; dictint phylogroups may persist even within a single panmictic population following a period of geographic isolation and differentiation with subsequent secondary contact. Nuclear DNA data would be crucial to truly ascertain whether there is gene flow between luschi and other forms. On the other hand, vocal data do appear quite suggestive, but, unless I am missing something, they have not been rigorously analyzed nor published in the peer-reviewed literature. Many proposals for splitting taxa have not been accepted owing to lack of published data, so if we want to be consistent, this reasonable proposal will need to wait for the completion of a published analysis of vocal variation.”
Comments from Stotz: “NO. The genetic evidence is not sufficient by itself to split this taxon. Although the nesting site evidence and voice seem like they would establish this as a distinct species, this material is unpublished. I’d like to wait for a publication with the voices seriously analyzed.”
Comments from Pérez: “NO. I was going to vote YES on this but Daniel’s and Doug’s comments on lack of published and more formal vocal analyses convinced me on the contrary. I think data are suggestive of two distinct species. but we need to be consistent in our criteria for evaluation of proposals. Similarly, addition of nuclear data to the molecular data set would be great, though the pattern of monophyly found in Russello et al. (2008)’s study was based on a fair sample size.
Comments from Zimmer: “A somewhat reluctant NO. The vocal differences and fairly stark differences in nesting biology are very suggestive to me that more than one species is involved. Unfortunately, as has been noted by others, none of this has been formally analyzed or published, and in similar cases with even stronger rationale for splitting, we have pretty consistently voted to wait for a published analysis before acting. In this case, there is published genetic data advocating a split, but as Daniel has pointed out, this data is not so impressive on close inspection. I do think that time will prove that there are two biological species involved.”