Proposal (754) to South American Classification Committee:

 

Elevate 13 taxa to species rank based on playback experiments

 

A.  Elevate Pseudocolaptes johnsoni to species rank

B.  Elevate Automolus virgatus to species rank

C.  Elevate Grallaria alticola to species rank

D.  Elevate Scytalopus intermedius to species rank [superseded by SACC 858]

E.   Elevate Ochthoeca thoracica to species rank

F.   Elevate Myadestes venezuelensis to species rank

G.  Elevate Pheugopedius schulenbergi to species rank

H.  Elevate Amazonian populations of Tunchiornis ochraceiceps to species rank

I.     Elevate South American populations of Basileuterus culicivorus to species rank

J.   Elevate Myiothlypis chlorophrys to species rank

K.  Elevate Myiothlypis striaticeps to species rank

L.   Elevate Atlapetes tricolor crassus to species rank

M. Elevate Amazonian populations of Arremon aurantiirostris to species rank

 

 

A prelude to a set of 13 proposals: background and methods from Freeman & Montgomery (2017):

 

Background:

Geographically isolated populations of birds often differ in song. Because birds often choose mates based on their song, song differentiation between isolated populations constitutes a behavioral barrier to reproduction. If this barrier is judged to be sufficiently strong, then isolated populations with divergent songs may merit classification as distinct species under the biological species concept.

 

Methods:

We conducted playback experiments to measure whether populations discriminated against song from a related, allopatric population - these experiments that simulated secondary contact between geographically isolated populations. Briefly, each experiment measured the behavioral response of a territorial bird to two treatments: 1) song from the local population (sympatric treatment) and 2) song from the allopatric population (allopatric treatment). All territorial birds responded to sympatric song by approaching the speaker (typically to within 5 m).

 

We defined song discrimination as instances in which the territory owner(s) ignored allopatric song, defined as a failure to approach within 15 m of the speaker in response to the allopatric treatment. We calculated song discrimination for each taxon pair as the percentage of territories that failed to approach the speaker in response to allopatric song. For example, a song discrimination score of 0.8 indicates that 80% of territorial birds (e.g. 8 out of 10) ignored allopatric song while simultaneously actively defending a territory. We assume that song discrimination is a proxy for premating reproductive isolation; that is, our experiments provide insight into whether these populations would recognize each other as conspecific and interbreed (or not) were they to come into contact with one another. It is unknown what degree of song discrimination is “enough” that song constitutes a strong enough premating barrier to reproduction that allopatric populations merit classification as distinct biological species. To provide a yardstick, we considered nine allopatric Neotropical taxon pairs that were recently split (or have pending proposals to SACC) in part based off differences in vocalizations. We found the average song discrimination in these nine taxon pairs to be ~ 0.6 (60% of territorial birds ignored allopatric song), and suggest that species limits deserve to be reconsidered when taxon pairs currently classified as subspecies have song discrimination scores above ~ 0.6.

 

In most cases, we played songs of populations A and B (where populations A and B comprise a taxon pair) to territorial birds of population A. That is, in the majority of cases we asked whether population A discriminated against song from population B but not the reverse. To date, we have conducted reciprocal playback experiments for 23 taxon pairs (13 oscines and 10 suboscines, see Table S2) in which we measured both discrimination of population A to song from population B and also discrimination of population B to song from population A and in which we conducted at least four experiments on each population (n = 11.5 ± 3.8 playback experiments/population, range = 4 – 23, see Table S2). Song discrimination in these reciprocal cases was highly correlated (r = 0.88, t = 8.4, df = 21, p-value < 0.0001, Figure 1). There were no examples with strongly asymmetric song discrimination (e.g. population A discriminates against population B, but population B does not discriminate against population A). We therefore assume that unidirectional data accurately describes song discrimination within taxon pairs in our database.

 

 

Please forgive the brevity of the following proposals. I did not have time to give each proposal the detail it deserves; nonetheless, I believe the “bare-bones” approach of these proposals provides sufficient relevant information to consider re-evaluating species limits in the following 14 cases.

 

Benjamin Freeman, 15 September 2018

 

 

754A. Elevate Pseudocolaptes johnsoni to species rank

 

Effect on SACC: Elevate Pseudocolaptes johnsoni to species rank (split from Central American Pseudocolaptes lawrencii).

 

Background: Related populations of Pseudocolaptes (tuftedcheeks) occur in Central America (lawrencii) and western Colombia and Ecuador (johnsoni). These allopatric populations are currently classified as conspecific, but differ in plumage and voice. Due to these differences in mate choice traits, they have sometimes been considered to represent two distinct species (e.g., HBW).

 

New data: Freeman and Montgomery (2017) conducted playback experiments on 10 territories of Central American lawrencii. They found that 9 out of 10 territorial birds discriminated against song playback of South American johnsoni (discrimination = fail to approach within 15 m of the speaker. For canopy species such as Pseudocolaptes, we calculated distance to speaker in the horizontal plane. That is, a bird perched high in the canopy but directly above the speaker would have a distance to speaker of 0 m). Perhaps relevant is that these two populations differ in ND2 sequences (mtDNA) deposited on GenBank by 8.5% in uncorrected p-distance, which suggests these two populations may have evolved strong postmating isolation as well, although this is speculative.

 

Competing proposals:

1)   NO = Retain the status quo.

2)   YES = Elevate Pseudocolaptes johnsoni to species rank (split from Central American Pseudocolaptes lawrencii).

 

Recommendation: Central American birds respond strongly to lawrencii song, but essentially ignore song from johnsoni. This suggests that vocal differences constitute a strong premating barrier to reproduction between these taxa. I therefore recommend treating johnsoni and lawrencii as distinct biological species. English names currently in use are Pacific Tuftedcheek for johnsoni and Buffy Tuftedcheek for lawrencii. However, at present “Buffy Tuftedcheek” refers to johnsoni + lawrencii. I am agnostic on English names for this (and every other) proposal.

 

Additional material added by Peter Boesman:

 

Morphological differences were summarized in del Hoyo & Collar (2016): “Until recently, normally considered conspecific with P. lawrencii, but differs in its stronger rufous (less buff-tinged) mantle and back (ns[1]); rich rufous vs grey-streaked cream-buff underparts (3); rufous-tan vs grey-black outer vanes of primaries (2); wing-coverts dark grey-brown with vague rufous edges vs blackish with strong rufous tips (2); shorter tail (sample size too small, but evidence indicative; ns).”

Vocal differences were treated by Spencer (2011) and Boesman (2016), and summarized in del Hoyo & Collar (2017): “divergent song, being a high-pitched (score 2) rattled series of notes, slowing into stuttering and ending (always) with a characteristic high-pitched down-slurred note (2), vs several well-spaced staccato notes followed by a trill, which usually ascends in pitch and then descends while slowing in pace (1).”

Playback response was evaluated in one direction. Both Spencer (2011) and (more systematically) Freeman & Montgomery (2017) found no response of lawrencii to playback other than its own taxon-specific voice.

Comparative genetic differences: data is available for the three groups GenBank, apparently a genetic tree which includes the three groups has not been published yet.

See:

Boesman, P. (2016). Notes on the vocalizations of Buffy Tuftedcheek (Pseudocolaptes lawrencii). HBW Alive Ornithological Note 87. In: Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. https://doi.org/10.2173/bow-on.100087 https://static.birdsoftheworld.org/on87_buffy_tuftedcheek.pdf

Spencer, A. (2011). Variation in Tuftedcheek vocalizations.  https://www.xeno-canto.org/article/99

 

 

754B. Elevate Automolus virgatus to species rank

 

Effect on SACC: Elevate Automolus virgatus to species rank (split from Amazonian Automolus subulatus).

 

Background: Related populations of Automolus woodhaunters occur west of the Andes (virgatus group in Central America and western Colombia and Ecuador), and east of the Andes (Amazon basin; subulatus group). These allopatric populations are currently classified as conspecific by SACC, but differ markedly in voice, and somewhat in plumage. Due to these differences, they have often been considered to represent two distinct species (e.g., HBW, many field guides).

 

New data: Freeman and Montgomery (2017) conducted playback experiments on 12 territories of virgatus group individuals (6 in Costa Rica and 6 in western Ecuador). They found that 11 out of 12 territorial birds discriminated against song playback of the Amazonian subulatus group (discrimination = fail to approach within 15 m of the speaker).

 

Competing proposals:

1)   NO = Retain the status quo.

2)   YES = Split Automolus virgatus from A. subulatus.

 

Recommendation: Central American and Choco birds respond strongly to local song, but essentially ignore song from Amazonian birds. This suggests that vocal differences constitute a strong premating barrier to reproduction between these taxa. I therefore recommend treating the virgatus group and the subulatus group as distinct biological species. English names currently in use are Western Woodhaunter for the virgatus group, and Eastern Woodhaunter and Amazonian Woodhaunter for the subulatus group.

 

Additional material added by Peter Boesman:

 

Data available in 2003 were summarized in proposal https://www.museum.lsu.edu/~Remsen/SACCprop40.htm.

 

Besides the main remark that no peer-reviewed paper had been published, there was also some uncertainty about cordobae.  Since then, no in-depth study has been published, but the following can be noted:

 

Morphological differences were summarized in del Hoyo & Collar (2016) after studying a series of specimens: virgatus group has duskier underparts , with pale flammulations more confined to upper breast (1) and slightly darker chestnut tail (1).

Vocal differences have been qualitatively described in a variety of sources, were treated more quantitatively in Boesman (2016), and summarized in del Hoyo & Collar (2017): “virgatus group has a highly divergent song: a series of evenly spaced identical short staccato notes “keek..keek..keek..keek” vs a series of just a few (usually 2-3) downslurred notes, often (perhaps when excited) followed by a low-pitched rattle, hence more (ns 1) and much shorter notes (3) with a double peak frequency (2).”

Genetic differences have been documented in Claramunt et al. (2013). Although both groups unsurprisingly are sisters (assimilis represents the virgatus group), divergence seems to have occurred earlier than is the case e.g. in species of the infuscatus complex.

 

 

and more recently also documented by Schultz et al. (2017):

 

 

Although sonograms of cordobae now definitely confirm it belongs to the western group, the remark in proposal 40 about a peer-reviewed paper documenting voice remains. The incentive for such a paper is, however. lower than ever. On the other hand, we have now a note quantifying vocal differences, a paper documenting playback response, and genetic studies indicating fairly high genetic divergence.

See:

Boesman, P. (2016). Notes on the vocalizations of Striped Woodhaunter (Hyloctistes subulatus). HBW Alive Ornithological Note 90. In: Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. https://doi.org/10.2173/bow-on.100090 https://static.birdsoftheworld.org/on90_striped_woodhaunter.pdf

Claramunt, S.; Derryberry, E.P.; Cadena, C.D.; Cuervo, A.M.; Sanín, S.; Brumfield, R.T. (2013). Phylogeny and classification of Automolus foliage-gleaners and allies (Furnariidae). Condor. 115 (2): 375–385.

Schultz, E., Burney, C.; Brumfield, R.; Polo, E.; Cracraft, J., Ribas, C. (2017) Systematics and biogeography of the Automolus infuscatus complex (Aves; Furnariidae): Cryptic diversity reveals western Amazonia as the origin of a transcontinental radiation. Molecular Phylogenetics and Evolution 107:503-515.

 

 

754C. Elevate Grallaria alticola to species rank

 

Effect on SACC: Elevate Grallaria alticola to species rank (split from G. quitensis).

 

Background: Grallaria quitensis inhabits high elevations (typically paramos) in the Northern and Central Andes. Three allopatric subspecies differ in vocalizations, and, to a lesser extent, plumage.

 

New data: Freeman and Montgomery (2017) conducted playback experiments on 9 territories of quitensis in Ecuador to measure response to alticola (restricted to the Eastern Andes in Colombia). They found that 6 out of 9 territorial birds in Ecuador discriminated against song playback of alticola (discrimination = fail to approach within 15 m of the speaker). Perhaps relevant is that these two populations differ in ND2 sequences deposited on GenBank by 5.4% in uncorrected p-distance, which suggests that the two populations may have evolved reasonably strong postmating isolation as well, though this is speculative.

 

Competing proposals:

1)   NO = Retain the status quo.

2)   YES = Elevate Grallaria alticola to species rank.

 

Recommendation: Birds from Ecuador respond strongly to local song, but, in the majority of cases, ignore song from andicola birds. This suggests that vocal differences constitute a strong premating barrier to reproduction between these two taxa. I therefore recommend treating alticola and quitensis as distinct biological species. I am not aware of existing English names; HBW uses “Northern Tawny Antpitta” for alticola and “Western Tawny Antpitta” for quitensis; there may be better options.

 

Additional material added by Peter Boesman:

 

Morphological differences between the 3 races were summarized in del Hoyo & Collar (2016) after studying a series of specimens.

Vocal differences have been quantified in Boesman (2016) and summarized in del Hoyo & Collar (2017). The two main vocalisations (‘song’ and ‘call’) differ significantly between all 3 races. They are also described in Greeney (2018).

Genetic data can be found for 2 races in Winger et al. (2015) and suggest paraphyly: “Grallaria quitensis quitensis was identified as the closest out-group to the bay-backed antpittas. However, the sample of G. quitensis alticola was recovered as sister to G. hypoleuca (Fig. 2A), rather than to G. q. quitensis, with low support”.

 

This case obviously reminds me of the recent publications about the Rufous Antpitta complex, with the three races of G. quitensis actually being the higher altitude replacement of resp. G.(r.) rufula, G. (r.) saturata, and G. (r.) gravesi, and thus -even more than the latter trio- separated by regions of unsuitable habitat.

 

 

We have here a very analogous situation of limited morphological divergence and significant vocal differences among allopatric populations separated by geographical barriers.

 

It boils down to the question whether a peer-reviewed paper is considered a requirement or if sufficient analogy with a well-documented case can be used as a convincing argument.

See:

Boesman, P. (2016). Notes on the vocalizations of Tawny Antpitta (Grallaria quitensis). HBW Alive Ornithological Note 72. In: Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. https://doi.org/10.2173/bow-on.100072 https://static.birdsoftheworld.org/on72_tawny_antpitta.pdf

Greeney, H. (2018) Antpittas and Gnateaters. Helm Identification Guides. 

Winger et al. (2015.) Inferring speciation history in the Andes with reduced-representation sequence data: An example in the bay-backed antpittas (Aves; Grallariidae; Grallaria hypoleuca s. l.) Molecular Ecology 24:6256-6277.

 

 

754D. Elevate Scytalopus intermedius to species rank

 

NOTE from Remsen: This proposal was superseded by SACC proposal 858.

 

Effect on SACC: Elevate Scytalopus intermedius to species rank (split from S. latrans).

 

Background: Scytalopus latrans inhabits high elevations in the Northern and Central Andes. Song is somewhat divergent between multiple populations. This proposal focuses on two groups; the population of latrans found in southeastern Ecuador, and intermedius, which occurs in Peru south of the Marañon Gap.

 

New data: Freeman and Montgomery (2017) conducted playback experiments on 8 territories of latrans in southeastern Ecuador. They found that all 8 territorial birds in Ecuador discriminated against song playback of intermedius (discrimination= fail to approach within 15 m of the speaker).

 

Competing proposals:

1)   NO= Retain the status quo.

2)   YES = Elevate Scytalopus intermedius to species rank.

 

Recommendation: Birds from southeastern Ecuador respond strongly to local song, but, in all cases, ignore song from intermedius. This suggests that vocal differences constitute a strong premating barrier to reproduction between these two taxa, which are found on adjacent and opposite sides of the Marañon Gap. I therefore recommend treating populations north and south of the Marañon Gap as distinct biological species. There is marked variation in vocalizations within latrans found north of the Marañon Gap, some of which may be relevant in the future to species limits within the latrans group (= all population found north of the Marañon Gap). I am not aware of existing English name.

 

 

 

754E. Elevate Ochthoeca thoracica to species rank

 

Effect on SACC: Elevate Ochthoeca thoracica to species rank (split from O. cinnamomeiventris).

 

Background: Ochthoeca cinnamomeiventris is widely distributed in the tropical Andes. Vocal and plumage variation is divergent between multiple populations. This proposal focuses on two taxa; cinnamomeiventris, found north of the Marañon Gap, and thoracica, which occurs in Peru south of the Marañon Gap. These taxa differ in song and plumage.

 

New data: Freeman and Montgomery (2017) conducted playback experiments on 5 territories of cinnamomeiventris in southeastern Ecuador. They found that all 5 territorial birds in Ecuador discriminated against song playback of thoracica (discrimination= fail to approach within 15 m of the speaker).

 

Competing proposals:

1)   NO = Retain the status quo.

2)   YES = Elevate Ochthoeca thoracica to species rank.

 

Recommendation: Birds from southeastern Ecuador respond strongly to local song, but, in all cases, ignore song from thoracica. This suggests that vocal differences constitute a strong premating barrier to reproduction between these two taxa, which are found on adjacent and opposite sides of the Marañon Gap. I therefore recommend treating cinnamomeiventris and thoracica as distinct biological species. An English name currently used for thoracica is “Maroon-belted Chat-Tyrant”; as far as I can tell, cinnamomeiventris is known as “Slaty-backed Chat-Tyrant,” which is also the English name widely used for the entire complex.

 

Additional material added by Peter Boesman:

 

Vocal differences have been quantified in Boesman (2016) and summarized in del Hoyo & Collar (2017).

(The case of nigrita remains to be solved (treated as a full species by IOC). However, a recording of mine of an unseen bird (XC430652) sounds very much like cinnamomeiventris, and seems to indicate limited vocal divergence.)

Genetic data can be found in Garcia-Moreno et al. (1998) (in which they propose a split): “The genetic differentiation between cinnamomeiventris and thoracica (0.053) is of the same magnitude as that between other sister species (e.g., 0.039- 0.063 within the S. diadema group, 0.042 between 0. leucophrys and 0. oenanthoides”. Also Cuervo (2013) reached similar conclusions.

 

We have thus here a suboscine case of two groups which differ moderately in morphology, significantly in voice, and show a fairly deep genetic divergence.

 

See:

Cuervo, A. (2013). Evolutionary Assembly of the Neotropical Montane Avifauna. Thesis, Louisiana State University.

García-Moreno J., Arctander P., Fjeldså J. (1998) Pre-Pleistocene differentiation among chat-tyrants. Condor 100:629-640.

Boesman, P. (2016). Notes on the vocalizations of Slaty-backed Chat-tyrant (Ochthoeca cinnamomeiventris). HBW Alive Ornithological Note 253. In: Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. https://doi.org/10.2173/bow-on.100253  https://static.birdsoftheworld.org/on253_slaty-backed_chat-tyrant.pdf

 

 

754F. Elevate Myadestes venezuelensis to species rank

 

Effect on SACC: Elevate Myadestes venezuelensis to species rank (split from M. ralloides).

 

Background: Myadestes ralloides is widely distributed in the tropical Andes. Vocal variation is markedly divergent among populations of M. ralloides. This proposal focuses on two taxa; venezuelensis, found north of the Marañon Gap in eastern Ecuador, and ralloides, which occurs in Peru south of the Marañon Gap.

 

New data: Freeman and Montgomery (2017) conducted playback experiments on 12 territories of venezuelensis in eastern Ecuador. They found that 10 out of 12 territorial birds in Ecuador discriminated against song playback of ralloides (discrimination= fail to approach within 15 m of the speaker).

 

Competing proposals:

1)   NO = Retain the status quo.

2)   YES = Elevate Myadestes venezuelensis to species rank.

 

Recommendation: Birds from eastern Ecuador respond strongly to local song, but, in nearly all cases, ignore song from ralloides. This suggests that vocal differences constitute a strong premating barrier to reproduction between these two taxa, which are found on adjacent and opposite sides of the Marañon Gap. I therefore recommend treating populations north and south of the Marañon Gap as distinct biological species. I am not aware of existing English names. There is further vocal variation between populations living on the Pacific slope in western Ecuador and those on the Amazonian slope in eastern Ecuador – these may also prove to constitute distinct biological species, but our (unpublished) playback experiments between these taxa is not sufficient to evaluate species limits at present.

 

Additional material added by Peter Boesman:

 

Morphological differences are analyzed in del Hoyo & Collar (2016) based on specimens in AMNH and indicate a yellower bill and a paler belly, but evidently, differences are rather small.

Vocal differences have been quantified in Boesman (2016). Southern ralloides appears vocally the most distinctive taxon, with plumbeiceps vs venezuelensis also showing smaller vocal differences.

Genetic differences can be found in Miller (2007). “Average pairwise distances between M. ralloides and M. coloratus (6.5%; range: 5.7–8.3%) and between M. ralloides and M. melanops (6.0%; range: 5.9–8.0%) only slightly exceeded the pairwise distance between M. ralloides populations across the Marañon valley (6.0%; range: 5.3–7.3%). Pairwise distances between M. coloratus and M. melanops averaged 2.0% (range: 1.4–3.6%), which is similar to the shallowest divergence between phylogroups within M. ralloides.” Cuervo (2013) reached similar conclusions.

 

 

This is thus a case somewhat similar to Catharus dryas in terms of differentiation (proposal 865).

See:

Boesman, P. (2016). Notes on the vocalizations of Andean Solitaire (Myadestes ralloides). HBW Alive Ornithological Note 435. In: Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. https://doi.org/10.2173/bow-on.100435 https://static.birdsoftheworld.org/on435_andean_solitaire.pdf

Cuervo, A. (2013). Evolutionary Assembly of the Neotropical Montane Avifauna. Thesis, Louisiana State University.

Miller, M., Bermingham, E., Ricklefs, R. (2007). Historical biogeography of the new world solitaires (Myadestes spp.) Auk 124:868–885.

 

 

754G. Elevate Pheugopedius schulenbergi to species rank

 

Effect on SACC: Elevate Pheugopedius schulenbergi to species rank (split from P. euophrys).

 

Background: Pheugopedius euophrys is widely distributed in the Northern Andes. Vocal and plumage variation is somewhat divergent between multiple populations. This proposal focuses on two taxa; longipes, found north of the Marañon Gap in eastern Ecuador, and schulenbergi, which occurs in Peru south of the Marañon Gap.

 

New data: Freeman and Montgomery (2017) conducted playback experiments on 19 territories of longipes in southeastern Ecuador. They found that 12 out of 19 territorial birds in Ecuador discriminated against song playback of schulenbergi (discrimination= fail to approach within 15 m of the speaker).

 

Competing proposals:

1)   NO = Retain the status quo.

2)   YES = Elevate Pheugopedius schulenbergi to species rank.

 

Recommendation: Birds from southeastern Ecuador respond strongly to local song, but, in most cases, ignore song from schulenbergi. This suggests that vocal differences constitute a strong premating barrier to reproduction between these two taxa, which are found on adjacent and opposite sides of the Marañon Gap. I therefore recommend treating populations north and south of the Marañon Gap as distinct biological species. Schulenbergi is called “Grey-browed Wren” by HBW.

 

Additional material added by Peter Boesman:

 

Morphological differences are summarized in del Hoyo & Collar (2016).

Vocal differences have been quantified in Boesman (2016).

Subspecies of P. euophrys show quite some morphological differences in between them, as with schulenbergi. The voice of schulenbergi is, however, remarkably different from all other subspecies, and even for an oscine passerine with vocal learning ability this seems to be quite a stretch to consider it a single species.

 

Some supportive genetic info is however highly desirable.

 

There is also the case of the undescribed ‘Mantaro Wren’, but until it is described as a new taxon, is better treated as a potential future case. 

See:

Boesman, P. (2016). Notes on the vocalizations of Plain-tailed Wren (Thryothorus euophrys). HBW Alive Ornithological Note 290. In: Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. https://doi.org/10.2173/bow-on.100290 https://static.birdsoftheworld.org/on290_plain-tailed_wren.pdf

 

 

 

754H. Elevate Amazonian populations of Tunchiornis ochraceiceps to species rank

 

Effect on SACC: Elevate Amazonian populations of Tunchiornis ochraceiceps to species rank (split from populations found west of Andes).

 

Background: Tunchiornis ochraceiceps consists of many named subspecies that are found both west and east of the Andes. There is marked vocal and plumage variation throughout its broad distribution. 

 

New data: Freeman and Montgomery (2017) conducted playback experiments on 10 territories of T. ochraceiceps in Costa Rica. They found that 8 out of 10 territorial birds discriminated against song playback from the western Amazonian ferrugineifrons group (discrimination = fail to approach within 15 m of the speaker).

 

Competing proposals:

1)   NO = Retain the status quo.

2)   YES = Split populations found west of the Andes from populations found east of the Andes.

 

Recommendation: Central American birds respond strongly to local song, but essentially ignore song from western Amazonian birds. This suggests that vocal differences constitute a strong premating barrier to reproduction between these allopatric taxa. It would be nice to have done further playback experiments in western Colombia and western Ecuador, but this was not possible. There are additional vocal differences within both west-of-the-Andes and east-of-the-Andes groups. In sum, though this is not as clear-cut as many of the other cases, I recommend treating the populations found east and west of the Andes as distinct biological species. I am not aware of existing English names that would be applied to west-of-the-Andes vs. east-of-the-Andes groups.

 

Additional material added by Peter Boesman:

 

Vocal differences have been analyzed in Boesman (2016). Three vocal groups were identified. NW group differs from Amazon group by having higher-pitched shorter whistles. Guianan group differs from Amazon group by having two-note whistles at different pitch.

Genetic data are given in Naka and Brumfield (2018).

 

 

Genetic and vocal analysis seem to go hand-in-hand, with luteifrons being most divergent, followed by NW populations vs Amazon.

 

The situation of rubrifrons/lutescens is not entirely clear however, and makes this case less clear-cut.

 

See:

Boesman, P. (2016). Notes on the vocalizations of Tawny-crowned Greenlet (Hylophilus ochraceiceps). HBW Alive Ornithological Note 168. In: Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. https://doi.org/10.2173/bow-on.100168 https://static.birdsoftheworld.org/on168_tawny-crowned_greenlet.pdf

Naka, L., Brumfield,R. (2018). The dual role of Amazonian rivers in the generation and maintenance of avian diversity. Sci. Adv. 2018-4: 1-13.

 

 

754I. Elevate South American populations of Basileuterus culicivorus to species rank

 

Effect on SACC: Elevate South American populations of Basileuterus culicivorus to species rank (split from populations found in Central America).

 

Background: Basileuterus culicivorus consists of many named subspecies found throughout much of Central and South America. There is marked vocal and plumage variation throughout its large distribution. This proposal focuses on two allopatric taxa; godmani, found in Costa Rica and Panama, and the cabanisi group which occurs in nearby Colombia and Venezuela.

 

New data: Freeman and Montgomery (2017) conducted playback experiments on 17 territories of godmani in Costa Rica. They found that 13 out of 17 territorial birds discriminated against song playback from the cabanisi group (discrimination = fail to approach within 15 m of the speaker).

 

Competing proposals:

1)   Retain the status quo.

2)   Elevate Basileuterus cabanisi to species rank.

 

Recommendation: Central American birds respond strongly to local song, but essentially ignore song from cabanisi. This suggests that vocal differences constitute a strong premating barrier to reproduction between these allopatric taxa. Thus, I recommend treating the populations found in South America as distinct from those in Central America. I note that species limits within South American populations may require further evaluation. English names: HBW uses “Stripe-crowned Warbler” for Central American populations, “Yellow-crowned Warbler” for populations in Colombia and Venezuela, and “Golden-crowned Warbler” for the additional South American populations. We have no playback data to evaluate differences between the cabanisi group and other populations in South America at this time. Still, the data we summarize above suggest that Central American populations represent a distinct species from those in adjacent northwestern South America; thus this proposal.

 

Additional material added by Peter Boesman:

 

Vocal differences have been analysed in Boesman (2016). Three vocal groups were identified.  These seem to go hand-in-hand with the three morphological groups (Curson et al. 1994), and led del Hoyo and Collar (2016) to assign them species rank.

Genetic data is provided in Vilaca et al. (2010), who identified 5 clades. Unfortunately, out of ca. 150 samples, only 2 were from the cabanisi group (1 taxon). Nevertheless, it would seem that the South American subspecies are a more recent colonisation from the East Mexico branch, which diverged earlier from West Mexico. Thus, this seems to be a case in which evolution in phenotypic traits have evolved at unequal rates in the distinct clades (which as in other cases may lead to paraphyletic species).

(It is also suggested that B. hypoleucus may be a colour morph of Golden-crowned Warbler, given there are no clear genetic of vocal differences. This is however another case…)

 

See:

Boesman, P. (2016). Notes on the vocalizations of Golden-crowned Warbler (Basileuterus culicivorus). HBW Alive Ornithological Note 380. In: Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. https://doi.org/10.2173/bow-on.100380 https://static.birdsoftheworld.org/on380_golden-crowned_warbler.pdf

Curson, J., Quinn, D., Beadle, D. (1994). New World Warblers. Helm Identification Guide. Helm. London.

Vilaca S.T., Santos, F.R. (2010) Biogeographic history of the species complex Basileuterus culicivorus (Aves, Parulidae) in the Neotropics. Molecular Phylogenetics and Evolution 57: 585–597.

 

 

754J. Elevate Myiothlypis chlorophrys to species rank

 

Effect on SACC: Elevate Myiothlypis chlorophrys to species rank (split from M. chrysogaster).

 

Background: Myiothlypis chrysogaster consists of two populations, one found in the Choco in western Colombia and western Ecuador, and a second that inhabits eastern Peru (and, narrowly, Bolivia).  These taxa are notably different in vocalizations and have been considered to be distinct biological species by various authors.

 

New data: Freeman and Montgomery (2017) conducted playback experiments on 11 territories of chlorophrys in western Ecuador. They found that 10 out of 11 territorial birds discriminated against playback of chrysogaster song (discrimination = fail to approach within 15 m of the speaker). We also recently conducted two playback experiments that showed that chrysogaster discriminates against (ignores) chlorophrys song (unpublished, and small sample size caveat, but I thought worth mentioning).

 

Competing proposals:

1)   NO = Retain the status quo.

2)   YES = Elevate Myiothlypis chlorophrys to species rank.

 

Recommendation: Chlorophrys responds strongly to local song, but essentially ignores song from chrysogaster. This suggests that vocal differences constitute a strong premating barrier to reproduction between these allopatric taxa. Thus, I recommend treating these two populations as distinct biological species.  These taxa are sometimes referred to by the English names “Choco Warbler” (for chlorophrys) and “Cuzco Warbler” (for chrysogaster).

 

Additional material added by Peter Boesman:

 

Proposal 68 (2003) already tackled this case. However, in those days lack of sonograms etc. did not allow for a proper comparison.

Morphological differences were summarized in del Hoyo and Collar (2016): chlorophrys has a broad green vs narrow yellow post-ocular supercilium, more olive flanks and shorter tail.

Vocal differences have been analysed in Boesman (2016), identifying two very distinct vocal groups (chrysogaster and chlorophrys).

Genetic data: Lovette et al (2010) only included the chlorophrys taxon. The two taxa may not have not been compared yet genetically.

 

See:

Boesman, P. (2016). Notes on the vocalizations of Golden-bellied Warbler (Basileuterus chrysogaster). HBW Alive Ornithological Note 377. In: Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. https://doi.org/10.2173/bow-on.100377  https://static.birdsoftheworld.org/on377_golden-bellied_warbler.pdf

Lovette et al. (2010).  A comprehensive multilocus phylogeny for the wood-warblers and a revised classification of the Parulidae (Aves). Molecular Phylogenetics and Evolution 57:753–770.

 

 

 

754K. Elevate Myiothlypis striaticeps to species rank

 

Effect on SACC: Elevate Myiothlypis striaticeps to species rank (split from M. luteoviridis).

 

Background: Myiothlypis luteoviridis is widely distributed in the tropical Andes. Vocal variation is somewhat divergent between multiple populations. This proposal focuses on two taxa; luteoviridis, found north of the Marañon Gap in eastern Ecuador, and striaticeps, which occurs in Peru south of the Marañon Gap.

 

New data: Freeman and Montgomery (2017) conducted playback experiments on 11 territories of luteoviridis in southeastern Ecuador. They found that 8 out of 11 territorial birds in Ecuador discriminated against song playback of striaticeps (discrimination= fail to approach within 15 m of the speaker).

 

Competing proposals:

1)   NO = Retain the status quo.

2)   YES = Elevate Myiothlypis striaticeps to species rank.

 

Recommendation: Birds from southeastern Ecuador respond strongly to local song, but, in most cases, ignore song from striaticeps. This suggests that vocal differences constitute a strong premating barrier to reproduction between these two taxa, which are found on adjacent and opposite sides of the Marañon Gap. I therefore recommend treating populations north and south of the Marañon Gap as distinct biological species. I am not aware of existing English names.

 

Additional material added by Peter Boesman:

 

Vocal differences have been analysed in Boesman (2016), identifying several vocal groups, with striaticeps and euophrys especially standing out.

Genetic data: Lovette et al (2010) only included the euophrys taxon. Cuervo (2013) provided a genetic tree in which the Marañon gap creates the earliest separation of northern and southern groups (>3Mio yrs).

 

 

The southern subspecies striaticeps and euophrys are thus clearly genetically and vocally distinct.

 

See:

Boesman, P. (2016). Notes on the vocalizations of Citrine Warbler (Basileuterus luteoviridis). HBW Alive Ornithological Note 438. In: Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. https://doi.org/10.2173/bow-on.100438 https://static.birdsoftheworld.org/on438_citrine_warbler.pdf

Cuervo, A. (2013). Evolutionary Assembly of the Neotropical Montane Avifauna. Thesis.

Lovette et al. (2010).  A comprehensive multilocus phylogeny for the wood-warblers and a revised classification of the Parulidae (Aves). Molecular Phylogenetics and Evolution 57:753–770.

 

 

754L. Elevate Atlapetes tricolor crassus to species rank

 

Effect on SACC: Elevate Atlapetes tricolor crassus to species rank 

 

Background: Atlapetes tricolor consists of two populations, one found in the Choco in western Colombia and western Ecuador, and a second that inhabits eastern Peru (and, narrowly, Bolivia).  These taxa are notably different in vocalizations (and morphology) and have been considered distinct biological species by several authors.

 

New data: Freeman and Montgomery (2017) conducted playback experiments on 6 territories of crassus in western Ecuador. They found that 5 out of 6 territorial birds discriminated against playback of tricolor song (discrimination = fail to approach within 15 m of the speaker).

 

Competing proposals:

1)   NO= Retain the status quo.

2)   YES = Elevate Atlapetes crassus to species rank.

 

Recommendation: Atlapetes crassus responds strongly to local song, but essentially ignores song from tricolor. This suggests that vocal differences constitute a strong premating barrier to reproduction between these allopatric taxa. Thus, I recommend treating these two populations as distinct biological species. “Choco Brush-Finch” has been used for crassus and “Tricolored Brush-Finch” for tricolor.

 

Additional material added by Peter Boesman:

 

Morphological differences are summarized in del Hoyo and Collar (2016).  

Vocal differences have been analysed in Sanchez-Gonzalez et al. (2015) and Boesman (2016).

Genetic data: Sanchez-Gonzalez et al. (2015) only included crassus, and Klicka et al. (2014) only included tricolor. They were found at different locations in the gene tree:

 

 

 

Sanchez-Gonzalez et al. (2015) summarizers: “In the taxa investigated, the subspecies were found to differ little from each other vocally, but one exception is A. t. crassus and tricolor, which are distributed in western Colombia and Ecuador, and 900 km away in central Peru. They also differ in elevational distributions 300–2000 m against 1750–3050 m) and morphologically (crassus with bill much larger, crown, back and underparts differently coloured). We suggest that the northern form is best treated as a full species: Choco Brush-Finch Atlapetes crassus. In fact, the study by Klicka et al. (2014) included samples of A. t. tricolor from Peru and recovered it as sister to our clade H, which includes Atlapetes from a clade including mainly eastern Andean slope forms, widely separated from our Ecuadorian A. t. crassus sample, thus confirming the taxonomic differentiation in these two taxa.”

 

See:

Boesman, P. (2016). Notes on the vocalizations of Tricolored Brush-finch (Atlapetes tricolor). HBW Alive Ornithological Note 365. In: Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. https://doi.org/10.2173/bow-on.100365 https://static.birdsoftheworld.org/on365_tricolored_brush-finch.pdf

Klicka, J., Keith Barker, F., Burns, K. J., Lanyon, S. M., Lovette, I. J., Chaves, J. A. & Bryson, R. W., Jr (2014). A comprehensive multilocus assessment of sparrow (Aves: Passerellidae) relationships. Molecular Phylogenetics and Evolution 77: 177–182.

Sánchez-González, L.A., Navarro-Sigüenza, A.G., Krabbe, N.K., Fjeldså, J., García-Moreno, J. (2015). Diversification in the Andes: the Atlapetes brush-finches. Zool. Scripta 44(2): 135– 152.

 

 

754M. Elevate Amazonian populations of Arremon aurantiirostris to species rank

 

Effect on SACC: Elevate Amazonian populations of Arremon aurantiirostris to species rank (split from populations found west of Andes).

 

Background: Arremon aurantiirostris consists of many named subspecies that are found both west and east of the Andes. There is marked vocal variation throughout its distribution.

 

New data: Freeman and Montgomery (2017) conducted playback experiments on 23 territories of occidentalis in western Ecuador, and playback experiments on 12 territories of spectabilis in eastern Ecuador. They found that 16 out of 23 territories of occidentalis discriminated against playback of spectabilis song, and that 8 out of 12 territories of spectabilis discriminated against playback of occidentalis song  (discrimination = fail to approach within 15 m of the speaker).

 

Competing proposals:

1)   NO = Retain the status quo.

2)   YES = Elevate Amazonian Arremon aurantiirostris spectabilis to species rank.

 

Recommendation: Arremon aurantiirostris populations in western and eastern Ecuador respond strongly to local song, but, in most cases, ignore song from each other. This suggests that vocal differences constitute a strong premating barrier to reproduction between occidentalis and spectabilis. Thus, I recommend treating these two populations as distinct biological species. I note that this complex likely harbors additional biological species (e.g., in Central America, populations on the Caribbean and Pacific slope show strong song discrimination). Thus, if this split is adopted, it should be recognized that this is not the end of the story (including choosing English names that would minimize confusion in the case of additional splits).

 

 

 

Comments from Stiles: "This is a most interesting proposal!  However, while highly suggestive of biological isolating mechanisms, in most of the individual cases presented I consider that the data presented are insufficient for SACC acceptance, for the following reasons:

 

1) Most of the cases presented involved presenting the song of one population to members of another; reciprocal playbacks would have been more convincing, as asymmetry in responses have been found in some other studies;

 

2) The 60% no-response threshold presented was insufficiently justified: just how much variation exists in this threshold (which was based upon a general average of nine such comparisons of subspecies vs. species responses); it would be helpful to know how much variation occurred around this value, and whether the “threshold” might vary between oscines vs. suboscines, especially given that several of the comparisons presented barely exceed this “threshold”.

 

3) Several of the comparisons were made between populations on either side of the Marañón gap; it is often not clear how close these were to the “dividing line” (in at least one case, a subspecies closer to the gap exists, but was not sampled). In other cases, the author did not specify how closely the respective populations approach each other, and how distant the sampled populations were from the point of closest approach;

 

4) No spectrographic analyses were made of multiple recordings to evaluate possible intrapopulation variation, which might influence the results in several cases; song dialects mediated by learning and cultural transmission are known in oscines;

 

5) In several cases, important distributional gaps occur between the populations sampled in which song variation is known to exist between sampled and unsampled populations (subspecies), which could easily influence interpretation of the results;

 

6) For nearly all cases, genetic data would have helped to clinch the decision, but only for two cases were such data presented;

 

7) The lack of nomenclatural precision often makes the results difficult to apply, as in a number of cases, the taxa involved are polytypic, which at a minimum would require a detailed study of distributions and name priorities essential for arriving at concrete names for the putative species; in several such cases, the subspecies sampled were not given;

 

8) For a number of cases, pertinent investigations are underway (or planned), especially where vocal differences of unsampled populations may very well exist (a similar case in another SACC proposal regarding Henicorhina leucosticta did not pass for this reason). I note that none of the experiments were performed in Colombia, which would have been a strategic area for deciding several cases. Such cases in the present proposal may best be taken as pointers for more comprehensive analyses.

 

"All this is not to say that any of the cases presented are incorrect in suggesting that two (or more!) biological species are involved, but the data are insufficient for SACC action as they stand.  It is also worth noting that several of these proposals were rejected by SACC due to the lack of detailed spectrographic analysis of vocalizations: the point at issue is whether playback experiments represent a sufficient surrogate or substitute for such analysis. I conclude that if the experiments show significant differences in responses to same vs. different populations, the results may be taken as valid. However, when the differences are very close to the threshold value or sample sizes are too small, I recommend caution in their acceptance. I now mention each case, with respect to the problems described above by letters:

 

754A: Pseudocolaptes-plumage, genetic and reciprocal playbacks all support this split, so YES.

 

754B: Automolus-data very suggestive; not clear which population of the subulatus group was taken (where in “Amazonia”?).  Were reciprocal playbacks done for the two virgatus populations, which are at nearly opposite ends of this group’s range? On the other hand, in proposal 40 treating this question, all members of the committee agreed that two species were indicated, given the vocal differences, but most preferred to await a study of sonograms (by Zimmer?) Although I am not aware that this study has been published, I consider that the experiments by Freeman constitute at least a partial surrogate that to me, tips the burden of proof onto those who would maintain these two as conspecific, hence YES.

 

754C: Grallaria-unfortunately, no experiments performed in Colombia, where the Eastern Andes population also differs vocally from that inhabiting the Central Andes, which would seem to be in limbo: the same as the SE Ecuador population or not? Therefore, the data here are incomplete; although genetic data suggest that the two populations sampled represent different species, data from the C Andes birds in Colombia are needed to complete the picture, and I suggest a tentative NO.

 

754D: Scytalopus-here again, the data represent just the tip of the iceberg, since both north and south of the Marañón gap there exist several subspecies with different plumages. Daniel Cadena has been collecting genetic and vocal data on as many named Scytalopus taxa as possible, and may be nearer to doing a comprehensive treatment of the latrans group. Hence, although the data show that at least two biological species may well exist in this assemblage, I feel that any decision should await more comprehensive data, so NO for now.

 

754E: Ochthoeca-another case where multiple, well-defined subspecies exist, especially N of the Marañón gap, according to plumage; presumably the Ecuador sample was of subspecies; a sample of only five experiments with thoracicus from S of the Marañón and here again, I consider the data very suggestive but incomplete: NO for now.

 

754F: Myadestes-nominate ralloides was named from Bolivia (from where were taken the recordings used for this form?); venezuelensis from Venezuela; SE Ecuador is a long way from its type locality. Here, a detailed examination of intraspecific variation in song from intermediate populations (e.g., in Colombia and, depending on the above, N Peru) of these oscines (where song learning and cultural transmission of song dialects could well occur) should be done, and genetic data might also help: once again, I consider the experiments presented here highly suggestive, but the data are as yet incomplete: NO for now.

 

754G: Pheugopedius-the SE Ecuador population (longipes, N of the Marañón gap) was tested against schulenbergi, S of this gap: however, another subspecies (atriceps) occurs closer to this gap than schulenbergi and was not sampled. Intrapopulation variation in songs was not mentioned. So, once more, the data are highly suggestive, but gaps remain. Also, the observed non-response percentage (63%) was very close to the “threshold” (see above), so NO for now.

 

754H: Tunchiornis-a widespread species, the nominate subspecies found from Mexico to W Panama, whereas cis-Andean ferrugineifrons occurs in S Venezuela, Colombia and perhaps S to EC Peru. Although the exact site from which the sample recording(s?) of the latter were taken was not given, evidence for species status of cis- vs. trans-Andean populations sampled is certainly suggestive. However, given the wide range of both forms, I am uneasy because there could well be vocal variation within both forms; hence, I think that more populations should be sampled for a conclusive answer: NO for now.

 

754I: Basileuterus culicivorus-this is a highly polytypic species, with several named subspecies in both Middle and South America. The tested population was godmani of Costa Rica to W Panamá, but the provenance of the recording of the “cabanisi group” was not specified (at least three subspecies of culicivorus occur in Colombia and Venezuela, and several more in cis-Andean South America). Clearly, a much wider sample of the various subspecies would be desirable, along with an evaluation of within-subspecies variation in at least some of these. Population genomics within this species would also be very interesting. Hence, I consider the available evidence too incomplete to justify this split at present; NO for now.

 

754J: Basileuterus chrysothlypis- This experiment dealt with a northern, trans-Andean subspecies (chlorophrys) and a more southern cis-Andean subspecies (nominate chrysothlypis); these two are thus widely separated geographically, such that parapatry is not relevant (or possible).  No other subspecies exist in this group. Here, the vocal evidence is stronger (including a very small sample of reciprocal playbacks). Although sonograms and genetic evidence would surely clinch the case, the available data seem to me to tip the burden of proof towards conspecifity, hence a tentative YES.

 

754K:. Myiothlypis luteiventris-Another comparison of subspecies N vs. S of the Marañón gap. The song differences, as described by Schulenberg et al. (2009) certainly seem considerable, but with only 8 of 11 (73%) no-responses of the northern luteiventris to songs of the southern striaticeps, the results should be considered tentative at present. Also, a subspecies further south (euophrys) shows greater morphological differences from striaticeps as well as possibly greater differences in song. So: NO for now, pending more data.

 

754L:  Atlapetes-This case is similar to no. 10 in comparing cis- and trans-Andean populations, but with a much smaller sample size (6); given that Atlapetes songs tend to be complex, intraspecific variation could exist. I consider the available evidence to be very suggestive but not conclusive, so NO for now.

 

754M: Arremon-This is another tip-of-the iceberg case, because aurantiirostris includes multiple subspecies with subtle morphological differences between them over a wide range (including two from Costa Rica, that differ noticeably in song). Hence, this result represents a small part of a much bigger problem. Because Jorge Avendaño is now investigating this problem in depth, I believe that any action by SACC should await the results of this study: NO for now.

 

Comments from Cadena: “I am going to vote NO on all these proposals out of principle. I think that the hard work done by Ben Freeman is exremely important and interesting, and is arguably the best evidence we have to evaluate species limits in these groups of birds. However, I agree with all the concerns voiced by Gary, especially with that related to the 60% threshold for discrimination. I am not sure exactly what this means, but say that 60% of the time, females of taxon A meeting males of taxon B discriminate against them. What happens the rest of the time? If on 40% of the encounters females of A do not discriminate against males of B, then inter-taxa matings would be extremely frequent and one would expect hybridization to be rampant, no? Maybe not, but then one should carefully consider other sources of evidence together with the playback data, which takes me to a general suggestion I have on all this. I think that the “bare-bones” approach taken by Ben leaves several open questions and suffers importantly from lack of detail. My suggestion is that all this should be placed in a paper (or papers) where the ranges of the taxa involved are properly described, variation in different characters is analyzed, and nuances of each case are discussed in detail to reach more informed decisions. There are several potential theses projects here for undergraduates with an interest in integrative taxonomy of birds in which Freeman et al. have already made important progress.”

 

Comments from Jaramillo: “A – YES mainly due to fact that this is a suboscine, and the genetic data.

B – YES

C – YES. The issue of other populations in Colombia which may also differ, or perhaps muddy this picture can be dealt with when those data appear.

D – YES. Scytalopus are so clear cut in response to playback, that I find that this may be enough, even though there may be other populations that should be sampled in the future. Or other molecular data will arrive in the future.

E – NO. Kind of on the fence on this one. But 5 experiments seems awful few.

F – YES.  Note also that Miller et al. 2007 published mtDNA data that also suggests a split north and south of the Marañon gap. Paper is available here. https://www.researchgate.net/profile/Matthew_Miller3/publication/228644579_Historical_biogeography_of_the_new_world_solitaires_Myadestes_spp/links/00b7d521e0aefa5c7c000000.pdf

G – NO. I would like to see more data here, 12 out of 19 is a lot of birds that did react positively. More data is necessary in this case.

H – NO. Given the huge variation in this species, I think a more widespread set of experiments, is necessary.

I -  NO, but not because I do not believe that there are multiple species here. But this one is one of those complex ones with possibly multiple species involved, furthermore B. hypoleucus may in fact be conspecific with one of these forms. So, it is complicated enough that I would rather base changes on the Vilaca & Santos (2010) paper. Copy available here:      https://s3.amazonaws.com/academia.edu.documents/46692562/Biogeographic_history_of_the_species_com20160621-14843-6idjqj.pdf?AWSAccessKeyId=AKIAIWOWYYGZ2Y53UL3A&Expires=1522809006&Signature=X%2FzDXcNowKX2AzmZ6ykEM8dpuNc%3D&response-content-disposition=inline%3B%20filename%3DBiogeographic_history_of_the_species_com.pdf

J – YES

K – YES, but tentative.

L – YES. Available molecular data corroborates. Sanchez-Gonzales et al. (2014) found that crassus was in a group with A. melanolaemus and A. forbesi. While Klicka et al. (2014) sampled A. tricolor tricolor and found it was in an entirely different clade with schistaceus, latinuchus etc. Sanchez-Gonzales et al. (2014) also confirm clearly defined differences in song of tricolor and crassus.

 

Klicka, J., Keith Barker, F., Burns, K. J., Lanyon, S. M., Lovette, I. J., Chaves, J. A. & Bryson, R. W., Jr (2014). A comprehensive multilocus assessment of sparrow (Aves: Passerellidae) relationships. Molecular Phylogenetics and Evolution, 77, 177–182.

 

M- NO. Playback experiments not quite conclusive here, and a very complex situation.

 

Additional comments from Stiles: “I recommended a YES on a few (!) of these, because I feel that they did tip the balance on  already accepted but still controversial splits (i.e., not accepted by SACC but widely implemented elsewhere).  I also don’t feel comfortable with a rather dogmatic NO to all without consideration of the contexts involved.”

 

Comments from Areta: “I am also going to vote NO on all proposals, and I agree with Daniel’s views. I agree with all the concerns voiced by Gary, and while I appreciate the effort spent by both Alvaro and Gary in analyzing each case separately, these analyses are not as thorough and complete as I would like to have before me to make an informed decision. I especially feel that the 60% threshold is rather artificial and insufficient. For example, by adding data on reciprocal playback experiments of Upucerthia dumetaria/saturatior, Pseudocolopteryx citreola/flaviventris and Poospiza nigrorufa/whitii (all of which show 100% discrimination) this value can change easily. Not to mention other Suboscines in which responses (even between sister species) are all or none. Also, it troubles me that there are no reports of cases in which the local population ignored its own local song and no assessment of whether the playbacks were done at comparative times of the year (e.g., peak breeding season, etc.). In sum, all these playback experiments are informative to understand some key behavioral traits of possibly separate species, but the taxonomically focused works needed to put these results in perspective are missing (i.e., assessment of validity and priority of names, wide geographic sampling, understanding of other phenotypic traits, evaluation of vocal traits of intervening and/or other closely related populations, possibly genetic data, etc.).”

 

Comments from Claramunt: “I agree with the several caveats raised by Gary regarding the evidence presented by Freeman & Montgomery. In particular, unless there is evidence of homogeneity within taxa, I’m skeptical about playback experiments involving only two populations that are far apart as a way of assessing reproductive isolation. At least, populations in close proximity or most likely to be in secondary contact should be evaluated. Only interpreted together with other information, the results of Freeman & Montgomery help to tip the balance in some cases, as Gary stated. I think we should take advantage of this opportunity to make decisions regarding species limits in light of this new bit of information. Waiting for the ideal playback experiments is not an option, in my opinion.

 

“A. YES to elevate Pseudocolaptes johnsoni to species rank. With a darker and more rufous plumage and a distinctly decurved culmen, johnsoni could be considered the most distinctive taxon in its genus. As confessed by Zimmer (1936), it was only because of its rarity (and scarcity of specimens) plus the uncertainty regarding its type locality what made him treat johnsoni as a subspecies of lawrencii, despite believing that it was a good species. Taxonomic inertia followed (with few exceptions). Now we know that the song of johnsoni is very different and is not recognized by lawrencii. A necessary and long overdue split.

 

B. YES to elevate Automolus virgatus to species rank. This complex shows considerable phenotypic variation that deserves thorough study. Birds from the Choco region (assimilis) are darker and do not have the distinctive slender beak of subulatus; they have instead a more Automolus-like beak. However, the slender beak, similar to that of subulatus, reappears in Central America in virgatus, although birds look much darker. A new relevant paper should also be considered: Schultz et al. 2017 (https://www.sciencedirect.com/science/article/pii/S1055790316304468). Schultz et al. 2017 found that subulatus and assimilis represent two distinct genetic groups divided by the Andes. Other subspecies were not sampled. mtDNA shows two reciprocally monophyletic groups corresponding to subulatus and assimilis. Nuclear data is harder to interpret because assimilis was only sequenced for BF7, and BF7 alleles are messy across the entire genus. However, the relevant information is that no BF7 alleles were shared between subulatus and assimilis (Supplemental Figure C7), thus suggesting no recent gene flow. The clustering algorithm used (BAPS) failed to detect this separation probably because of the missing nuclear data for the trans-Andean populations. A pending question is whether assimilis is indeed conspecific with virgatus or represents a third species, an issue that could be addressed by studying the Panamanian populations, where a contact zone could exist. In the meantime, splitting Amazonian from trans-Andean forms is a step forward.

 

“C. NO to elevate Grallaria alticola to species rank. Playback experiments show some degree of discrimination, but populations tested are far apart. If song structure or song preference vary geographically, then the experiments are irrelevant. No other traits differentiate Grallaria alticola, except it body size, but a formal analysis of geographic variation is required to determine if variation is continuous or discrete.

 

“D. NO to elevate Scytalopus intermedius to species rank. Skimming over what is available in xeno-canto suggests tremendous and complex variation in vocalizations in SE Ecuador and N Peru. The test based on just two populations in this complex is not very informative of what is going on in the region. Much more work is needed.

 

“E. YES to elevate Ochthoeca thoracica to species rank. Although the number of independent experiments was low (5), this information should be interpreted in light the additional information available. Plumage and song variation is prominent and discrete, and matches the taxonomic divide. To the eyes of the subspecies-lover ornithologist of the mid XX century, this variation was only worth subspecific distinction. Freeman and Montgomery (2017) showed that for the birds themselves, this variation means much more, and suggest that these two separate lineages are reproductively isolated because of divergent mating signals. Furthermore, a mitochondrial tree by Andres Cuervo (https://digitalcommons.lsu.edu/gradschool_dissertations/275/), including a large sample across the entire distribution of this complex, shows that thoracica and cinnamomeiventris are reciprocally monophyletic, combining a high degree of divergence and low intra-taxon genetic variability. Therefore, multiple lines of evidence (phenotypic distinctness, playback experiments, genetics) demonstrate that this pair of taxa constitute separate species.

 

Addendum. Note that Ochthoeca thoracica and Ochthoeca cinnamomeiventris were treated as separate species by Cory & Hellmayr and they were lumped later by Peters without providing a rationale. So, this proposal should not be viewed as few playback experiments in isolation but as evidence for whether two taxa that are differentiated in plumage, song, and mtDNA are able to discriminate each other based on playback experiments. Although sample size is not great, the answer seems yes. So, for this case that has been historical in the borderline we finally have evidence of behavioural reproductive isolation.”

 

“F. NO to elevate Myadestes venezuelensis to species rank. The playback experiments are suggestive but geographic variation in other traits needs to be studied.

 

“G. NO to elevate Pheugopedius schulenbergi to species rank. Song discrimination was partial and geographic variation in songs and plumage is high across the complex.

 

“H. NO to elevate Amazonian populations of Tunchiornis ochraceiceps to species rank. There is much geographic variation in this complex and a test of reproductive isolation based on just two distant populations is not very informative. Moreover, the mitochondrial tree of Naka & Brumfield (2018, http://advances.sciencemag.org/content/4/8/eaar8575) indicates that Amazonian populations are paraphyletic because trans-Andean populations are nested within them. Therefore, the situation is complex and warrants more studies before redefining species limits.

 

“I. NO to elevate South American populations of Basileuterus culicivorus to species rank. Song discrimination was partial, and the population tested was far away from the potential contact zone. Also, geographic variation in songs and plumage is high across the complex, and a phylogeographic study did not recovered the central American taxa as monophyletic (Vilaça & Santos 2010, Mol. Phyl. Evol.  57:585-597).

 

“J. YES to elevate Myiothlypis chlorophrys to species rank. I don’t have much additional information on this case. The two taxa are widely allopatric. Plumage differences seem subtle, but that is typical in this genus. On the other hand, songs differ dramatically and Freeman and Montgomery (2017) showed that birds discriminate strongly against songs from the other taxon.

 

“K. NO to elevate Myiothlypis striaticeps to species rank. These forms are phenotypically very similar, and some Ecuadorian birds did respond to alien songs. So, I don’t see compelling evidence for a separation.

 

“L. YES to elevate Atlapetes tricolor crassus to species rank. Not mentioned by the proposal is the possibility that tricolor and crassus are not each other’s closest relatives: tricolor seems to be related to schistaceus, seebohmi and related species (Klicka et al. 2014 Mol. Phyl.  Evol. 77:177-182), whereas crassus forms a clade with melanolaemus and forbesi (Sánchez González et al. 2015 Zoologica Scripta 44:135–152). I know that this does not make sense biogeographically or plumage-wise, and needs to be corroborated by an analysis in which the two forms are analyzed together. But taken together, songs, phylogeny, and playback experiments all point to separate status for these two forms despite plumage similarity, which we know is highly homoplastic in Atlapetes.

 

“M. NO for now to elevate Amazonian populations of Arremon aurantiirostris to species rank. We have a small series of specimens of at the ROM, and it strikes me as very distinct: short and decurved culmen, orange underwings (instead of yellow), and other details. I think that it is a different species. Not sure how it was decided that it belongs into aurantiirostris. However, it has been treated as a subspecies of aurantiirostris forever. and playback experiments show that they recognize each other to some degree, so I would wait for the forthcoming more detailed study.”

 

Summary comments from Peter Boesman (see individual contributions to each subproposal in the main proposal): “I personally believe that -staying at the conservative side- at least case A, B, E, F, J and L should go through.  (I am also quite convinced about C and G, but am aware there is little published evidence)”

 

Additional comments from Claramunt of 754C: “Regarding Grallaria alticola, a clarification regarding the phylogenetic evidence: only in the mtDNA the two samples analyzed by Winger et al. (one of alticola and one of quitensis) did not appear as sister, but this results lacked strong statistical support. The genomic dataset, in contrast, showed the two samples as sister with moderate to strong support (Fig. 2B). Therefore, although the genetic distance between the two samples was high in both cases, it seems that they are sister taxa.

 

“Morphological differences seem slim, as far as I can see, and the playback experiments revealed only partial discrimination, suggesting that the differences in songs are not that significant for the birds.

 

“So, I maintain my NO on this sub proposal.”

 

New comments from Jaramillo: “Very little change. No comments on the ones where there was no change. Some additional comments where confusion arose or perhaps now data is better but suggests a more complex re-organization that may require a new proposal?  Here we go:

 

A – YES

B – YES

C – YES.

D – YES.

E – YES - this is a change from my previous vote. Based on the new information, characterization of vocal differences and published genetic data

F – YES

G – NO

H – NO. I am confused here now. No change from my previous voting. However, it seems like the new genetic and vocal data suggests that the real outlier is the Tepui population. So perhaps this should be expanded as a new proposal? I am not sure how to deal with this one. But something is going on here.

I - NO, see my previous comments. May require re-writing this one as a new proposal? More information needs to be unpacked for this one.

J – YES

K – YES, now stronger based on new data.

L – YES.

M – NO. Playback experiments not quite conclusive here, and a very complex situation.”

 

New comments from Stiles: “To begin with, I believe that it is incumbent upon us to take this proposal seriously enough to evaluate each subproposal based not only upon the playbacks themselves, but such other evidence as exists in each case. Much additional evidence has been gathered by Boesman for most of the proposals that merit consideration. I am impressed by his careful evaluation of vocal differences in particular, and he has brought to bear several pertinent sources not readily available (e. g., Andrés Cuervo’s thesis). With reference to Santiago’s comment that Freeman did not report results of playbacks of one population to its own songs, Freeman stated that all such “sympatric” playbacks produced strong positive reactions (approach to 15 m or less), although he did not give the number of same for each case. Considering that the alternatives in each case are to retain the status quo (a single species) or split this into two, I think that one must decide whether the information presented is sufficient to tip the burden of proof from those favoring the split onto those who would maintain the status quo. However, this with the qualifier that although the evidence may favor the two-way split, the proposal is embedded within a wider problem requiring further work to disentangle. I might also mention that in some cases, the method used for the playbacks could bias the results. A positive result for an “allopatric” experiment (i.e., playing the voice of one population to a bird of a distinct population) could produce some degree of approach simply because of its novelty to the recipient: in effect, mere curiosity rather than an aggressive response.

 

“On to specifics: my votes for all subproposals:

A.   YES to split Pseudocolaptes johnsoni from P. lawrencii. Boesman has marshalled morphological, vocal and genetic data to clinch this case.

B.   YES to split Automolus virgatus from A. subulatus. Again, Boesman presents a more convincing case.

C.  NO, albeit barely – burdens of proof nearly even on both sides. The vocal evidence of Boesman for recognizing three species in G. quitensis is quite convincing, however genetic evidence is incomplete and inconsistent (no single study has included all three, and sample sizes here are limited: denser sampling accompanied by including nuclear genes and haplotype sharing would certainly clinch the case, even given the subtle morphological differences. Strongly suggestive of the G. rufula study!

D.  Already done by Krabbe (proposal no. 858).

E.   YES to split Ochthoeca thoracicus from O cinnamomeiventris – additional evidence gathered by Boesman definitely tips the balance.

F.   NO, albeit tentatively, to splitting Myadestes venezuelensis from M. ralloides. I am on the fence here. Genetic evidence favors the split, but could be bolstered by including nuclear genes and haplotypes, and intraspecific variation in songs and calls should be evaluated with larger sampling from all subspecies. Morphological differences might be given more thorough examination as well.

G.  NO to splitting Pheugopedius schulenbergi from P. mystacalis, basically for the same reasons: gaps in both vocal and genetic evidence that should be filled in to clinch the case.

H.  NO to splitting Tunchiornis into cis- and trans-Andean species, at least until the biogeography and intraspecific variation can be sorted out more completely. The genetic evidence suggests that three or four species could be recognized, in line with vocal evidence briefly mentioned by Boesman, but the biogeography looks complicated. Claramunt noted that the Mesoamerican-Chocó population appeared to be genetically embedded within the two “Amazonian” populations, but this seems to me to be a function of how the branches are ordered: flip Centromerica-Chocó to the top, (above that including the W of rio Branco and south Amazon) and you get a north-to-south ordering of these three, which seems biogeographically logical. The fly in all this ointment is the Guiana (E of rio Branco) population: it is widely divergent from the population the other side of the river, as well as that of Centroamerica-Chocó, so how and when did it reach its present range without passing through the area occupied by the latter? If the tree given by Boesman was exclusively for mitochondrial genes, adding nuclear genes and an analysis of haplotype sharing might clarify the picture.

I.     NO to splitting Basileuterus culicivorus into 2?3? species. The vocal analysis by Boesman is suggestive, but taxon sampling could be improved; the genetic data for South America in particular are decidedly sparse; especially lacking are data from Colombia, where the two populations (godmani and cabanisi) may come into contact.

J.    YES to split Myiothlypis chlorophrys from M. chrysogaster. Boesman demonstrates pronounced vocal differences; the morphological differences are roughly on a par with those between several other species pairs in this genus; and the wide latitudinal separation on different slopes of the Andes would be most unlikely for a single species.

K.   A tentative YES to splitting Myiothlypis striaticeps from M. luteoviridis.  Morphological differences exist (at least comparable to the previous case), and the vocal analysis by Boesman suggests differences between these; especially notable are the genetic data by Cuervo, which indicate a very deep split between these lineages on opposite sides of the Marañón, which to me tips the balance of proof.

L.   YES to splitting Atlapetes crassus from A. tricolor: detailed genetic data demonstrate that the two are not close relatives within Atlapetes, let alone sisters.

M. NO to splitting E Costa Rican and E Ecuadorian populations of Arremon aurantiirostris into two species; here there are several other subspecies to be considered; genetic and morphological data are sparse and taxon sampling insufficient. (Unfortunate that while in Costa Rica, Freeman did not do experiments between the Caribbean and Pacific populations of the species, which have quite different songs.)”

 

Comments from Lane:

 

“ A. NO, although Boesman’s comments, in conjunction with the newly published Harvey et al. phylogeny (which would suggest that the two taxa are *not* sisters) would probably be enough to tip the scales if presented in a revised proposal.

B. NO. The playback used sounds like it only compared trans-Andean birds to playback of cis-Andean birds, and not with playback from other named trans-Andean taxa, if I am reading the original paper correctly. This seems a bit of an oversight, and would have been a useful datapoint to include.

C. NO. Again, there is an additional taxon, atuensis, which should also be considered for species status.

E. NO. There are multiple taxa within this complex, and it is not clear what to do with several of them following this split.

F. NO. Once again, there are several taxa in addition to the two considered here, and where they would fit into the split is unclear

G. YES. I am actually inclined to consider this case as enough evidence to separate the very differently voiced schulenbergi as a separate species from the rest of the taxa presently under the name euophrys, with the understanding that there may be further taxonomic assessment necessary later for the remainder of the complex. I would say, in response to Boesman’s comment on the Mantaro bird, that its inclusion with euophrys rather than eisenmanni is speculative at best and, in my opinion, incorrect. But, until that population is named, it can’t be considered as a player in this game.

H. NO. The number of taxa involved makes this a messy case that cannot be resolved with such limited.

I. NO. There are many taxa involved, both in Middle America and South America, and this playback experiment barely scratches the surface.

J. YES. This is another case where I believe the differences are so stark that this one-way playback experiment is convincing enough for me to accept the split of the two forms. Plus, there are no other named taxa to consider.

K. NO. The “luteoviridis” complex includes more than these two taxa and the relationships among them are likely more complex than this study can establish. I suspect a proposal including the phylogenetic work and voice analyses mentioned by Boesman would be sufficient to consider, however

L. NO. Atlapetes no doubt have a number of surprises left for taxonomists, but this case simply isn’t sufficient to sway me.

M. NO. Once again, there are far too many taxa within this complex for this one study to suffice in judging how best to divide them up.”

 

Comments from Pacheco:

“A. YES. Favorable from the available morphological, vocal and genetic data.  Also, the "taxonomic inertia" mentioned by Santiago.

B. YES. A convincing split considering Schultz et al. 2017, with information obtained in South America and more closely. The future may show a third taxon involved, as Santiago alerts.

C. NO. It lacks better genetic evidence and a better sampling of populations from different subspecies located more closely.

E. YES. Another case of "taxonomic inertia" remembered by Santiago. Considering the genetic evidence (and others) mentioned by Boesman and Santiago, I vote for this late split.

F. NO. The separation in this case seems premature. 

G. NO. The data are suggestive, but the existence of gaps is evident.

H. NO. Although suggestive, it is desirable that an analysis of the complex be carried out with more geographic breadth.

I. NO. Similar to the previous case. A better distributed sampling over the great gradient of the distribution is desirable before a decision.

J. YES. Vocal repertoire and distinct morphology with striking latitudinal separation. I agree with Santiago: in this case, the burden of proof must fall on anyone who wishes to demonstrate conspecificity.

K. NO. The evidence for a split is still incomplete, mainly due to the gaps mentioned by Dan.

L. YES. As highlighted, the available genetic data demonstrate that these two taxa are not even related.

M. NO. It is premature to decide based on the information available.”

 

Comments from Robbins: “After reading Gary Stiles’s earlier and more recent comments coupled with recent ones by Dan Lane, I’m now persuaded in not accepting any of these proposals. Yes, for many of these, I suspect that more than one species is involved, however, as Dan points out in several cases other taxa need to be considered.”

 

Comments from Stiles: “The playback experiments of Freeman et al.: we can´t do anything here if people keep voting NO “on principle”. My own feeling is that this is something of a cop-out, for two reasons. First, I think that the birds themselves are the best judges of whether a given recording is their species or something else. Therefore, where these experiments were conducted with adequate replicates and clear preferences were indicated (which I note was not always the case), they provide important evidence regarding species status; this ESPECIALLY where other evidence is available (including more information on vocalizations by Boesman, plumage, genetics etc.) such that the playbacks might suffice to shift the balance of proof to favor splitting the species in question, AND there is precedent (at least, among the several most authoritative world lists) that the split has already been made. Hence, I think that 3-5 of the 13-14 proposals are sufficient to justify at least considering SACC action. So, over to the committee.”

 

Comments from Remsen: “I acknowledge the validity of the points made against this approach by many of you.  If we were dealing with novel splits in a species complex for which there were no previous classifications that treated them as separate species or for which there was no indication in the literature that species limits were questionable, then indeed I would not endorse any of the proposals.  However, as pointed out by several of you, many of these splits were previously anticipated or implemented based on anecdotal information.  Others seek to rectify unsupported lumps from the Lumperama Era.  So, case-by-case seems the best approach in my opinion.  Votes to follow “soon.”

 

Additional comments from Stiles: “I definitely agree with approval of B, J and L, and could be persuaded on E (are there any genetic data for nigrita of Venezuela??). I note that both playback and genetic data also support A).”