Lynx-BirdLife Taxonomic Checklist (2 Viewers)

[jalid]

But it has something to do with BSC if reproductive isolation is taken into account.

I don't think it is very relevant for determining species status if two taxa have some kind of "mixing zone" or not. More relevant is the amount of mixing, hybrid fitness, width of the zone in relation to the dispersion and geography and so on. (But the parameters of mixing zone need quite a lot of work to estimate ant there is so many in the world). I think that the LBTC method simplifies this too much.

 

[MJB]

But it has something to do with BSC if reproductive isolation is taken into account. I don't think it is very relevant for determining species status if two taxa have some kind of "mixing zone" or not. More relevant is the amount of mixing, hybrid fitness, width of the zone in relation to the dispersion and geography and so on. (But the parameters of mixing zone need quite a lot of work to estimate ant there is so many in the world). I think that the LBTC method simplifies this too much.

Surely also relevant is the (historical) stability of the "mixing zone", as opposed to any dynamic movement. I have in mind the zone between Yellowhammer and Pine Bunting, mostly in Russia...
MJB

 

[Richard Klim]

BirdLife vs BOU

Overall, the BirdLife Taxonomic Working Group criteria (Tobias et al 2010) appear to be more conservative than the BOURC Taxonomic Subcommittee guidelines (Helbig et al 2002).
Tobias et al includes a test case against the Helbig et al guidelines. Of a selection of 23 potential splits, only 2 pairs of taxa (9%) qualified for species status under the Tobias criteria, whereas 17 pairs (74%) qualified under the BOU guidelines.
So if the BOU guidelines were to be applied on a worldwide basis, there would presumably be a significantly larger number of splits (compared with HBW/BirdLife)...?

Fwiw, a quick comparison reveals that the non-passerine (Vol 1) splits are actually quite closely balanced in the case of taxa directly or indirectly relevant to The British List...

BOU splits not adopted by BirdLife:

• Anas (crecca) carolinensis – Green-winged (Common) Teal
• Hydrobates (Oceanodroma) (castro) jabejabe – Cape Verde (Band-rumped) Storm Petrel
• Puffinus (lherminieri) baroli – Macaronesian (Audubon's) Shearwater
• Butorides (striata) virescens – Green (Green-backed) Heron
• Numenius (phaeopus) hudsonicus – Hudsonian Whimbrel
• Sterna (Thalasseus) (sandvicensis) acuflavida – Cabot's (Sandwich) Tern

BirdLife splits not adopted by BOU:

• Melanitta (deglandi) stejnegeri – Siberian (White-winged) Scoter
• Pterodroma (feae) deserta – Desertas (Fea's) Petrel
• Larus (glaucoides) thayeri – Thayer's (Iceland) Gull
• Sternula (albifrons) antillarum – Least (Little) Tern
• Circus (cyaneus) hudsonius – Northern (Hen) Harrier

[There are of course numerous other BirdLife splits of extralimital forms (including many widely recognised by other authorities) which have no impact on the scientific or local colloquial names used in the British List and have therefore never been explicitly considered by BOU – although, in some cases, species treated as polytypic by BOU would become monotypic.]

Perhaps there will be greater divergence in Vol 2 (passerines)...

 

[jmorlan]

How do HBW/Tobias score cryptic species which overlap, but do not hybridize or form intergrades? Birds like Eastern/Western Wood-Pewee or the Trail's Flycatcher species pair? Does the lack of a hybrid zone subtract from the virtually nonexistent diagnosablilty scores in these cases?

How can this be considered to have anything at all to do with classical BSC?

 

[l_raty]

I think that the LBTC method simplifies this too much.

Taxonomy as a whole is very much about making an often complex reality fit into a simplistic system, though: when the simplifications becomes "too much" is not straightforward to determine... Isn't the whole traditional idea that "zone of hybridization = barrier to gene flow" vs. "zone of transition = gene flow", actually also quite an oversimplification?
I see much more restriction to gene flow in the southern greenish warbler contact zone (Irwin's classical AFLP data; despite the intermediate population being apparently "entirely hybrid"), than there seems to be in the hooded/carrion crow hybrid zone (99.72% of the genome undifferentiated across the hybrid zone, hence presumably flow through it)...

 

[jalid]

How do HBW/Tobias score cryptic species which overlap, but do not hybridize or form intergrades?

Sympatry scores seven points. And in the case of sympatry, there should be some other character(s) for diagnosability, of course.

 

[jmorlan]

Sympatry scores seven points. And in the case of sympatry, there should be some other character(s) for diagnosability, of course.

Seems like the deck is stacked in favor of splitting. Sympatry adds points; intergradation adds points, hybridization adds points, allopatry adds points...

 

[l_raty]

Masked Lapwing

Vanellus novaehollandiae and V. miles were lumped by Bock, 1958, who simply commented:

The ranges of miles and novaehollandiae as given in the literature appear to be allopatric. The major differences between these forms are an extension of the black crown down the hind neck and sides of the breast in novaehollandiae and a difference in the wattles and body size. They are similar in all other features and as their ranges seem to be allopatric, it is assumed in this paper that they are conspecifie. However, there is still doubt as to whether or not the ranges of these forms overlap in Queensland and if they do, miles and novaehollandiae must be regarded as distinct species, and in that case would constitute a superspecies.

...IOW, "I find them similar and they are allopatric, thus I treat them as conspecific, even though this may be plain wrong."

The lump was later followed by van Tets et al., 1967, who described the presence of intermediate birds, along with pure birds of both phenotypes, in Townsville, Queensland; they also noted that pinioned miles in the Canberra zoo interact with local novaehollandiae, apparently forming temporary mixed pairs; and further suggested that the contact between the two lapwings was possibly recent and of anthropic origin, being a consequence of the clearing of rain forest along the Queensland coast.
(What they described suggests hybridization, not clinal intergradation; of course pinioned exotic ducks interact in a similar way with local birds of other species everywhere in the world; if the contact is recent and non-natural, this might blur the significance of the current situation in the contact zones.)

More recently, Marchant & Higgins, 1993 (HANZAB, Vol. II, pdf [36.1MB!]) noted:

Nominate miles and novaehollandiae interbreed in zone of intermediates (Figs 6b, 7b). Distributional limits of subspecies not fully understood; often assumed that there is a broad continuous zone of intermediates (e.g. Hayman et al. 1986) but only two areas adequately known and described: (1) breeding ranges of miles and novaehollandiae meet in Townsville, n. Qld, where intermediates also occur; only miles occurs at Cairns (c. 280 km farther N) and only novaehollandiae occurs at Mackay (c. 330 km farther S) (van Tets et al. 1967); (2) SAM holds large series of intermediates, including breeding individuals, collected throughout large L. Eyre catchment area under the direction of late S.A. Parker. One record is of nominate miles, 13 of novaehollandiae and 46 are intermediates. Interbreeding of subspecies obviously common in this area, though it is not clear how much (if any) bias towards collection of intermediates occurred. In both areas, occurrence of most characters of miles in intermediates is correlated, e.g. individuals with large facial lappets usually also have pale upperparts, restricted black on crown, sides of breast and tips of spurs. In some intermediates, dark areas on lateral breast are mostly light grey-brown (c91), sometimes with black patches towards centre of breast. In novaehollandiae-like intermediates, characters of miles most often expressed are slightly enlarged lappets, with lobe of forehead lappet extending slightly behind eye. Most persistent character of novaehollandiae in miles-like hybrids is usually slightly larger black cap, with black stripe running down hind neck.

Situation thus far from clear. Although suggestions of a broad continuous zone of intergradation have been published, hybridization actually documented from two localities only; evidence that pure phenotypes could be absent from any of the contact zones (Short's "all-hybrid" zone) apparently lacking.

Is there more elsewhere?

 

[GMK]

This new scheme appears to turn everything that has a hybrid zone into a new species and allows subspecies only under what conditions? [Shrug]. I don't get it.

Can I ask: have you read the Introduction to the book, specifically pp. 32-33? Perhaps you have and still have your doubts as to whether del Hoyo and Collar know how to interpret BSC correctly (proponents of which they patently are, contra bowhead whale), but given how ornithologists of all taxonomic persuasion have treated Yellowhammer and Pine Bunting for decades (as Mike Blair already intimated), their scoring system with respect to hybrid zones is far from nonsensical. If you haven't read it, you'll find a discussion of how and why the authors treat hybrid zones in the way they do. And, incidentally, the whole introduction is a very nice read, even if you not persuaded by their approach.

 

[Richard Klim]

Can I ask: have you read the Introduction to the book, specifically pp. 32-33?

The Distributional criteria section (Introduction, p31–33) is included at the link I posted a few days ago...

Also: Taxonomic scoring system.

 

[jmorlan]

Vanellus novaehollandiae and V. miles were lumped by Bock, 1958, who simply commented:

...IOW, "I find them similar and they are allopatric, thus I treat them as conspecific, even though this may be plain wrong."

The lump was later followed by van Tets et al., 1967, who described the presence of intermediate birds, along with pure birds of both phenotypes, in Townsville, Queensland; they also noted that pinioned miles in the Canberra zoo interact with local novaehollandiae, apparently forming temporary mixed pairs; and further suggested that the contact between the two lapwings was possibly recent and of anthropic origin, being a consequence of the clearing of rain forest along the Queensland coast.
(What they described suggests hybridization, not clinal intergradation; of course pinioned exotic ducks interact in a similar way with local birds of other species everywhere in the world; if the contact is recent and non-natural, this might blur the significance of the current situation in the contact zones.)

More recently, Marchant & Higgins, 1993 (HANZAB, Vol. II, pdf [36.1MB!]) noted:

Situation thus far from clear. Although suggestions of a broad continuous zone of intergradation have been published, hybridization actually documented from two localities only; evidence that pure phenotypes could be absent from any of the contact zones (Short's "all-hybrid" zone) apparently lacking.

Is there more elsewhere?

Not that I know of. I've written to the HANZAB author to see if there's anything new.

But I think the lump by Bock needs to be understood in historical context. Closely related allopatric populations have a taxonomic status that is essentially unknowable. The prevailing view at the time as advocated by Mayr, was that it is preferable to treat such populations as subspecies rather than full species. The stated advantage of this bias is that important biological information is imparted directly in the nomenclature. I.e. the populations are very closely related AND that the populations are allopatric.

By considering them separate species without known actual sympatry, we are saying nothing useful about their biology, their distribution, etc.

Although their "hybrid zone" has been studied in only two places, that's enough to establish considerable reproductive compatibility regardless of the width or size of the hybrid zone. If it were to be established that there was a zone of overlap and hybridization (which I now see appears to have been the case on a closer reading of the HANZAB account), or that the two forms exhibit positive assortative mating, or that the hybrids are at a selective disadvantage, then I think it would be appropriate to split them.

I remain confused by the HBW scoring system partly because they score hybrid zones as a PLUS in deciding species status based on the width of the zone. The logic as I understand it as that narrow hybrid zones indicate that hybrids are at a selective disadvantage, otherwise hybrid zones should be expanding. To me, the width of a hybrid zone is more often a consequence of the amount of time the subspecies have been in secondary contact then it is a measure of their inferred inherent reproductive isolation.

 

[njlarsen]

The logic as I understand it as that narrow hybrid zones indicate that hybrids are at a selective disadvantage, otherwise hybrid zones should be expanding. To me, the width of a hybrid zone is more a consequence of the amount of time the subspecies have been in secondary contact then it is a measure of their inferred inherent reproductive isolation.

Correct me if I am wrong, but I think for example in Yellow-rumped Warbler there was a study demonstrating that the hybrid zone between two of the subspecies had been stable for about a 100 years, which seems a long time for a species with such a short generation interval. Therefore, I am not sure your a priori expectation is better than the a priori expectation used in HBW.

I write this not really confident whether I otherwise am confortable with the scoring system.

Niels

 

[jmorlan]

Correct me if I am wrong, but I think for example in Yellow-rumped Warbler there was a study demonstrating that the hybrid zone between two of the subspecies had been stable for about a 100 years, which seems a long time for a species with such a short generation interval. Therefore, I am not sure your a priori expectation is better than the a priori expectation used in HBW.

I write this not really confident whether I otherwise am confortable with the scoring system.

Niels

Yellow-rumped Warbler is a classic case of a presumably stable narrow hybrid zone. It's been looked into a couple of times since the original data was gathered by Hubbard and published in 1969. More recent analysisconcludes that they are separate species, a recommendation adopted by IOC but not by AOU. Earlier analysis by Barrowclough concluded that the two came into secondary contact 7500 years ago and now interbreed. The hybrid zone extends 150 km in either direction and will probably continue to grow as time passes. It has been calculated that it will take more than 6 million years for these taxa to completely fuse.

Different interpretations or different data?

 

[njlarsen]

jmorlan wrote

The hybrid zone extends 150 km in either direction and will probably continue to grow as time passes.

Brelsford and Irwin wrote

Temporal stability and limited width of the hybrid zone

(http://www.bioone.org/doi/abs/10.1111/j.1558-5646.2009.00777.x )

The temporal stability is another way of saying that the hybrid zone did not increase in the past so why should it in the future?

There are more problems between other parts of this complex which is why AOU did not adopt this split.

Niels

 

[jmorlan]

Cape York Friarbird

The IOC has consistently split the Cape York Friarbird or Hornbill Friarbird (Philemon yorki) from the Helmeted Friarbird (Philemon buceroides). Today I noticed that HBW Alive lumps these two as did the original HBW. I'm looking for an explanation of this; particularly what the Tobias scoring system says about the two, and the basis for the IOC split.

Thanks in advance.

 

[Richard Klim]

The IOC has consistently split the Cape York Friarbird or Hornbill Friarbird (Philemon yorki) from the Helmeted Friarbird (Philemon buceroides). Today I noticed that HBW Alive lumps these two as did the original HBW. I'm looking for an explanation of this; particularly what the Tobias scoring system says about the two, and the basis is for the IOC split.

As you say, Philemon (buceroides) yorki is treated as a distinct species by IOC: "Status of Philemon yorki uncertain whether endemic ne AU species or conspecific with Papuan Friarbird (Sibley and Monroe 1990, Boles and Christidis 2008, P.Gregory comments)".

But yorki is treated as a ssp of P buceroides by Christidis & Boles 2008 and HBW; as a monotypic ssp group of P buceroides by H&M4 and eBird/Clements; and as a ssp of P novaeguineae by BirdLife.

We'll probably have to wait until 2016 (Illustrated Checklist Vol 2) for the results of BirdLife's application of the Tobias criteria to passerine species...

 

[Mysticete]

Yep...we haven't gotten the Tobias scoring results for Passerines yet, which should be REALLY interesting, if the non-passerines are anything to go by.

 

[Richard Klim]

Illustrated Checklist Vol 1

Knox 2014. Reviews: HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 1. Non-Passeriformes. Brit Birds 107(11): 706–707.

 

[Melanie]

There is a recent interview with Del Hoyo in the German magazine "Der Falke" (translated into German). Del Hoyo hopes that the second volume will be published in November 2016.

 

[Richard Klim]

Taxonomy adopted by CMS

BIRDS Alive, the HBW Alive Newsletter: No. 6, Dec 2014...

HBW and BirdLife International taxonomy officially adopted by the United Nations Convention on the Conservation of Migratory Species of Wild Animals (CMS)

During the eleventh meeting of the Conference of the Parties to CMS (COP11), celebrated in Quito, Ecuador last November, the HBW and BirdLife International Illustrated Checklist of the Birds of the World Volume 1: Non-passerines, published in July, was adopted as the CMS standard reference for bird taxonomy and nomenclature for non-passerine species.

One of the motivations behind the proposal was that agreeing upon a bird taxonomy and nomenclature to be used among the parties would facilitate the implementation of conventions and conservation tools with a direct benefit to the birds being protected. The same resolution requests the CMS Scientific Council to consider the future adoption of the HBW and BirdLife International Illustrated Checklist of the Birds of the World Volume 2: Passerines, due to be published in 2016, as a standard reference for passerine bird taxonomy and nomenclature.

Logically, this taxonomy has also been adopted by BirdLife International and the International Union for Conservation of Nature (IUCN), including The IUCN Red List of Threatened Species™. Thus, the Checklist continues to grow in influence and importance, especially in terms of bird conservation.