'Menorcan Shearwater' (1 Viewer)

[Richard Klim]

A report by Russell Wynn of the SeaWatch SW 2010 field expedition to the Balearic Islands includes pictures of 'Menorcan Shearwaters' at the La Mola, Menorca colony:
http://www.birdguides.com/webzine/article.asp?a=2091

[These birds (Puffinus mauretanicus/yelkouan) were pictured, recorded and discussed by Robb et al 2008 (Petrels night and day).]

Richard

 

[Aleix Comas]

The following link is an article of a study that sampled Puffinus shearwaters in the Balearic Islands. It is in Spanish but has an English summary. Aparently there's yelkouan introgression in Menorcan Shearwaters and the study points to some degree of hybridisation:

http://www.mma.es/secciones/el_ministerio/organismos/oapn/pdf/oapn_inv_art_0212.pdf

 

[Acrocephalus]

Hi,

I saw the following on Facebook, may be of interest (an identification article posterior to the “Seawatch SW 2010 field expedition”)

Gutiérrez, R. 2010. Spring plumages of Mediterranean and Balearic Shearwaters. Rare Birds in Spain. Retrieved from http://www.rarebirdspain.net/arbsi034.htm

regards

 

[Richard Klim]

International workshop, A Coruña 2007

Actas del 6º Congreso del GIAM y el Taller internacional sobre la Ecología de Paiños y Pardelas en el sur de Europa. Proceedings of the 6 Congress of GIAM and the International workshop on petrels and shearwaters ecology at southern Europe. Boletín GIAM 34 (2011). [pdf]

• Yésou. Los cambios en la taxonomía de la pardela balear. The changing taxonomy of the Balearic Shearwater. 147–150.
  
  The Balearic Shearwater Puffinus mauretanicus, which breeds on islands and islets within the Balearic archipelago, is presently considered as a full species differentiated from the closely related Yelkouan Shearwater Puffinus yelkouan which occupies a number of islands through most of the Mediterranean (but not the Balearics). This taxon has previously been given different systematic positions, first as a subspecies of the Manx Shearwater Puffinus puffinus, then as a subspecies of the Yelkouan Shearwater. Recent discoveries in Menorca and a reappraisal of characters supposed to differ between mauretanicus and yelkouan (characters which are not as clear cut as some authors initially thought) lead to the proposal that these two taxa might be re-united as a single Mediterranean endemic species. Under such a proposal, the Balearic Shearwater should be named Puffinus yelkouan mauretanicus.
  
  
• McMinn & Rodríguez. Pardela Mediterránea Puffinus cf. yelkouan nidificando en la isla de Menorca. Mediterranean Shearwater Puffinus cf. yelkouan nesting on the island of Menorca. 151–157.
  
  Using the current 'at sea' identification criteria, the birds of Menorca are identified as Mediterranean Shearwaters. The birds of Menorca share mauretanicus and yelkouan mtDNA genotypes, but there is no relation between mtDNA genotype and morphology or body size. The discrepancy between genetics and morphology needs to be investigated including other populations of small shearwaters of the Mediterranean.
  
  
• Genovart, Oro, Juste, Louzao & Bertorelle. Pardelas de Menorca, ¿yelkouan o mauretanicus? Shearwaters from Menorca, yelkouan or mauretanicus? 158–162.
  
  Adults with phenotypic traits of Yelkouan Shearwaters Puffinus yelkouan were observed in a peripheral colony (Menorca Is.) of Balearic Shearwater P. mauretanicus. We investigated the genetic (two mithocondrial DNA regions) and phenotypic variability of Balearic Shearwaters Puffinus mauretanicus throughout their entire breeding range. Despite the philopatry of shearwaters, connectivity among colonies was higher than expected. Many individuals with haplotypes corresponding to the Yelkouan Shearwater were detected in Menorca. Individuals from Menorca were also smaller than birds from the other breeding sites, but MtDNA haplotypes were not correlated with morphological differences. The presence of both species breeding in Menorca was discarded and genetic evidence of maternal introgression from the sibling species was reinforced, but almost uniquely in this peripheral colony.

[With thanks to Andy Paterson for posting on Seabird News and WestPalBirds.]

 

[jurek]

Yet another oversplit group waiting for a merge.

BTW - another example to my case that BirdLife and IUCN should recognize subspecies and populations of birds like with most other groups: mammals, sea fish etc. Conservation status of shearwaters in Balearics now may change dramatically, because only full species are considered of conservation value. If species, subspecies and populations/stocks of birds are all evaluated, conservation of shearwaters in Balearics (and many other seabirds) can go normally independently of taxonomic debate.

 

[RaMa]

Well, fish taxonomists virtually don't use subspecies at all! There are at most 300 currently recognized subspecies of fishes compared to more than 30,000 species (don't have the source at hand, will look for it). And their number is declining... Subspecies in fishes now seem to be confined to a few groups, e.g. North American freshwater fishes, killifish and cichlids, the latter groups being dominated by amateur taxonomists. Subspecies have been completely eliminated from Western Palearctic freshwater fish during the last 15 years.

Ant taxonomists have abandoned this concept since the 1950's. Spider taxonomists (and those for many other groups) seem to have never had any need for it.

The problem with the subspecies concept, besides from introducing a typological concept in a classification system that is otherwise dominated by evolutionary thought, is that treatment of subspecies is highly inconsistent. Still today anything from strikingly different allopatric taxa, which are only supposed to be able to interbreed, to mere segments of a cline or populations differing only in minor details, apparent only in large numbers of specimens, may be thrown together in the catchall category "subspecies". Obviously there are many different kinds of "subspecies". Which ones should be evaluated by BirdLife? Who decides? By which criteria?

Rainer

 

[Richard Klim]

I fully agree with Rainer. It would require BirdLife to consider c30,000 taxa, compared with c10,000 now. It would be a huge additional effort to undertake threat evaluations at subspecies level, or even to decide which should be recognised as meaningful conservation units. Conservation funding would inevitably be spread even more thinly.

Large numbers of subspecies have highly questionable merit (many being points on a cline, and often just an excuse to immortalise someone's name), and recognition or synonymisation by different authors and authorities is performed on a very casual, subjective basis.

 

[jurek]

Subspecies concept is alive and well for larger organisms with visible differences: mammals, reptiles, butterflies etc. In fish people usually talk about stocks or populations from one ocean, river system etc. But they correspond to earlier subspecies.

However some taxonomists have big problems with so-called inconsistency of subspecies, they might remember that it is inevitable if one believes in evolution as gradual change, producing complete range of populations from little to very different.

 

[Ben Wielstra]

There is a population where the two forms come into contact that shows somewhat intermediate features and some mtDNA introgression. Secondary contact and introgressive hybridization is not a weird scenario for closely related species (why would they even expect a correlation between mtDNA and morphology???). Only if there is evidence for extensive and far reaching gene flow there would be a case for merging them. However, the limited available data do not seem to indicate that, right? The geographical distribution of weird shearwaters is limited.I would say a recent displacement of mauretanicus by Yelkouan fits the available data better.

 

[jurek]

It would require BirdLife to consider more than 30,000 taxa, compared with about 10,000 now. It would be a huge additional effort to undertake threat evaluations at subspecies level, or even to decide which should be recognised as meaningful conservation units. Conservation funding would inevitably be spread even more thinly.

1. I agree that slightly differentiated or clinal subspecies are not meaningful conservation units.

2. You may not realize it, but re-evaluation of 30,000 bird subspecies is de facto happening now. You yourself are reporting it. Only a way it is done is circular, selective and arbitrary. First, field researchers split more divergent subspecies into species level. Then BirdLife recognizes a new species and evaluates the status. There is indeed a talk that adopting PSC for birds worldwide will result in 20,000 or so species.

If you recognize subspecies as units of conservation, this would speed starting conservation and make it independent of taxonomic debates. It would also save the effort of renaming subspecies into species, which by itself contributes nothing new no knowledge or conservation.

3. Just few days ago somebody (not me) said that having many endangered birds is good for conservation, because this sends strong message and brings more donations. I disagree with it. But here I see simply two different tactics in conservation.

4. I proposed before that not updating the status of widespread birds with large populations will save resources. The effort would go to rare bird forms at the border of species and subspecies. This would particulary help conservation of islands and mountain chains where many birds are on a borderline of clear subspecies/species. Examples are Azores and many Indonesian island groups. The same hotspots have also other localized organisms which may benefit from bird conservation.

 

[Richard Klim]

I would say a recent displacement of mauretanicus by Yelkouan fits the available data better.

And, although the papers were presented in 2007, it's notable that nothing has yet been formally published recommending a lump of the two species...

 

[jurek]

Only if there is evidence for extensive and far reaching gene flow there would be a case for merging them. However, the limited available data do not seem to indicate that, right?

Not right. Many or most species are not naturally pan-mictic, and gene flow between any populations (even within species) are limited. Like in case of most tubenoses.

 

[MJB]

And, although the papers were presented in 2007, it's notable that nothing has yet been formally published recommending a lump of the two species...

Good point, Richard, for it leads to one of my hobby-horses...:t:

Once again, we're up against the limits of the English language (et al) in channelling thinking by quibbling over definitions that can be at best described as 'working definitions' in that they usually apply, but as in this case, don't. We really need to consider 'diagnosable populations' in a way that doesn't automatically exclude clines (whose existence are not attributable to any single cause for convenience or argument).

The concepts covered (initially, for much remains to be added after debate) in such as "Quantitative criteria for species delimitation" (Tobias et al 2010), "Is it a species?" (Winker 2010 in Ibis) and "Pitfalls in comparisons of genetic distances: A case study of the avian family Acrocephalidae" (Fregin et al 2011) need to be at the centre of thinking in what has been called 'integrative taxonomy' and in conservation policy and management.

Rehashing old arguments simply isn't enough.

I've now used up my provocation quotient for Marcho.
MJB

 

[Richard Klim]

I've now used up my provocation quotient for March o.

Mike, I used up mine a couple of days ago!

 

[Ben Wielstra]

Not right. Many or most species are not naturally pan-mictic, and gene flow between any populations (even within species) are limited. Like in case of most tubenoses.

In this case there is a zone of secondary contact (i.e. no geographical isolation). And limited but still regular gene flow due to individuals meeting rarely is something else then a little permeable barrier to gene flow due to negative selection.

 

[njlarsen]

4. I proposed before that not updating the status of widespread birds with large populations will save resources. The effort would go to rare bird forms at the border of species and subspecies. This would particulary help conservation of islands and mountain chains where many birds are on a borderline of clear subspecies/species. Examples are Azores and many Indonesian island groups. The same hotspots have also other localized organisms which may benefit from bird conservation.

In practical terms, that is already the way it is done to the best of my knowledge. Every year, relatively few species are chosen for update, with the rest of the list basically brought over unchanged. Birds that are listed as critically endangered are much more likely to be included in such a review.

Niels

 

[njlarsen]

Well, fish taxonomists virtually don't use subspecies at all! There are at most 300 currently recognized subspecies of fishes compared to more than 30,000 species (don't have the source at hand, will look for it). And their number is declining... Subspecies in fishes now seem to be confined to a few groups, e.g. North American freshwater fishes, killifish and cichlids, the latter groups being dominated by amateur taxonomists. Subspecies have been completely eliminated from Western Palearctic freshwater fish during the last 15 years.

Ant taxonomists have abandoned this concept since the 1950's. Spider taxonomists (and those for many other groups) seem to have never had any need for it.

The problem with the subspecies concept, besides from introducing a typological concept in a classification system that is otherwise dominated by evolutionary thought, is that treatment of subspecies is highly inconsistent. Still today anything from strikingly different allopatric taxa, which are only supposed to be able to interbreed, to mere segments of a cline or populations differing only in minor details, apparent only in large numbers of specimens, may be thrown together in the catchall category "subspecies". Obviously there are many different kinds of "subspecies". Which ones should be evaluated by BirdLife? Who decides? By which criteria?

Rainer

There was a very long discussion of the merits of subspecies a while back, and the Ornithological Monograph on (defending) subspecies was an important part of that. (actually several discussions: http://www.birdforum.net/showthread.php?t=182417; http://www.birdforum.net/showthread.php?t=168201; http://www.birdforum.net/showthread.php?t=157440

Niels

 

[njlarsen]

There is a population where the two forms come into contact that shows somewhat intermediate features and some mtDNA introgression. Secondary contact and introgressive hybridization is not a weird scenario for closely related species (why would they even expect a correlation between mtDNA and morphology???). Only if there is evidence for extensive and far reaching gene flow there would be a case for merging them. However, the limited available data do not seem to indicate that, right? The geographical distribution of weird shearwaters is limited.I would say a recent displacement of mauretanicus by Yelkouan fits the available data better.

Of relevance to this discussion is the recent thread discussing the paper "Genetic Introgression: an integral but neglected component of speciation in birds": http://www.birdforum.net/showthread.php?t=217782

Some of the ideas in that paper fits very well with ideas brought forward by Grant & Grant in their book How and Why species multiply, based on their work in Galapagos.

Niels

 

[RaMa]

If you recognize subspecies as units of conservation, this would speed starting conservation and make it independent of taxonomic debates.

I sincerely doubt that. BirdLife will always have to draw a line between populations they think should be evaluated, and those which should not. Currently this line is the distinction between species and subspecies. Sometimes taxa flip from one side of the line to the other or back, but there are established guidelines and procedures for handling this, based on the underlying species concept.

Now evaluating some, but not all, subspecies would simply mean to shift the line. But still every single taxon would have to be judged whether it belongs on one or the other side of the line. These will probably be as much taxonomic judgements as the present decisions on species status! Only that there's currently no established and broadly accepted guideline for distinguishing between different categories of subspecies. On the other hand the number of populations to be judged this way would be significantly higher. Note, I'm not talking about evaluating the taxon's conservation status; that comes in addition!

Another way to shift the line would simply be to use another species concept that recognizes more taxa. Both the PSC and Evolutionary Species Concept (my personal favorite) would probably emphasize populations on tropical islands. Especially the latter would not recognize clines or broadly intergrading forms without known reproductive barriers.

Taxonomic discussions could also be saved by BirdLife simply adopting e.g. IOC classification.

Rainer

 

[jurek]

Currently this line is the distinction between species and subspecies. Sometimes taxa flip from one side of the line to the other or back, but there are established guidelines and procedures for handling this, based on the underlying species concept.

Not at all - BirdLife simply adopts the most recent publication, which encourages authors to flip the birds into "species" category.

It also creates unstability: population appears or disappears from the radar depending of renaming species/subspecies. Now, the general knowledge whether a form is significantly different is much more stable. It is also additive, in a sense that more genetic diversity is conserved in 5 significantly different subspecies than in 1 species just on the other side of the borderline.

These will probably be as much taxonomic judgements as the present decisions on species status!

Not, because subspecies already exist and are named. And requirements of the IUCN don't include evaluating all taxa. And such requirement in future is highly unlikely, because for less-known organisms there is not enough knowledge.

Another way to shift the line would simply be to use another species concept that recognizes more taxa. Both the PSC and Evolutionary Species Concept (my personal favorite) would probably emphasize populations on tropical islands. Especially the latter would not recognize clines or broadly intergrading forms without known reproductive barriers.

Adopting one of new and lesser-known species concepts will put chaos in communication with all the existing conservation sources which use different names. Subspecies, in contrast, are long recognized and generally known.