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Redpolls (1 Viewer)

Perhaps our regular crossbill correspondents can comment usefully...

(I'm just an interested, but rather ignorant, observer. ;))
 
Indeed. I noted those papers on the other thread referenced earlier:
www.birdforum.net/showpost.php?p=2179232&postcount=4

The split is recognised by BOURC [therefore also Cornell (Clements/eBird), who systematically follow BOU for WP species] and CSNA, following Knox, Helbig, Parkin & Sangster 2001. Unsurprising given that Knox, Parkin and Sangster are members of BOURC-TSC, and Sangster is a member of CSNA.



I do not understand why the ssp. were then divided?


R.
 
I do not understand why the ssp. were then divided?
Knox et al 2001:
ABSTRACT
Lesser Redpoll Carduelis cabaret has until recently been widely regarded as a subspecies of Common Redpoll C. flammea. In the past, it was geographically isolated from other redpolls during the breeding season, but expansion of its range since the 1950s has brought it closer to nesting Common Redpolls in southern Scandinavia. In 1994, breeding occurred sympatrically without mixed pairs being noted. Lesser Redpoll is diagnosably distinct from all other redpolls, and there are preliminary reports of vocal, molecular and behavioural differences. It is recommended that Lesser Redpoll is best treated as a separate species.
Unfortunately, BB 94(6) [Jun 2001] seems to be missing from the online archive: www.britishbirds.co.uk/search.
 
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Thanks, ...but reality is different ...:
Lifjeld, J.T. & Bjerke, B.-A. 1996. Evidence for assortative pairing by the cabaret and flammea subspecies of the common redpoll Carduelis flammea in SE Norway. Fauna norvegica Series C, Cinclus 19: 1-8.,
http://export.nbii.gov/xml/CSA-PL/41/4081493.html
I'm not arguing in favour of Knox et al, but this is the exactly the evidence that they cited for sympatric assortative breeding: Lifjeld & Bjerke 1996.
Why do you think this is different to Knox et al's position?
 
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I'm not arguing in favour of Knox et al, but this is the exactly the evidence that they cited for sympatric assortative breeding: Lifjeld & Bjerke 1996.
Why do you think this is different to Knox et al's position?

Thanks,

I did not have an abstract ... but we know from experience that "hybrids" are fertile. Genetic analysis confirms this. I think that kind of recognition is necessary to Genetic incompatibility, what is not here.
How do you think it will be solve further ...?

R.
 
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How do you think it will be solve further ...?
Well, as I said, I'm just an unqualified observer. Irrespective of proof of sympatric breeding, CSNA would probably recognise cabaret as a diagnosable PSC species anyway. That effectively leaves BOU as the only significant authority actively asserting its treatment as a BSC species, but in 10 years that view has attracted little support...

PS. Parkin & Knox 2010 (The Status of Birds in Britain & Ireland) comments:
There are anecdotal reports of weakness in this analysis [Knox et al. 2001], but no refutation has been published, and we retain C. cabaret as a third species of redpoll.
 
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Offspring fertility isn't the sole factor in recognizing a species. The offspring could be fully fertile, but if they have reduced fitness (odd moult timing, weird calls, less attractive to the opposite gender) this will contribute to reproduction isolation.

Not saying this is the situation with Redpolls, just saying it is usually more complicated than simple hybrid fertility.
 
Offspring fertility isn't the sole factor in recognizing a species. The offspring could be fully fertile, but if they have reduced fitness (odd moult timing, weird calls, less attractive to the opposite gender) this will contribute to reproduction isolation.

Not saying this is the situation with Redpolls, just saying it is usually more complicated than simple hybrid fertility.


I know from the breeding practices of the redpoll it does not...Certainly, the capture is something different ...
So where are the boundaries between species and subspecies??
But otherwise the agreement ..

Radim
 
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Lifjeld and Bjerke have apparently shown, that flammea and cabaret do not interbreed in nature and, consequently, do not produce hybrids in nature, even though it is highly likely that they could, if they wanted. Under these circumstances it is irrelevant in the first place, whether hybrids are fertile or not, or have lower fitness. Or have Lifjeld and Bjerke's results been disproven or contradicted by others? I mean, have hybrids been found in nature in the meantime? Any references? I'm not up to date on Redpoll research, admittedly.

Based on Lifjeld and Bjerke alone (!), both taxa must undoubtedly be considered as biological species: they are diagnosably distinct and do not share a common gene pool. Accepting that their morphological, behavioural, vocal etc. differences have a genetic basis, there must be molecular differences, even though these may not yet have been localized in the genome, let alone quantified. The taxa are not fading one into the other through clinal variation. There's not even a localized hybrid zone (or is there elsewhere?). Hence they had separate evolutionary histories, long enough to account for those differences, and will very probably - due to their assortative mating - have separate evolutionary fates.

It is the taxonomist's job to describe biological diversity as it actually exists in nature, not what could be made of it under captive conditions. Otherwise we would have to lump Canary, Red Siskin and Hooded Siskin as well.

Rainer
 
Lifjeld & Bjerke 1996

Based on Lifjeld and Bjerke alone (!), both taxa must undoubtedly be considered as biological species...
AERC TAC 2003. AERC TAC's Taxonomic Recommendations [p72-74]:
The proposal by Knox et al. (2001) was mainly based on their interpretation of a paper by Lifjeld & Bjerke (1996), going further than the one in the original paper. The first author of Lifjeld & Bjerke (1996), J. Lifjeld (in litt. 23 May 2003), however, agrees with the new AERC TAC and explains why: 'I fully agree that the split seems premature. I feel somewhat responsible for this, due to my paper on assortative pairing by cabaret and flammea in the Norwegian journal Cinclus in 1996 [Lifjeld & Bjerke 1996]. However, it was based on a very small sample, and it seems that there are intermediates in both the alpine and coastal populations in Norway, making the situation more complex than I first anticipated. The situation is therefore far from clear. I have taken on a PhD student now, and over the next three years she will look for diagnostic markers, using AFLP and microsatellites of cabaret and flammea, as well as hornemanni. I am not confident we will find any clear differentiation between the former two. Given the current strong research interest in this issue I think it is quite sensible to await further results before making any changes in the taxonomy. The second author of the paper, B. Bjerke, is my museum technician. He may not have any strong opinions in this matter. He collected the birds described in our 1996 paper. Otherwise, he hasn't worked much on this issue.' Ottvall et al. (2002) – among others co-authored by J. Lifjeld – and important new information since the publication of Knox et al. (2001) found no genetic differentiation between flammea and cabaret...
The quoted written statements of the original lead author are perhaps the 'anecdotal reports of weakness in this analysis' referred to in Parkin & Knox 2010 (see post #27).
 
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Lifjeld and Bjerke have apparently shown, that flammea and cabaret do not interbreed in nature and, consequently, do not produce hybrids in nature, even though it is highly likely that they could, if they wanted. Under these circumstances it is irrelevant in the first place, whether hybrids are fertile or not, or have lower fitness. Or have Lifjeld and Bjerke's results been disproven or contradicted by others? I mean, have hybrids been found in nature in the meantime? Any references? I'm not up to date on Redpoll research, admittedly.

Based on Lifjeld and Bjerke alone (!), both taxa must undoubtedly be considered as biological species: they are diagnosably distinct and do not share a common gene pool. Accepting that their morphological, behavioural, vocal etc. differences have a genetic basis, there must be molecular differences, even though these may not yet have been localized in the genome, let alone quantified. The taxa are not fading one into the other through clinal variation. There's not even a localized hybrid zone (or is there elsewhere?). Hence they had separate evolutionary histories, long enough to account for those differences, and will very probably - due to their assortative mating - have separate evolutionary fates.

It is the taxonomist's job to describe biological diversity as it actually exists in nature, not what could be made of it under captive conditions. Otherwise we would have to lump Canary, Red Siskin and Hooded Siskin as well.

Rainer



Suppose that Redpoll are in the process of differentiation on the species, the process is obviously a longer time ... I think. Probably can not say unequivocally at this point, whether or not this species. ... (still occurring hybrids just confirms).

Radim
 
Wait, you guys do know this paper right? http://www.sciencedirect.com/science/article/pii/S1055790308000961 I get the impression some redpoll splitters happily ignore it!

Based on Lifjeld and Bjerke alone (!), both taxa must undoubtedly be considered as biological species: they are diagnosably distinct and do not share a common gene pool. Accepting that their morphological, behavioural, vocal etc. differences have a genetic basis, there must be molecular differences, even though these may not yet have been localized in the genome, let alone quantified. The taxa are not fading one into the other through clinal variation. There's not even a localized hybrid zone (or is there elsewhere?). Hence they had separate evolutionary histories, long enough to account for those differences, and will very probably - due to their assortative mating - have separate evolutionary fates.

It is the taxonomist's job to describe biological diversity as it actually exists in nature, not what could be made of it under captive conditions. Otherwise we would have to lump Canary, Red Siskin and Hooded Siskin as well.

Rainer

This is perhaps the nub of the argument. They behave as different biological species, and i count them as such - just as i do Siberian Chiffchaff. And as Rainer says, if they are different in structure, plumage, vocalisations etc then they are different genetically, just not to a given threshold in a particular test.
 
You seem to confuse 'they behave as different biological species' with 'somebody once said they might behave as different biological species' ;-). The Redpoll case is quite similar to Crossbills (is it just a coincidence these are closely related or are they adapted to being a taxonomical mess?).
 
Not really Ben, unless you have reason to disbelieve the Lifjeld & Bjerk paper? I've certainly never heard anything contradicting their findings.
 
In summary...
  • Cabaret is diagnosably distinct and so can be considered to be a PSC species, which is adequate for CSNA acceptance (eg, as per wagtails).

  • But BOU's acceptance relied upon treatment as a BSC species, based specifically upon proven sympatric assortative breeding (Lifjeld & Bjerke 1996, but later effectively retracted by the principal author).

  • Otvall et al 2002 and Marthinsen et al 2008 have subsequently concluded that genetic differentiation does not provide support for species status.
 
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