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AOU 2017 Checklist proposals (1 Viewer)

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2. Preference to deal with the whole Red Crossbill complex at one time. This seems like it is really an opinion situation more than anything else. I would say that, while preferable in some cases (like has happened with groups like the Yellow-rumped Warbler before), with the holarctic monster that is Red Crossbill, I suspect that we might have to wait another hundred years for such a complex-wide solution. For such a complex situation (pun!), I think piecemeal splitting is more appropriate, rather than wait forever. When we have data that supports at least one taxon of the complex that warrants species-level status separate from the rest of the complex, we should split that taxon. Also, for what it is worth, this particular population of crossbills likely won't wait around 100 years for this ultimate solution, and will instead likely shortly be extinct as written about [here].

On the suggestion of piecemeal splitting, including samples of nominate L. c. curvirostra (from e.g. Sweden) should not be a problem, and would be a major improvement to the study.
 
On the suggestion of piecemeal splitting, including samples of nominate L. c. curvirostra (from e.g. Sweden) should not be a problem, and would be a major improvement to the study.

ah but would inclusion of that data actually influence this study? I would hypothesize that any Old World Crossbill samples included would either:

come out as the sister taxon to the North American forms.

just show up within the smear of non South Hills Crossbill forms with no change in resolution.

It seems extraordinary unlikely that a few samples from Europe or Asia would influence at all any of the results they show here, unless you think its likely that the South Hills form is descended from Swedish birds somehow, and that explains the gene differences and assortive mating.

Don't get me wrong...tackling the old world forms would be an important extension of this study that I am sure Benkman and colleagues are probably involved with or looking into. But I am not sure it really affects the outcome for this proposal
 
ah but would inclusion of that data actually influence this study? I would hypothesize that any Old World Crossbill samples included would either:

come out as the sister taxon to the North American forms.

just show up within the smear of non South Hills Crossbill forms with no change in resolution.
If previous studies are any indication, Palearctic populations of plain-winged crossbills (i.e., L. curvirostra + pytyopsittacus + 'scotica') should form the sister group of Nearctic populations.
 
My suspicion is that it would show nominate L. c. curvirostra to be sister to [South Hills + other N American crossbills], with a split of L. sinesciuris thus also necessitating a split of L. minor (Brehm, 1846) for all the other N American crossbills :t:
 
My suspicion is that it would show nominate L. c. curvirostra to be sister to [South Hills + other N American crossbills], with a split of L. sinesciuris thus also necessitating a split of L. minor (Brehm, 1846) for all the other N American crossbills :t:

necessitating? only if you believe in the phylogenetic species concept, I believe. In a biological species concept, lack of monophyly is not a problem at the species level as has already been stated in this thread.

Niels
 
necessitating? only if you believe in the phylogenetic species concept, I believe. In a biological species concept, lack of monophyly is not a problem at the species level as has already been stated in this thread.

Niels

But it's the same justification as was used for splitting Western Scrub Jay - Californian were closer to Island, than to Woodhouse's.
 
But it's the same justification as was used for splitting Western Scrub Jay - Californian were closer to Island, than to Woodhouse's.

The jays were split because of what was happening in the hybrid zone, which was extremely narrow with little to no gene flow outside the zone.

Andy
 
Lack of monophyly at the species level may not be a problem if there is 'something' at play that unifies 'the species' as a whole -- e.g., actual gene flow between parts that look like they are non-sister; uniformity within 'the species' in some aspect that is central to reproductive isolation between one of its parts and its sister group; etc. If this is not the case, then it's somewhat problematic.
In the present case, you would need some (preferably good) reason to split South Hills Crossbill rather than splitting 'Loxia minor' from L. curvirostra. If the only information you have is that these two are reproductively isolated from one another, how do you choose?

*****
PS -- I know the proposal was written by the author of the name, but the South Hills Crossbill was really described as Loxia sinesciuris, not 'L. sinesciurus'.
(Benkman et al 2009 [pdf]:
We name this species Loxia sinesciuris because it occurs in an area without tree squirrels, and the absence of tree squirrels is key to its evolution. Sine sciuris is the Latin phrase “without squirrels.”
sine: without, preposition requiring ablative; sciurus, -i (from Gr. σκίουρος): squirrel; albative plural: sciuris.)
 
Nutcracker:
But it's the same justification as was used for splitting Western Scrub Jay - Californian were closer to Island, than to Woodhouse's.
Kratter:
The jays were split because of what was happening in the hybrid zone, which was extremely narrow with little to no gene flow outside the zone.

I think the phylogenetic distance was the argument in the proposal first time around -- which was not approved by the committee. I also remember reading the info on the hybrid zone in the second time around as the new info that made the difference.

For another example of lack of monophyly, see this SACC proposal and the Trinidad Motmot - there is a link to the actual paper: http://www.museum.lsu.edu/~Remsen/SACCprop412.htm

Niels
 
Lack of monophyly at the species level may not be a problem if there is 'something' at play that unifies 'the species' as a whole -- e.g., actual gene flow between parts that look like they are non-sister; uniformity within 'the species' in some aspect that is central to reproductive isolation between one of its parts and its sister group; etc. If this is not the case, then it's somewhat problematic.
In the present case, you would need some (preferably good) reason to split South Hills Crossbill rather than splitting 'Loxia minor' from L. curvirostra. If the only information you have is that these two are reproductively isolated from one another, how do you choose?

*****

Not sure I follow. from a BSC approach, the only thing that really matters is reproductive isolation from other sympatric crossbills. Old World crossbills are not relevant to this in the sense that none of those populations come into contact with the South Hills form.

There is no reason not to split South Hills from other taxa, and address old world versus new world divisions later.
 
Very interesting discussion. Is the crossbill case unique among birds or are there comparable examples in other avian taxa?
 
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Very interesting discussion. Is the crossbill case unique among birds or are there comparable examples in other avian taxa?

Darwin's finches seem to have something similar going on, and are probably the even more classic example of sympatric speciation. In fact seed-eating birds seem to in general be good candidates for sympatric speciation, since specialization for different types of seeds can result in changes in bill size and subsequent call. Something like this might be going on within Evening Grosbeaks and Pine Grosbeaks, although I think there is generally less work done on these.

Something like this might also be going on with Whydahs and some other groups of brood parasites, although in this case it's more specialization on parasitizing certain songbirds rather than specialization for diet.

Those are the other bird taxa off the top of my head. Not sure what other examples exist outside of birds however.
 
Not sure I follow. from a BSC approach, the only thing that really matters is reproductive isolation from other sympatric crossbills. Old World crossbills are not relevant to this in the sense that none of those populations come into contact with the South Hills form.

I think what Laurent is thinking about is the more general question of when monophyly would be required vs not. To take the Motmot example: from the middle of a clade, one group of birds moved to an island. They went through some bottleneck and some fast selection and became different enough that they now are considered a different species.
The thing that "that unifies 'the species' as a whole" is that the rest are all present on the mainland and are connected through gene flow.

Laurent, if I have misunderstood, please correct.

Niels
 
Darwin's finches seem to have something similar going on, and are probably the even more classic example of sympatric speciation. In fact seed-eating birds seem to in general be good candidates for sympatric speciation, since specialization for different types of seeds can result in changes in bill size and subsequent call. Something like this might be going on within Evening Grosbeaks and Pine Grosbeaks, although I think there is generally less work done on these.

Something like this might also be going on with Whydahs and some other groups of brood parasites, although in this case it's more specialization on parasitizing certain songbirds rather than specialization for diet.

Those are the other bird taxa off the top of my head. Not sure what other examples exist outside of birds however.

Thanks for that, much appreciated. Looks like I've got some serious catch-up reading to do. . ..
 
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... the South Hills Crossbill was really described as Loxia sinesciuris, not 'L. sinesciurus'.

It seems that "sinesciuris" is difficult for taxonomists to spell. (I don't mean to make fun of anybody, I'd be likely to misspell it too.)

Clements checklist update, Dec 2009:

A new species of crossbill in the Red Crossbill complex, the South Hills Crossbill Loxia sinescuria, recently was proposed from south central Idaho, United States.

Clements checklist update, Feb 2011:

Red Crossbill (South Hills) Loxia curvirostra sinescuria
Correct the spelling of the subspecies name to Loxia curvirostra sinesciurius.

Clements checklist update, Aug 2011:

Red Crossbill Loxia curvirostra
Correct a typographic error, and change the spelling of the subspecies name from Loxia curvirostra sinesciurius to Loxia curvirostra sinesciuris.
 
ABA's take on AOU/AOS 2017 check-list proposal. I like the Cassia idea.
http://blog.aba.org/2017/01/2017-aos-check-list-proposals-part-1.html .

I also liked this caption: 'One reason “South Hills” Crossbill is so unique is that it lives in mountain ranges that lacks Red Squirrels, a fact reflected in its latin name sinesciurus, literally “without squirrels”'.

A uniqueness shared with rather a large number of other species, starting with Andean tanagers.

Keith
 
I wonder what those three species of arboreal rodents were then, that I saw in the Andes...

I always thought they were Red-tailed, Guayaquil and Bolivian Squirrel. ;)
 
I also liked this caption: 'One reason “South Hills” Crossbill is so unique is that it lives in mountain ranges that lacks Red Squirrels, a fact reflected in its latin name sinesciurus, literally “without squirrels”'.

A uniqueness shared with rather a large number of other species, starting with Andean tanagers.

Keith

The context being unique "amongst crossbills"...
 
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