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Should we consider lumping more subspecies? (1 Viewer)

If Redpolls are all one despite Arctic being 15% bigger than Lesser and morphologically different, I'm not sure of the boundaries any more.
I also find the redpolls very confusing. I know that things are very messy in Greenland, but in other places ID of the different types takes work, but is possible.

In Norway I have visited areas where excilipes breeds (but in winter, when I only saw birds wintering with Meally’s). The reported breeding habitat is willow scrub, so I understand quite different from the normal taiga forest of Meally.

Also I recall reading in Dutch Birding of a ringer using a caged Redpoll to attract Redpolls for ringing. The bird was not screened so it could have been vision or sound that attracted finches for trapping, but the bird attracted birds of its own kind - I may be wrong but I recall it was a Meally and attracted other Meally’s rather than Lesser which was normally more common in the area.

Papers in the past have also talked of the distinctive calls of Arctic (at least at sonogram level).

If all this is right, it seems that these birds are isolated by attraction (call and/or plumage), and some by breeding habitat.

I note that despite genetics inferring that they aren’t even subspecies and more akin to morphs, taxonomies have retained the subspecies. At least the white morph Gyrfalcon once had its own subspecies name (I recall canadensis), until we switched to just saying white morph. Perhaps one day we will have the slightly unpalatable situation of having to say Redpoll - Eurasian Arctic Morph of something similar.
 
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The finch is on both islands.
Sorry my mistake. In China at the moment, so working ‘from memory’.

But my point was really that lots of places weren’t physically isolated in the last ice age, due to lower sea levels.

That said, lowlands will have been flooded by rising sea levels, so species and subspecies could still have evolved in mountain ranges still isolated from other ranges, but for a time part of the same island - say the highlands of PNG, which presumably were once a mountain range in northern Australia. So perhaps the Nuthatch could have evolved in Corsica and been prevented from reaching now Sardinia by unsuitable lowlands. I suppose finches are less sedentary than Nuthatches and the finch could perhaps have crossed any lowland divide.
 
Yeah...different processes = different dates. I just assume from a biotic isolation standpoint otherwise sedentary species would have been able to move over the Doggerland until pretty recently.

A cursory online look says that Britain was completely covered by glaciers as recently as 22,000 years ago. Any sort of endemic subspecies would have to be younger than that. Although there are pretty distinct forms in North America that are not much older. IIRC Juncos only started diverging in the Late Pleistocene, as did Yellow-rumped Warblers.

The whole effects of geography on shaping speciation and diversity in Eurasia vs the Americas is honestly fascinating. The whole east-west axis of mountains in Eurasia + the Mediterranean meant that the temperate and warmer weather faunas just got pulverized with each glacial. Doggerlands rapid flooding means that a lot of critters never made it to across to Great Britain. In the Americas the axis of mountains is largely north-south, so critters had few barriers stopping them from moving south. Hence why you get patterns like there being more native turtle species in Wisconsin than there is in all of Europe.
Have a reference on that? Would like to read more about it.
 
15% is quite drastic, but i accept its variable. Hornemann's and Lesser just seem like different species to me.
But that's an interesting point, so thank you.
To be fair (caveat mammals are not birds) in humans there is a difference of about 15% in average height between the places with largest and smallest individuals (and even greater in weight). Humans are a bit of a weird subject there, but from a BSC point of view, we're a single taxa.
 
I'm just totally confused by it all to be honest.

If Redpolls are all one despite Arctic being 15% bigger than Lesser and morphologically different, I'm not sure of the boundaries any more.

Divers/loons, Wagtails, Crossbills, geese etc.
Look to humans! We are one species. The difference in weight and appearance does not change that.
In my opinion, if the willingness to differentiate as species in birds based on mm differences in wing length and single DNA differences were applied to humans we'd be in deep trouble. Just because a technique makes it possible to differentiate based on small differences in DNA doesn't mean the interpretation is correct (which I in many cases doubt). Have look at the different breeds between members of the same domestic animal species and be surprised!
Per
 
Sorry my mistake. In China at the moment, so working ‘from memory’.

But my point was really that lots of places weren’t physically isolated in the last ice age, due to lower sea levels.

That said, lowlands will have been flooded by rising sea levels, so species and subspecies could still have evolved in mountain ranges still isolated from other ranges, but for a time part of the same island - say the highlands of PNG, which presumably were once a mountain range in northern Australia. So perhaps the Nuthatch could have evolved in Corsica and been prevented from reaching now Sardinia by unsuitable lowlands. I suppose finches are less sedentary than Nuthatches and the finch could perhaps have crossed any lowland divide.
The land rise after the last (of many) glaciations is interesting: we live by the seashore here in Norway, only that was a few thousand years ago, now we are 186 meters above. We have a cabin on a small island on a lake in mid-Norway (great for birding!) and in the silt/beaches (132 m above mean sea level) you find marine seashell shells.
Two kilometers thick ice is heavy, and that was only 12000 years ago. It also shaped our fjords, and the ice ages forced most species together in a smaller land area (and of course supported differentiation) whereupon they then followed the edge of the ice as it melted.
Per
 
Reading up on subspecies, I sometimes come upon statements that read something like: "Not readily diagnosable" sometimes not even with measurements. For example I tried to learn about Taiga Bean Goose subpopulations, but apparently it's impossible to distinguish Anser fabalis fabalis from A. f. johanseni.
...
Therefore, I would like to ask the birdforum crowd:
What's the use of subspecies that are not diagnosable (except perhaps by range) or only by minute characteristics? Do we need fewer subspecies?
The answer to your question is 'yes' - there are many subspecies that probably should not be recognised. Also, there are many populations in Asia and S America that lack a name or should have one, and many cases where subspecies ranges should be studied properly and restated.

But here is a challenge - try getting published a taxonomic revision in an ornithological journal on subspecies limits! It's very difficult because there is little consensus on subspecies definitions and papers get reviewed to death and often have to be abandoned.
  • Some PSC people do not believe in subspecies at all.
  • Some BSC people want any valid subspecies to be a species (fully diagnosable).
  • Traditionally, there is a '75% diagnosability' test but there is no consensus how to run that statistically.
  • There are numerous situations where birds in different geographical regions are quite different, but where there are zones of intermediates of varying size. Some people want to split most of these as actual species, especially Nearctic/Palearctic people. Some won't even allow a subspecies to be recognised on the same facts, especially those studying the tropics.
This presents troubles getting research published. I reached the point of concluding that, for S America:
  • It's not possible 'in the real world out there' to lump a subspecies unless you can show it is invalid under every concept (does not even pass a t-test for a single measured variable and <50% diagnosable.
  • It's not possible 'in the real world out there' to describe a subspecies unless you can show it is basically something that would be called a species if it occurred in N America or Europe.
Result: continued recognition forever of many dubious subspecies and non-description of many populations that ought to be named. Sad fact is that many ornithological taxonomists prefer historical treatments over consistency/rationality.

That's what the powers want, it seems.
 
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A cursory online look says that Britain was completely covered by glaciers as recently as 22,000 years ago. Any sort of endemic subspecies would have to be younger than that
I don't think that's correct. The maximum extent of ice during the last ice-age didn't extend to south and south east England.
 
I don't think that's correct. The maximum extent of ice during the last ice-age didn't extend to south and south east England.
I asked Gemini:
About 22,000 years ago, during the Last Glacial Maximum (LGM), ice sheets reached their greatest extent.
* Northern Hemisphere: Ice sheets covered much of North America, Europe, and Asia. In North America, the ice sheet extended as far south as the northern United States. In Europe, it covered all of Scandinavia and the British Isles, extending into northern France and Germany. In Asia, ice sheets covered much of Siberia.
* Southern Hemisphere: Ice sheets were smaller in the Southern Hemisphere, but still covered parts of Antarctica, South America, and New Zealand.
The LGM had a significant impact on the Earth's climate and environment. Sea levels were much lower than they are today, and the Earth was much colder. The LGM also caused significant changes in plant and animal distributions.
The LGM began to end about 20,000 years ago, and the ice sheets began to retreat. This marked the beginning of the Holocene epoch, which is the current geological epoch.
 
I asked Gemini:
About 22,000 years ago, during the Last Glacial Maximum (LGM), ice sheets reached their greatest extent.
* Northern Hemisphere: Ice sheets covered much of North America, Europe, and Asia. In North America, the ice sheet extended as far south as the northern United States. In Europe, it covered all of Scandinavia and the British Isles, extending into northern France and Germany. In Asia, ice sheets covered much of Siberia.
* Southern Hemisphere: Ice sheets were smaller in the Southern Hemisphere, but still covered parts of Antarctica, South America, and New Zealand.
The LGM had a significant impact on the Earth's climate and environment. Sea levels were much lower than they are today, and the Earth was much colder. The LGM also caused significant changes in plant and animal distributions.
The LGM began to end about 20,000 years ago, and the ice sheets began to retreat. This marked the beginning of the Holocene epoch, which is the current geological epoch.

Sometimes it is better to just google, instead of asking AI....

Within 5 seconds one can find this map of the extent of the ice in the last glaciation in Europe:
1024px-Weichsel-W%C3%BCrm-Glaciation.png


So yes, parts of England and Ireland were icefree and there was certainly no ice in Northern France (not sure where gemini made that up)

A cursory online look says that Britain was completely covered by glaciers as recently as 22,000 years ago. Any sort of endemic subspecies would have to be younger than that. Although there are pretty distinct forms in North America that are not much older. IIRC Juncos only started diverging in the Late Pleistocene, as did Yellow-rumped Warblers.

While England wasn't completely covered in ice, the habitats would be significantly different and I would assume that many species currently represented by "subspecies" must indeed have arrived later, given that there wouldn't be much of suitable habitat (unless you were a steppe/tundra bird).
 
Sometimes it is better to just google, instead of asking AI....

Within 5 seconds one can find this map of the extent of the ice in the last glaciation in Europe:
1024px-Weichsel-W%C3%BCrm-Glaciation.png


So yes, parts of England and Ireland were icefree and there was certainly no ice in Northern France (not sure where gemini made that up)



While England wasn't completely covered in ice, the habitats would be significantly different and I would assume that many species currently represented by "subspecies" must indeed have arrived later, given that there wouldn't be much of suitable habitat (unless you were a steppe/tundra bird).
Gemini is Google. And remember: the channel didn't exist then.
Quote from Bethan Davis' blog: In Britain, the Last Glacial Maximum was reached around 27-21 ka[3], but different parts reached their maximums at different times. Like many ice sheets at their maximum, it was constrained at its northern limits by the steep drop in the sea floor at the continental shelf edge. Likewise in Patagonia, the ice sheet reached the continental shelf edge and could go no further on its Pacific, western margin[6]. In the Antarctic Peninsula, the Antarctic Ice Sheet reached the continental shelf edge at around 25,000 years ago[9].

A recent publication, Quaternary Glaciations – Extent and chronology, a closer look, edited by Ehlers, Gibbard and Hughes[10], provides detailed information on each of these ice sheets at their maxima. It even provides GIS shapefiles that you can download to examine the LGM of each ice sheet yourself:

 
Gemini is Google. And remember: the channel didn't exist then.
Quote from Bethan Davis' blog: In Britain, the Last Glacial Maximum was reached around 27-21 ka[3], but different parts reached their maximums at different times. Like many ice sheets at their maximum, it was constrained at its northern limits by the steep drop in the sea floor at the continental shelf edge. Likewise in Patagonia, the ice sheet reached the continental shelf edge and could go no further on its Pacific, western margin[6]. In the Antarctic Peninsula, the Antarctic Ice Sheet reached the continental shelf edge at around 25,000 years ago[9].

A recent publication, Quaternary Glaciations – Extent and chronology, a closer look, edited by Ehlers, Gibbard and Hughes[10], provides detailed information on each of these ice sheets at their maxima. It even provides GIS shapefiles that you can download to examine the LGM of each ice sheet yourself:


You can give me all kinds of links, but that doesn't change the fact that Northern France and the south of England were ice free. Use "glacial maximum weichselian" as search term and you will see, the Saalian (the ice age before) is a different matter. AI isn't always better than just a regular search engine where you can process information yourself...
 
Considering subspecies in general, I would leave them as a current mess, because 1) even a very small genetic difference can result in a population which is ecologically different and irreplaceable and / or visually very different, 2) a subspecies is really the only rank lower than species.

About the history of Britain - the part not covered by ice was tundra, continuous across Eurasia. There was no forest birds, and tundra birds were not isolated from other populations in Eurasia.
 
Considering subspecies in general, I would leave them as a current mess, because 1) even a very small genetic difference can result in a population which is ecologically different and irreplaceable and / or visually very different, 2) a subspecies is really the only rank lower than species.

About the history of Britain - the part not covered by ice was tundra, continuous across Eurasia. There was no forest birds, and tundra birds were not isolated from other populations in Eurasia.
I totally agree with you wrt species: subspecies is an old, well-tested descriptive in zoology. It denotes a genetically distinct population of a species which is still interbreedable within the species. And always remember: even within species there will be incompatible breeders.
As to the tundra: thanks!
Per
 

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