The Taxonomy Thread

jbnbsn99

jbnbsn99

Well-Known Member
How about a thread where we discuss all things taxonomic? I know I've gotten into long discussions with other members over taxonomic minutiae. Why not have a central place for it?

First topic:

Looks like the IUCN has recognized the Somali or Blue-Necked Ostrich (Struthio molybdophanes) as a full species.

Struthio molybdophanes (Somali Ostrich)

Makes sense to me. The fauna in the Horn of Africa region is, in most regards, distinct from that of the rest of the continent. A full ostrich species is expected.
 
If there is enough evidence ( by sight or genecticly ) why not. For conservation proposes it is of course a better thing to protect a species as a subspecies. Discovered however that the new species is currently not kept in any European collection ( Zootierliste ).
Does anybody know if it is kept in other regions ( America, Asia, Africa ) ?
 
vogelcommando said:
Does anybody know if it is kept in other regions ( America, Asia, Africa ) ?
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From what I've read they were/are kept in American zoos but as the AZA wants to focus on strictly keeping the Red-Necked Ostrich, all other ostriches in AZA zoos have been marked as generics and set for phase-outs. So while we probably do still keep them, they're not listed and are set for phasing-out.

Really unfortunate, especially since anyone who wants to see one before they are gone won't even know if the ostrich they're starring at is a Somali, a Masai, or an actual generic hybrid.

~Thylo:cool:
 
Several years ago, when I first visited Oklahoma City Zoo, they claimed that their ostrich was a blue-necked. However, it was a one-eyed female and I could see no diagnostic markings which made me think otherwise.
 
the Somali ostrich probably is a valid species (see the last paragraph of this post) but it is worth noting that the 2014 split from "regular" ostriches was not for any genetic reasons. It was a BirdLife split using an algorithm based on physical and behavioural elements (invented by a group headed by Joseph Tobias and hence generally known by such names as the "Tobias criteria"). This gives a numerical value for such things as morphology, behaviour, voice, distribution, etc. Apply the algorithm to a bird and the resulting value determines whether it is a species or subspecies. Genetic data is largely (not entirely) ignored.

The upcoming http://www.zoochat.com/183/hbw-illustrated-checklist-birds-world-376782/ uses the "Tobias criteria" (because it is a BirdLife publication), hence the 200-odd "new" species just in the non-passerine volume alone.

On the plus side, genetic results do show that the Somali ostrich is distinct from the other ostriches, and also it apparently has differences in behaviour and ecology. I was just reading that molybdophanes is a browser while masaaicus is a grazer, which is interesting. Those two forms have neighbouring ranges and yet are not close genetically. Speaking for myself, I am happy with accepting the split.
 
If I remember well the Tobias criteria were also used for the upcoming update of the IUCN redlist and actually led in Cyanoramphus to putting the different red-fronted species back as subspecies, which is some cases could be unhelpful for the conservation of some of the populations like Cyanoramphus cookii.
 
DDcorvus said:
If I remember well the Tobias criteria were also used for the upcoming update of the IUCN redlist and actually led in Cyanoramphus to putting the different red-fronted species back as subspecies, which is some cases could be unhelpful for the conservation of some of the populations like Cyanoramphus cookii.
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yes the IUCN redlist follows the BirdLife taxonomy. The "Tobias criteria" is a good idea in some ways - in broad terms it can determine relatively simply whether a particular taxon is "valuable" enough for protection without having to wait for DNA testing - but it falls down in not taking the genetic evidence into account. And there is some criticism that for particularly uniform groups of birds - say swifts or warblers - it may not be at all accurate. I imagine there would also be quite a few birds where the behaviour and voice simply weren't well enough known - or even known at all in many neotropical forms - to take them into account, and splits/non-splits would therefore be judged basically on morphology (e.g. coloured parts, size of crest, length of tail, etc). It has been argued that the "Tobias criteria" method of using physical differences and ignoring genetic differences is pretty much the exact opposite of most taxonomy research nowadays. More importantly, there is the criticism that there is not a body of back-up work to the decisions. Generally speaking when taxa are split or lumped, there are reasons given to the effect of "we did this research, and took into account these peoples' studies, etc etc". With BirdLife's "Tobias" splits it is more a case of "we have split/lumped this. Accept it."

I do get the intent behind the use of the "Tobias criteria" (they are covering every bird in the world and need an all-encompassing technique in the absence of genetic data for many of them) but it lacks finesse.
 
This sounds like a version of Numerical Taxonomy that was promoted by Sokal and Sneath back in the 1970's. During the sometimes very vocal debates between the (then) new cladistics method of classification and the traditional evolutionary taxonomy, Sokal and Sneath would enter the discussions with their Numerical Taxonomy, which they claimed was the most scientific form of classification as mathematics is the only 'pure' science. I noticed nobody disputed their arguments, and I got the impression it was because nobody understood Numerical Taxonomy.

:p

Hix
 
Continuing on the theme of subspecies being full species or not what do you think in about the West African Crocodile aka Desert Crocodile (crocodylus suchus/ crocodilus niloticus suchus) is it a subspecies of the nile crocodile ( crocodylus niloticus) which would make it crocodylus niloticus suchus or is it a full species making it crocodylus suchus. Personally I think it warrants full species status but what do any of you think???
 
Consensus is strongly heading towards suchus being recognised as a distinct species, and moreover not even all that closely related to niloticus!
 
Hix said:
This sounds like a version of Numerical Taxonomy that was promoted by Sokal and Sneath back in the 1970's. During the sometimes very vocal debates between the (then) new cladistics method of classification and the traditional evolutionary taxonomy, Sokal and Sneath would enter the discussions with their Numerical Taxonomy, which they claimed was the most scientific form of classification as mathematics is the only 'pure' science. I noticed nobody disputed their arguments, and I got the impression it was because nobody understood Numerical Taxonomy.

:p

Hix
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I wonder if this led to a group of taxonomic mathematicians?:rolleyes:
 
LaughingDove said:
Continuing on the theme of subspecies being full species or not what do you think in about the West African Crocodile aka Desert Crocodile (crocodylus suchus/ crocodilus niloticus suchus) is it a subspecies of the nile crocodile ( crocodylus niloticus) which would make it crocodylus niloticus suchus or is it a full species making it crocodylus suchus. Personally I think it warrants full species status but what do any of you think???
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it is pretty well accepted that suchus is a valid species. I mean you're going back about a decade since the first molecular results suggesting it were published, and there's been a lot of work since then.

In broad terms, suchus is distributed in the west and north of the continent, and niloticus in the south and east. However they were both obviously more widepread in the past, and they also occurred sympatrically (as shown by studies of Egyptian mummies and ancient Egyptian written records); there are also still living populations outside these general distributions (e.g. niloticus in Gabon).

Interestingly enough, genetically the niloticus African crocs fall into a group with the American crocodiles despite today having a largely eastern African range, while suchus seems more closely related to the Asian crocodiles.

It would be interesting to know what sort of feeding or habitat differences there are between niloticus and suchus, because they aren't that different morphologically. It isn't like saltwater and Johnstone's crocs having the same distributions in Australia, or gharials, saltwaters and muggers in India.
 
If you search the IUCN redlist though you dont get results for crocodylus suchus but you do get it in the catalogue of life (although that does contain a number of dubious species like crocodylus raninus). I would agree that it is definately different from niloticus but I guess the IUCN hasn't 'gotten around to it yet'
 
LaughingDove said:
If you search the IUCN redlist though you dont get results for crocodylus suchus but you do get it in the catalogue of life (although that does contain a number of dubious species like crocodylus raninus). I would agree that it is definately different from niloticus but I guess the IUCN hasn't 'gotten around to it yet'
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they mention the split in the IUCN Crocodile Specialist Group - iucncsg.org - Crocodilian Species - (and in the [earlier] pdf attached there) but because the limits of the two species ranges are not properly known they still treat it as an overall population for conservation purposes. It is a bit weird it isn't even mentioned on the Crocodylus niloticus page of the IUCN Red List site though.
 
TeaLovingDave said:
Consensus is strongly heading towards suchus being recognised as a distinct species, and moreover not even all that closely related to niloticus!
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Not only are they not all that close, genetic evidence shows that West Africa is sister to a clade with American croc and relatives. The Nile croc is more distinctly related. If keeping Nile and West African together we would get a polyphyletic species.

Chlidonias said:
It is a bit weird it isn't even mentioned on the Crocodylus niloticus page of the IUCN Red List site though.
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Unless making an entirely new evaluation, IUCN typically don't change their pages. The page version of the Nile crocodile hasn't been updated since 1996 and without better information on the West African's range there may not be sufficient information to justify an entirely new evaluation. Of course they could slap a "data deficient" rating on West African, but the IUCN are now trying to limit its use.

ThylacineAlive said:
From what I've read they were/are kept in American zoos but as the AZA wants to focus on strictly keeping the Red-Necked Ostrich, all other ostriches in AZA zoos have been marked as generics and set for phase-outs. So while we probably do still keep them, they're not listed and are set for phasing-out.
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I suspect no Somali ostriches remain in Western zoos and in any case the numbers were so low that I doubt it would have been viable to start a serious program for them. The name "blue-necked" has sometimes also been used for the southern ostrich (S. c. australis) and this can cause some confusion. The southern has a somewhat blue-gray neck, but lighter and not as blue as in the Somali. The same confusion exists with the name "red-necked". It has been used both for the Masai (S. c. massaicus) and North African (S. c. camelus). Both have a pinkish neck, but it is darker and stronger in color in North Africa. The North African is by far the rarest ostrich, but it is only recently that some zoos seem to have focussed on it. Despite its overall precarious situation, the Somali also survives in a number of relatively well-protected reserves in Kenya. Southern and Masai both have large captive and wild populations. In contrast, the entire wild population of North African lives in a region that is highly unstabil because of war and poverty. Essentially the same region as scimitar oryx, addax and dama/addra/mhorr gazelle. If the IUCN had rated the ostrich subspecies, North African would be a clear case of "Critically endangered" -- last stop before extinct/extinct in the wild.
 
temp said:
Not only are they not all that close, genetic evidence shows that West Africa is sister to a clade with American croc and relatives. The Nile croc is more distinctly related. If keeping Nile and West African together we would get a polyphyletic species.
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I'm assuming you made a typo there? The Nile (east Africa) croc is more closely related to American crocs. That's the unusual thing, that the more unrelated croc (the West African) is (today) bracketed between the other two which are closely related. There are several theories floating about to try and explain that.

temp said:
Unless making an entirely new evaluation, IUCN typically don't change their pages. The page version of the Nile crocodile hasn't been updated since 1996 and without better information on the West African's range there may not be sufficient information to justify an entirely new evaluation. Of course they could slap a "data deficient" rating on West African, but the IUCN are now trying to limit its use.
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I actually forgot to check the date of the page's last update (I usually do, because it can make things a bit clearer!)



Good to have you find the thread temp. You always make taxonomic discussions better.
 
Chlidonias said:
I'm assuming you made a typo there? The Nile (east Africa) croc is more closely related to American crocs.
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oops yes, switched by mistake in my post: phylogram
(Nile+(American+Orinoco+Morelet's+Cuban))+West African.

When seeing such results, my first hunch would be poor sampling, but with karyotype and phylogeny (mt and nDNA) all pointing in same direction and with high posterior probability, it's hard to dispute their accuracy.
There has been some research into leapfrog distributions in birds, including species that are poor dispersers (various suboscines and Australian/New Guinea species), and a bit of comparable research in plants and poison dart frogs, but I'm not aware of anyone doing it for reptiles.

Now we only need someone to fully review the Bornean "saltwater" crocodile (C. raninus) and dwarf crocodiles...
 
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Alright, I've got some food for thought! Now while I know we've discussed the taxonomy of Canis lupus and the other wolves of North America at length before on this site, we've not really talked about the Old World wolves apart from Dingos/New Guinea Singing Dogs. So, excluding those two, what are your thoughts on the different wolves of Eurasia?

Personally, I expect the Indian Wolf (C. l. pallipes) and Tibetan Wolf (C. l. chanco) to be split, with the Himalayan Wolf (C. (lupus) "himalayensis") ending up a subspecies of C. chanco.

I also expect the Arabian Wolf (C. l. arabs) and Egyptian Wolf (C. l. lupaster) to either represent two full species or two subspecies of the same species.

Thoughts and opinions?

~Thylo:cool:
 
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