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Maciamo
09-09-16, 08:09
I woke up this morning to the most shocking news, something that most people around the world didn't see coming. I am not talking about North Korea's nuclear test (we saw that one coming), but to a new German study (http://www.cell.com/current-biology/abstract/S0960-9822(16)30787-4) published in Cell Biology showing that giraffes aren't a single species but four distinct species that hadn't mixed with each others for millions of years (in contrast Neanderthal split from Homo sapiens only 600,000 years ago).

Those four species include:



southern giraffe (Giraffa giraffa),
Masai giraffe (G. tippelskirchi),
reticulated giraffe (G. reticulata)
northern giraffe (G. camelopardalis), which includes the Nubian giraffe (G. c. camelopardalis) as a distinct but related subspecies.


Axel Janke, the lead author of the paper, explains that the genetic differences between the four species is as big as between polar bears and brown bears. That also means, I believe, that the genetic gap is about the same as the one between dogs, wolves, foxes and jackals. Yet we have clearly distinct words for these animals, and hundreds more of appellations for races of dogs. Does that mean that we should come up with new names for each giraffe species? Or should toddlers start at the very least to learn to recognise the patterns and say 'reticulated giraffe' and 'Masai giraffe' instead of just 'giraffe'? How will Japanese deal with the change, when their word for giraffe (kirin) was borrowed from a term for chemerical mythological beast (https://en.wikipedia.org/wiki/Qilin) that looks nothing like a giraffe, instead of having to import yet another new foreign word? That is bound to cause more confusion in the mind of school children who already had to share a word for giraffe with that of a horned and hooved dragon.

That's a lot to think about before breakfast. I'll let it cool down a bit in my brain for the moment.

bicicleur
09-09-16, 08:20
Do all four species live exclusively in Africa?
Do their territories overlap?

Maciamo
09-09-16, 09:24
Do all four species live exclusively in Africa?
Do their territories overlap?


All giraffes live exclusively in Africa (if you exclude zoos, of course). Their territories do not overlap, except very slightly in Kenya for the Masai and reticulated giraffes.

Before this study all sub-species were regarded as more or less equally distant from one another. This map from Wikipedia shows the old classification (the main article on giraffes has already been amended though).


https://upload.wikimedia.org/wikipedia/commons/1/1d/Giraffa_camelopardalis_distribution.svg


But it now transpires that many of these subspecies are actually variants of the so-called northern giraffe, or Nubian giraffe (G. camelopardalis). Far from being limited to the north, it includes western, central and southern sub-species too, like the West African giraffe (G. c. peralta), the Kordofan giraffe (G. c. antiquorum), the Rhodesian giraffe (G. c. thornicrofti) and the Angolan/Namibian giraffe (G. c. angolensis), in addition to the northern Rothschild's giraffe.

This new Giraffa camelopardalis species appears to be the best adapted to a wide range of environments and the most adventurous.


Note that the previous phylogenetic tree (pictured below), based on mitochondrial DNA only, had the classification of sub-species entirely wrong. This goes to show that mtDNA is not reliable and accurate enough to distinguish populations, as mtDNA distribution rarely reflects autosomal DNA variations. The yellow, orange and pink branches below represent the three new species that are clearly distinct from all other G. camelopardalis-derived subspecies.

https://upload.wikimedia.org/wikipedia/commons/1/1c/Genetic_subdivision_in_the_giraffe_based_on_mitoch ondrial_DNA_sequences.png

Boreas
09-09-16, 11:11
https://upload.wikimedia.org/wikipedia/commons/1/1d/Giraffa_camelopardalis_distribution.svg



This map has been created in 2010, maybe that's why it is not shocking news. Some people have already known different type of giraffes like me

bicicleur
09-09-16, 11:12
I recall there was a tree based on mtDNA showing how Denisovans, Neanderthals and modern humans related to each other.
Now they have autosomal DNA and the three looks quite different.