Caspian Tigers

[Dicerorhinus]

I thought I would start a new thread to discuss the recent mitochondrial DNA research and subsequent revelation that the Caspian Tiger (Panthera tigris virgata) was very likely a Sub-population of Siberian Tiger (P. t. altaica).

Its thought that the population inhabited a contiguous range which was later divided through human activity.

For those of you interested here is the paper in question:
PLoS ONE: Mitochondrial Phylogeography Illuminates the Origin of the Extinct Caspian Tiger and Its Relationship to the Amur Tiger

Should the Caspain Tiger be restored by Introducing Siberian Tigers into the range countries ?

Are there any ramifications for conservation programs of other species (Its also very likely that Ganges and Indus River Dolphins are infact the same species) ?

 

[Ned]

Thanks for posting that. I’ve just read the abstract so far but a few questions for you as you probably know more than me about these things. The mitochondrial DNA is similar but could it be that the nuclei DNA differs substantially? Would it be possible though genetic engineering to alter the one nucleotide that differs and recreate the Caspian tiger?
Either way this shows the value of museum specimens.

 

[jbnbsn99]

The most recent research on that now says that the Caspian and Amur Tigers split genetically less than 100 years ago.

Absolutely, if it is possible, Amur Tigers should be reintroduced over much of their former range.

 

[Maguari]

Thanks for posting that. I’ve just read the abstract so far but a few questions for you as you probably know more than me about these things. The mitochondrial DNA is similar but could it be that the nuclei DNA differs substantially? Would it be possible though genetic engineering to alter the one nucleotide that differs and recreate the Caspian tiger?
Either way this shows the value of museum specimens.

As a general rule, mitochondrial DNA evolves more quickly than nuclear DNA (which is one of the reasons it is used for this type of study). If the split has only been as recent as 100 years ago, the nuclear DNA difference would likely be very small.

 

[Pertinax]

Always been fascinated by the idea of them roaming the forests and marshlands of Middle Eastern countries. Another example of a species that was probably exterminated(if indeed it was- there re still rumours it may just persist in Eastern Turkey)) just a very short time before modern conservation reached it.

I hope that reintroduction schemes using Siberian Tigers can take place when that species is more secure. The few photos of genuine Caspian Tigers show the two subspecies, not surprisingly given their extremely close relationship, to be very similar indeed. The main difference apparent in the early black and white photo at Berlin Zoo (with rockwork backdrop) is that the animal appears rather chunky with narrow stripes,and has a distinctive 'lynx' like ruff around the face. Another, less often seen photo probably taken at the same time, shows two tigers lying in the same cage, again the lynx like 'ruff' is apparent on both animals.

Reintroducing Tigers into the wild is certainly not the easiest task. There would have to be large protected areas available, well stocked with Deer, Boar etc as prey, and very effective protection too. Russia and the far/middle East would not be easy places to effect this.

 

[condor]

As a general rule, mitochondrial DNA evolves more quickly than nuclear DNA (which is one of the reasons it is used for this type of study).

Being inherited exclusively from the maternal line it is also much easier to get misleading results from mtDNA as all it takes is one case of interbreeding in a bottleneck population to render large portions of the populations identical in mtDNA. There are tons of examples of this and history suggests this is possibility in these tigers: The Caspian and Amur were apparently in contact until a few hundred years ago and the Caspian experianced a very significant population bottleneck. With those results in mtDNA it is a bit strange they didn't choose to include nDNA for further suppport. It can be more difficult and $$$ to extract nDNA from old samples but it should still be possible when n=23 as it was for mtDNA. As a very general rule, mtDNA is good if you find a difference AND the split is relatively recent (e.g., kya to a few mya), but less reliable if you don't find any difference OR the split is old.

Driscoll et al. 2009 are also more balanced in their conclusion, using words like 'suggesting' and 'might' several times, than some popular science reports I've seen quoting that very same paper and claiming it is an indisputable fact that the Caspian = Amur. Driscoll et al. 2009 made a good case for Caspian = Amur, but not proven beyond all doubts.

The most recent research on that now says that the Caspian and Amur Tigers split genetically less than 100 years ago.

I wouldn't be surprised if some newspaper or webpage wrote that (bad science in newspapers and webpages are all too common) but if some researcher made that claim he should have his licence revoked. It would be impossible to get a result like 100 years or for that matter 400 with acceptable support (bootstrap etc) in a species with a generation length like a large cat. The change in base pairs is far to slow and separation by just a few hundred years wouldn't show in a phylogenetic tree based on maximum parsimony, likelihood etc.

Would it be possible though genetic engineering to alter the one nucleotide that differs and recreate the Caspian tiger?

Yes it is possible to alter one nucleotide. It has been very expensive but the prices have fallen exponentially in the last few years. The problem is that it's rarely only one nucleotide. Here it's only one nucleotide within the small section of mtDNA that they sampled successfully. Cloning is an easier solution than checking the entire DNA for differences and altering them individually.