Here is a large summary about
the different studies about this:
Mazák (1981; 1983) stated that there is one
tiger species and eight subspecies (although based in very few specimens).
Latter, Kitchener (1999) stated that there are no significant differences to
show that there are subspecies at all, but based in morphological evidence (few
specimens again), stated that there are only three subspecies (1. Mainland, 2. Island and 3. The
On the genetic side, Cracraft et al. (1998) proposed that there is not
enough difference subspecies between the mainland tigers, but that the Sumatran
tigers are different enough to separate them like a different species (not even
subspecies). Luo et al. (2004; 2010)
presented genetic evidence to show that there are in fact, enough genetic
evidence to sustain the differentiation of five modern tiger subspecies and
even proposed a sixth one (Malayan-jacksoni).
Latter, Mazák & Groves (2006), using a
morphometric study, stated that there are enough differentiation between
mainland tigers (Corbetti only) and
the Sonda tigers, to classified them like a different species, but disproved the
claim of Luo et al. (2004) about the
separation of the Malayan tigers as a subspecies, because they don’t found any difference
between them and those from Indochina. The final study of Mazák (2010) on the Craniometrical
variation of tigers show, again, that there is great differences between the mainland
group and the island group and that the Sumatran tigers were probably a hybrid between
the two populations.
About the Caspian tigers, Driscoll et al. (2009) found that the Caspian
tiger population was genetically undistinguishable from the Amur tigers and
proposed to join the two groups into one subspecies (Virgata), discarding the statement of Kitchener (1999) that this
group was a different subspecies. Besides, Mazák (2010) also found that the
Caspian tigers had many morphological characteristics in common with all the
other mainland tigers (disproving Kitchener (1999) again) and that the most different
of all the mainland specimens were those from Amur, which were practically the
most earlier in evolve.
Finally, Kitchener & Yamaguchi (2010)
repeated the same claim from 1999, adding several complaints about all the
previous studies, for example:
1. The genetic study of Luo et al. (2004) had not enough specimens and
that they can’t explain why Bengal tigers are far away than Sumatran tigers in the
2. The morphometric study of Mazák & Groves
(2006) don’t used other mainland skulls, which according with Kitchener (1999)
also present the narrow occiput of the Javanese tigers (although he used fewer
specimens than those used by Mazák and Groves).
3. The differentiation of the Malayan tigers is
invalid as they don’t present a holotype and the genetic evidence is not enough
to establish it as a species.
However, they slightly mention the fact that
Kitchener (1999) was wrong about the Caspian tigers and that his biogeographic analysis
(Kitchener & Dungmore, 2000; repeated in 2010) failed in predict the
populations of tigers in that area.
Here is what I can quote from memory right now and
based in all this, I can state that there are several forms to assimilate all
this information. I prepared three cases, which can be used for tiger
Case 1 - The most simply
* Mainland tiger: (Panthera tigris) - no subspecies.
* Island tiger: (Panthera sondaica) - no subespecies.
Case 2 - Based in morphometric
and genetic analysis
Three species with subspecies (or two and one
* Mainland tiger: (Panthera tigris):
Bengal tiger (P. t. tigris).
Caspian-Amur tiger (P. t. virgata).
South China tiger (P. t. amoyensis).
Indochina tiger (P. t. corbetti) -
* Island tigers: (Panthera sondaica):
Javan tiger (Panthera sondaica sondaica).
Bali tiger (Panthera sodaica balica).
* Sumatran tiger: (Panthera sumatrae (tigris x sondaica)).
Case 3 - Proposed by
One species (Panthera tigris) with two subspecies and one hybrid:
* Mainland tiger (Panthera tigris tigris) - only cline variations.
* Island tiger (Panthera tigris sondaica).
* Sumatran tiger (Panthera tigris sumatrae (tigris x sondaica)).
Personally, I support the second case, but I
will like to know, which are your opinions on all this?