B2 and Other Great Tiger Pics from India

[GuateGojira]

(07-27-2015, 10:15 PM)Pckts Wrote:

Spalea\ dateline='\'1438005169' Wrote: @GuateGojira : One fundamental difference :

Natural predation (or "struggle for life"):  elimination of the weakest. The predators killed the weakest at first.

Human predation: elimination of the strongest: The men killed at first the elephant with the biggest tusks, the lions with the biggest manes, the biggest male bears, tigers , the most horned rhinoceros, buffalos and so on. Therefore natural order makes the animals' size decreased... And after if they (the scientists) want to call some other subspecies...

 

Sub species must have a different DNA code to be considered "sub species" correct?
So more than just habitat, prey or territory have to come in to play, if the DNA sequence is different than all factors came in to play to create a different cat. I am by no means a genetic expert nor will I begin to say I know what it takes to change one genetic code to another, the time it takes or what is occuring, but im curious to know what happens and how it happens. They don't just classify something as a "sub species" without scientific data to back it. I just wish we had a genetic expert here to discuss it with more.

 

To be sincere, I found both replays interesting but a little confusing. Based in my personal interpretation of them, IF I made it correctly, this is my reply to them:

@Spalea: Natural selection is the base of all animals, only the strongest survive, although this "strength" is not just material, but also the capability of adaptation. In this form, the smaller specimens from the Sundarbans were the "stronger" and at the end, they adapted to this new environment, influenced by the humans, of course. The interesting here is that although the hunting of the largest specimens changed the modern Sundarbans and Amur tigers, this seems not to be the case for the mainland Indian-Nepalese tigers, which based in comparisons of old and modern records, they stay about the same. Prey base and its density is also very important, even more than selective hunting, Sunquist et al. (1999) states that the low densities of the prey base was, probably, the principal cause of the extinction of the Caspian and Javan tigers. This could be the case with the Sundarbans tigers, however as the density of chital deer is somewhat high, the smaller tigers adapted to this new prey base and changed its body size and now live at lower densities. However, I most act like the Devil's Advocate here, because we most remember that the few modern specimens captured in the area were all frail, underweight and some of them were even incapable of hunting, but at the same time, its body dimensions still fit in the low ranges of the mainland tigers. It is possible (but this is just a guess), that the prime Sundarbans tigers are probably not so small, and among the size than the Island tigers, represented in modern days only by the Sumatran tigers.

@Pckts: DNA is a modern way the found the ancient origin of species and its species/subspecies differences. However, like @tigerluver have pointed out, the results are too open to interpretation and it depend of the believes of the investigator. For example, you remember the old study of 2009 about the cave lion from Dr Barnett and his team? In that document they stated that they have found "3 different taxas", which means "3 different species" per se, after all, they found no interbred between the American lion (Panthera atrox) and the Cave Eurasian lion (Panthera spelaea), and no interbreed between the Cave Eurasian lion and the modern African-Asian lion (Panthera leo). If these 3 "species" lived alongside and NEVER interbreed, even with no geographic barriers, this means that they were different species and this is stated in the document. HOWEVER, in popular media, Wikipedia and even in a popular document from the same author (Barnett), it is stated that they were "subspecies" of the same "species" Panthera leo, under this new interpretation there are not 3 taxas but only 1 with 3 subspecies. So, what happen here???? It is like the personal interpretations of one of the authors and the popular believe changed the results of the original document with no apparent reason. Interestingly, not a single specimen of Panthera atrox from Rancho La Brea was used, and the "4" specimens used are too close to the northern ice sheet that the possibility of been "washed" specimens from northern areas can't be ruled out.

Other example is the modern tiger DNA studies. The original documents of Luo et al. (2004 and 2010) found "significant" differences between 5 putative tiger subspecies and even proclaimed a new one. However, newer studies and comments stated that those "differences" were overemphasized by the small size of the samples and at the end, there is no such thing as "differences" (Kitchener & Yamaguchi, 2010). Using the same database, together with new specimens, new studies state that there are no more than two subspecies and that the genetic variations between populations disappear when more specimens are added (Wilting et al., 2015; Mondol et al., 2015).

The mutations in the DNA are mostly caused by habitat change and prey selectivity (probaby other natural factors also cause them), but in the case of modern animals, human intervention seems to be the greatest factor. In the case of the Sundarbans tigers, DNA showed that they are related with the Central Indian population, so DNA don't provide evidence to classify them as a "subspecies" and logically are not part of they morphological changes; human intervention seems to be the real factor here. Reply