WildFact
›
Premier Section
›
Edge of Extinction
ON THE EDGE OF EXTINCTION - A - THE TIGER (Panthera tigris)
ON THE EDGE OF EXTINCTION - A - THE TIGER (Panthera tigris)
|
ON THE EDGE OF EXTINCTION - A - THE TIGER (Panthera tigris)
|
  (03-14-2015, 10:16 AM)'sanjay' Wrote: Hello @Gaido , Welcome to the forum. The biggest species of crocodile family the salties (saltwater crocodiles) do interacted with tigers in the past and the present. The interaction took place in the East coastal area of India ( Coastal areas of Tamilnadu, Andhrapradesh, Orissa, West Bengal and also Bangladesh). There is a high degree of mutual respect between these two predators. In general tigers were said to have dominated the salties in the past before human intervention. But since the humans have took over most of the lands both these animals were destroyed from their former territory. The possible interaction at present between Tigers and Salties may take place in Orissa and Sunderbans (West Bengal and Bangladesh). 
New findings on the phylogeny of the Javan and Bali tigers, see attached.
The latter conclusion that, "The close phylogenetic relationship among Sunda tiger subspecies suggests either recent colonization across the islands, or else a once continuous tiger population that had subsequently isolated into different island subspecies." supports my theory that there used to be a large pandemic population of tigers spread from China to the Sunda shelf (much above water at the time) which were not subspeciated. It's interesting and encouraging to see genetic evidence support a claim made only on scant fossil record, goes to show little evidence is still significant evidence. 
JAVA AND SUMATRA SKULLS
Good find, Tigerluver. A very interesting read. I will respond in detail in some time. The focus will be on Table 1, as I measured, photographed and determined nearly all (20 out of 23) skulls myself between 2004-2012, meaning I should be able to find out more about the skulls. Although I will continue to visit museums and private collectors in the next years, I, last year, decided I have enough to get to tables on every tiger subspecies. Before I started, I went over every skull again. It took me many months, but it had to be done, because quite many skulls I measured were mentioned in different articles and books. I started with Sumatra and Java, because of the large sample. The total number of classified entries for Java was 76 (34 wild ♀, 3 captive ♀, 37 wild ♂ and 2 captive ♂) and for Sumatra it was 114 (43 wild ♂, 22 captive ♂, 31 wild ♀ and 18 captive ♀). Most of the 190 entries were on skulls, but I also added reliable measurements and weights of wild animals. As I was able to distinguish between young adults and adults, the averages are a bit different than those in other tables. DUISBURG This weekend, I was in Duisburg. I didn't visit the zoo, but I talked to some staff members in a large mall in the city centre. They didn't know anything about the giant male in V. Mazak's book (1983). It was well before their time. They don't have Amur tigers at the moment, but they will in the near future, when the new tiger enclosure is ready. I'll visit the zoo this summer. Before I do, I will visit Leipzig. Duisburg, by the way, is an interesting and spacy city. After the war, it was, of course, rebuilt. They're, in fact, still at it. Part of the old harbour has been transformed and in the city centre it will take you some time to see a car. The Kultur- und Stadthistorisches Museum has a number of interesting exhibitions. We concentrated on the one on Köningsberg (now Kaliningrad and Russian), but the one on Copernicus and one of his students (who made a drawing of Duisburg in the late Middle Ages) also was worth while.  (03-16-2015, 10:17 PM)'tigerluver' Wrote: New findings on the phylogeny of the Javan and Bali tigers, see attached.Did you remember the three models of tiger taxonomy that I proposed? It seems that this document support the one about "one species and only two or three subspecies". I most read the document yet, but like Peter said, I will share my conclusions and how they will affect our previous conceptions about tiger evolution and taxonomy. The only true thing here is that the old classification of eight-nine subspecies from Mazák (1981) should be discarded as is no based on an ecological point of view, like Kitchener (1999) states.
In my opinion, modern humans expansion has forced the tiger into ecotypes, as we can't argue that there is reproductive isolation between populations now. The problem is the term "subspecies" has different meanings to different people.
I will say this. From a conservation aspect, the more classified subspecies the better, as it is easier to motivate a group to protect something that is exclusive to them.  (03-17-2015, 09:50 PM)'tigerluver' Wrote: In my opinion, modern humans expansion has forced the tiger into ecotypes, as we can't argue that there is reproductive isolation between populations now. The problem is the term "subspecies" has different meanings to different people. I wonder if more is better? I wonder if dividing a "sub species" makes those who are not close to that place care less? Maybe its better to just call them "Tigers" so people just realize they are endangered. I think when we start saying 30% increase in tiger population in India people think "Oh great, they are not endangered now" but really the increase is caused by protected areas but that doesn't mean that all tigers are doing well. Just my 2 cents.
You have a point, but I made my statements on the basis of a few things. One, there's been an issue in species where there are clear ecotypes/subspecies, but taxonomy denies it. Ecotypes then go extinct as their uniqueness is not recognized. This issue seems to be happening to island species and marine mammals.
Another issue is, in terms of government enforced conservation, only the people who there matter. One country cannot really make another act. By giving a country something more exclusive to them, they might act on their on innate will. 
Some animals will recieve less help simply because they appear too average. The Syrian brown bear, the Gobi bear, and the Tibetan blue bear will never recieve the recognition comparable to the giant panda or the polar bear. Pretty much everyone can recognize those two. Popularity can play a major role in whether or not an animal species or sub-species recieves any help at all.
GENETIC ANCESTRY OF THE EXTINCT JAVAN AND BALI TIGERS (Xue et al, 2015)
The article is interesting in more than one way. I especially liked the introduction (pp. 2) and the discussion (pp. 6-7). This post has a number of conclusions regarding the evolution of tigers. For now, they can be considered as the final word on tiger evolution. In order to prevent problems, I decided for quotes only. 01 - Fossils and the common ancestor of modern tigers " ... The earliest tiger fossils found in northern China and Java ... date back to 2 million years ago ... in the early Pleistocene. Molecular genetic imputation traces all living tigers back to a common ancestor as recent as 72 000-108 000 years ago. It has been speculated that the Toba vulcano super eruption in Sumatra approximately 73 500 years ago may have contributed to this recent coalescence for modern tigers ... " (pp. 2). 02 - Tiger subspecies " ... The most important application of genetic techniques has been in resolving taxonomic uncertainty surrounding tiger subspecies ... " (pp. 2). " ... current tiger taxonomy, informed by molecular genetic evidence, now recognizes 6 living subspecies ...; Bengal tiger (Panthera tigris tigris), Amur tiger (Panthera tigris altaica), south China tiger (Panthera tigris amoyensis), Sumatran tiger (Panthera tigris sumatrae), Indochinese tiger (Panthera tigris corbetti), and Malayan tiger (Panthera tigris jacksoni) ... " (pp. 2). 03 - The Sunda Shelf and Sunda tigers " ... Populations from islands are generally given subspecies status in taxonomy; however, named island subspecies may not carry significant genetic distinctiveness, particularly if gene flow between them occurred recently. During the Pleistocene, sea level fluctuations repeatedly exposed vast areas of the Sunda Shelf, forming land bridges intermittendly among the islands of Sumatra, Java and Bali as recently as the Last Glacial Maximum (LGM, c. 20 000 years ago) and enabling recent population connectivity and possible gene flow. However, other studies indicate that the ability of animals to move across the exposed Sunda Shelf may have been restricted and populations or subspecies have deeper divergence dating back to even millions of years ... (pp. 2-3). 04 - Sunda tigers and Mainland Asia tigers " ... Geographic distribution of mtDNA haplotypes among voucher tiger specimens with recorded origins from the islands of Sumatra, Java, and Bali indicates a recent common ancestor among these subspecies. SON and BAL were 2 haplotypes exclusively found in Java and bali; none of the 8 haplotypes from the living voucher Sumatran tigers (SUM1-8) existed in Java or Bali. No mtDNA haplotype is shared among voucher Sumatran, Javan and Bali tigers. All 9 voucher Javan tigers carry haplotype SON and both voucher Bali tigers carry BAL ... " (pp. 6). " ... Phylogenetic analysis of mtDNA haplotypes representing all 9 tiger subspecies ... produced congruent topologies corresponding to major geographic partitions. Tigers from the 3 Sunda Islands clustered into a monophyletic group with 11 haplotypes. The 2 haplotypes (SON and BAL) in vouchers P.t. sondaica and P.t. balica formed a statistically robust subgroup within the Sunda tiger population ... " (pp. 6). " ... Mainland Asia tigers parse into 5 distinct groups corresponding to major phylogeographic clustering and prior subspecies recognition ... P.t. tigris on the Indian subcontinent is genetically distinct from the other mainland subspecies, corresponding to an early divergance ... " (pp. 6). 05 - Estimated coalescence time " ... The estimated coalescence time of mtDNA haplotypes for all tiger subspecies ... using Panthera ssp. divergence times as calibration ... is 94 500 years ..., highly consistent with a previous estimation of 108 000 years. The recent coalescence in modern tigers, as compared to some other Panthera species ..., is consistent with a late Pleistocene bottleneck in tigers ... " (pp. 6). 06 - Taxonomic status of Javan and Bali tigers " ... Our results provide consistent molecular genetic evidence that tigers on Bali, Java, and Sumatra recently derived from a common matrilineal genetic lineage. This mtDNA similarity needs to be validated ... yet the close association among the 3 subspecies is supported by the clustering of all mtDNA haplotypes from the 3 Sunda Islands leading to a strongly supported monophyletic clade distinct from other mainland subspecies; the existence of a recent ancestral Sunda tiger lineage that later evolved into present populations on Java, Bali, and Sumatra ... " (pp. 6). 07 - The Sumatran tiger " ... Previous paleontological and morphological studies have suggested that the Sumatran tiger is a hybrid of mainland tigers and the Javan tiger; however, this conclusion is not supported by maternal mtDNA ... markers ... " (pp. 6). " ... Our molecular phylogenetic and phylogeographic analysis supports geographic subdivision within the Sunda tiger group, with haplotypes SON and BAL exclusevely found from Java and Bali respectively. The genetic differentiation between Sumatran, Javan, and Bali tigers is also significant, indicating a restriction or lack of matrilineal gene flow among the three islands ... " (pp. 6). " ... Nevertheless, the similarity among the Sunda tiger mtDNA haplotypes ... suggest common origin and rapid divergence of island subspecies, and may reflect that the somewhat distinctive morphological features in each subspecies have evolved rapidly after each island was colonized ... " (pp. 7). 08 - The Javan tiger " ... All estimates consistently put the coalescence time of modern tiger lineages within the last 100 000 years. Mitochondrial DNA haplotypes from tigers from Java and Bali fall into the Sunda tiger clade that belongs to modern tigers. Therefore, these genetic data do not support the hypothesis that the modern Javan tigers is an autochthonous descendant of a historic tiger population, whose fossils were found in Java and dated to 1.3-2.1 MYA. Instead, early to middle Pleistocene tiger populations in the Sunda Islands may have been eliminated because of drastic biogeographical events associated with glacial-interglacial and/or the Toba vulcano super eruption ... (pp. 7). 09 - Modern tiger evolutionary history a - " ... We are now able to construct, for the first time, the intraspecific phylogeny for the tiger based on all the 9 recognized subspecies. The position of P.t. amoyensis and its relation P.t. sumatrae/P.t. sondaica/P.t. balica ... suggests a once widespread tiger population from China to the Sunda Shelf that became isolated, likely by rising sea levels during interglacial periods ... " (pp. 7). b - " ... A second wave of tiger expansion and divergence (P.t. tigris, P.t. corbetti, P.t. jacksoni, P.t. altaica and P.t. virgata) replaced much of the range of P.t. amoyensis on the mainland and evolved into modern populations in Indochina, the Indian Subcontinent, the Caucasus, and the Russian Far East, where tiger fossils are only found from the Holocene ... " (pp. 7). 10 - Conclusions This paragraph was added to get to a general picture on tiger evolution. Although based on the article discussed in this post, I added a few ideas I've had for some time. - Although tiger fossils of up to 2.1 million years old have been found, all modern tigers can be traced to a common ancestor. - Modern tigers evolved between 72 000 - 108 000 years ago. - From -a- and -b- follows that tiger evolution probably had at least one population bottleneck. - The Late Pleistocene population bottleneck probably was a result of the Toba vulcano super eruption. - The common ancestor of all modern tigers evolved in south China or northern Indochina. - From south China or northern Indochina, tigers first spread south to the Sunda Shelf. - During an interglacial period, Sunda tigers and south China tigers became seperated. - In the last 100 000 years or so, Sunda tigers occupied different regions. - Over time, they left Palawan and Borneo, but they survived on Bali, Java and Sumatra until recently. - Towards the end of the Pleistocene, south China and northern Indochina tigers tigers spread west. - India was reached about 12 000 years ago. The other regions were occupied in the Holocene. - In the Holocene, 5 distinct types or subspecies evolved. The most recent subspecies probably is the Amur tiger. - Although Bali, Java and Sumatra tigers belong to one subgroup, they are distinctly different from each other. - The three types probably evolved when the islands they occupied became isolated as a result of rising sea levels. - Although all three subspecies are different, Javan and Bali tigers are closer to each other than to Sumatran tigers. - Sumatra could have been the last island colonized, as they differ markedly from all other subspecies. 11 - Panthera tigris jacksoni How about a hand for our newest member? Jacksoni, after he was severely tested by our most respected senior members, is here to stay, so it seems. One wonders why we didn't see him in all these years, as he was there long before we were. Different from both corbetti and sumatrae, he must have occupied the southernmost tip of Malaysia unseen somewhere between 72 500 - 12 000 years ago. He reminds me of Sunderban tigers in more than one way. Jacksoni is a small animal as well and he too seems to have shrunk with age in the last century or so. Some years ago, I bought an article that was based on an interview with the Sultan of Johore. The Sultan was a hunter. Tigers. His bag, in spite of the modest average, had a few specimens well over 9 feet 'between pegs' and there's at least one skull well over the average for adult Indian males. A few decades later, however, those with experience in Perak, Terengganu and Johore, however, agreed not one male exceeded 8.8 'between pegs'. A result of overhunting or isolation? Time for a little research, I'd say. I'll post what I have on jacksoni and propose a small debate. Is he really different from Terengganu and Perak tigers? If so, in what respects? Most likely causes?
I don't think this supplementary file to the document I posted earlier will of much use to anyone, but the figures are a nice phylogenetic tree. I've attached the supplement. Here's the figure we can use most:
 *This image is copyright of its original author Also, here's tiger phylogeny based on craniometrics Mazak (2008):  *This image is copyright of its original author All studies show that the Sumatran tiger is the intermediate between the Javan and mainland forms. From the successful interbreeding, at least the early Javan form cannot be classified as a separate species. 
Base on the canine tooth, those of the Indochinese tiger look quite similar to those of the Amur tiger.
Maybe this is also demonstrating some degree of morphological affinity between these two subspecies.
TIGERS AND CROCS
A week ago, a new member asked about tigers and crocs. In my pm, I referred to the incident described by Burton (1933) and the incidents discussed on different forums. I promised I would try to find more. From now on, I will post on tigers and crocs when I find something. In most cases, the information is from books. This post has two incidents. The first one happened just before World War Two in Johore (Malaysia). I found it in Locke ('Tigers of Terengganu'). A tiger and a croc were found dead near a river. From the description Locke gave, I concluded the croc got hold of the tiger in or, more likely, near the bank of a river. Although the grip was a good one, it wasn't good enough. The tiger apparently was able to turn the tables to an extent and seriously injure the croc. The question is how it was done. I remember more incidents and in those in which the croc killed the tiger, the croc struck once. In most cases, the skull was targeted. As the tiger in Johore was killed, my guess is the first bite was lethal. The question is how the tiger was able to kill the croc assuming he wasn't able to use his skull. I don't think the tiger was able to get to the vertebrae of the neck. The only other way to kill a croc is to rip the belly and injure a major blood vessel. Just speculating here. As the incident happened in Johore, my guess is the croc probably was a saltwater crocodile:  *This image is copyright of its original author The second incident happened in India and was filmed. Valmik Thapar, who featured in a BBC-documentary about Ranthambore tigers, said he heard about an incident in which a croc was killed by a tiger. The tiger turned out to be a tigress and she apparently had had some experience with crocs. Big cats have to learn how to fight a croc. The trick is to refrain from striking out with the paws. When the croc is able to get hold of the paw or a leg and starts his specialty (the 'death-roll'), the cat is doomed in that he or she will be seriously injured, if not lose the leg. When the tiger survives the death-roll, the most likely result will be a serious injury. As this means the cat won't be able to hunt, the most likely result will be starvation. The best strategy is to turn to croc on his back, as this will expose his belly. When the croc is too heavy, the neck has to be targeted. It wouldn't be easy to kill a croc in this way, because it is difficult to penetrate the skin and damage the vertebrae. Tigress 'Machli' apparently knew how to do it. The croc, a large mugger, was killed. They say it measured 13-14 feet, but I never saw a report on the mugger. Anyone able to find the video is invited to post it. This photograph is from the video:  *This image is copyright of its original author
(03-25-2015, 02:01 AM)'peter' Wrote: As the incident happened in Johore, my guess is the croc probably was a saltwater crocodile: "Draw" of malayan tiger with saltwater croc? Quite an achievment... And if the croc got the hold of the tiger first then the tigers performance is even more impressive...tigers are very tough animals ofc we dont know what was the gender, age and size of those combatants...
Machli killing the Croc
Edit: I read that he only saw the carcasses and not the incident that took place. Im very curious as to how they died and why they both their carcasses where lying on the bank unless maybe they were both washed to shore by currents which would be guess. |
| Users browsing this thread: |
| 1 Guest(s) |