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Interspecies hybrids: natural & artificial
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I believe that jaglion should be genetically healthier than both liger and tigon since lion and jaguar are supposed to be more closely related to each other than they do with tiger.
 (06-19-2014, 07:15 AM)'Siegfried' Wrote: Here are both jaglions at Bear Creek. The male is very impressive looking.Amazing video. Did you want to see the "real" Panthera atrox? Then, you most see the jaglions. I bet that the skull of these cats is equal to that of Panthera atrox. GrizzlyClaws is absolutely right, a jaglion most be more healthy than a liger or tigon, as jaguars and lions are more closely related. However, following this path, the most "healthy" of the hybrids most be the "lion x leopard" mix, as these two separated about 550,000 years ago, even after than the separation of the cave "lion" (Panthera spelaea) at about 700,000 years ago.  (06-19-2014, 08:24 PM)'GuateGojira' Wrote:(06-19-2014, 07:15 AM)'Siegfried' Wrote: Here are both jaglions at Bear Creek. The male is very impressive looking.Amazing video. Did you want to see the "real" Panthera atrox? Then, you most see the jaglions. I bet that the skull of these cats is equal to that of Panthera atrox. Panthera atrox is american lion right ? Ive heard they are twice as big as African lions ? But these jaglions are smaller than african lions. Then how come they are equal ? I saw a pic of atrox and african lion skull (from Bold) and the skull of atrox is double the size.
I find the taxonomy of these cats both quite interesting and very confusing. First, there is the concept of hybrid vigor:
hybrid vigorn.Increased vigor or other superior qualities arising from the crossbreeding of genetically different plants or animals. Also called heterosis. But how different it too different? Hybridization between tiger subspecies is said to produce monster tigers, yet for some reason this seems to not be the case with lions as seen in this article: http://news.bbc.co.uk/2/hi/south_asia/4101049.stm The article above even refers to the different subspecies of lions as different species. Here is the simple commonly used loose definition of species that I have always used: if two animals can produce fertile offspring of both sexes they are therefore by definition of the same species. Lions and tigers are clearly two distinct species as seen in the lack of fertility in male tigons and ligers. DNA and genetics however, seem to complicate taxonomic definitions. I have read (sorry, can't find a link to it) studies indicating that there is such a genetic difference between island tigers and mainland tigers that they should be considered different species altogether rather than merely different subspecies of tigers. Perhaps someone can provide more on this. Are the offspring (both genders) of mainland tiger subspecies hybridization fertile? Are those between island and mainland tigers fertile? Then, there are these two pages: http://messybeast.com/genetics/hyb-lion-subspecies.htm http://messybeast.com/genetics/hyb-tiger-subspecies.htm There are also hybrids of polar and brown bears. Does anyone (Brotherbear) offer more about these hybrid bears? Like I said, both interesting and confusing. Thoughts?
Mmmmmm, very interesting topic. I will put some data on cats, Brotherbear put some data on bears already in the topic of "King of bears". There is said that polar and brown bears separated since only about <500,000 years ago, and they are already a different species now. In fact, the author states that the separation could be much earlier, about 300,000 years ago, showing that genetically, species don't need too much time to be separated. This can be applied with the cave lion (Panthera spelaea), which based on DNA and fossils, separated from the modern lion and the leopard about 700,000 to 600,000 years ago (depending of the source), this is much earlier than the leopard itself! However, for the tiger, although Mazák & Groves (2006) found evidence that the Island tigers are a different species from the mainland population, the separation time (about 75,000 years, since the Toba eruption), is too few, from my point of view, but I will go deeper here in my next post.
I will focus on tigers-lions-leopards, in order to see they genetic variation. It is also interesting to see that pumas and leopards can mate and produce litters, even when we know the fact that they are two completely different species of cats, from to different clades. [img]images/smilies/tongue.gif[/img]
Thanks. I certainly am not in favor of these breedings. They really serve no purpose other than the exploitation of the resulting offspring. I do however, like the taxonomic structure and seeing what fits where in the genetic puzzle.
I can't add much useful information about the breeding of Barren ground grizzlies and polar bears, other than from what reading I've done, I have learned that the mixing of the two species is a very rare event but nothing new. Grizzly bears have been breeding with polar bears for thousands of years, but again, only in rare events. One thing that I have not read about, is it always a male grizzly and a young female polar bear, or do male polar bears mate with female grizzly bears as well?
I would suspect it goes both ways as to the gender combinations of these interspecies breedings. A horny guy is a horny guy. And who doesn't find an exotic female appealing?
The eastern wolf is said to be either a subspecies of Canis lupus lycaon or the result of continual crossings over many years between wolves and coyotes and thereby constitute being a species of its own Canis lycaon. Canids are said to hybridize far easier than felids. 
This is from 'Forty years among the wild animals of India, from Mysore to the Himalayas' (F.C. Hicks, Allahabad, 1910). Hicks was Assistent-Conservator of the Imperial Forest Service of India and had forty years of experience. It's the only authentic report on a wild hybrid I consider reliable. The total length was measured 'between pegs' and Hicks probably shot the animal in 1889, when he was mauled by a tigress in Mandla (Central Provinces).
A 'dogla', by the way, was a common name for a large forest panther. In those days, many hunters thought there was a distinct difference between small leopards living close to villages ('pantherets', to quote Hicks) and forest leopards or panthers. An average male forest leopard was about 7.5 in total length and 150 pounds, whereas an average 'pantherets', again according to Hicks, seldom exceeded 50 pounds (...) and 6 feet. Both, of course, later joined Panthera pardus. Sexual dimorphism in Panthera pardus is more outspoken than in all other big cats. The hybrid Hicks described seems a bit far-fetched, but it is a fact there is another reliable story on what seemed like an alliance between a very old male tiger and a large male leopard in Central India in 'Call of the tiger' (M.M. Ismael, London, 1964, pp. 94-146). Both often walked together and both were seen many times by villagers. It seemed the more aggressive leopard made all kills, but before he did the tiger had said booohh. Ismael, most unfortunately, later shot the leopard. It was a thick-set male with a massive head and a powerful body measuring no less than 7.10 in total length ('between pegs'). Everything he found during his quest confirmed both animals had worked closely together. Strange, but in the forest anything is possible. Here's Hicks on the hybrid he saw:  *This image is copyright of its original author .
I sometimes wonder the degree of human civilization's effect on subspeciation. It seems to make sense that as humans inhabited larger areas, the populations of big cats became more fragmented. This limited the influx of fresh genetics and the populations became more isolated and genetically distinct. If humans went away, wouldn't the ranges of the different subspecies within a species increase and thereby eventually overlap? Although I could be wrong, I'm pretty certain that a male Bengal tiger would see a female South China tiger as just another female tiger. The distinct DNA differences that are the basis of subspeciation would eventually disappear, right?
TIGER EVOLUTION
It would have made sense when tigers would have evolved in the last millenium or so, Siegfried. However. We know they didn't. Tigers evolved more than two million years ago and spread to different parts of southern Asia from southern China. Then the Toba erupted. The blast must have been tremendous. Based on what I read, my guess is the intensity of sunlight could have been affected to a degree. Same, perhaps, for oxygen levels. All living organisms would have suffered. Scientists found population bottlenecks in many species and most of these could be traced back to a period just after the Toba super eruption (70 000 - 100 000 years ago). Also remember the eruption happened at the end of the Pleistocene, when many parts of Asia were covered with ice. Most species who survived seem to be tolerant of cold and my guess is this could be the reason. In the last stages of the Pleistocene, many species recovered. Tigers again spread to the southeast of Asia to colonize Palawan, Borneo and many other parts of what was then the Sunda Shelf. When the ice melted, the Sunda Shelf was inundated and many species again became isolated. Tigers survived on Bali, Java and Sumatra until very recently. I agree they became extinct as a result of human intervention on Bali and Java, but that wasn't the reason they were different from other subspecies. When the Sunda Shelf was inundated just before the Holocene, mainland Asia tigers spread from China to the southwest and the west. Indian tigers (Panthera tigris tigris) are distinctly different from other subspecies. The other subspecies spread in the Holocene and replaced the Chinese tiger. One question is if they reached Manchuria and Korea before the Caspian. Another is if they reached the Caspian by crossing the western part of the Himalayas or by going west from northern China. My guess is it wasn't either-or, but and-and. Caspian tigers showed two distinct types, with those in the southwest and west smaller than those in the eastern part of Iran and Kazachstan. When they started struggling in the west, tigers from northern China and Manchuria might have started their move west. This would explain the similarity between the last Caspian and Amur tigers. Most researchers, however, think Caspian tigers spread east, towards eastern Russia. Anyhow. There's, I think, no question tiger subspecies evolved well before humans took over. First, there is the difference between mainland Asia and Indonesia. Fysical isolation would have resulted in significant differences between both. We also have to take climate, elevation and vegetation into consideration. We could talk about the results for mammals and we could debate the status of the subspecies proposed by Pocock in 1929, but there's no question tigers inhabited very different regions in Asia and it would have shown in morphology, coat, skull and behaviour. Maybe it was a cline after all and maybe it wasn't. I think there were distinct local types, but I also think there was gene exchange. Tigers, like most mammals, are great walkers. FUTURE The trick is gene exchange. It happened until it was halted by the inventions of Mr. Colt, Mr. Mauser, Mr. Winchester and Mr. Kalashnikov. Today, as a result of unchecked capitalism and the collapse of states, more and more humans have access to weapons way more sophisticated than those in use a century ago. The only thing lacking is a nice excuse to use them on a scale that would result in total chaos and my guess is we are not that far away. If it happens, it will have three major results. One is new states and no constitutions, two is giant cities and three is depopulation of rural regions and the collapse of agriculture. As a result of a lack of organisation, we might see something that will dwarf the achievement of even the most sophisticated mosquitos. If they are able to weather the storm for a few more decades, tigers still might stand a chance. |
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