Tiger Speciation

Tiger Speciation

An interesting article came out a few days ago as of writing this article.  Researchers from China sequenced the genomes of six populations of tigers and discovered that they are genetically distinct from one another. According to the species concept they use, this qualifies each as a separate sub-species.  This was done as part of an effort to determine how tigers ought to be conserved and where best to expend resources. Based on this research, the scientists hope to be able to better conserve the tigers in the wild.

Wild tiger numbers are undoubtedly much lower in their natural habitats than they were even fifty years ago, which has led to massive conservation efforts.  However, is that truly a bad thing? Certainly, no one wants the tigers to go extinct but where tigers are found, often they are pests. They hunt livestock and even sometimes man. Is it any wonder that farmers kill them off? In a Biblical sense then, what is potentially in the balance is human good versus tiger good.  Since man is made in God’s image and was given the mandate to subdue the earth, then consideration ought to fall on the side of mankind, rather than tigers.  This is not to say we should not try to keep the tigers alive in the wild.  Instead, its just important to keep in mind that the benefit of mankind should not be overlooked to benefit the tigers.

All the conservation stuff out of the way, let’s take a look at tiger speciation. Tigers are one of the most recognizable species in the world. They feature in films, and even children stories, with Winnie the Pooh being perhaps the most famous example.  According to the research done on their genome, researchers concluded that there are as many as six subspecies of tiger. However, as they freely admitted, there are some problems with this conclusion.

The most obvious problem is one the researchers themselves freely admit.  They did not use a wild-type tiger for the South China tiger. Instead, they used one specimen from captivity as the source for their DNA sequence. This opens up the possibility for errors. The first error is due to the small sample size. One sample does not make a population, and I think the researchers recognize that.  Further, I’d be interested to hear if the captive specimen was wild caught or bred in captivity. If it was bred in captivity, the likelihood of it being a mix between two of the subspecies is exponentially higher than it would be in the wild.  This would lead to a potentially different genome sequence. Thus, pending further evidence, I would be hesitant to proclaim more than five tiger sub-species.

This does raise an interesting problem for biologists who study speciation. In the case of these tigers, where ranges of the subspecies overlap, they will freely interbreed.  This makes it much harder to propose conservation efforts, as it is hard to delineate subspecies in need of any saving.  It is equally hard to know what to call the offspring of a mating between two subspecies. The term used by default is hybrid, but this is incredibly confusing as the term also refers to the offspring of breeding between separate species. Ernst Mayr, perhaps the premier expert on speciation of the 20th century, was strongly bothered by using the word hybrid for breeding between separate populations of the same species, but had no other word to use. To rectify that issue,  I’m going to use a word I borrowed from Finnish, risteytys for the offspring of the breeding of two separate subspecies. The word itself means “cross” which is appropriate for the breeding of two subspecies.

Interestingly, the researchers proposed that the tiger population went through a population bottleneck around 110,000 years ago. If they dropped off about 106,000 years, they’d be right on target, except it wasn’t just tigers that went through that population bottleneck. Every land-based kind on earth went through a population bottleneck that dropped the population to one or seven pairs in the Global Flood.  After the flood, the cat kind would have exited the ark and begun to speciate out.

We know in the present lions and tigers can interbreed, but are not classed as the same species.  Thus they would be classed as the same created kind.  The genetic information for the tiger, lion and so on must have been present at that time. As the new populations migrated to new habitats, either to avoid competition or on the trail of prey, natural selection and epigenetics would have fitted them to their habitats. However, buried in the newly speciated tiger genome, were the genes for the legendary white coats.  To my knowledge (and feel free to leave a comment correcting me) tigers are the only cats with this abnormal coat morphology. Domestic cats, having been selectively bred, don’t count in that regard.  Other special features were also present in the tiger genome, and others were eventually fixed there as a result of epigenetics.

Tiger speciation is interesting if a bit tangential. However, it is illustrative of the speciation that took place after the flood and has continued since then.  The sub-species of tiger are the result of several thousands of years of speciation and likely have reached close to the limits of the variation available to the information in their genomes. In order to gain new traits, they’d likely have to be hybridized with another species of cat for several generations consistently to introduce the information to the genome. This fixing of the genome is expected based on the speciation model proposed by creationists in the postflood world.




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