I read an article from a Scientific American blog focused on the wide variation of dogs due to artificial selection. In this post, I will be examining and reflecting on different aspects of the blog. Although I do not know if the author, Christie Wilcox, had this intention, while reading her article, the main theme I found myself focusing on was speciation.
Variation leading to speciation is a topic that I have found popping up a lot during this semester. Dr. Walker talked about it in her talk at UMKC, I ran across it in my Endless Forms Most Beautiful chapter and subsequent research for my capstone presentation. After 4 years of biology classes where you learn some pretty cut and dry concepts, processes, theories, and laws, it is interesting to run across an area that is not cut and dry. Speciation is not a black and white subject in biology and I'm not even sure if a universally accepted approach to speciation is out there.
I think dog breeds and this articles were a great place to explore this concept. As Wilcox points out, dog breeding has been around for thousands of years and has led to the existence of some 400 distinctly different breeds. 400 breeds of the same "species". Species is in quotations because is it even evolutionarily proper/correct to call dogs a species, are they not but a subspecies to wolves? Growing up, I remember hearing about dogs and wolves being cousins. Would it not be a more accurate analogy to call wolves the dogs' grandparents?
The scientific name for the wolf is Canis lupus and the dog is Canis lupus familiaris. Even in the dogs scientific name, it clearly states the main, number one difference between the wolf and the dog. The dog is "familiar", the dog is something humans brought in to their homes and made "familiar" or common. They domesticated the dog to make it more behaviorally acceptable to have around.
In part of the blog, Wilcox talks about the skull variation within dogs. It is a type of variation in dogs that is not as obvious as size or coat style but shows a lot of evidence of the variation of this subspecies. Wilcox states that if you look at the skull variation in dogs compared to the skull variation in the rest of the Carnivora order, you will be surprised to see more variation in the skulls of one subspecies then the entire rest of the Carnivora order. She states, "the difference between the skulls of the Pug and Great Dane...are greater than the differences between the skulls of a weasel and a walrus." This is when I started to think that if there is that much variation between dog breeds and it is not enough for them to be different species from each other, will there ever been enough variation between dogs and wolves to definitively say they are more than just a subspecies?
If bone structure is not enough variation to lead to speciation....are other physical traits enough? Is the mere fact that some breeds of dogs are just too big or too small to mate with other animals enough to constitute as different species? It is not likely we will be seeing Great Dane-Chihuahua mixes anytime soon but is the physical logistic of sexual reproduction enough to separate species? Or does the variation have to be deeper than that?
Ten different dog breeds' genomes were mapped by people at the University of Washington and the Veterinary School of UC and 150 different regions were found to show evidence of strong artificial selection. These are probably regions that do not code for the development of the dog, since as far as I know, all dogs develop relatively the same. These would be regions that code for things that change between breeds: coat texture, size, skull shape, color, shape, wrinkles, hair type, etc. Wilcox explains that two-thirds of these regions contain genes that are uniquely modified for only one or two breeds. These are genes that code for traits that are breed-specific. My favorite example of this is the wrinkled-skin in the Shar-Pei breed. No other breeds with have the same modified genes as the Shar-Pei because no other breed has skin-wrinkling specific genes. But is having wrinkly skin, although the cutest trait, enough to constitute a new species?
At one point in the blog, Wilcox states, "Indeed, dogs are well on their way to speciation." Are they though? In my head, with as much variation as I can see, I would think yes. Dogs aren't just on their way to becoming a new species but it would be more logical to already call them a new species and possibly multiple species within the dog population. But with all the physical and genetic variation we already see and know about for sure, they are still a subspecies, is it ever going to happen?
People, including Wilcox, tend to say that dogs are a great example of the possibilities of evolution. I think this statement should be altered to say a great example of the possibilities of manipulated evolution. The genes, traits, and possibilities are there. But to say that it is a great example of the possibilities of evolution, I feel is to say we can possibly see this happen in other species down the road. I don't think this is true unless the other species is also acted on by artificial selection. In Dr. Walker's talk at UMKC, she talked about how if left to their own devices and allowed to mate and evolve not under the thumb of humans, dogs were basically undo all the artificial selection and would probably become a homogenous population looking somewhat like their ancestor the wolf.
At one point in the blog, Wilcox states, "Indeed, dogs are well on their way to speciation." Are they though? In my head, with as much variation as I can see, I would think yes. Dogs aren't just on their way to becoming a new species but it would be more logical to already call them a new species and possibly multiple species within the dog population. But with all the physical and genetic variation we already see and know about for sure, they are still a subspecies, is it ever going to happen?
People, including Wilcox, tend to say that dogs are a great example of the possibilities of evolution. I think this statement should be altered to say a great example of the possibilities of manipulated evolution. The genes, traits, and possibilities are there. But to say that it is a great example of the possibilities of evolution, I feel is to say we can possibly see this happen in other species down the road. I don't think this is true unless the other species is also acted on by artificial selection. In Dr. Walker's talk at UMKC, she talked about how if left to their own devices and allowed to mate and evolve not under the thumb of humans, dogs were basically undo all the artificial selection and would probably become a homogenous population looking somewhat like their ancestor the wolf.
Wilcox ends her blog by talking about Russia's feral dog population. I did some more research on Moscow feral dogs and found some interesting videos and research on it so in my next blog I will be looking deeper into this subject than Wilcox explains it.
