Dog Breeders Speed Up Evolution
A recent case study of St. Bernards has led scientists to conclude that artificial selection for certain traits by breeders has dramatically sped up the process of evolution for these canines. In nature the evolutionary process would have been much slower with dogs selecting mates on their own and natural selection being the only force driving their evolution. When breeders select dogs with desirable traits and mate them with each other, the process moves along rapidly. In this particular study the emphasis was on skull structure and scientists looked at skulls from 1885 to the present. They found that the skulls in todays St. Bernards are much wider and also posses some characteristics that would probably never have evolved naturally because they don't provide the dogs with any evolutionary advantage.
The artificial selection that has contributed to the evolution of the St. Bernards we see today has been guided by breeding standards that were established in the late 19th century. Since that time the dogs have evolved from much more wolf-life ancestors to the domesticated pets they are today. The scientists who conducted this study estimate that if the changes that have occurred in the last 100 years had occurred via natural selection, it would have taken anywhere from 4000 years to possibly millions of years. It would be interesting to see what St. Bernards would look like today if their evolution had depended upon their survival and behavior alone.
Posted by Christina Breed (5)
posted by PWH @ 5:59 PM
5 comments
5 Comments:
I find it interesting that Darwin speculated that domestic dogs must have evolved from more than one ancestor because of the wide variation between breeds. We now know that all breeds evolved from one ancestor, the gray wolf (Vila et al. 1997).
Morkeski (5)
Humans breed dogs for various intents and purposes- some for work and durability, some to produce a desired set of characteristics, others just for the heck of it. How about creating smart dogs through artificial selection? Some of the brightest dogs right now (determined by the ability to understand and obey new commands) are the Bordor Collie, Poodle, German Sheppard, and Golden Retriever. At the current rate of evolution, consider the possibilities!
Posted by Mayur Patel (5)
I think that this is a very interesting topic. I assume that anything that has to deal with evolution can only derive traits that are beneficial to an organism. In this artificial selection done by humans I wonder if any traits come up that are actually harmfull and would not allow them to have the same level of fitness if not being taken care of.
If you think about it, this makes common sense. Basically what the breeders have done was basically evolutionary process. The way that evolution works is by selecting against individuals that are better suited in some way for survival. Conversely, the breeders weren't picking traits for survival purposes but for ones they want. In a nutshell this study sounded like a common sense study, but a necessary one.
Andrew Thompson (5)
This topic is actually a major issue when it comes to animal welfare. Traits are being selected for that confer no advantage to the animal with them (which is fine), but periodically some traits are detrimental to the health of the animal.
For example pekingese dogs now have eyes that can fall out of the sockets due to changes in skull structure and many flat faced dogs have developed difficuly breathing due to the extreme changes in their nasal cavity. Merle is a very popular color among dog lovers, but it can cause severe health problems when a dog is born with 2 copies of the gene.
While it's awesome that we can have such an effect on an animals biology, is it okay for us to deliberately breed for animals that have such difficult and sometimes pained lives for a breed standard based on an abstract ideal?
~Michelle Vigeant
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