Exercise 6: Domesticating Dogs
An evolutionary tree was constructed to compare wolves and dogs from Wayne’s data. The tree provides information about the lineage of the dogs and wolves. The tree tells us whether the dogs derived from a single wolf lineage or from several lineages. The tree does not tell us where in the world the most recent wolf ancestors of today’s various dogs lived. The geographic origin of the most recent common ancestor is still unknown. METHODS
Genetic analyses can be used to determine the relationship between dogs and wolves. By using genetic analysis we can show the differences between populations that have split apart and accumulate over time. It is best to use mitochondrial DNA rather than nuclear DNA to deduce these relationships because there is a lower recombination rate. A lower recombination rate allows us to easier trace back lineages. Mitochondrial DNA is used to build trees with Unweighted pair Group Method (UPGMA). UPGMA determines the genetic differences among all possible pairs. Once the most closely pairs have been determined the ‘sister’ populations can be connected with a tree branch.
Another factor to be accounted for is mutation. Mutation causes variation which is essential for the processes of natural selection. Mutations on a tree can also tell us how closely related species are. The more mutations that there are between species, it is safe to assume that they are less closely related. The less mutations there are between species the more likely that is they are more closely related. The more closely related they are the more likely that they share a most recent common ancestor. From this information genetic trees can be built and we can begin to see the relationships between the wolves and dogs.
The amount of time that elapses between each generation is information that can be used to further construct the tree. The trees branches are the indicators of the amount of time that has elapsed....
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