Which example best shows how taxonomy can us understand the evolutionary relationship among species

Taxonomy is a science that serves to classify living beings according to their species, kingdom and family. Together with phylogeny (science that studies evolutionary relationship between species) is formed the phylogenetic systematics that is a methodology used to find ancestral descendants that make up the evolutionary (phylogenetic) tree. Therefore evolution is known through branching. Through taxonomy Darwin had a basis for creating the theory of evolution, based on phylogeny.

"1. it should be, it has been for about 20 years, and it's really not much different in the end than breeding animals to have particular traits. there are always concerns about genetically engineered animals/plants affecting the environment in unexpected negative ways, but i can't think of an example where the fears didn't turn out to be baseless.  

first, as you point out, it would be a great advance in pharmacology, to be able to tailor drugs and their doses to me. the pros involve better medical treatment. the cons involve privacy issues like insurance companies denying coverage to people with genetic risk factors. looking at dna markers wouldn't affect the frequency of genetic diseases, but it would allow detection of them earlier. and ok, actually i suppose that if people used this information to avoid having children with genetic diseases, some might decrease in frequency."