Natural Selection : The evolution of an organism based on success of heritable biological traits, and their positive interaction with said environment.
Artificial Selection: A process in which certain qualities and traits are produced and or maintained by human intervention.
Today's modern dogs have been a work in progress sense the prehistoric era. Our ancestors purposefully fed and protected dogs that appeared beneficial, leaving other unwanted traits and dogs in the past. This practice and way of thinking continued through history leading us to present day breeding and our beloved "groups/categories".
A lot of people ask about the original breed of dog, simply put it was the ever beautiful and stoic Wolf. With the help of Paedomorphism selection (also known as "Neoteny" or "Juvenilization") they maintained juvenile physical characteristics. Juvenilization is a process in which traits only seen on juveniles are retained into maturity. (such as fluffy ears, soft coat,small stature,ex.) In doing such the animal / organism becomes "cuter/attractive" to surroundings I.E. us. In nature attractiveness is unnecessary except for impression for mating purposes.(example being birds, the males are more vibrant to impress female, Bucks and their rack and so on). Unfortunately we are not in nature watching new traits form from necessity, we are watching evolution based on convenience due to prolonged interaction and protection form us. Think about it we tend to shy away from unappealing animals, so if you had pick of litter and they all share equal functionality and adaptability but 2 of them are more aesthetically pleasing than the rest those two will be your first choice. Thus those will be the 2 that are fed and protected and will grow to breed well tempered, functional, aesthetically pleasing offspring.(It has been noted that a female wolf will protect a litter of "dog" pups more defensively than a litter of wolf pups)
In the beginning only the wealthy had "purebred" working dogs. Now a days buying a "purebred" dog with AKC Registration is as easy as looking in a newspaper or searching the internet,they are as common as a truck in the south. With this being stated I will add that you do get what you pay for more times than not in terms of breeding dogs. I do not intend to say that a "cheap" dog is a bad dog or that it will be a bad breeding dog, only that in many cases you will find the quality of Pedigree and or Genetics are or have in the past been muddied. For a breeder this means future prospect of flawed unsatisfactory dogs whelped and distributed. While genetics play a pivotal role in dog temperament and health so does Environment. Another issue with "discount" purebreds is Puppy Mills! For most animals involved in puppy mills the standard of living is very low, along with choice of traits.The living conditions in many mills are hazardous at best, which can lead a dam or sire spreading illness or disease to pups and other dogs.
Health problems can arise from the smallest of things from genetic predisposition to a fall off the porch during play time with other animals. Even if a dog is not in a mill the risk of various health issues can be present even if in its line you never had more than a small flaw (i.e. 56% - 44% color ratio in a piebald). Like i said say a pup slips of the porch and hits its head, you take it to the vet and everything seems fine but 3 days later it begins to seize ... thus continuing for the entirety of its life. This is one way environment can play a role as well even in temper you never really know the breeder you get the pup from. One minute the may be abusing the dogs and the next smiling and taking your money.Though it can happen with any breeder the risk is far greater in "off the grid" breeders or Puppy mills.
This being said this does not mean that any and every dog/pet bought at a discount with be ill mannered, ugly, bad breeding material,or dangerous, a loving forever home can change many things. Though this does mean you should consider the possible out comes for both you and the dog, coupled with diligent care and prevention that will be required.
Another thing to keep in mind is while the modern "Domestic Dog" is a descendant of the stoic wolf it is not "A WOLF". Many people have their own opinions on this subject and so shall you so please enjoy.
Every one knows the "pack mentality" or as a general rule of thumb most people have been advised to rule your house as the "Alfa". I will admit I for many years I believed this same exact idea and while you can get your point across with force ehhh why would you ?
.... more coming soon