Hi Len There is a difference between line breeding to isolate specific characteristics(which dog breeders use) and isolation causing a new species. Dogs are line bred to create all the different breeds/populations that we have today. The same is so with fancy show guppies, different colour angels, expensive butterfly koi etc. A specific trait is identified and only specimens with that trait are bred with other specimens of the same trait. There are also sex variables for example taking a male horse and a female donkey you get a mule but take a male donkey and a female horse you get a hinny. Different traits are carried over from different sexes. To answer some of your questions, 1. It can take a very long time for a species to become identifiably different but it can also happen quite quickly. There is a lionfish in the Red sea that has evolved over the last 40 years. It has yet to be identified as a new species but only more studying into the fish will determine that. 2. Generally no, science does not recognise man made species and they will not have a scientific name. But domestic dogs are all referred to as Canis lupus familiaris 3. There are more factors involved with the subject that just bloodline. There are environmental factors to be considered. As Andre said introducing new blood is advisable to squeeze out recessive traits that show up in later generations but this would in fact be starting the process fresh.