Yes they can. All dogs are actually the same species, despite their apparent differences. They have been selectively bred to produce many different sizes and shapes, but genetically they are not so different. In fact they are still the same species as the wolves they were bred from.
Dogs are our familiar pets which have been bred from wolves. Many different shapes and breeds exist. Prairie dogs are small ground squirrels which live in burrows in the plains of North America.
Many dogs are used, but the most common is the pit bull.
Corn is an example of a selectively bred plant, with modern varieties bred to have higher yields, resistance to diseases, and specific traits like sweetness or color. Dogs, such as poodles or dachshunds, are selectively bred animals for specific physical characteristics and temperament.
Mixed, or cross-bred dogs usually exist for one reason. Strays. Many dogs, that are from a POund have been cross-bred because a house-dog got away and bred or the are a mix of 2 strays. However, cross breeds are becoming increasingly popular, and some breeeds are being formed currently.
There are about 100-250 different pure bred dogs in the entire world. yes i agree but maybe even 150 to 300.
I'm not sure what you mean. a pedigree dog that isn't registered with the kennel club isn't illegal. or do you mean dogs that have been banned like pitbulls?
depends.. why is an unhealthy dog being bred?
Breeding dogs is common, and many people do it because they say if one dog is a champion, then their offspring will become dog show, obedience, or agility chanpions too. Others do it to make a lot of money off of pure-bred dogs.
No two dogs simply make a collie. They are the result of high drive herding dogs from multiple countries, which were bred many hundreds of years ago. They're an ancient breed that can only continue by being bred collie-to-collie.
There are many different breeds bred by puppy mills, usually popular breeds that you see in the pet stores, very often these dogs will have health problems, and sometimes abused in their time with the parents' owner.
Labradors are selectively bred for their hunting qualities. They have been bred to have webbed paws so they can swim into water to retrieve the fowl that their owners have shot. When retrieving the bird, hunters want the dogs to have the softest mouths possible so not to damage the bird more than necessary.