What is the breed

The basic category of domestic animals is the species, as is the case with wild animals. The species of domestic animals are differentiated into breeds, while that of wild animals are differentiated into subspecies. A breed is defined as a group of animals that has been selected by humans to possess a uniform appearance that is inheritable and distinguishes it from other groups of animals within the same species. Domestication and selective breeding have changed some species of domestic animals (camel, reindeer) very little. But in others, including the oldest and the most important species of domestic animals, tens and hundreds of breeds have been developed; compare for example the pocket-sized Chihuahua with the huge mastiff or Saint Bernard dog. Some specialized breeds are not able to carry out an independent existence. Others become wild without any problem and are able to set up feral populations under suitable conditions. People used artificial selection from the early days of breeding even though they did not know the rules of heredity and the selection of features was varied. For example, European cattle were bred to increase milk and meat production and working capacity, while African pastoralists preferred to increase the size of horns.

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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