SELECTIVE BREEDING

AMANDA, TREY, PEDRO AND CHELSEA

WHAT IS SELECTIVE BREEDING?The intentional breeding of organisms with desirable traits in an attempt to produce offspring with similar desirable characteristics or improved traits. Examples of traits include appearance, intelligence, and more.

EXAMPLE #1: CHIHUAHUA• Gray wolf different dog breeds • Descended from Techichi, a type of companion dog • “Deer head” and “apple head” varieties desired – large head

and smaller body • Possibility of genetic defects (hip dysplasia, heart conditions)• “Modern” equivalent Chihuahua first appeared 100 AD, and

eventually recognized in 1904 • Work dogs versus toy dogs

EXAMPLE #2: BELGIAN BLUE COW• Originally for dairy and beef• Cross bred with Shorthorn• “Modern” cow first appeared in the late 1800’s • Artificially inseminated in 1960’s for Myostatin gene

EXAMPLE #3: SWEDE• Bred in the 17th century• Root vegetable • Desired fleshy roots that were easily to harvest• Cross between a cabbage and a turnip

EXAMPLE #4: WHEAT• Wheat was originally small and weak• Desired larger and stronger grain to harvest for next

season • Can now survive in harsher climates and yields bigger

crops

HOW IS THIS EVIDENCE FOR EVOLUTION?• Evolution is “change in the inherited characteristics of a

population over time”• Shows that species can change over time • Specimens are bred for specific traits, which speeds up

the process • Following generations have more commonly desired traits