Artificial Selection Breeding for a purpose Dogs bred

Artificial Selection Breeding for a purpose

Dogs bred as sighthounds clockwise from top left: Whippet, Borzoi, and Saluki Can you see the similarities in their anatomy? What physical characteristics do you think were selected?

14 th century print of a hunt. Can you spot the sighthounds? How did you decide?

Dogs bred as herding dogs – clockwise from top left – Border collie, Lancashire heeler, Rottweiler, Old English Sheepdog Do you think the characteristics that are bred for are physical or behavioural? Why?

Dogs – bred for a purpose • Dogs have been selectively bred for a purpose for 15, 000 years • Starting with some wolves, dogs were initially bred to help with: – hunting; producing hounds, terriers, and retrievers – farming; producing herding dogs and guard dogs • Modern breeding has given us companion dogs and toy dogs – whose purpose is to keep us company… funnily enough

The Auroch – where all domesticated Meat cattle were bred from Dairy Draft

Artificial selection in plants

Wheat • Tall wheat plants have a high yield, but are easily damaged in wind and rain • Dwarf wheat plants have a low yield, but are robust against nasty weather • Q: What do you think happened when the two types were cross-bred? • A: A dwarf wheat with high yield that was robust! • Other types were produced, but they were discarded

How would you…? • Discuss how you would breed for: – Better quality of milk from cows – - Increased number of offspring in sheep

In summary… • Selective breeding = Artificial selection • Has been used for animals and plants • The method: – The desired characteristics are identified – They are bred together – Only the offspring exhibiting the desired characteristics are bred – This is repeated over several generations until the desired trait is fully developed

In summary… • Problems: • Traits are chosen to benefit humans, not the animal – Physical problems often occur in domestic animals eg. Inflammation of the udder (mastisis) in cows due to increased milk production • Usually involves inbreeding, which can lead to reduced genetic diversity

Would it be right to selectively breed humans? ? • Adolf Hitler believed in a master race (the Aryans) and implemented a plan to create this race. • This involved eugenics – the selective breeding of humans.

Nazi eugenics • Those considered “not worthy of life”, - let alone allowed to have children - included (but was not limited to) the criminal, degenerate, dissident, feeble-minded, homosexual, idle, insane, and the weak • 400, 000 people were sterilised against their will and 70, 000 were killed

What do YOU think?