1.4

AIM: How can organisms be improved using the idea of natural selection?

Warm – up:In evolutionary terms, why is one

organism more likely to survive than another?

Artificial selection

§ Artificial breeding can use variations in populations to create vastly different “breeds” & “varieties”

Artificial selection

§ Artificial breeding can use variations in populations to create vastly different “breeds” & “varieties”

“descendants” of the wolf

Artificial selection

§ Artificial breeding can use variations in populations to create vastly different “breeds” & “varieties”

“descendants” of the wolf

“descendants” of wild mustard

Artificial selection

§ Artificial breeding can use variations in populations to create vastly different “breeds” & “varieties”

“descendants” of the wolf

“descendants” of wild mustard

Selective Breeding

Selective Breeding

Selective Breeding: Process in which

Selective Breeding

Selective Breeding: Process in whichparticular individuals are chosen and allowed

Selective Breeding

Selective Breeding: Process in whichparticular individuals are chosen and allowed to breed, whereas others are prevented from

Selective Breeding

Selective Breeding: Process in whichparticular individuals are chosen and allowed to breed, whereas others are prevented from breeding.

Selective Breeding

Selective Breeding: Process in whichparticular individuals are chosen and allowed to breed, whereas others are prevented from breeding.

• Alleles that give characteristics favored by humans are retained, while undesirable characteristics are eliminated.

Selective Breeding

Selective Breeding: Process in whichparticular individuals are chosen and allowed to breed, whereas others are prevented from breeding.

• Alleles that give characteristics favored by humans are retained, while undesirable characteristics are eliminated.

• Raw genetic material is hidden and often allows for hidden variations to show through

Selective Breeding

Selective Breeding: Process in whichparticular individuals are chosen and allowed to breed, whereas others are prevented from breeding.

• Alleles that give characteristics favored by humans are retained, while undesirable characteristics are eliminated.

• Raw genetic material is hidden and often allows for hidden variations to show through

Selective Breeding

Selective Breeding: Process in whichparticular individuals are chosen and allowed to breed, whereas others are prevented from breeding.

• Alleles that give characteristics favored by humans are retained, while undesirable characteristics are eliminated.

• Raw genetic material is hidden and often allows for hidden variations to show through

Selective Breeding

Selective Breeding: Process in whichparticular individuals are chosen and allowed to breed, whereas others are prevented from breeding.

• Alleles that give characteristics favored by humans are retained, while undesirable characteristics are eliminated.

• Raw genetic material is hidden and often allows for hidden variations to show through

Selection

§ Artificial selection is similar to directional selection.

§ Similarities?

§ Differences?

Inbreeding

§ Involves breeding between closely related individuals with some desirable trait as the outcome

§ Loss of genetic diversity

§ If loss occurs to the extent at which every individual has identical alleles, that is referred to as complete homozygosity

§ Why is this a problem?

Yorkshire Terriers (Yorkies)

Yorkshire Terriers (Yorkies)

Yorkshire Terriers (Yorkies)

Bassett Hound

Bassett Hound

Bassett Hound

Example of Inbreeding in Plants

§ Wheat plants generally self pollinateØ High yieldØ Short stemsØ Pest resistanceØ High protein content of grain

Outbreeding

§ Involves crossing individuals from genetically distinct strains to form hybrids.

§ Hybrids have characteristics which are superior to the characteristics in either parent. (Hybrid vigour / Heterosis)

Liger

Mule

Mule

Mule

Mule

HOMEWORK

§ Complete Ques. 3 from Classwork H.O.

§ Read p. 450 – 453