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13-1 Changing The Living World
Section 13-1 Changing the Living World
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Selective Breeding The Wide Variety of Animals & Plants Used By Humans, Have Been Developed By Selective Breeding – Allowing Only Those Animals & Plants With Desired Characteristics Are Allowed To Reproduce.
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Selective Breeding Key Concept:
Humans Use Selective Breeding To Pass Desired Traits On To The Next Generation of Organisms Apples, Corn, Potatoes Dogs, Cattle, Mice, Yeast
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Selective Breeding Luther Burbank 1849-1926 800 Varieties of Plants
Disease Resistant Potatoes
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Selective Breeding - Hybridization
Crossing Dissimilar Individuals To Bring Together The Best Of Both Organisms Often Hardier Than Parents Disease Resistance + Increased Food Producing Capacity
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Selective Breeding - Hybridization
Postzygotic Barriers Reduced Hybrid Viability Embryos Don’t Develop Reduced Hybrid Fertility Offspring Vigorous but Sterile Hybrid Breakdown 1st Generation Viable & Fertile 2nd Generation Feeble & Sterile
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Selective Breeding - Inbreeding
Used To Maintain A Desired Characteristic Dog Breeds Higher Risk of Homozygous Recessive Alleles for Genetic Defect. Blindness & Joint Problems In German Shepherds & Golden Retrievers
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Increasing Variation Key Concept:
Breeders Can Increase The Genetic Variation In A Population By Inducing Mutations
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Increasing Variation Selective Breeding Impossible Without A Diverse Gene Pool Importance Of Diversity In Wild Populations Mutations Induced Through Radiation Chemicals
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Most Mutations Undesirable Few Mutations Desirable
Increasing Variation Most Mutations Undesirable Offspring Destroyed Few Mutations Desirable Breed To Maintain
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Increasing Variation – New Kinds of Bacteria
Easy To Induce Mutations In Millions At Once Mutations Particularly Useful Produce Oil Eating Bacteria Plastic Eating Bacteria
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Increasing Variation – New Kinds of Plants
Drugs Disrupt Chromosomal Separation During Meiosis Offspring 2X or 3X Chromosomes (Polyploidy) Usually Fatal For Animals Tolerated & Useful In Plants
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Increasing Variation – New Kinds of Plants
Polyploidy May Instantly Produce A New Species Larger & Stronger Than Their Diploid Relatives Bananas, Oats, Cotton, Tobacco, Wheat
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Increasing Variation – New Kinds of Plants
Allopolyploid Two Different Species Form A Polyploid Hybrid Bread Wheat – Triticum aestivum 8000 years ago Cultivated Wheat & Wild Grass
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Allopolyploid Polyploid formed between two species
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