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Natural Selection Presented by Kesler Science
Natural SelectionPresented by Kesler Science
1. How can you identify changes in genetic traits over several generations?
2. What are the differences between natural selection and selective breeding?
Essential Questions:
Natural Selection
Organism
An individual animal, plant or single-celled life form
Environment
The surrounding or conditions in which a person, animal or plant lives.
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What are genetic traits?
• Characteristics that are passed on to you (inherited) from you parents.
• Genes in your cells carry the information that determine your traits.
• Both plants and animals have inherited traits from their parents.
Natural Selection
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These puppies came from the same
parents, but have different traits.
Quick Action – INB Template
Natural Selection INB Template1. Cut out the Template
along the solid line.
2. Glue tabs into your notebook.
3. The Template should open like windows.
4. Write your notes behind each flap.
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Charles Darwin
• Born in England (1809-1882)
• Famous for his work on natural selection
• Spent 5 years doing research on his ship the HMS Beagle
• Wrote “On the Origin of Species”, which was hugely controversial
Natural Selection
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Natural Selection
Adaptation• A body part, feature, or
behavior that helps a living thing survive and function better in its environment
• Happens through natural selection
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Natural Selection
• The process whereby organisms better adaptedto their environment tend to survive and produce more offspring.
• Favorable traits become more common over long periods of time.
Natural Selection
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Darwin’s Finches• Darwin studied finches on the
Galapagos Islands.
• He theorized that 13 species had a common ancestor.
• The finches have developed distinctive beaks through the long-time process of adaptation.
• Each species of finches eat different types of food.
Natural Selection
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Medium ground finches vary in
size and shape and make good
subjects of study.
Natural Selection
Other Bird Beaks• A cone-shaped bill found in many birds,
including finches, is good for cracking seeds.
• Thin, slender pointed beak are used to pick insects off of twigs and bark.
• Woodpecker have strong beaks which form a chisel for pecking holes in trees to get to the insects.
• Birds of prey have hooked beaks used to bite and tear their prey.
• Mallard duck’s bill are fringed to strain plants , seeds and small animals from mud and water.
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Other Examples of Natural Selection
1. In Nebraska deer mice that moved to the sand hill changed from dark to light brown to better hide from predators.
2. In one ecosystem, lizards adapted long legs that could climb better to avoid floods and reach food.
3. Peacocks with bigger and brighter tails mate more often. Fainter colored peacocks are becoming rare.
Natural Selection
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Quick Action – Natural Selection
Draw SomethingTalk to a partner about this scenario.
Rat snakes are very similar except for the color variations. Some are green, black, and orange and even striped. If they come from a similar ancestor, why is there such a wide variation of colors?
Fold a piece of paper into fourths. Based on its color quickly draw each rat snake in the environment in which it is likely to live. You have 5 minutes. Go!
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Natural Selection
Selective Breeding
• The process by which humans choose a plant or animal to breed based on specific traits.
• This is done by choosing which plants or animals will sexually reproduced to create the desired offspring.
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Natural Selection
Selective Breeding
• Also called elective breeding
• Only occurs when humans intervene
• Adaptations happen over a shorter period of time than natural selection.
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Quick Action – Natural Selection
Say Something
Brainstorm with your partner other plants and animals which have been selectively bred.
Share the answers with the class.
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Natural Selection
• Engineered to contain foreign DNA that the organism could not obtain in traditional breeding.
• Usually used to introduce a beneficial trait
• Controversy as to whether GMO foods should be labeled as such
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Examples
Corn - insect resistance
Soybeans - herbicide tolerance
Rice - vitamin enrichment
Potatoes - virus resistance
GMOs – Genetically Modified Organisms
Check for Understanding
Can you…
1. Identify changes in genetric traits over several generations?
2. Differentiate between natural selection and selective breeding?
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