Artificial Selection

Artificial Selection

Middle School

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Learning Objectives

• Define artificial selection and see how it differs from natural selection.

• Explain how selective breeding works for both plants and animals.

• Learn how genetic engineering is used to create Genetically Modified Organisms (GMOs).

• Analyze the good and bad results of using artificial selection.

Key Vocabulary

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Artificial Selection

Humans select parent organisms with desired traits to produce offspring with those same qualities.

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Breed

A group of domestic animals with a similar appearance and behavior that distinguishes them from others.

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Genetic Engineering

The process of directly adding one or more new traits to an organism by manipulating its genes.

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GMOs

Genetically modified organisms are organisms whose genetic material has been artificially altered in a laboratory setting.

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Hand-pollination

The manual transfer of pollen from one plant to another by humans to control breeding outcomes.

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Hybrid

The offspring that results from combining the qualities of two organisms of different plant varieties or cultigens.

Key Vocabulary

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Crossbreed

The resulting offspring from mating two different breeds or species of animals, like a mule.

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What is Artificial Selection?

• Artificial selection is when humans choose organisms with desired traits to reproduce.

• This process is also known by the name selective breeding.

• It is different from natural selection, where the environment chooses favorable traits.

• All dog breeds, like Chihuahuas and Mastiffs, come from artificial selection.

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Multiple Choice

Which statement best defines artificial selection?

• A process where humans choose which organisms reproduce based on desired traits.

• A process where the environment determines which traits are passed on.

• A process where organisms randomly develop new features.

• A process that only applies to the creation of different dog breeds.

Multiple Choice

What is the key difference between artificial selection and natural selection?

• Artificial selection happens quickly, while natural selection happens slowly.

• Artificial selection applies to animals, while natural selection applies to plants.

• In artificial selection, humans choose the traits, while in natural selection, the environment does.

• Artificial selection is a new process, while natural selection is an ancient one.

Multiple Choice

Using the concept of artificial selection, what is the best explanation for how dog breeds as different as Chihuahuas and Mastiffs came to exist?

• They evolved naturally in different environments to have different traits.

• They are entirely different species that are unrelated to each other.

• They were bred by humans who selected for specific traits over many generations.

• Their traits are the result of random mutations in a single generation.

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The Process of Selective Breeding

Animal Breeding

• The science of caring for and breeding animals to have desired traits is known as animal husbandry.

• Ranchers mate a male and female that both have a desired trait, like a smooth gait in horses.

• This selective pairing increases the chances of the desired trait appearing in their offspring.

Plant Breeding

• Gregor Mendel first demonstrated how this same process of selective breeding can also be applied to plants.

• A key technique called hand-pollination involves humans manually transferring pollen between specific plants to control reproduction.

• This method avoids random pollination and ensures that only plants with the desired traits are crossed.

Multiple Choice

What is the primary purpose of the process of selective breeding?

• To increase the chances that offspring will have desired traits.

• To create new species of plants and animals.

• To make animals and plants grow much larger.

• To study how animals and plants live in the wild.

Multiple Choice

What is the relationship between hand-pollination and the selective breeding of plants?

• It allows breeders to control which plants are crossed to avoid random pollination.

• It makes the plants produce pollen more quickly.

• It combines the traits of plants and animals together.

• It guarantees that all offspring will be identical to the parents.

Multiple Choice

A rancher who practices animal husbandry wants to raise horses that have a naturally smooth gait. What would be the most effective strategy to achieve this goal?

• Find a male and female horse that both have a smooth gait and mate them.

• Let the horses reproduce randomly and hope for the best outcome.

• Train a horse to have a smooth gait and then breed it.

• Use hand-pollination techniques on the horses.

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What Is Genetic Engineering?

• Genetic engineering is a modern form of artificial selection that happens in a lab.

• Scientists alter an organism's genes, creating a Genetically Modified Organism or GMO.

• The process, called gene splicing, adds or removes sections of an organism's DNA.

• Bt corn is a GMO with a bacterial gene that helps it resist pests.

Multiple Choice

What is genetic engineering?

• A process where scientists directly change an organism's genes in a lab.

• A process where organisms naturally adapt to their environment over time.

• A process for classifying different types of organisms based on their traits.

• A process for studying the fossils of ancient organisms.

Multiple Choice

What is the primary purpose of using gene splicing?

• To add or remove sections of DNA to create an organism with specific, desired traits.

• To create an exact copy of an entire organism without changing its genes.

• To remove all the DNA from an organism to see what happens.

• To observe how an organism's genes change on their own in nature.

Multiple Choice

Based on the example of Bt corn, what is the most likely outcome if a bacterial gene for pest resistance is added to a corn plant's DNA?

• The corn plants with the bacterial gene would be more likely to survive a pest attack.

• The corn plants would start producing bacteria instead of corn kernels.

• The corn plants would become smaller than corn plants without the gene.

• The corn plants would require more water to grow than regular corn.

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Outcomes of Artificial Selection

Positive Outcomes

• A single wild mustard plant has been bred to create kale, broccoli, and cabbage.

• Artificial selection allows us to create fruits with new flavors and desirable traits.

• It helps in developing crops that can resist and survive in cold weather climates.

Negative Impacts

• Focusing on a single trait can accidentally weaken other traits or create new problems.

• Tomatoes that were bred to be durable for shipping ended up losing their flavor.

• Selective breeding in dogs for appearance has led to more genetic health problems.

Multiple Choice

What is the primary goal of artificial selection?

• To develop organisms with specific, desirable traits.

• To create organisms that are identical to their wild ancestors.

• To increase the number of genetic health problems in animals.

• To study how organisms behave in their natural habitats.

Multiple Choice

What is a potential negative consequence of focusing on a single trait during selective breeding?

• It can lead to the weakening of other important traits.

• It always results in fruits with better flavors.

• It guarantees that crops will be resistant to all diseases.

• It helps animals to better survive in the wild.

Multiple Choice

A farmer selectively breeds chickens to produce the most meat possible. Based on the information provided, what is a likely unintended outcome?

• The chickens might become more likely to get sick.

• The chickens will definitely have a better taste.

• The chickens will also develop the ability to fly long distances.

• The chickens will be better prepared for cold weather.

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Common Misconceptions

Misconception	Correction
Artificial and natural selection are the same.	Humans select traits in artificial selection; nature selects in natural selection.
All GMOs are unnatural “sci-fi” creations.	Most GMOs are common produce with a specific gene added to help them.
Selective breeding only produces positive results.	It can cause unintended negative results, like genetic health problems in dogs.

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Summary

• Artificial selection is when humans breed plants and animals for desired traits.

• It is different from natural selection and has created diverse breeds and varieties.

• Modern genetic engineering directly manipulates genes, creating GMOs with specific advantages.

• The process offers benefits but can cause issues like genetic health problems.

Poll

On a scale of 1-4, how confident are you about the concepts covered in today's review?

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