Selective Breeding

Selective Breeding

Middle School

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Learning Objectives

• Define selective breeding and differentiate it from natural selection.

• Describe the main types of artificial selection, like inbreeding and hybridization.

• Identify the benefits and risks of selective breeding and modern biotechnology.

• Provide examples of organisms developed through selective breeding.

Key Vocabulary

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Artificial Selection

Humans select organisms with desired traits to develop new organisms with those specific characteristics.

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Inbreeding

This involves mating related individuals to ensure a desired trait is passed on to the offspring.

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Hybridization

This is the breeding of organisms with different traits to create offspring with both traits.

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Genetic Engineering

This involves the direct transfer of a gene from one organism to another for improvement.

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Cloning

Cloning is making a genetically identical copy of an organism, which eliminates all genetic variation.

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What is Selective Breeding?

Selective Breeding

• Humans choose specific plants or animals with desired traits to breed.

• This process is guided by humans and does not happen naturally.

• The goal is for the offspring to inherit these specific traits.

Natural Selection

• Nature selects organisms with traits best suited for survival in their environment.

• This is a natural process that happens over a very long time.

• The goal is to ensure the species is well-adapted to its surroundings.

Multiple Choice

What is the primary difference between natural selection and artificial selection (selective breeding)?

• Artificial selection is driven by humans to get desired traits, while natural selection is driven by nature for survival.

• There is no difference; they are the same process.

• Artificial selection happens over a very long time, while natural selection is a quick process.

• Natural selection is used for plants, while artificial selection is used for animals.

Artificial Selection

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Selective Breeding

• ​Organisms with desirable traits are chosen by humans to reproduce.

• ​​The goal is to pass specific traits to the next generation.

• ​A large bull is bred with cows for larger offspring.

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Inbreeding

• ​This involves mating related individuals, such as siblings or cousins, reproduce.

• ​​This method is used by humans to enforce a desired trait.

• ​It can cause health problems like breathing issues in some pugs.

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Hybridization

• ​This involves breeding organisms from different species or with different traits.

• ​​New offspring are created with a combination of those desired traits.

• ​A low-shedding, friendly dog can be created for a family.

Multiple Choice

A scientist breeds a plant that is resistant to disease with a plant that produces large fruit. What type of artificial selection is this?

• Cloning

• Hybridization

• Natural Selection

• Inbreeding

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Modern Biotechnology in Breeding

Genetic Engineering

• ​This technique involves transferring a gene from one organism to another.

• ​​Organisms changed this way are called genetically modified (GM) organisms.

• ​It is used to improve crops and create medicines like insulin.

Cloning

• ​This process creates a genetically identical copy of a single parent.

• ​​Since it is an exact copy, it eliminates all genetic variation.

• ​Dolly the sheep was the first mammal cloned from an adult cell.

Multiple Choice

What is the key outcome of the cloning process?

• It creates a genetically identical copy of an organism.

• It mixes the traits of two different organisms.

• It helps organisms adapt to their natural environment.

• It introduces new genes to improve nutrition.

Risks of Genetic Modifica

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Reduced Genetic Variation

• ​Selective breeding can lead to a lack of genetic variation.

• ​​There is a higher risk of inheriting diseases in the population.

• ​The population may struggle to adapt to new environmental challenges.

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Genetic Pollution

• ​Human-created hybrids can interbreed with organisms in the wild.

• ​​This introduces non-native genes into a wild population.

• ​This process can have unpredictable and negative effects on the environment.

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Risks of GM Crops

• ​Genetically modified crops could cause adverse health reactions in humans.

• ​​They can also limit the biodiversity of the local ecosystem.

• ​Cross-pollination with wild plants might create herbicide-resistant "super weeds."

Multiple Choice

What is the primary risk associated with a lack of genetic variation caused by selective breeding?

• The creation of 'super weeds' in the wild.

• An increased risk of diseases within the population.

• The introduction of non-native genes into wild populations.

• An increase in the number of dominant genes.

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Common Misconceptions

Misconception	Correction
Selective breeding is a natural process.	It is a human-guided process, unlike natural selection.
Selective breeding is always beneficial.	It can reduce the gene pool, increasing the risk of genetic diseases.
Bred animals are healthier than wild ones.	Inbreeding can make some bred animals prone to health problems.
GMOs are the same as selectively bred organisms.	Genetic modification involves directly manipulating DNA in a lab.

Multiple Choice

Why does inbreeding, a type of artificial selection, increase the risk of disease in a population?

• It increases the chances of inheriting genes that cause disease.

• It makes the organisms larger and weaker.

• It only allows the strongest individuals to reproduce.

• It introduces new, harmful genes from other species.

Multiple Choice

How does the practice of artificial selection by animal breeders act as a supporting evidence for the theory of natural selection?

• It demonstrated that organisms do not change over time.

• It proved that all species were related to each other through a common ancestor.

• It showed that significant changes in traits could occur over time, suggesting natural processes could do the same.

• It showed that genetic mutations happen randomly in nature.

Multiple Choice

A farmer wants to create a new type of corn that is both resistant to drought and produces larger kernels. Which method should the farmer use and why?

• Genetic pollution, to introduce wild genes into the corn.

• Hybridization, to combine the desired traits from two different parent plants.

• Cloning, to make an exact copy of a single corn plant.

• Inbreeding, to enforce a single trait from one type of corn.

Multiple Choice

What is the most likely long-term result for a wild plant population if it frequently cross-pollinates with a farm's genetically modified, herbicide-resistant crops?

• The genetic diversity of the wild plants would increase, making them healthier.

• The wild plants could also become herbicide-resistant, creating 'super weeds'.

• The wild plants would be unable to reproduce.

• The genetically modified crops would die out.

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Summary

• Humans use selective breeding to develop organisms with desirable traits.

• It is directed by humans and is faster than natural selection.

• Modern techniques like genetic engineering offer more precise control over traits.

• Risks include loss of genetic variation and increased disease susceptibility.

Poll

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

• 1

• 2

• 3

• 4