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Selective breeding, also called artificial selection, is when humans breed plants and animals for particular genetic characteristics. Free notes and FAQs.
What is Selective Breeding and How Does it Work? is part of Variation and evolution in GCSE Edexcel Higher Biology.
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Selective breeding, also called artificial selection, is when humans breed plants and animals for particular genetic characteristics. Free notes and FAQs.
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Use this lesson to stay inside Variation and evolution while connecting the detail back to the wider Topic 4: Natural selection and genetic modification topic.
Read the core explanations from What is Selective Breeding and How Does it Work? before testing yourself from memory.
Every dog you see - from tiny Chihuahuas to massive Great Danes - descended from wolves. Every wheat plant in a field producing bread flour came from wild grasses that barely had any edible seeds. How did this transformation happen?
The answer is selective breeding. Humans have been shaping the living world around them for over 10,000 years, choosing which plants and animals get to reproduce based on the traits we find useful.
Trap: Many students think selective breeding is 'creating new genes'. Actually, we're just choosing which existing genes get passed on more often. The genes were already there in the population - we're just changing their frequency.
The process sounds simple, but it requires patience and careful planning over many generations. Here's how it works step by step.
Worked example: The Selective Breeding Process
A farmer wants to breed cows that produce more milk. How would they use selective breeding?
Answer: Eventually, nearly all offspring will show the desired high milk production trait
The key insight is that this takes many generations. You can't create a super-cow in one breeding season. Each generation, the average gets slightly better as the genes for high milk production become more common in the population.
Selective breeding has given us most of the food we eat and the animals we live with. The characteristics chosen fall into two main categories: usefulness and appearance.
Breeding for Usefulness:
Disease resistance in food crops: Farmers select wheat plants that survive fungal infections, then breed only from these survivors. Over generations, the crop becomes naturally resistant to disease without needing pesticides.
Animals that produce more meat or milk: Dairy farmers choose cows producing 30+ litres of milk daily. Pig farmers select breeding stock with larger muscle mass and less fat. This increases food production efficiency.
Breeding for Appearance:
Domestic dogs with gentle nature: Over thousands of years, humans selected wolves and early dogs that were less aggressive and more cooperative. This gave us breeds like Golden Retrievers and Labradors that are naturally friendly.
Large or unusual flowers: Rose breeders select plants with bigger blooms, unusual colours, or stronger fragrances. This is why garden roses look so different from wild roses.
Why does selective breeding work? It's all about genes and inheritance. Every characteristic you can see - milk production, flower colour, disease resistance - is influenced by genes.
When you choose parents with a particular trait, you're really choosing parents with particular versions of genes (called alleles). These parents are more likely to pass those 'good' alleles to their offspring.
Over many generations, the 'good' alleles become more common in the population while the 'less useful' alleles become rarer. Eventually, almost all individuals in the population will have the desired characteristic.
Important: Selective breeding doesn't create new genes - it just changes how common different genes are in a population. The variation was already there; humans just decide which variants get to reproduce more.
Like any powerful tool, selective breeding has both benefits and drawbacks. Understanding these helps explain why it's so widely used, but also why scientists are developing new approaches.
Advantages:
• Increased food production: Higher-yielding crops and more productive livestock help feed growing populations
• Disease resistance: Crops and animals can be bred to resist specific diseases, reducing the need for medicines or pesticides
• Improved quality: Better taste, longer shelf life, or more attractive appearance in food products
Disadvantages:
• Reduced genetic diversity: Focusing on a few 'ideal' individuals means the population becomes more genetically similar
• Vulnerability to new diseases: If all individuals are genetically similar, a new disease could wipe out the entire population
• Time-consuming: Takes many generations to achieve significant results
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Move to the related lessons or back to the topic page when you need the wider sequence before exam-style practice.
Selective breeding is the process by which humans breed plants and animals for particular genetic characteristics, also called artificial selection. Humans have done it for over 10,000 years; for example, every dog, from Chihuahuas to Great Danes, descended from wolves.
Examples of selective breeding include disease resistance in food crops such as wheat, animals that produce more meat or milk, domestic dogs with a gentle nature such as Labradors, and large or unusual flowers such as garden roses.
Artificial selection is another name for selective breeding: humans choosing which plants and animals reproduce based on useful traits. Humans have been shaping the living world this way for over 10,000 years.
Advantages of selective breeding include increased food production, disease resistance and improved quality. Disadvantages include reduced genetic diversity, vulnerability to new diseases because individuals are genetically similar, and the fact that it takes many generations to achieve significant results.
Selective breeding starts with a mixed population, then individuals with the desired trait are chosen as parents and bred together. From the offspring, the best are selected again, and the process is repeated over many generations until nearly all offspring show the desired characteristic.
Selective breeding takes many generations. In a dairy herd, it can take 10-20 generations of choosing the cows that produce the most milk before most cows produce 25+ litres daily, because favourable genes become more common gradually.
Dogs were selectively bred from wolves over thousands of years by humans choosing wolves and early dogs that were less aggressive and more cooperative. This gave breeds like Golden Retrievers and Labradors that are naturally friendly, and every dog breed descended from wolves.
Selective breeding does not create new genes; it changes how common existing alleles are in a population. Choosing parents with a trait means their alleles are passed on more often, so over many generations the desired alleles become more common.
Farmers selectively breed cows for more milk by choosing the cows that produce the most milk and mating them with bulls from high-milk families. They then select the calves producing the most milk and repeat this each generation until most cows produce 25+ litres daily.
Disease-resistant crops are made by selecting plants, such as wheat, that survive fungal infections and breeding only from these survivors. Over generations the crop becomes naturally resistant to disease without needing pesticides.
Selective breeding works because parents with a chosen trait carry particular alleles and are more likely to pass them to their offspring. Over many generations the useful alleles become more common and the less useful ones become rarer.
Selective breeding reduces genetic diversity because it focuses on a few ideal individuals, so the population becomes more genetically similar. If all individuals are genetically similar, a new disease could wipe out the entire population.
Roses have been selectively bred by choosing plants with bigger blooms, unusual colours or stronger fragrances. This breeding for appearance is why garden roses look so different from wild roses.