What is Artificial Selection? Give examples.

SouravOctober 26, 2024

Answer

• Definition: Artificial selection, also known as selective breeding, is the process by which humans intentionally select and breed individuals with specific desirable traits or characteristics to produce offspring with those traits. This is a form of selection that contrasts with natural selection, where the environment drives the selection of traits.
• Key aspects:
  • Human intervention: Breeders or scientists deliberately choose which individuals to breed.
  • Trait focus: The selection process targets specific, desired traits.
  • Accelerated evolution: Artificial selection can lead to rapid changes in a population’s characteristics over a few generations.

Examples of Artificial Selection:

Plant Examples

1. Corn (Maize) Development
   • Original Trait: Hard outer shell, small kernels (Teosinte, the wild ancestor)
   • Selected Trait: Larger, softer kernels, varied colors and uses (sweet corn, popcorn, flour corn)
   • Outcome: Dramatic changes in morphology and use over approximately 9,000 years
2. Apple Varieties
   • Original Trait: Small, sour, wild apples (Malus sieversii)
   • Selected Traits: Larger size, sweetness, disease resistance, and diverse flavors/colors (e.g., Red Delicious, Granny Smith, Gala)
   • Outcome: Over 7,500 known apple varieties worldwide, each with unique characteristics

Animal Examples

1. Dog Breeding
   • Original Trait: Wolves or early dog-like species with generalist traits
   • Selected Traits: Size (Chihuahua to Great Dane), behavior (guarding, herding, companionship), physical attributes (ear shape, coat type)
   • Outcome: Over 340 recognized breeds, each with distinct characteristics
2. Cattle Breeding for Milk Production
   • Original Trait: Dual-purpose cattle (meat and moderate milk production)
   • Selected Trait: High milk yield, specific fat content, and dairy-oriented body type
   • Outcome: Breeds like Holstein Friesian, producing significantly more milk than their ancestors

Aquaculture and Poultry Examples

1. Salmon Farming
   • Original Trait: Wild salmon with natural growth rates and disease susceptibility
   • Selected Traits: Faster growth rate, disease resistance, and improved feed conversion
   • Outcome: Genetically improved farmed salmon with enhanced production efficiency
2. Broiler Chicken Breeding
   • Original Trait: Dual-purpose chickens (eggs and meat) with slower growth
   • Selected Traits: Rapid growth rate, larger size, and efficient feed conversion for meat production
   • Outcome: Modern broiler chickens reach market size in about half the time of their mid-20th-century counterparts

Common Outcomes of Artificial Selection Across Examples:

• Rapid Trait Evolution: Desired traits are amplified over relatively few generations.
• Increased Productivity: Whether in agriculture, animal husbandry, or aquaculture, artificial selection aims to enhance output or efficiency.
• Diversity of Forms and Functions: Artificial selection has led to a wide range of varieties and breeds, each suited to specific human needs or preferences.