Short introduction to
selective breeding

Emi Tanaka

Australian National University

2025-07-09

Wild vs Cultivated

What is this?

Image source

Image source:

Wild vs Cultivated

What is this?

Image source: Matt Lavin

Image source:

Evolution of corn (maize)

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Breeding cycle

For plant breeding, the number of locations generally increase for later stages.

Why do selective breeding?

• Production
• Population
• Production per capita

• Arable land
• Yield

Yield = Production / Area Harvested

What trait to optimise?

Yield

(economic driver)

Quality traits, disease resistance, and other desirable traits.

Aim of selective breeding in a nutshell

🎯 Increase genetic gain

• Genetic gain measures improvement in the average genotype performance of a population over time due to selection for specific traits.

For other ways to calculate \(\Delta G\), see Rutkoski (2019) A practical guide to genetic gain. Advances in Agronomy

Analytical strategies for selective breeding

• Improve selection accuracy
  • Use effective experimental design that separate out sources of variation for the response
  • Use appropriate models to disaggregate “noise” from “signal” to get accurate estimates of breeding values
• Marker assisted selection
  • Identify DNA markers related to desirable traits (e.g. disease resistance)
  • Some traits are dependent only for a small number of DNA markers
  • Screen candidate genotypes based on these markers
• Genomic selection
  • Use a training population to estimate the additive marker effects
  • Predict breeding values of candidate genotypes