Fast diffusion of domesticated maize to temperate zones

Area of Science:

• Population Genetics
• Agricultural Science
• Bioinformatics

Background:

• Maize (Zea mays) adaptation to temperate climates was crucial for its global expansion.
• Understanding the demographic history of maize is key to identifying genes for important traits.

Purpose of the Study:

• To explore the demographic processes behind maize adaptation to temperate climates.
• To model the genetic differentiation between temperate and tropical maize populations.

Main Methods:

• Utilized a diffusion-based method to model population differentiation.
• Employed sequential Markovian coalescent (SMC) approaches for demographic inference.
• Applied composite likelihood methods to pinpoint divergence events and effective population sizes.

Main Results:

• Estimated tropical and temperate maize divergence between 3,000-5,000 years ago, with a population size reduction post-divergence.
• Identified a specific divergence event around 4,958 years ago from an ancestral population of 24,162 individuals.
• Observed continuous gene flow between tropical and temperate maize, evidenced by shared long identical-by-descent tracts.

Conclusions:

• The study elucidates the demographic history of maize diffusion and adaptation.
• Findings support continuous gene flow and potential artificial selection in temperate maize development.
• This research aids in identifying selection regions and genetic underpinnings of important agronomic traits in maize.