Population-Specific Selection on Standing Variation Generated by Lateral Gene Transfers in a Grass

Area of Science:

• Genomics
• Evolutionary Biology
• Plant Science

Background:

• Eukaryote-to-eukaryote lateral gene transfer (LGT) is increasingly documented.
• Selective pressures driving LGT gene fate in recipients are under-explored.
• LGT has been observed between grass species.

Purpose of the Study:

• To investigate the selective pressures and evolutionary fate of multigene lateral gene transfer fragments in the grass Alloteropsis semialata.
• To test the hypothesis that successful LGT confers an advantage and is rapidly selected for.
• To understand the role of LGT in generating genetic variation and adaptation.

Main Methods:

• Whole-genome sequencing
• Population-level RAD sequencing
• Analysis of gene presence-absence polymorphisms

Main Results:

• Multigene LGT fragments were rapidly integrated into the recipient genome, suggesting positive selection for novel functions.
• Physically linked 'hitchhiking' genes were also retained, contributing to gene presence-absence polymorphisms.
• One hitchhiking gene showed secondary rapid spread in some populations, indicating delayed adaptive consequences.

Conclusions:

• Short-term LGT integration is facilitated by positive selection on transferred genes.
• Retained hitchhiking genes can augment standing genetic variation and lead to delayed local adaptation.
• Eukaryotic LGT can contribute to intraspecific ecological diversification.