Selfish chromosomal drive shapes recent centromeric histone evolution in monkeyflowers.

Area of Science:

• Evolutionary genetics
• Molecular biology
• Genomics

Background:

• Centromeres are crucial for chromosome segregation but show diverse DNA sequences and kinetochore proteins across species.
• The selfish centromere model proposes an evolutionary arms race between centromeric DNA and kinetochore proteins.

Purpose of the Study:

• To test the selfish centromere model in a natural population of Mimulus guttatus.
• To investigate the co-evolutionary dynamics between driving centromeres and kinetochore proteins.

Main Methods:

• Quantitative genetic mapping to identify modifiers of meiotic drive.
• Population genetics analyses to detect selective sweeps.
• Structural and genetic characterization of centromeric DNA.

Main Results:

• A driving centromere (D haplotype) in Mimulus guttatus is structurally distinct and has rapidly increased in frequency.
• Drive strength is context-dependent, influenced by competitor chromosome vulnerability and an unlinked modifier.
• The kinetochore protein Centromere-specific Histone 3 A (CenH3A) shows evidence of a recent selective sweep, linked to drive interactions.

Conclusions:

• Demonstrates an active co-evolutionary arms race between centromeric DNA and kinetochore proteins in Mimulus.
• Highlights the role of meiotic drive in rapid molecular and fitness evolution.
• Provides evidence for adaptive evolution of kinetochore proteins in response to selfish centromeres.