The Evolutionary Fates of a Large Segmental Duplication in Mouse

Area of Science:

• Evolutionary genetics
• Genomics
• Population genetics

Background:

• Gene duplication and loss are key drivers of genetic polymorphism and genome evolution.
• Understanding the history of specific gene duplications is crucial for deciphering evolutionary processes.

Purpose of the Study:

• To reconstruct the origin and evolutionary history of the R2d segmental duplication in Mus musculus.
• To investigate the structural variation and mutational processes associated with the R2d duplication.

Main Methods:

• De novo assembly of ancestral (R2d1) and derived (R2d2) copies of the R2d duplication.
• Analysis of gene conversion events and structural variation across diverse wild mouse populations.
• Investigation of meiotic drive and mutation rates in relation to R2d2 copy number.

Main Results:

• The R2d duplication (127-kbp) contains the Cwc22 gene and has undergone extensive nonallelic gene conversion.
• R2d2 exhibits extreme copy-number variation (0 to >80 copies) in wild mice, with the reference genome being hemizygous.
• High R2d2 copy number is linked to meiotic drive, suppressed crossovers, and high mutation rates (>1 per 100 transmissions).

Conclusions:

• The R2d duplication provides a model for rapid allelic diversity generation through duplication and subsequent variation.
• De novo assembly in a phylogenetic framework is essential for understanding mutation dynamics in duplicate genes.
• The study demonstrates how duplication can lead to complex evolutionary trajectories and population-level genetic phenomena.