Limited Lifespan of Fragile Regions in Mammalian Evolution

TL;DR

This study shows that fragile regions in mammalian genomes are transient, undergoing a birth and death process, which explains their limited shared breakpoints across lineages and suggests dynamic locations of rearrangement hotspots.

Contribution

It introduces the concept of fragile regions having a limited lifespan due to a birth and death process, clarifying their transient nature in mammalian genome evolution.

Findings

Fragile regions are subject to a birth and death process.

Limited shared chromosomal breakpoints across lineages.

Active fragile regions are predicted in the human genome.

Abstract

An important question in genome evolution is whether there exist fragile regions (rearrangement hotspots) where chromosomal rearrangements are happening over and over again. Although nearly all recent studies supported the existence of fragile regions in mammalian genomes, the most comprehensive phylogenomic study of mammals (Ma et al. (2006) Genome Research 16, 1557-1565) raised some doubts about their existence. We demonstrate that fragile regions are subject to a "birth and death" process, implying that fragility has limited evolutionary lifespan. This finding implies that fragile regions migrate to different locations in different mammals, explaining why there exist only a few chromosomal breakpoints shared between different lineages. The birth and death of fragile regions phenomenon reinforces the hypothesis that rearrangements are promoted by matching segmental duplications and suggests putative locations of the currently active fragile regions in the human genome.