The evolutionary impact of Robertsonian fusions: linking genomic architecture, recombination and reproduction.

Determining the genomic basis of speciation remains a central challenge in evolutionary biology, including the role of large-scale structural genome reorganizations, such as inversions and chromosomal fusions. While extensive theoretical and empirical work has shown that inversions can facilitate adaptation and speciation by suppressing recombination and maintaining co-adapted gene complexes, the evolutionary role of chromosomal fusions remains comparatively underexplored. This gap contrasts with the widespread occurrence of chromosomal fusions across eukaryotes. Here, we synthesize current knowledge on the mechanisms driving the formation of chromosomal fusions in mammals and their consequences for genome architecture, recombination and evolution. We discuss how fusions reshape recombination landscapes and meiotic patterns, highlighting emerging evidence that these structural rearrangements influence higher-order chromatin organization. Together, the available data support a mechanistic link between genome architecture, reproduction and evolutionary processes. Integrating molecular and cellular insights into evolutionary frameworks is therefore essential to understand how structural variation contributes to adaptive divergence and the emergence of reproductive isolation.