Syntenic

Synteny refers to the conservation of blocks of genes on the same chromosome across different species. In comparative genomics, syntenic regions are segments where a set of neighboring genes remains linked on a chromosome in two or more species, reflecting shared evolutionary ancestry. The term can describe either the general notion that genes reside on the same chromosome across species or the more specific concept of syntenic blocks—clusters of genes whose relative content is preserved, though not always in exact order.

A related concept, collinearity, denotes a stricter condition where both the content and the order and orientation of genes are preserved within a block. Synteny blocks may retain gene content despite rearrangements such as inversions, translocations, or genome duplications that alter order. Over evolutionary time, chromosomal rearrangements can break synteny, yet detectable syntenic relationships often remain between related species, such as mammals and other vertebrates.

In practice, identifying syntenic regions aids genome annotation, reconstruction of ancestral karyotypes, and transfer of functional information between species. It supports comparative studies of genome evolution, helps locate conserved regulatory landscapes, and can improve the assembly of fragmented genomes by aligning contigs to a reference. Methods rely on mapping homologous genes (orthologs and paralogs), assessing their order and proximity, and visualizing results with dot plots or dedicated software that identifies conserved blocks. Synteny thus provides a framework for understanding how genomes evolve while preserving essential gene content.