Gene duplication

Creation of an additional inherited copy of a gene. Copies can be lost, retain shared functions, undergo subfunctionalization, or undergo neofunctionalization; duplication alone does not guarantee a useful novelty.

Duplication of the full genomic complement. gene loss, subfunctionalization and neofunctionalization can obscure the original duplicated organization.

The hypothesis that two early large-scale duplication rounds contributed to the multiple paralogous genomic regions of jawed vertebrates. Hox clusters are one informative set of loci; a single family does not by itself establish genome-wide duplication.

Creation of adjacent copies of a gene or genomic segment. Subsequent divergence can produce a local gene family while preserving aspects of ancestral order.

A tandem duplication creates an additional copy of a genomic segment adjacent to the original. A duplicated gene can initially increase dosage, after which the copies can diverge or one can lose function. Adjacency distinguishes tandem copies from duplicates moved to distant positions. Repeated near-identical copies can also complicate genome assembly because short sequencing reads may not identify which copy they came from. ^[ref]

Gene-family evolution through duplication and retention of some copies and loss or pseudogenization of others.

A relationship between genes arising through duplication. It differs from orthology, which concerns divergence through lineage splitting.

A gene related to another through duplication. Comparing paralogues as if they were orthologues can mislead inference about lineage-specific sequence change.