Orthologues

Part of speech: noun

Definitions

1. Genes found in different species that descended from the same ancestral gene and typically keep the same function across those species
2. Corresponding genes in separate species that trace back to a single gene in their shared common ancestor and often perform similar roles
3. Matching genetic sequences in different organisms that arose from a common ancestor gene through speciation and usually share a function

Etymology: "Orthologues" is the plural of "orthologue", a term from modern biology. It combines "ortho-", from Greek "orthos" meaning "straight" or "correct", with "-logue", from Greek "logos" meaning "word", "reason" or "study". The sense is "true" or "correct" counterpart: where a gene in one species is the direct descendant of one ancestral gene, rather than a copy made after the two lineages split. The pairing of "ortho-" with "-logue" follows the pattern of "paralogue", a gene copy that arose within a single genome, which the term was coined to contrast with.