What defines orthologs in genetics?

Orthologs are defined as genes in different species that have evolved from a common ancestral gene and typically retain the same function across those species. The focusing aspect of orthologs is the evolutionary relationship and functional conservation that arises from speciation events, where the organisms diverge but maintain similar genetic sequences due to their shared ancestry.

When two species share a gene that is derived from a common ancestor, those genes are classified as orthologs. This concept is crucial in bioinformatics and evolutionary biology for understanding gene function, evolutionary relationships, and analyzing the genomic makeup across diverse organisms.

The other options do not accurately encapsulate the definition of orthologs. Identical genes within the same organism refer to paralogs, which arise from gene duplication events within that single species. Genes produced by gene duplication can refer to both orthologs and paralogs, but they do not specifically signify orthologs unless they exist in separate organisms. Finally, genes that no longer function refer to pseudogenes, which do not represent orthologs as they have typically lost their ability to encode functional proteins.