An ortholog is a term used in genetics and genomics to describe genes in different species that have evolved from a common ancestral gene. Orthologous genes are similar in sequence and function and are found in different species due to their shared evolutionary history. The term "ortholog" is derived from the Greek words "ortho," meaning "correct" or "true," and "logos," meaning "word" or "relation."
Orthologs play a crucial role in comparative genomics and evolutionary biology as they allow researchers to study the conservation and evolution of genes across different organisms. By identifying orthologous genes, scientists can gain insights into the functions and biological processes that are conserved throughout evolution. Orthology can help in understanding the genetic basis of diseases, predicting gene function, and studying the evolutionary relationships between species.
Orthologs are typically identified through computational methods that compare the DNA or protein sequences of genes from different species. These methods involve sequence alignment, phylogenetic analysis, and statistical approaches to determine the degree of similarity and evolutionary relatedness between genes.
It's important to note that the concept of orthology is distinct from paralogy. Paralogs are genes that have arisen through gene duplication events within a single species, whereas orthologs are genes that diverged through speciation events and are found in different species.