Horizontal gene transfer refers to the transfer of genetic material through a mechanism other than reproduction. This mechanism is a common source of new genes in prokaryotes, sometimes thought to contribute more to genetic variation than gene duplication. It is a common means of spreading antibiotic resistance, virulence, and adaptive metabolic functions. Although horizontal gene transfer is rare in <answer>eukaryotes</answer>, likely examples have been identified of protist and alga genomes containing genes of bacterial origin.
In what type of organism is horizontal gene transfer rare?
eukaryotes