Summary
Movement of genes between unrelated organisms, important in bacterial evolution.
In depth
Mechanisms: transformation, transduction and conjugation. It is the main route of spread of antibiotic resistance and virulence genes. It also moved genes between domains, such as endosymbiotic gene transfer, and challenges tree-like views of microbe evolution.
HGT is rare in eukaryotes but important: bdelloid rotifers hold many foreign genes, aphids acquired carotenoid genes from fungi, and sea slugs (Elysia) keep algal chloroplasts and some genes. Transfer from endosymbiont organelles to the nucleus is another form. In bacteria, it drives the pan-genome concept, in which a species has a core genome and a variable accessory genome; E. coli has about 4000 core and over 20,000 accessory genes.
HGT blurs the tree of life near its base, which looks more like a network. It also drives pathogen evolution: toxin genes carried by phages turn harmless Vibrio cholerae and Corynebacterium diphtheriae into dangerous strains.
Frequently asked questions
What is Horizontal Gene Transfer?
Movement of genes between unrelated organisms, important in bacterial evolution.
Which area of biology covers Horizontal Gene Transfer, and how advanced is it?
Horizontal Gene Transfer is one of the 53 topics in Evolution. It is rated Advanced, so it suits learners who want specialist depth. Related topics in this area include Antibiotic Resistance Evolution, Evolution of Sex, Evolutionary Trade-offs.
Why does Horizontal Gene Transfer matter?
HGT is used in genetic engineering (Agrobacterium transferring T-DNA to plants) and explains the fast spread of resistance.
Can you give an example of Horizontal Gene Transfer?
Genes for photosynthesis in some sea slugs may have come from algae.
What should I learn before Horizontal Gene Transfer?
Work through the Beginner topics in Evolution first, such as Evolution, Natural Selection, Charles Darwin, then return to Horizontal Gene Transfer. Advanced topics assume the Intermediate vocabulary.
What topics are related to Horizontal Gene Transfer?
The closest topics to Horizontal Gene Transfer are Antibiotic Resistance Evolution, Evolution of Sex, Evolutionary Trade-offs, Evolution. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Horizontal Gene Transfer?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Horizontal Gene Transfer. To practise the whole of Evolution, use the Evolution quiz.
How is Horizontal Gene Transfer different from Antibiotic Resistance Evolution?
Horizontal Gene Transfer: Movement of genes between unrelated organisms, important in bacterial evolution. Antibiotic Resistance Evolution: Bacteria with resistance genes survive antibiotic use and multiply, making resistance more common. Read both side by side and note what each one explains.
How should I study Horizontal Gene Transfer step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Antibiotic Resistance Evolution and explain the difference aloud. Finally, take the Evolution quiz and come back to this page for any question you miss.