Genetics and Evolution: The Role of Horizontal Gene Transfer in Evolution
What Is HGT?
Horizontal gene transfer (HGT) is also known as lateral gene transfer (LGT). Horizontal gene transfer involves the transmission of genetic material between distinct evolutionary lineages. It is the non-sexual exchange of genetic material between species. HGT is prevalent among single-celled organisms. Horizontal gene transfer was first described in Japan in the year 1959. HGT is more common between organisms that are separated by short and intermediate evolutionary distances. Artificial horizontal gene transfer is a type of genetic engineering.
Horizontal gene transfer was first described in Japan
Role Of HGT in Evolution
Horizontal gene transfer in bacteria has been and is a subject of research study of many experts worldwide. "Horizontal gene transfer has played a major role in bacterial evolution and is fairly common in certain unicellular eukaryotes. However, the prevalence and importance of HGT in the evolution of multicellular eukaryotes remain unclear", say research scientists Richard and Palmer. Experts are of the opinion that phagotropic (engulfment of food) predatory lifestyle of many eukaryote cells facilitates transfer of genes from the prey to the predator. Recently research scientists attempted to integrate HGT with the neo-Darwinian paradigm of evolution. But generally HGT involves the exchange of genetic material between different organisms in a single generation.
Horizontal Gene Transfer Drives Evolution
Studies have proved that HGT is an important force driving the evolution of Archaea. HGT can occur between domains in all possible directions. The results of a network analysis of shared genes reveal that HGT leaves no gene family untouched. HGT is widely documented and accepted in bacterial and archaeal evolution. Studies reveal that between 1.6 and 32.6 per cent of the genes of each microbial genome have been acquired by HGT. Informational genes are less prone to HGT than operational genes.
Research studies have shown that HGT has contributed to the evolution of bdelloid rotifers (a class of rotifers found in fresh water and moist soil). Many genes found in bdelloid rotifers appeared to have originated in fungi, plants and bacteria. One such gene (originated from bacteria) was over expressed in Escherichia coli and yielded an active enzyme.
Research scientists at Riken (a research organization in Japan) have identified the evidence of nuclear gene transfer from the host to the parasite plant species. Another study conducted in Europe has revealed that the haloalkane-degrading bacteria Rhodococcus rhodochrous NCIMB 13064, Pseudomonas pavonaceae 170 and Mycobacterium sp. strain GP1 share a highly conserved haloalkane dehalogenase gene (dhaA).
Peter Gogarten, a molecular biologist, describes horizontal gene transfer as "A new paradigm for biology". It is an important force modulating evolution in the prokaryotic world and the evolution of particular eukaryotes. HGT is exciting because it facilitates acquisition of new abilities by organisms and increases their speed of evolution.
Do you find molecular biology exciting?
- Horizontal gene transfer is also known as lateral gene transfer.
- Horizontal gene transfer has played a major role in bacterial evolution.
- Horizontal gene transfer is an important force driving the evolution of Archaea.
- Horizontal gene transfer has contributed to the evolution of bdelloid rotifers.
- Horizontal gene transfer is an important force modulating evolution in the prokaryotic world and the evolution of particular eukaryotes.
Almost all aspects of life are engineered at the molecular level, and without understanding molecules we can only have a very sketchy understanding of life itself.— Francis Crick