Final answer:
Horizontal gene transfer is the exchange of genetic information between different species within the same generation, influencing phenotypes. Various methods enable HGT, like in fungi producing an anti-cancer drug from acquired yew tree genes or bacteria genetically engineered to produce human insulin.
Step-by-step explanation:
Horizontal gene transfer (HGT) is when genetic material is introduced from one species to another within the same generation. It influences their phenotypes and is different from the vertical transmission of genes from parent to offspring. An example of HGT in eukaryotes is seen in fungi acquiring genes from yew trees to produce the anti-cancer drug paclitaxel. In prokaryotes, an example is bacteria that have obtained the human insulin gene and can produce insulin.
These transfers can occur between species that do not share a lineage and cannot interbreed, such as between rice and millet plant species. Here, transposons, or "jumping genes," facilitate the transfer. This gene transfer significantly impacts evolutionary processes by introducing genetic variation, which is essential for natural selection. Methods of HGT include conjugation, transduction, and transformation.