Stanford, CA—We generally think of inheritance as the genetic transfer from parent to offspring and that evolution moves toward greater complexity. But there are other ways that genes are transferred between organisms.
Sometimes a “host” organism can obtain genes from another organism that resides within its own cell (called an endosymbiont) through a process known as endosymbiotic gene transfer. At other times, an organism can obtain genes from a creature that lives in the surrounding environment, or from something that it eats, which is called horizontal gene transfer.
Furthermore, some levels of gene transfer can result in extensive loss of genes and genome reduction,