The Malaysian plant Rafflesia cantleyi is a parasite, attaching itself to another plant and deriving all its food from its unfortunate host. But Rafflesia doesn't stop there. It swipes genes from its host, sometimes actually completely replace its old genes.
All of us take part in gene sharing - we all get genes from our parents, and many then pass on genes to their kids. It's a process called vertical gene transfer since it happens during reproduction from one generation to the next. Horizontal gene transfer happens when two different organisms swap genetic information - the best-known example is when bacteria share their resistance to antibiotics between each other.
While most horizontal gene transfer is the domain of microscopic species, some larger organisms are capable of this trick as well. In the case of Rafflesia, individual organisms have used their lifelong linkups to their hosts - which are, somewhat confusingly, named Tetrastigma rafflee - to upgrade their genes. These aren't minor changes - some of the plants have stolen the genes for such fundamental processes as respiration and metabolism from the host, then thrown it away. They now quite literally wouldn't be able to live without their plundered genetics.
An international team of researchers has found evidence for the transfer of some 49 different genes from host plant to the parasite. These gene transfers can then be passed on when the individual plants reproduce, eventually taking hold in the species at large. Harvard professor and project co-leader Charles Davis explains further in a statement:
"The elevated rate of horizontal gene transfer between T. rafflesiae and its parasite R. cantleyi raises the possibility that there is a 'fitness' benefit to the parasite. For example they may improve the parasites ability to extract nutrients from the host, or help it evade the host's defences, as has been seen for a bacterial pathogen of citrus trees. Furthermore it appears that about one third of the parasites own genes have evolved to be more like those of T. rafflesia. Finding out how T. rafflesia manages its genomic deception will provide us with real insights into the slow war between plant parasites and their hosts."