was sampled and examined also using FISH to determine the aposymbiotic and acquisition life cycle stages as larvae and settled larvae >250μm in length. Implications of horizontal transmission include the critical need for specificity in recognition and acquisition methods and the larger genetic diversity maintained by the symbiont species. Recognition specificity can be achieved through complex signaling through the release of hormones, such as with Rhizobia species and legumes. The release of the symbiont allows it to exchange genetic material with external microbes as well as between the genetically diverse individuals within the host. This maintaining of genetic exchange allows for the symbiont's host range to be extended and the selection for new functionality or adaptations of hosts, symbionts, and holobiont. An example of a horizontally transmitted symbiont with a high specificity recognition and acquisition method is the Rhizobia-Legume symbiosis. The establishment of the symbiosis begins with the aposymbiotic plant releasing flavinoids that are detected by a specific Rhizobium species and triggers the induction of nod genes in the bacterium. Nod factors, which are lipooligosaccharide signals, are released as a result of the expression of the nod genes and when detected by the host plant initiate root nodule formation which eventually trap the Rhizobia. The established symbiosis can be further contained in a symbiosome in which the Rhizobia symbionts reside and carry out the nitrogen-fixation. Anthropological Cultural transmission may also be horizontal which is explicitly reified in Dual Inheritance Theory. Horizontal transmission is implicit in the meme theory of cultural evolution, where the "meme" has been characterized by Richard Dawkins as a "Virus of the Mind". See also Horizontal disease transmission Horizontal gene transmission Vertical transmission References Infectious diseases