THE ROLE OF SEED DISPERSAL IN THE EVOLUTION OF MYCORRHIZAE

The fungi in mycorrhizal associations often show a lack of specificity and are acquired by horizontal rather than vertical transmission. Mod els of the development of symbiosis suggest that such a situation is m ore likely to lead to parasitism than mutualism. The fact that in many plants most seeds only disperse 1-2 canopy diameters means that seedl ings are likely to come into contact with fungi genetically identical to those associated with their parent plant. This creates conditions s imilar to vertical transmission of the symbiont and makes mutualism mu ch more likely to evolve.