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. Models of the development of symbiosis suggest that such a situation is more likely to lead to parasitism than mutualism. The fact that in many plants most seeds only disperse 1-2 canopy diameters means that seedlings are likely to come into contact with fungi genetically identical to those associated with their parent plant. This creates conditions similar to vertical transmission of the symbiont and makes mutualism much more likely to evolve.