Location: Santa María Jaltianguis x 0 1 2 3 4 5 6 Nx 22 6 1 1 0 0 0 Nx .s 26 1 1 1 1 0 0

Table 3: Number of pools comprised by leaf samples from Oaxaca, Mexico (2009), with a positive 35S PCR band based on 30 fields and 300 maize leaves per field. x indicates the number of positive pools, Nx is the observed frequency of each category at this location and Nx.s is the frequency of each category simulated as-suming π=0.001324 and δ=0.045.