Appendix A. Numerical algorithm used in this paper to investigate the influence of dissimilar fecundities of species on mean time to fixation (MTF).
| Step 1: Eliminate an individual. Choose a cell randomly and let the cell become empty, then reduce the abundance of the corresponding species by one. Step 2: Recruit an individual. Count the number of individuals of each species within the dispersal distance of the empty cell; denote them as n1 and n2 for species 1 and species 2, respectively. The probability that an individual of species 1 is recruited is n1w/(n1w + n2), where w denotes the per capita fecundity factor of species 1 relative to species 2. The per capita fecundity rate will be the same when w equals 1, which is the case of neutral community drift model. The probability that species 2 occupies the empty cell is n2 /(n1w + n2). Repeat steps 1 and 2 for D (number of deaths in one year) times, then increase the absolute time by one. The above process is repeated until complete dominance by one species is reached. Then record the time to fixation. Repeat the calculation 100 times; the mean time to fixation (MTF) is calculated as the median of 100 replicates. |