Figure 1
Simulation of genetic diversity and structural consequences of persistent small population size and interactions with gene flow and inbreeding. Simulations were performed using EASYPOP (Balloux, 2001), for hermaphrodite individuals surveyed at 10 microsatellite loci (no linkage), each with 10 alleles (stepwise mutation model, rate=0.01) of equal frequency, distributed randomly across individuals of a population. For all simulations, nine populations were arranged in a 3 × 3 spatial array. Three population sizes were used of 500, 50, and 20 individuals. For simulations with population sizes of 50 and 20, two gene flow regimes, which followed a stepping stone model, were tested: one simulating panmixia between all nine populations (gene flow=1) and the second where 10% of individuals contributed to gene flow per generation (gene flow=1). Inbreeding was also varied in isolated population scenarios (where population size was 50 and 20), and individual inbreeding rates of 20% were allowed. Thus, a total of nine situations were simulated: (1) unconnected populations with 500 individuals and no inbreeding (500); (2) unconnected populations with 50 individuals and no inbreeding (50-isolated); (3) unconnected populations with 50 individuals and 20% inbreeding (50-selfed (0.2)); (4) populations with 50 individuals, no inbreeding and panmictic gene flow between the nine neighbouring populations (50-gene flow (1)); (5) populations with 50 individuals, no inbreeding, and restricted gene flow between the nine neighbouring populations (50-gene flow (0.1)); (6) unconnected populations with 20 individuals and no inbreeding (20-isolated); (7) unconnected populations with 20 individuals and 20% inbreeding (20-selfed (0.2)); (8) populations with 20 individuals, no inbreeding, and panmictic gene flow between the nine neighbouring populations (20-gene flow (1)); (9) populations with 20 individuals, no inbreeding, and restricted gene flow between the nine neighbouring populations (20-gene flow (0.1)). Allele frequency data were analysed using FSTAT (Goudet, 2001) and allelic richness, heterozygosity (He), genetic differentiation (Fst), and inbreeding coefficient (Fis) were averaged over the simulated populations and are plotted for 10 generations.
