The model try accompanied using numerical simulator recording feature wavelengths within the for every sandwich-people throughout the years. Just like the a separate replication of one’s abilities, the fresh new design has also been adopted as a single-centered design where somebody as well as their traits try clearly simulated, and therefore provided nearly-identical performance (look for S1 Abilities).

Migration rather than acculturation removes ranging from-category adaptation.

Without acculturation, migration always eliminates between-group variation, just as in Wright’s original island model sugar baby SC and specified by Eq 1. Fig 1 shows time series of F_ST for low (m = 0.01), typical (m = 0.1) and high (m = 0.3) migration rates. In all cases, the grey a = 0 lines fall to zero. Each trait in each population converges on the mean frequency of that trait across the whole population. Because each sub-population is equally sized, and each trait starts out at unity in one of these s sub-populations, this mean frequency = 1 / s for every trait. This can occur rapidly: for m = 0.01, the perfect between-group structure completely disappears within 300 timesteps, while for m = 0.1 it disappears within 30, and for m = 0.3 within 10.

Time series showing changes in F_ST over time for (A) a low migration rate m = 0.01, (B) a typical migration rate m = 0.1, and (C) a high migration rate m = 0.3, at varying strengths of acculturation, a. Other parameters: s = 5, n = 5, r = 0.

Conformist acculturation is care for anywhere between-group social variation.

Fig 1 shows that as conformist acculturation increases in strength, between-group cultural variation is maintained (F_ST > 0) at equilibrium. When migration is low or moderate then complete acculturation (a = 0, red lines) causes F_ST to remain at 1, indicating the maintenance of complete between-group cultural variation. Values of a between 0 and 1 generate equilibrium values of F_ST between 0 and 1, at a level at which migration and acculturation balance out. That is, the decrease in a common trait’s frequency due to migration is equal to the amount by which conformist acculturation increases the common trait’s frequency after migration. At low migration rates, even small amounts of acculturation can restore F_ST to realistically high values. In Fig 1, when m = 0.01, then a = 0.1, or an extra 10% chance of adopting majority traits per timestep, maintains F_ST at approximately 0.87, which is already higher than the highest F_ST found by . An F_ST of approximately 0.35 can be maintained with just a = 0.02. When m = 0.1, then higher acculturation rates are needed to maintain between-group structure, but an a of just 0.2 is needed to maintain F_ST at realistic levels of around 0.35. At high migration rates (m = 0.3), the maximum strength of conformist acculturation (a = 1) does not maintain complete between-group cultural variation, and higher values of a are needed to prevent the loss of all between-group cultural variation. Nevertheless, even with such high migration, conformist acculturation can still maintain plausible levels of between-group variation.

Fig 2 shows how the full range of conformist acculturation strength a affects F_ST, for three different migration rates and four different values of n. Fig 2 confirms that higher F_ST can be maintained with stronger acculturation (larger a) and lower migration (smaller m). For high migration rates (here, m = 0.1 and m = 0.3), equilibrium F_ST also increases with n. At low migration rates (m = 0.01), n = 3 is just as effective as larger values of n. This is because the migration rate is so low as to maintain homogeneity in demonstrators no matter how small the sample. When migration is high (m = 0.3), the minimum number of demonstrators that are required for conformity to work, n = 3, fails to maintain any between-group variation at any value of a. This shows that conformist acculturation crucially depends on n as well as a.