Resolution:
standard / ## Figure 2.
To what extent can variation in human microsatellite length be predicted by demographically
induced variation in heterozygosity and allele length skew?. Separate general linear models were fitted to data from each of 783 microsatellites
genotyped in 53 worldwide populations, with mean allele length as the response and
distance to Africa, distance from Africa squared, skew in allele length and log(modern
population size) plus all second order interactions as predictor variables. Distance
from Africa is taken as the land-only distance from Addis Ababa in kilometres [22,23]. Data are from [29]. Each model was simplified by backward elimination to achieve the minimum adequate
model, MAM. The significance of the three primary terms (skew, log population size,
distance + distance^{2}) were then estimated by dropping each in turn and using ANOVA to compare the resulting
MAM with the MAM produced when all terms were fitted. Figure 2a: number of models
achieving a given level of significance for the full models (black bars) and for dropping
skew (grey bars), population size (white bars) or distance + distance^{2 }(striped bars). Values on the X axis refer to lower bin boundary; i.e. '1' indicates
non-significant models with P > 0.05, '0.05' indicates models with P-values lying
between 0.05 and 0.01. Figure 2b: number of models explaining a given proportion of
the null deviance. Colour coding of the bars is the same as in Figure 2a but X axis
values are upper bin boundaries
Amos |