Gas Production
Total gas production over the 6 week-period was approximately 10%
greater in adapted communities compared to both control and pre-adapted
communities (Figure 2A, one-way ANOVA, F(2,32)=12.9,P value < .0001, Tukey HSD: Pre-adapted – Adapted,
mean = 353.7, mean difference 95% CI [-529.8, -177.5],
p<0.001, Control - Adapted, mean = 245.9, mean difference 95%
CI [-422.0, -69.7], P = 0.005). The effect of community
treatment on gas production varied over time (Figure 2B, LMM; effect of
time × adaptation treatment on gas production: χ2(10) = 66.03, P value < 0.001), with
gas production being significantly higher in the adapted communities
from 3 weeks onwards (see Supplemental Table 1 for contrasts). This
delay in the increase in gas production argues against the possibility
that gas production increased in the adapted communities because of
physiological or nutritional changes resulting from the 1% addition of
the pre-adapted communities. Instead, the delay suggests community
members introduced from the pre-adapted communities that contributed to
higher gas production increased in frequency from rare.