Figure 4: Evidence for antagonistic pleiotropy in immune-compromised mice.

Selective effect of gatZ allele relative to gatC allele in (a) WT (left panel) and Rag2^−/− (right panel), (b) WT co-housed with Rag2^−/− mice (left panel) and Rag2^−/− co-housed with WT mice (right panel). Competitions were performed in independently housed WT and Rag2^−/− mice (n=8) or in mice co-housed for 1 month (n=9). In a, mice from the same litter are represented by the same shape symbols (triangles, squares or circles) and in b, mice co-housed in the same group are represented with the same shape (triangles, squares or diamonds). (c) Comparison of the selective effects of the gatZ over gatC inferred from the slope of the linear regression of ln(gatZ/gatC), over 3 days of in vivo competition in WT, Rag2^−/−, WT co-housed and Rag2^−/− co-housed. The mean relative fitness effect differs between Rag2^−/− and WT (ANOVA with Tukey’s post hoc test, P<10⁻³), but upon co-housing no significant difference was detected between animals (ANOVA with Tukey’s post hoc test P>0.99). Co-housing with WT results in an increase in the mean selective effect of gatZ versus gatC in immune-compromised mice (ANOVA with Tukey’s post hoc test, P<10⁻³) but not in WT mice (ANOVA with Tukey’s post hoc test, P>0.99). NS, not significant, P>0.05, ***P<0.001.