Figure 2: Host survival for coevolving sympatric and allopatric
pairs of worms and E. faecalis . Microbe-mediated protection was
assessed for (A) sympatric pairs of coevolved worms and E.
faecalis, (B) allopatric pairs of evolved worms and ancestral E.
faecalis , and (C) allopatric pairs of ancestral worms and evolvedE. faecalis . Bigger symbols represent mean ± S.E. and consists of
six biological replicates and four technical replicates. Smaller symbols
indicate the data distribution. Circles indicate sympatric pairs of
coevolved E. faecalis and worms, squares indicate ancestral pairs
of E. faecalis and worms and triangles indicate allopatric pairs
of E. faecalis and worms. Letters indicate results of a GLMM,
followed by a Tukey Post-hoc Test. The same letter indicates no
significant difference. Axis scales were chosen to be the same across
all plots.
Infection with S. aureus over evolutionary time in the experiment
led to the substantial enhancement of microbe-mediated protection, with
the evolutionary background of the sympatric pair of host and E.
faecalis having a significant impact on host survival (Mixed Effects
Model, X2=42.479, df=4, p<0.001; Figure 2A).
Higher microbe-mediated protection in comparison to the Ancestor
occurred in all evolutionary histories involving pathogen presence
across the temporal heterogeneity treatments in our evolution experiment
(Always, 2.1. and 5.1.). However, this did not occur in the pathogen
absence (Never) treatment. Host evolutionary history alone had a
significant effect on host survival (Mixed Effects Model,
X2=35.779, df=5, p<0.001; Figure 2B), but
did not reveal the same pattern as for sympatric pairs. No effect of
bacteria evolutionary history alone on infected host survival was
observed (Mixed Effects Model, X2=3.2511, df=5,
p=0.6613; Figure 2C). Taken together, enhanced microbe-mediated
protection evolved only as a product of coevolution and pathogen
presence for sympatric pairs; this occurred regardless of the temporal
heterogeneity.