Fig. 6.

The effects of different models on host fitness. The vertical axis in each figure represents the log final fold change (after 200,000 generations) of average host fitnesses (from five replicates) with respect to the initial levels. The categories on the horizontal axes represent different selective models; colors label different host parental contributions to offspring or environmental microbiomes (see Fig. 5 for description). Each barplot corresponds to a combination of host and microbial selection parameters, both of which have three different levels: 10, 100, and 1000. Host fitness is most strongly affected when HS and HMS apply (even when parental contributions to offspring or environmental microbial communities are absent). Compared with HS and HMS, the improvement of HS alone on host fitness under high parental contribution becomes unobservable