Conventional Wisdom Revised in Terms of a Diversity‐Uncertainty Model for the Effect of Host Genetic Diversity on Mean Epidemic Size and Its Variability

ABSTRACT Developing ‘conventional wisdom’ that less genetically diverse host populations tend to experience larger epidemics on average, I re‐analyse 211 effect sizes from outside of the plant literature to investigate my Diversity‐Uncertainty model. By combining unduplicated effect sizes from Ekroth et al. 2019 (67) and Gibson and Nguyen 2020 (155, total 211), I find evidence to suggest that an epidemic's size (via ‘parasite success’) is influenced by a combination of the genetic diversity of not only host, but also parasite populations. Additionally, I argue that conventional wisdom could be reframed because it only seems to apply to parasites where their host range is narrow (1 species) compared with those with a relatively broader host range (> 1 species). The impact of these results is relevant for predicting the occurrence of particularly large and severe epidemics.