Schematic representation of niche construction. Conceptual representation of the action niche of construction in the baculovirus system. The build up of EGT within a lepidopteran host over successive viral generations (A) is an instance of ecological inheritance, which leads to a change in the host behaviour by time T (the ‘zombie’ trait of the virus; see Methods). This enhances the transmission of the virus if it liquefies the host (the ‘gooey’ trait). As described in ’Genetic structure’ below, we study four viral genotypes encoding these two traits: zg (non-zombie, non-gooey), Zg (zombie, non-gooey), zG (etc.), ZG; the genotype fitnesses in this figure are arbitrary chosen for illustrative purposes. In (B) we represent a potential pathway through genotype space for the virus over evolutionary time. (A) shows the change in fitness landscape as a result of the viral niche construction (i.e. its host manipulation), while (B) shows the evolutionary consequences of this niche construction activity for the virus.