FIGURE 1.

Schematic representation of long-term pathogen–pathogen interactions. Competition over growth limiting resources and/or host niches can initially create high diversity, but low stability. Overtime, competition restricts diversity and allows competitive species to outgrow less competitive ones (A–C). Alternatively, neutral interactions occur when pathogens co-reside distinct niches within their host (D) or arrive at various time intervals (E). Question marks represent less studied cases where toxin production may lead to reduce fitness in the absent of competitors.