SMB2020 subgroup Poster Prize: Shota Shibasaki

Congratulations to Shota Shibasaki, one of the 4 winners of the SMB2020 PDEE poster prizes!

View the prizewinning poster here

Microorganisms often live in fluctuating environments. For example, the gut microbiota of a host experience fluctuating resources due to the host’s feeding rhythm (e.g., the host is eating food or starving). As recent studies show that species interactions can change depending on the amounts of resources and toxin, environmental fluctuations are then expected to change species interactions. Such changes in species interactions can result in those in species diversity. However, the time scales of environmental fluctuations may vary; in the example of the gut microbiota, some hosts may eat food three times per day while other hosts may eat more in a day (like some of you during working from home).

How does a rate of environmental fluctuations affect species interactions and diversity? We addressed this question by building a mathematical model that describes the dynamics of resources, toxins, and microbial species in a chemostat where resource supplies switch. The strength of competition between species differed over the switching rate, but it peaked at either low, high, or intermediate switching rates depending on the species’ sensitivity to toxins. Importantly, however, we can predict how species diversity changes over the switching rate once we know how the strength of competition between two species changes. Such prediction works from two- to ten-species communities.

In sum, predicting the effect of environmental switching on competition and species diversity is difficult, because the properties of community members also matter. By regarding a rate of environmental switching rate as a frequency of disturbance, these results may explain the contradicting results of earlier studies on the intermediate disturbance hypothesis. Species diversity is not always maximized at an intermediate frequency of disturbance (or an intermediate switching rate).