Exploring Ecological Stability in Real Communities Using Mathematical and Modeling Approaches

Maximos Goulakos ’23

Student: Maximos Goulakos ’23
Research Mentors: Craig Jackson (OWU Department of Mathematics and Computer Science) and Amy Downing (OWU Department of Biological Sciences)

Our research is mainly concerned with the different aspects of ecosystems that affect how stable the populations are. We see how different species interact with one another and study these relationships to see whether or not any of these tend to have a strong impact on the behavior of the populations. Because scientists have a multitude of different ways to measure stability, we are also concerned with how consistent the observed effects are across these different measures.

In any ecosystem, the populations within all interact with one another in a multitude of different ways, and these interactions are what determine the dynamics of the system as a whole. When these interaction strengths are measured, they can be used to quantify the stability of the ecosystem in various different ways; each of these measures analyze different aspects of the population change over time, but they all are related to the general movement back to the ecosystem’s equilibrium position. It is understood that the presence of many weak interactions tends to stabilize the effects of a few strong interactions in plankton ecosystems, but what is generally unknown is how the different types of interactions will affect the measures of stability. We ran sensitivity analyses on various zooplankton and phytoplankton population data sets that were gathered in 2012 to observe which particular interactions were most likely to change the dynamics of the ecosystem given a perturbation of the interaction strength itself. For each individual interaction, there were 8 unique measures of sensitivity calculated. From these values, tentative statistical analysis shows that interspecies interactions (interactions between two different species) tended to be less stabilizing than intraspecies interactions (interactions between the members of one species on itself). Furthermore, there seem to be no statistical differences between the contributions of bottom up interactions, top down interactions, and interspecies interactions; however more studies need to be done on other sets of data to validate these results.