How can i create dynamic variables on the fly in c# using Reflection?

How can i create dynamic variables on the fly in c# using Reflection?

I'm creating a simulator of ecosystems where species can be used to
simulate various diseases, my problem is that I start using 4 species but
if I need more ... I need more variables to store, my question is, Is
there any way through Reflection to let me create dynamic variables during
the execution of an event in my program? Thank you! i'm using Windows
Presentation Foundation and C#