Island size and drift

Among the four rules that govern community assembly, drift is maybe the effect that at the beginning is harder to understand for students. Not because it is a difficult concept, it is in fact super easy, but just because the wording does not help, in comparison to dispersal, speciation of environmental selection that are quite evocative. So, back in the days, I made a little netlogo model to show drift to students. I also included different island sizes to show how island size influence drift. You can find it here.

Species (agents with different colors) occupy patches on the islands. You can set up different parameters such as die rate and reproductive rates as well as carrying capacity of each patch. When an agent die, it is replaced by an agent living in the proximity of it.

The code shows that in smaller islands, the effect of drift is faster as species casually diminish faster than in larger islands.

To run it:

1)Set up the parameters the way you want the,

2)click setup islands. The go button runs the code.

The code is on my github.